TALLOW FOR LAYING HENS (POULTRY,FAT, PERFORMANCE, AMINO ACIDS).

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Baco, Abdul·Aziz Ishak

TALLOW FOR LAYING HENS

The University of Arizona

University Microfilms

International 300 N. Zeeb Road, Ann Arbor, MI48106

8603334

PH.D. 1985

TALLOW FOR LAYING HENS

by

Abdul-Aziz Ishak Baco

A Dissertation Submitted to the Faculty of the

COMMITTEE ON NUTRITIONAL SCIENCES (GRADUATE)

In Partial Fulfillment of the Requirements for the Degree of

DOCTOR OF PHILOSOPHY

In the Graduate College

THE UNIVERSITY OF ARIZONA

1 985

THE UNIVERSITY OF ARIZONA GRADUATE COLLEGE

As members of the Final Examination Committee, we certify that we have read

the dissertation prepared by Abdul-Aziz Ishak Baco --------------------------------------------

entitled TALLOW FOR LAYING HENS ------------------------------------------------------------

and recommend that it be accepted as fulfilling the dissertation requirement

for the Degree of Doctor of Philosophy

~~ss(L ~ ,K g~i2

Date

Date

Date

Date" /

Final approval and acceptance of this dissertation is contingent upon the candidate's submission of the final copy of the dissertation to the Graduate College.

I hereby certify that I have read this dissertation prepared under my direction and recommend that it be accepted as fulfilling the dissertation requirement.

Dissertation Director Date

STATEMENT BY AUTHOR

This dissertation has been submitted in partial fulfillment of requirements for an advanced degree at the University of Arizona and is deposited in the University Library to be made available to borrowers under rules of the Library.

Brief quotations from this dissertation are allowable without special permission, provided that accurate acknowledgment of source is made. Request for permission for extended quotation from or reproduction of this manuscript in whole or in part may be granted by the head of the major department or the Dean of the Graduate College when in his or her judgment the proposed use of the materials is in the interests of scholarship. In all other instances, however, permission must be obtained from the author.

SIGNED

DEDICATION

In the name of ALLAH (God),

the most merciful,

the most compassionate

01 ~ 1 ii 'J \

01 I . 'L......... ~Yr' ... ..)

If .L;~1 .. ~ l\ ~ . U--

·0 . ?" '1

To my parents to whom lowe everything,

To my three daughters (Amena, Asma and Alaa)

with them I shall ask Allah to protect me from the hell fire,

To my lovely wife

iii

ACKNOWLEDGEMENTS

The author is sincerely grateful to Dr. Bobby L. Reid for his

guidance, encouragement and continued moral support throughout the

entire graduate program and the accomplishment of this project.

Appreciation is also due to the committee members, Drs. J. A.

Marchello, R. L. Price, W. H. Brown, and M. R. Selke for their

suggestions and constructive criticisms.

Special thanks to Phyllis Maiorino for her contribution in

editing this dissertation, and to Rebecca Mitchell and Angelo Longo as

well as to the staff of the Poultry Research Center for their technical

assistance during the research period.

The author would like to thank his family members, parents

and brothers, Abdul-Sattar, Mohammad Ali, for their help and

encouragement.

Finally, deepest appreciation to my wife, Bushra, for her

sacrifice, support, understanding and encouragement throughout my

academic program.

I.

II.

III.

TABLE OF CONTENTS

LIST OF TABLES • • • •

LIST OF ILLUSTRATIONS

ABSTRACT • • •

INTRODUCTION

LITERATURE REVIEW

EFFECTS OF ADDED TALLOW ON DIETARY NUTRIENT UTILIZATION Introduction • • • • • Experimental Procedure • Results and Discussion • S UIIIIIla ry . . . . . . . . . . . .

IV. EFFECTS OF TALLOW SUPPLEMENTATION IN MINIMAL AMINO ACID DIETS

Introduction • • • • • • Experimental Procedure • Results and Discussion. Summary

REFERENCES • •

v

Page

vi

vii

. viii

1

3

19 19 20 24 36

38 38 40 43 51

53

LIST OF TABLES

Table Page

1. Composition of basal diet (Experiment 1) 21

2. Fatty acid composition of tallow 23

3. Tallow supplementation and laying hen performance (Experiment 1) . . . • • • . . • •••••. 25

4. Effect of dietary tallow level on energy utilization in laying hens (Experiment 1) . • . • • • • • • 27

5. Effects of environmental temperature and age on laying hen performance (Experiment 1) • • • • • • • • • • • • 30

6. Effect of laying hen age on ME of tallow (Experiment 1) 32

7. Effect of tallow on nutrient utilization (Experiment 1) 32

8. Effect of tallow supplementation on average amino acid retention by laying hens (Experiment 1) • 34

9. Effect of tallow supplementation on average fatty acid retention by laying hens (Experiment 1) • • 35

10. Temperature means during experimental periods (Experiment 2) • • • • • • • • • • 41

11. Composition of experimental diets (Experiment 2) 42

12. Tallow, protein and amino acid composition of experimental diets (Experiment 2) • • • • • • •

~3. Effects of experimental diets on performance of laying

44

hens housed at different temperatures (Experiment 2) 45

14. Experimental diet effects on energy utilization by laying hens housed at different temperatures (Experiment 2) 49

vi

Figure

1.

LIST OF ILLUSTRATIONS

Partition of ingested energy

Vl.l.

Page

8

ABSTRACT

Effects of tallow supplementation on dietary nutrient and

minimal amLno acid utilization in the laying hen were studied in two

experiments. In the first experiment diets contained six levels of

animal tallow ranging from 0 to 10%. Percent egg production and egg

mass were not significantly affected by tallow. Body weight was

significantly increased by 2% tallow was maximum at 6%. Addition of up

to 6% fat improved feed conversion without adversely affecting other

production characteristics. Metabolizable energy (ME) intake increased

from 305.1 to 322.4 kcal/hen/d over the range of 0 to 6% tallow with no

further improvement at higher tallow levels. Maximum net energetic

efficiency was obtained with 2 and 4% tallow.

Ability to digest tallow declined significantly with hen age.

Higher tallow ME values were obtained from calorimetry data than from

digestibility measurements due to beneficial effects of tallow on

digestibilities of fat and protein in the basal diet. No improvement

in starch retention was observed with tallow supplementation.

In the second experiment, diets containing four levels of

protein (15.0, 13.6, 15.0 + methionine, and 17.0%) without and with 3%

tallow were fed to hens housed in an open cage house or an insulated,

evaporatively cooled house. Egg production and egg mass were

significantly higher in the insulated house.

viii

1X

This study indicates that reducing total protein below the

National Research Council (NRC, 1984) recommended level significantly

reduced egg production by birds housed in an open house. Supplemental

methionine to provide .60% TSAA was required for maximum egg

production. Egg production was significantly improved with the low

protein diet when 3% tallow was added; however, egg production rate

supported by this combination was significantly below that obtained

with the 17% protein diet either with or without added tallow.

For birds housed in the insulated, evaporatively cooled house

the diet based on the NRC amino acid recommendations appeared to be

optimal for performance, even with a lower protein level. No

additional benefits were obtained in egg production with 3% tallow in

any of the diets under these housing conditions.

CHAPTER 1

INTRODUCTION

The greatest part of the cost of a balanced poultry diet is

incurred in providing energy, and fats have been an important source of

dietary energy for poultry for more than 25 years. In addition to

providing energy in a concentrated form, fats often have a favorable

influence on performance and physical characteristics of the diet.

Improved laying hen performance occurs as a result of the

"extra caloric effect" as reported by Carew and Hill (1964), Touchburn

and Naber (1966) and Jensen, Schumaier and Latshaw (1970). They found

that fat supplementation resulted in greater improvements in

performance than were expected from the increased energy content of the

diet. This effect has been suggested to be totally due to reduced heat

increment (HI) or increased assoc iative dynamic effect. The" extra

caloric effect" has also been attributed to an increase in net

energetic efficiency resulting from improved utilization of

metabolizable energy (ME) with the addition of fat.

There is another phenomenon which occurs at the absorption

level and is measurable as increased ME values with fat

supplementation. The synergism between the supplemental fat and the

basal fat in the test diet often causes improved absorption of the

supplemental fat, thereby increasing ME (Young and Garrett, 1963;

Sibbald and Kramer, 1978). The size of this improvement depends on the

1

2

type of added fat and the level of application, as well as the type of

basal diet used. In addition, fat may enhance the absorbability of the

non-fat portion of the test diet by slowing the rate of food passage

(Mateos and Sell, 1980a). This effect commonly results 1n a calculated

ME value for fat which exceeds its gross energy (GE) value. This

greater than expected ME value was called "extra metabolic effect" by

Horani and Sell (1977a) to distinguish it from the "extra caloric

effec t" of decreased HI.

The profitable effects of supplemental fats in nutritionally

balanced rations on poultry performance were reported a number of years

ago by Yacowitz (1953), Lillie et~. (1952), Dam ~ al. (1959)

and Gerry (1963). Feed efficiency improvements are noted consistently,

and frequently productive performance is improved.

Environmental temperature is another factor which affects the

bird's energy needs. Efficient poultry production requires that

dietary composition change with environmental teffiperature. At low

environmental temperatures more ME is needed to maintain body

temperature which can be done by consuming more feed or at the expense

of energy use for production at limited feed intakes. More energy is

needed to dissipate heat produced during periods of high environmental

temperature and results in lowered energetic efficiency. If energy

intake decreases during high ambient temperatures, the dietary

concentration of nutrients must increase and vice versa.

CHAPTER 2

LITERATURE REVIEW

Feed represents 70-75% of poultry production cost (John,

1976) and 67% of the cost of egg production when pullet rearing costs

are included (Hill and Hunt, 1980). Feed intake, with a few

exceptions, is inversely related to dietary energy concentration;

consequently, nutrient intake can be regulated by control of dietary

energy:nutrient ratios. Feed intake is controlled by the available

energy of the diet; therefore, accurate dietary energy measurements are

needed if inputs and outputs are to be manipulated to provide optimum

productivity and maximum benefits.

Animals eat to meet their energy requirements, and dietary

nutrient intakes usually depend upon dietary energy density. Kleiber

(1945) concluded that available energy should be the baseline for

establishing nutrient requirements. An inverse relationship between

feed intake and dietary energy density was found by Warkentin,

Warkentin and Ivy (1943), and they proposed that rats eat for calories.

Peterson, Grau and Peek (1945) found that chicks attempt to eat to

satisfy their energy requirements only at high dietary energy

concentrations. Moreover, Powell ~ al. (1974) stated that feed

intake of hens decreases when a sucrose solution was substituted for

drinking water. Also, Gleaves and Salim (1982) reported that hens fed

2% lactose had reduced feed intakes.

3

4

There are some conditions in which animals do not eat to

satisfy their energy requirements •. Low energy diets, due to physical

incapacity (bulk) reduce feed consumption, and unpalatable feeds may

not be consumed in adequate amounts (Davidson ~ ~., 1961).

Laying hens tend to overconsume energy when dietary energy levels were

raised by inclusion of up to 11% tallow (Dillon, 1974). Dale and

Fuller (1979) reported that as energy from fat replaced that from

carbohydrate, chicks increased their energy intake as dietary energy

concentration increased. The increase in energy intake associated with

high fat qiets may be due in part to a reduction in HI. An appetite

for calcium in laying hens was found to result in surplus feed intake

by Mongin and Sauveur (1974). Davidson ~ al. (1961) reported that

chicks tended to make up for an amino acid imbalance by increasing feed

intake. Solberg (1971) also reported that birds increased feed intake

to compensate for a mild lysine deficiency.

Birds are homeotherms and as such their energy requirements

are determined in part by environmental temperature. Scott, Matterson

and Singsen (1947) were among the first to indicate that rations high

in energy content tended to stimulate more rapid growth and better feed

conversion in chickens than rations of lower energy content. Adams

et al. (1962a) and Dale and Fuller (1980) found that increased -- --dietary energy resulted in improved growth and feed conversion in both

a cyclic hot temperature system (23 to 33 to 23°C) and a cool

environment (14 to 22°C). The effects of two energy levels (2830 and

3300 kcal ME/kg) were measured with broilers reared at two temperatures

(21 and 32°C) by Adams et al., (1962a), and they suggested that

the adverse effects of the 32°C temperature could not be offset by

increasing dietary energy level. Vohra, Wilson and Siopes (1979)

reported that maintenance energy requirements (ME ) with diets m

containing 2830 or 1980 kcal/kg were 132.6 and 171.3 kcal/kg· 75 /d,

respectively, at 15.6°c, and 114.9 and 140.2 kcal/kg· 75 /d at

26.7°C. Hurwitz, Sklan and Bartov (1978) also found that maintenance

energy requirements (ME ) decreased as the temperature increased from m

12 to 24°C. The lowest energy requirements for maintenance were

between 24 and 28°C, and as temperature was elevated above 28°C,

maintenance energy requirements increased.

Bacon, Cantor and Coleman (1981) estimated the effects of

three dietary energy levels ranging from 3090 to 3310 kcal ME/kg on

broilers grown in a cool (23°C) or a warm (26°C) environment. Energy

level did not significantly affect body weights at 49 days of age ~n

5

either environment. Reece and McNaughton (1982) reported no changes ~n

7-week body weights due to dietary energy level when broilers were

reared at 26.7°C. However, rearing broilers at 18.3°C resulted in a

3.1% increase in body weight as dietary energy level increased from

3175 to 3325 kcal ME/kg.

Feed intake, a necessary element when considering nutritional

requirements of chickens, is inversely correlated with environmental

temperature and dietary energy (Dale and Fuller, 1980). Hurwitz et

~. (1978) indicated that feed intake declined due to the decreasing

maintenance energy requirements as temperature increased up to 27°C.

Increasing dietary energy with supplemental animal or

vegetable fat improved growth and feed utilization of broilers grown at

6

21 or 29°C environments (Mickelberry, RogIer and Stadelman, 1966).

However, Dale and Fuller (1980) found that growth was not affected by

added fat when broilers were reared at a constant 31°C. Reid (1981)

found that supplemental tallow, at levels of 1-5% increased consumption

of ME above maintenance at temperatures above 27°C and resulted in

improved egg production.

The lower critical temperature (CT) is the environmental

temperature below which heat production of a fasting, resting animal

will increase to prevent lowering of body temperature. Mitchell and

Haines (1927) found the average CT of laying hens to be 17°C; while,

Barott and Pringle (1946) found metabolism of laying hens to be minimal

at 21°C. However, Kleiber and Dougherty (1934) found no evidence of a

CT in laying hens. Under practical conditions, poultry are seldom

fasted; consequently, the concept of a thermoneutral zone (TNZ) seems

to have greater application than CT. The TNZ is defined as lithe

effective ambient temperature where heat production at the

thermoneutral rate is offset by net heat loss to environment without

aid of special heat conserving or heat dissipating mechanism ll (National

Research Council (NRC), 1981). The relationship of poultry to their

thermal environment was studied by Osbaldiston and Sainsbury (1963),

and they found that substantial improvements in feed efficiency

occurred as the temperature increased from 12 to 15 to 18°C.

An inverse relationship between environmental temperature and

feed intake occurs in laying hens although time is required to

acclimatize to a change in the ambient temperature (Davis, Hassan and

Sykes, 1972). The decline in energy intake with increases Ln

7

environmental temperature was quantitated as: ME (kcal/body weight

kg· 75 )/d = 203 - 1.13T where T is ambient temperature in degrees

Celsius (Davis ~~., 1973). Interestingly, there was no CT or

TNZ predicted by this regression, and egg production was normal within

the temperature range of 7.2 to 35°C. The practical importance of

this relationship is explained by Daghir (1973) who found a seasonable

variation of 10-15% in energy intakes for laying hens. Emmans (1974)

has also derived regression equations which predict voluntary energy

intake for laying hens under specific conditions.

Efficient poultry production demands that dietary composition

change with the environmental temperature. As feed intake decreases

with higher energy diets, the dietary concentration of nutrients

relative to available energy must be maintained in order to assure

adequate intake of essential nutrients (Nivas and Sunde, 1969).

Partition of ingested energy (IE) in the chicken is described

schematically in Fig 1. The terminology and abbreviations are taken

from NRC (1981). Most of the IE which is not digested and absorbed 1S

voided as feces energy (FE). The difference IE - FE is apparent

digestible energy (ADE). The expression "apparent" is used because

feces contain, in addition to the energy of feed residues (F.E), a 1

metabolic fraction (F E) comprising bile, mucosal cells and m

unabsorbed intestinal secretions.

During the process of digestion, gas 1S produced by

microflora. The energy lost as a gas (GE) is usually neglected in

avian balance experiments but in ruminants the loss can be significant

and is treated as a metabolic loss (Scott, Nesheim and Young 1982).

r-__________ I_n_g_e_s_t_e~dl Energy (IE)

Apparent Digestible Energy (ADE)

Fecal Energy (FE) Gaseous Energy (GE)

Fecal Energy of Feed (F.E)

~

Apparent Metabolizable Energy (AME)

Urinary Energy (UE) Metabolic I

Endogenous

I I

Urinary Fecal Energy (F E)

m Urinary Energy (U E)

Energy of Feed (U.E)

~ 1- True Metabolizable Energy (TME)

J e

r---------~ Heat Increment (H.E) ~

Heat of Fermentation (HfE)

8

Heat of Digestion and Absorption (HdE)

I Net Energy for Maintenance (NE )

m

Basal Metabolism (H E) e

Heat of Activity (H.E) J

Net Energy (NE) I

Heat of Thermal Regulation (H E) c

Metabolic Fecal Energy (F E) m

Endogenous Urinary Energy (U E) e

Heat of Product Formation (H E)

r Heat of Waste

Formation and Excretion (H E)

w

I Net Energy for Production (NE r )

Tissue Growth

Fat Accretion

Carbohydrate Storage

Eggs

Semen

Figure 1. Partition of ingested energy

9

A portion of the absorbed energy is excreted in urine without

having been completely catabolized (UiE), mostly as uric acid in

birds. Waring and Shannon (1969) determined that urine of birds fed

soybean diets had a GE content of 12 kcal/g N. They suggested that

ur1ne contains appreciable quantities of energy yielding components

other than uric acid (8.22 kcal/g N). Urinary energy (UE) also

contains an endogenous fraction (U.E) which is the product of tissue 1

catabolism. The difference IE - FE - GE - UE is apparent metabolizable

energy (AME).

Several metabolic functions in the transformation of IE yield

heat increment (H.E). H.E includes heat of digestion and 1 1

absorption, heat of product formation (HrE), heat of microbial

fermentation (HfE), and heat of waste formation and excretion

(H E). H.E is normally considered to be waste but it does w 1

contribute to the maintenance of body temperature in cool environments.

Net energy (NE) is the difference between ME and H.I and 1

compr1ses that portion of IE used either for body maintenance (NE ) m

or for productive purposes (NE). Maintenance energy costs also r

include basal metabolism (H E), heat of activity (H.E) and heat e 1

lost as a result of maintaining body temperature 1n hot or cool

environments (H E). The NE is the energy retained 1n the body or c r

voided as a useful products such as egg and semen (Emmans, 1974).

Use of added fat to increase the energy concentration of

poultry diets is common practice. A number of different sources of

supplemental fat have been used in poultry diets to improve feed

efficiency and body-weight gains; these include the vegetable oils,

10

animal fats, and mixtures of animal and vegetable fats. Biely and

March (1954) found that edible tallow improved both weight gain and

feed utilization when fed to chicks from 1 day to 10 weeks of age. In

the above research, improvements of 6.5% in weight gains and 3.5% in

feed efficiency were recorded. Research by Waibel (1958) on the use of

a stabilized mixture of equal parts of beef and pork fat, reported that

when the mixture comprised 10% of the diet, feed efficiency and body

weight were improved.

Supplementing vegetable oils to turkey diets improved

production; older turkeys (16 to 24 weeks of age) were able to use

rapeseed oil as effectively as soybean or sunflower oil. However,

rapeseed oil had a harmful effect on growth of young turkeys from 0 to

6 weeks of age (Blakely, MacGregor and Hanel, 1965). Rapeseed oil

contains a high concentration of erucic acid which is toxic and thereby

impairs performance. Corn oil has also been used as a supplemental fat

source for growing chicks. Carew and Hill (1964) found that levels of

3.5 to 10% supplemental corn oil were effective in improving the

efficiency of energy metabolism. Diets supplemented with an

animal-vegetable fat blend have been shown to produce positive results

in both weight gain and feed efficiency. The weight gain response

J. varied from .7 to 1.6% improvement per 1% added fat (Sell and Owings,

1980).

A synergistic effect between fats has been reported by a

number of researchers and is normally attributed to improved absorption

of the more saturated fats as a result of the presence of

polyunsaturated fatty acids and phospholipids in the diet. A

11

considerable degree of interaction between blended fats of differing

chemical structure has been observed. This interaction among fats may

be of importance during determinations of their ME. It has been

established that mixing fat containing a high percentage of unsaturated

fatty acids with one with a majority of saturated fatty acids will

improve the absorption and subsequent dietary energy value of the

latter. A similar reaction has been illustrated with individual fatty

acids (Young, 1961). The utilization of palmitic and stearic acids is

enhanced by the addition of oleic and linoleic acids.

Blending an equal mixture of a mostly saturated fat (~.

tallow) and a relatively unsaturated one (~. soybean oil) resulted

in higher ME values than the average of the two individual fat values

(Sibbald and Kramer, 1977). The optimum amount of polyunsaturated fat

needed to improve the dietary energy value of saturated fats was

studied by Lewis and Payne (1966). They suggested that the addition of

only 5% soybean oil relative to tallow (at a total fat inclusion level

of 10% of the diet) improved the mixture utilization by almost 16%. To

quantify the degree of synergism, measurements of the ratio of

unsaturated to saturated fatty acids in a mixture has been used in

studies by Lall and Slinger (1973). They found that the ratio of

2.15:1 (unsaturated:saturated fatty acids) produced optimum energy

values.

Interactions between added fats and the non-fat components of

the basal diet have been shown by Mateos and Sell (1980a). Such

effects have been attributed to added fat decreasing the entire rate of

passage through the gut, thus allowing greater time for digestion and

12

absorption of dietary nutrients. Sibbald, Slinger and Ashton (1961)

reported an increase in the AME of tallow for chic!cs when fed in a

blend with soybean oil. Also, Sibbald and Kramer (1978) found that

tallow true metabolizable ene~gy (TME) varied with the basal diet;

whereas, Dale and Fuller (1981) showed an inverse relationship between

the amount of fat in the basal diet and resulting TME of corn oil.

The existence of mineral ions in the basal diet has been

associated with decreasing the availability of an added fat in poultry

diets due to the formation of soap (Sibbald and Price, 1977). Free

fatty acids are more likely to produce insoluble soaps in vivo.

It has been recommended that the protein level in the basal

diet may affect availability of added fat; higher protein diets have

been reported to support improved absorption of lard (Young, Garrett

and Griffith, 1963) and tallow (Sibbald et al., 1961) compared to

lower protein diets.

Evaluating the synergism between supplemental fat and basal

fat is important in predicting 'the dietary energy value of a

supplemental fat. Dietary energy value attributed to a fat has been

shown to be dependent upon the level at which it is added in the basal

diet (Lesson and Summers, 1976). Thus, inclusion level and basal diet

composition have both been found to influence the ME value obtained for

fats. Sibbald et al. (1961) found values of 6.02 and 7.24 kcal/g,

respectively, for tallow fed at 10 and 20% in a basal diet comprising

24.4% protein, and values of 6.79 and 7.69 kcal/g for the same tallow

fed at 10 and 20% of a 34.0% protein basal diet. Horani and Sell

(1977a) also reported that the major effect of supplemental fat on

13

ration ME occurred when the supplement was utilized at levels of 4-6%

of the diet. However, Fuller and Rendon (1979) determined that level

of fat supplementation had no effect upon its dietary energy value when

measured at 5%, 10% and 20% inclusion levels.

Wiseman and Cole (1983) studied the effect of level of

inclusion (from 0 to 10% in successive 1% increments) of a commercial

fat blend into a synthetic fat-free or commercial basal with 3 week old

broilers. They found that the chemical structure of a fat has a marked

influence upon its ME value and with the substitution method of

determining ME values the results obtained may be influenced by fat

inclusion level, and the nature of the basal. Extrapolation of linear

functions to 100% fat inclusion resulted in AME values for the fat of

6.45 and 6.5 kcal/g when included in the semi-synthetic and commercial

basal diets, respectively.

As for the effect of added fat on the rate of passage,

Mateos, Sell and Eastwood (1982) found that transit time increased

linearly, with adult hens, when levels of fat added into a commercial

basal were increased from 5% to 30% in 5% increments. This observation

may be helpful in understanding the nature of the extra metabolic

effect of fat in poultry diets. By increasing transit time,

supplemental fats may improve digestibility of other dietary

constituents and thereby increase the utilization of dietary energy.

The "extra caloric effect" of dietary fat has been assumed to

be largely if not completely made up of the reduced HI or increased

associative dynamic effect (ADE) of fat (Jensen ~ al., 1970).

This effect was first studied by Forbes and Swift (1944) and resulted

14

from a reduction of the HI or heat loss that occurs when nutrients are

fed in combination, compared with the sum of the HI of individual

nutrients. The largest reduction in heat loss occurred when the

combination of nutrients included fat.

In an experiment with broiler chicks, Carew and Hill (1964)

found that replacement of dietary carbohydrate with corn oil increased

the efficiency of energy utilization. Mateos and Sell (1980a) studied

the effect of inclusion of 4, 8 or 12% yellow grease in

sucrose-containing diets. Results showed that supplemental yellow

grease increased ME of diets containing sucrose more than expected.

Protein and amino acid requirements of 1a:'ing hens are

functions of egg production rate, egg weight, body weight and body

weight gain. If expressed as dietary concentrations rather than

absolute daily intakes, the two additional variables of dietary energy

concentration and environment, both determinants of feed intake, must

be added (Hurwitz et a1., 1978).

Protein requirements for hybrid pullets have been evaluated

to be around 14-15 g/d by Thayer et a1. (1974); while others have

found that around 17 g/d was needed for the optimum performance of

laying hens (Aitken, Dickerson and Gowe, 1973; and Reid, 1976). These

variations in protein requirement can be interpreted on the basis of

dietary essential amino acid levels. A diet containing adequate lysine

and methionine, relatively low protein (13%), was found to be as

effective as diets containing 15, 17 or 18% protein for maintaining egg

production and egg size (Fernandez, Salman and McGinnis, 1973). In a

study of the effectiveness of sulfate on TSAA requirements of laying

15

hens, Reid and Weber (1974) reported that the feeding of a 14% protein

diet comprising .55% TSAA supported maximum egg production.

Daily protein and amino acid requirements of laying hens may

be calculated using a modification of the equation Model B as reported

by Hurwitz and Bornstein (1973), which considers needs for maintenance,

gaLn, egg mass and egg composition. The equation is as follows:

AA = Am w/.85 + (~W)(AT) + %p/100 x EW (62 Ay + 59 Ao + 52 At)

where:

AA = Daily amino acid (mg)

Am = Amino acid needs for maintenance (mg)

W = Body weight (kg)

D"W = Daily body weight change (g)

At = Amino acids in body 'tissue as (%) of N x 6.25

%p = Percent egg production

EW = Egg weight (g)

Ay = Amino acids in yolk as (%) of N x 6.25

Ao = Amino acids in ovalbumen as (%) of N x 6.25

The values for Am, At, Ay and Ao are a fraction of the respective amLno

acid in protein for maintenance, tissue, yolk and ovamucoid,

respectively. The values for Am were 100% of the maintenance needs

suggested by Leveille, Shapiro and Fisher (1960). The advantage of

using this model is to calculate the amino acid requirements of laying

hens for any combination of the three variables that make up the total

requirements. The model could be used to calculate the amino acid

requirements for large birds such as the turkey or small birds such as

quai 1.

16

One of the most difficult problems facing the poultry

industry is reduced performance during adverse hot weather conditions.

Feed intakes are normally reduced and the rate of gain and egg output

decline with high temperature.

Adams et al. (1962a) examined the use of increased

dietary energy and protein levels to overcome the adverse effects of

high environmental temperature on the performance of chicks. From 4 to

8 weeks of age birds were exposed to temperatures of 21 or 32°C.

Energy levels were increased by 2% by substitution of a soybean

meal-fish soluble blend for corn. Increasing the energy level of the

ration improved growth rate and efficiency of feed utilization at both

temperatures. Increasing the vitamin, mineral or protein content of

the ration failed to improve growth at either temperature.

Adams et~. (1962b) also investigated the total sulfur

am~no acid (TSAA) needs of broiler chicks from 4 to 8 weeks of age

maintained at 21 or 29°C. The chicks were fed diets ranging from .4

to .9% TSAA. They found that the amino acid needs of the chick,

expressed as dietary percentages, were higher at the higher

temperature.

The effects of differences in energy input both from diet and

from environmental temperature on the response of chicks to diets

containing different levels of lysine, were studied by March and Biely

(1972). Performance was depressed when the environmental temperature

and/or the dietary energy level was increased.

McNaughton et al. (1978) examined the influence of 15.6

and 29.4°C environmental temperatures on 2- to 4-week broiler

17

requirements. Dietary lysine levels of between .80 and 1.15% in .05%

increments were fed. ~hey found that feed was more efficiently

utilized by 4-week old cockerels fed either 1.10% dietary lysine in the

15.6°C environment or .95% dietary lysine in the 29.4°C environment.

It is usually suggested that protein and amino acid levels for laying

hens be increased at higher environmental temperature to overcome the

reduction in feed intake. Valencia, Maiorino and Reid (1980) reported

that increasing the dietary protein level of layer diets resulted in an

increase in egg weight and total daily egg production. Egg weights

were significantly higher at lower environmental temperature and with

the feeding of the higher protein diets.

The concept of the energy:protein ratio was developed as a

simple means to balance the protein and energy contents of broiler and

hen diets (Matterson ~ al., 1955 and Donaldson et al., 1955).

It was noticed that chicks fed high energy diets needed higher dietary

protein contents for maximum growth than those fed on low energy diets.

In addition, carcass fat content is highly correlated with the dietary

energy:protein ratio (Donaldson, Combs and Romoser, 1956). Carcass

water decreased and carcaSs lipid increased as the ME:protein ratio

increased from 13.9 to 17.89 kcal/g (Pesti, 1982). He concluded that

carcaSS lipid of 3-week old male chicks can be manipulated within 10 to

20 g/kg with diets producing good gain.

Hill and Dansky (1950) observed that growth rate was

decreased in comparison with a high protein level when a high energy -

low protein ration was fed, but that growth was restored when the

energy level was lowered. Sunde (1956) showed that a ration high in

protein and low ~n energy reduced growth and feed efficiency and that

the addition of energy to this ration improved both growth and feed

efficiency. Although many studies with poultry have suggested the

usefulness of energy:protein ratios in formulation (Hochreich et

~., 1958), more recent practices express the amino acid requirements

of hens in relation to the energy content of the diet, ~e., percent

of am~no acid per Mcal of ME.

18

As early as 1955, Baldini and Rosenberg showed that

methionine requirement of chicks increased as the energy level of the

ration was increased. Guillaume and Summers (1970) have studied the

effects of amino acid balance on energy utilization and showed that an

improvement in ME utilization occurred due to improved amino acid

balance in the diet, and a reduction in HI was observed due to the

improved am~no acid balance. On the other hand, HI increased when

alanine, asparagine and phenylalanine were fed in excessive amounts

(Burlacu, 1969). Recently, Reid and Maiorino (1984) studied the

effects of TSAA deficiency and methionine toxicity on energy

utilization of laying hens housed at 15.6 and 32.2°C. They found that

feed intake and ME intake of nontoxic TSAA diets decreased

significantly at 32.2°C, whereas significant decrease occurred at both

temperatures with toxic diet. Energy balance and efficiency of

conversion of dietary ME to NE increased at both temperatures as

dietary TSAA increased up to .51%. However, maintenance energy

requirements remained unchanged at .51% TSAA level. Overall, the

results of this study recommended that optimum energy utilization

produced by intakes of 609 mg TSAA/d and 17.3 g protein.

CHAPTER 3

EFFECTS OF ADDED TALLOW ON DIETARY NUTRIENT UTILIZATION

Introduction

Addition of fat to poultry diets increases the metabolizable

energy (ME) more than anticipated from the additivity of the ME's of

the particular ingredients (Wilder, Cullen and Rasmussen, 1959; Jensen

et al., 1970; Horani and Sell, 1977b; Sell, Tenesaca and Bales,

1979; Mateos and Sell, 1980a). For example, ME values of yellow grease

were found to be 8.92 to 9.53 kcal/g which are higher than anticipated

and even exceeded the gross energy (GE) (Wilder et al., 1959).

This effect could be due to a positive interaction between fatty acids

supplied by the added fat and fatty acids present in the basal diet or

carrier material. However, there is a possibility that supplemental

fat improves the digestion and absorption of other nutrients, thus

elevating the ME of diets (Sibbald ~ al., 1961; Sibbald, 1978;

Sibbald and Kramer, 1978; Mateos and Sell, 1980b; Dale and Fuller,

1981).

Gomez and Polin (1974), Sibbald and Kramer (1978), and Mateos

and Sell (1981) reported that interactions between supplemental fat and

non-lipid dietary constituents improved utilization of dietary energy.

Moreover, Horani and Sell (1977b) found that the effects of

supplemental tallow depended upon the composition of the laying hen

diet. Changes in ration ME caused by fat, measured experimentally,

19

20

exceeded that anticipated on the basis of calculated ME values of the

ration. Kalmbach and Potter (1959) and Sell and Mateos (1981) found ME

values for yellow gr'ease of 8.50 and 8.21 kcal/g in corn and wheat

based diets. It is thought that supplemental fats increase the

utilization of other dietary components by decreasing the rates of feed

passage, thereby enhancing the ME of diets.

There have been several studies since the early 1950's that

document the beneficial effects of supplemental fats in poultry rations

(Yacowitz, 1953; Lillie et al., 1952; March and Biely, 1963; Reid

and Weber, 1975). Improvements in efficiency of feed utilization were

noticed consistently, and frequently productive performance was

enhanced.

The objectives of this experiment were to study the

usefulness of animal tallow in laying hen rations, and to determine the

effect of added fat on the energy and nutrient utilization of the

rations fed.

Experimental Procedure

One hundred and ninety-two SC White Leghorn hens (Shaver

288A) of similar age and weight were used in this study. Each

experimental diet was fed to 32 birds (4 replications of 8 birds),

housed 4 birds per cage, for nine 28-day periods.

The basal diet shown in Table 1 was formulated by linear

programming techniques to meet the nutri~nt levels recommended by the

National Research Council (NRC, 1984) for the laying hen. The

experimental diets consisted of six levels of animal tallow (0, 2, 4,

Table 1. Composition of basal diet (Experiment 1)

Ingredient %

Ground milo Soybean meal (48.5%) Dehy. alfalfa meal DL-methionine Ground limestone Dicalcium phosphate Salt 1 Vitamin mix Pr-9

. l' 2 Trace m1nera m1X Chromium oxide

Total

Nutrient3

Protein, % ME, kcal/g Met + Cys, % Lysine, % Calcium, % Avail. Phosphorus, %

62.05 21.14 5.00

.13 8.55 1.48

.35 1. 00

.10

.20

100.00

16.98 2.69

.63

.87 3.80

.38

ISupplied the following per kg of diet: 3,966 IU vitamin A, 615 ICU vitamin D3 ,

1.78 mg riboflavin, 11.2 mg niacin, 4.5 mg calcium pantothenate, 5.3 pg vitamin B12 , 2.2 IU d-alpha tocopheryl acetate,

.88 mg menadione sodium bisulfite, 175 mg choline chloride, and 50 mg ethoxyquin

2Supplied the following (ppm): 20 Fe, 60 Zn, 60 Mn, 4 Cu, and 1 Mo

3Calculated analysis

21

22

6, 8 and 10%) added to the basal diet at the expense of the total

percentage to provide a range of ME levels. Fatty acid composition of

the animal tallow used in this study as determined by gas

chromatography are shown in Table 2. Hens were supplied feed and water

ad libitum. Egg production, body weight, egg weight and feed

consumption data were recorded throughout the experimental period and

summarized every 28 days.

Feed and excreta samples collected during periods 2, 4, 6,

and 8 were analysed for GE, protein, amino acids, starch, fat and fatty

acids. GE was determined using a Parr adiabatic oxygen bomb

calorimeter. Nitrogen determinations were carried out by the

micro-Kjeldahl method and protein estimated as 6.25 x %N (ADAC, 1980).

Feed and excreta samples were hydrolyzed for determination of amino

acids in 6N HCI in the presence of mercaptoacetic acid sodium salt to

preserve methionine. Following hydrolysis in an autoclave for 16-18

hours at 121°C (15 psi) samples were evaporated to dryness under

vacuum and dissolved in 10 ml sodium citrate buffer (pH 2.2).

Fluorescent o-phthalaldehyde amino acid derivatives were separated

using a Spectra-Physics SP8000B high pressure liquid chromatograph

(HPLC) with a 3 p RP-18 column (Jones, Paabo and Stein, 1981).

Starch analyses were carried out by the anthrone method described by

Clegg (1965). Chloroform:methanol (2:1 v/v) extraction was employed to

determine total fat content. Fatty acid methyl esters were prepared

using a boron trifluoride:methanol reagent (ADCS, 1972) and were

assayed using a Shimadzu GC-8 gas chromatograph equipped with a

Spectra-Physics 4270 integrator and a 10% DEGS column (Ackman, 1969).

T bl 2 'd" f 1 a e . Fatty ac~ compos~t~on 0 tallow

Fatty Acid 2 % of Sample

14:0 4.47 14:1 1. 37 14:2 .64 16:0 29.04 16:1 4.29 16:2 .54 16:3 .93 17:0 .59 18:0 11. 95 18: 1 43.87 18:2 2.31 20:0 Trace

Saturates 46.05 Monoenes 49.53 Dienes 3.49 Trienes .93

IValencia et al., 1980

2Number of carbon atoms:number of double bonds

3Relative amounts of fatty acids in weight percent of saponifiable fraction

23

3

24

The analytical values obtained were used to calculate

nutrient retentions using the inert marker (chromium oxide) technique.

Analyses of variance were accomplished to determine statistical

significance, and the means were separated at P<.05 using LSD (Iman and

Conover, 1983). Regression analyses were run to evaluate the effects

of added tallow on the utilization of dietary nutrients and to estimate

the ME of the added tallow.

Results and Discussion

Egg production and egg mass were not significantly affected

by tallow level (Table 3). Egg weight was not affected by tallow

supplementation up to 6% and decreased as the fat level increased to 8

or 10%. Average hen-day feed consumption decreased from 110.7 to 98.2

g) as the level of added fat increased from 0 to 10%, respectively).

Feed conversion was significantly improved from 1.67 for the

unsupplemented diet to 1.55 kg/doz at the 6% tallow level and was not

significantly affected by the higher tallow levels fed. These results

are in agreement with those reported by Horani and Sell (1977a,b) and

Jackson, Kirkpatrick and Fulton (1969) in that addition of fat to

laying hen diets resulted in significant improvements in feed

conversion without adversely affecting other production

characteristics. Reid (1984) summarized the effects of tallow

supplementation on laying hen perfor.mance and found that optimum tallow

levels for egg mass, production rate and feed converS1on were 4.93,

5.06 and 5.78%, respectively. Body weights were significantly higher

Table 3. Tallow supplementation and laying hen performance (Experiment 1)

Criteria

Egg production (%)

Egg Mass (g/d)

Egg Wt. (g)

Supplemental Tallow (%)

o 2 4 6 B

BO.3 BO.2 7B.l B1. 2 79.1

47.2 46.9 46.2 4B.2 46.4

s9.0abc sB.6c

25

10

7B.s

45.9

Feed Conversion (kg/dz) 1.67 a 1.64a 1.62ab 1.ss c 1.s7bc 1.s2c

Body Wt. (kg) 1.Bl c 1.BBb 1. 91ab 1.9sa 1.93a 1.B9b

Body Wt. Chg. (g/hen/d) .B6 1.07 1.27 1.2B 1.37 1.21

Feed Intake (g/hen/d) 110.7a 10B.lb 104.0c 104.3c 101.2d 9B.2e

Protein Intake (g/hen/d) IB.B a IB.Ob 17.0c 16.7c ls.Bd 15.0e

TSAA Intake (mg/hen/d) 696.6 a 666.4b 627.9c 616.B c 5Bs.4d 556.1 e

Lysine Intake (mg/hen/d) 959.1 a 917.5 b B64.5 c B49.2c B06.0d 765.7 e

a-e ' h' h . Means W1t 1n a row not aV1ng common letter superscripts are significantly different (P<.05)

for all birds fed the tallow supplemented diets 1n compar1son with

those fed the basal diet (Table 3).

26

The effects of tallow on dietary nutrient intakes are shown

in Table 3. Protein intake levels dropped significantly as tallow

levels increased in the diet due to reductions in feed intake. The

highest level of tallow (10%) resulted in an average protein intake

which was slightly below that recommended (15.95 g/d) by the NRC

(1984). Total sulfur-containing amino acid (TSAA) intakes decrea~ed to

below the 600 mg/d requirement as tallow levels increased to 8 and 10%,

dropping from 696.6 mg/d for the basal diet to 556.1 mg at the 10%

tallow level. Lysine (Lys) intakes also decreased from 959.1 to 765.7

mg/d as tallow levels increased from 0 to 10%, but these were all in

excess of the NRC (1984) recommended amounts.

ME consumption was significantly improved with tallow levels

of 6% and above (Table 4). ME intake increased from 305.1 to 322.4'

kcal/hen/d with 6% tallow. There was no further improvement in ME

intake noticed at the 8 or 10% tallow levels. Energy balance,

calculated from egg mass (1.6 kcal/g) and body weight change (5.0

kcal/g) data, showed a significant improvement with 6% added tallow

(Table 4). In view of the lack of a statistically significant response

1n egg mass, the increases in energy balance were due mostly to changes

in body weight as a result of increased ME intakes associated with

tallow.

Gross energetic efficiency, the ratio of energy balance to ME

intake, was not significantly affected by tallow level. Net energetic

efficiency which represents the percentage conversion of ME intake

27

Table 4. Effect of dietary tallow level on energy utilization in laying hens (Experiment 1)

Supplemental Tallow (%)

o 2 4 6 8 10

Dietary ME (kcal/g) 2.76d 2.79d 2.93c 3.09b 3.16ab 3.24a

ME Intake (kcal/d) 305.1 b 303.0b 305.2b 322.4a 320.5 a 319.9a

Energy Balance (kcal/d) 79.8 80.4 80.2 83.5 81.0 79.6

Dietary NE (kcal/g) 2.00bc 2.09b 2.21 ab 2.27 a 2.30a 2.30 a

Gross Energetic Eff. (%) 26.3 26.5 26.2 25.9 25.2 24.8

Maint. Energy (kcal/d)

ME Intake above Maint. (kcal/d) 110.2 106.7 106.4 113.1 110.5 111.4

Heat Increment + Activity a 85.3 (kcal/d)

Net Energetic Eff. (%)

a-d . h· h . 1 . Means w~t ~n a row not av~ng common etter superscr~pts are significantly different (P<.05)

Regression of Energy Balance on ME Intake above Maintenance:

Energy Balance = .757 (ME Intake above Maint.) - 10.19 (r

Regression of Dietary NE on % Tallow

Dietary NE .0312 (% Tallow) + 2.039

Tallow NE 5.17 kcal/g

.954 )

above maintenance to net energy (NE), increased significantly with 2

and 4% added tallow, but was not significantly different from the

unsupplemented diet for higher tallow levels. Regression of energy

balance on ME intake above maintenance produced a significant (P<.05)

correlation coefficient (r = .954) with a regression coefficient of

.757, indicating an average net energetic efficiency of 75.7% for the

hens in this study.

28

Maintenance energy needs, calculated according to Emmans'

(1974) equation, increased as the tallow level exceeded 4% due to

increases in body weight. Dietary NE increased from 2.0 to 2.3 kcal/g

feed and determined dietary ME improved from 2.76 to 3.24 kcal/g as

tallow levels increased from 0 to 10%. Regression of NE on tallow

level yielded a predicted NE value for tallow of 5.17 kcal/g,

representing 64.2% of the estimated ME (8.05 kcal/g) of tallow in this

study (Table 4). Heat increment (HI) decreased significantly at the 2

and 4% tallow levels and increased with the higher tallow levels due,

apparently, to the TSAA deficiency since it has been shown that poor

amino acid balance produces increases in HI.

Two factors appear to have affected performance in this

study. The first was associated with the increased ME intakes with

supplemental tallow which became significant at the 6% tallow level and

produced a higher ME intake above maintenance and slightly higher egg

production and egg mass. The second factor was found in the

improvements in net energetic efficiency with either 2 or 4% added

tallow and produced slight, but non-significant, increases in energy

balance with slightly lower ME intakes above maintenance.

The effect of age and temperature on hen performance are

summarized in Table 5. As expected, egg production and egg mass

decreased significantly from 90.7% and 49.1 g/hen/d to 65% and 38.8

g/hen/d at the end of the experiment. Egg production, after the peak

in production, was significantly depressed during the January period

and declined slowly thereafter. Body weight change also became

negative during this period.

29

Feed consumption declined from about 112 g feed/d during the

cold periods to about 95 gld during the hot periods (June and July).

These results are consistent with those of Davis et al. (1972),

Reid and Weber (1973) and Emmans (1974) in that an inverse relationship

between high environmental temperature and feed intake occurs in laying

hens. The decline in feed intake with an increase in environmental

temperature results in less energy available for productive purposes.

The decrease in feed intake could be explained by the decrease in

maintenance energy requirements and lower egg production rates during

hot periods. Maintenance energy requirements of the hens during hot

periods were 14% less than those in cold periods, while ME intake

decreased by 21%.

Net energetic efficiency was adversely affected by

temperature during the experiment. Net energetic efficiency was

significantly reduced during the January to April periods and was

significantly higher during the beginning and ending periods of the

study. These periods of lowered net efficiency also corresponded to

the periods of highest maintenance needs. Maintenance energy during

these periods ranged from 212.1 to 222.4 kcal/hen/d, while values of

Table 5. Effects of environmental temperatu~e and age on laying hen performance (Expe~iment 1)

Criteria

Egg Production (%)

Egg Mass (g/d)

Egg Weight (g)

Feed Conversion (kg/dz)

Body Weight (kg)

Body Wt. Chg. (g/hen/d)

Feed Intake (g/hen/d)

Protein Intake (g/hen/d)

TSAA Intake (mg/hen/d)

Lysine Intake (mg/hen/d)

HE Intake (kcal/d)

Energy Balance (kcal/d)

Gross Energetic Eff. (%)

Haint. Energy (kcal/d)

Net Energetic Eff. (%)

T REA THE N T PER I 0 D S

1 2 3 4 S 6 7 8 9 Nov. Dec. Jan. Feb. Mar. Apr. Hay June July

11.7°C l2.2°C 10.3°C II.8°c IS.7°C 18.2°C 22.3°c 28.I o c 29.7°C

90.7a 88.8a 84.1b 83.Sb 80.1bc 77.7cd 7S.1de 6S.0f 7l.1 e

49.1 a SO.Oa 48.4a SO.Oa 48.Sa 47.6ab 45.2bc 38.8d 43.7c

54.2g 56.3f 57.5e 59.9cd 60.6bc 6l.2ab 60.I cd 59.6d 6l.4a

I.3l e 1.45d 1.54c 1.63b 1.68b 1.69b 1.62b 1.80a 1.63b

1.77e I.90cd

1.87d 1.87d 1.90cd 1.93bc 2.00a 2.03a I.99ab

2.80b 4.69a _.8gef _.03de 1.08cd l.08cd 2.5I bc .99cd -l.65 f

96.6de 95.5e

l5.6de 15.4e

99.0cd 107.0b 107.7b

16.0cd l7.3b l7.4b

112.5a 112.0a 108.8b 100.8c

18.2a l8.1 a l7.6b l6.3c

592.I cd 640.Ib 644.5b 673.4a 670.4a 65l.3b 602.7c 577.7de 571.7e

8lS.2cd 881.3b 887.4b 927.2a 923.0a 896.7b 829.8c 795.3de 787.I e

301.0d 324.9c 327.3bc 336.6a 334.9ab 327.7abc 304.2b 280.3e 277.2e

92.6b 103.4a 73.0de 79.9cd 83.1c 8I.5cd 84.8bc 67.0ef 61.6f

30.8a 31.8a 22.4cd 23.8cd 24.8cd 24.9c 27.9b 23.8cd 22.2d

179.9d

19I.6c 222.4a

220.7ab

214.7ab

212.1b

195.4c 194.1c

19S.8c

76.6a 77.la 69.Ib 68.5b 69.2

b 70.4

b 77.3a 77.34

HE Intake> Haint. (kcal/d) 121.0b l33.3a 104.9d 1I6.0bc 120.2b lI5.6bc 10S.8cd S6.2e

7S.4a

8l.5e

68.5b HI + Activity (kcal/d) 7l.0b 74.5b 101.64 106.6a 103.7a 97.4a 69.6

b 63.9b

a-fMeans within 4 row not having common letter superscripts are significantly different (P<.05) w o

179.9 to 194.1 kcal/d were observed during the other periods of the

study. Waring and Brown (1965, 1967), Shannon and Brown (1969) and

Valencia et~. (1980) have reported similar results.

31

Body weight increased significantly from 1.77 to 1.99 kg and

egg weight increased from 54.2 to 61.4 g as the birds became older

(Table 5). Poorest feed conversion (1.8 kg/doz) was obtained when the

temperature was around 28°C. Protein intake decreased in hot periods

as a result of low feed intake. Accordingly, TSAA and Lys intakes

decreased in hot periods.

Effects of bird age on tallow utilization are shown in Table

6. Tallow ME (kcal/g) obtained from linear regression analyses

decreased significantly from 8.88 to 7.32 kcal/g as the birds became

older. Percentage of tallow digestibility also decreased significantly

from 87.1 to 73.3 at the end of the experimental period. Tallow ME

(kcal/g) obtained from digestibility data also decreased significantly

from 8.19 to 6.89 kcal/g with age. The lower ME values for tallow

obtained using digestibility data indicate some effect of added tallow

on the digestibilities of nutrients in the basal diet.

The differences ~n ME values obtained with the two methods

led to investigations of the utilization of other nutrients in the

basal diet (Table 7). No improvement in starch retention was observed

due to tallow supplementation or age (Table 7). Starch retentions were

uniformly high, ranging from 93.4 to 95.29%.

Fat retention, however, was increased significantly from

55.7% for the basal diet to around 76% when 10% tallow was fed (Table

7). Maximum fat retention occurred with 10% added tallow. The

32

Table 6. Effect of laying hen age on ME of tallow (Experiment 1)

Periods (Age)

2 4 6 8 Means

Tallow ME (kcal!g) 8.88a 8.45 b 7.70c 7.32d 8.09 (Regression)

Tallow Dig. (%) 87.1 a 84.3b 79.1 c 73.3d 81. 0

Tallow ME (kcal!g) 8.19a 7.92b "7.43c 6.89d 7.61 (Digestibility)

a~ ., h . Means w~th~n a row not av~ng common letter superscripts are significantly different (P(.05)

Table 7. Effect of tallow on nutrient utilization (Experiment 1)

Apparent Retention (%) Diet

Fat Starch Protein

Basal Diet 55. 71 b 95.29 20.80

+ 2% Tallow 71. 09a 94.93 12.76

+ 4% Tallow 71. 64a 94.23 25.31

+ 6% Tallow 73.12a 94.42 26.86

+ 8% Tallow 75.22a 94.09 24.50

+ 10% Tallow 75.99a 93.94 29.28

a_bMeans wi ~hin a column not having common letter superscr~pts are significantly different (P(.05 )

33

significant improvements obtained with tallow supplementation suggest

that the increased ME values calculated from calorimetry data were due

partially to improvements in fat retention from the basal diet or to

the well documented synergistic effect of fats.

Protein retention increased from 20.8% for the basal diet to

around 30% with 10% added tallow. Protein retention improved as the

amount of ME derived from tallow was increased (Table 7). This may

also partially explain the differences in the ME of tallow between

values based on calorimetry and those derived from digestibility data

(Table 6).

The effects of tallow supplementation on amino acid

retentions were quite variable, and thus no significant differences 1n

am1no acid retentions were obtained in this study (Table 8).

Supplemental tallow effects on fatty acid retentions are

presented in Table 9. Only the total saturated fatty acids were not

significantly increased due to fat supplementation. These data suggest

that the feeding of tallow improved utilization of some of the fatty

acids in the basal diet. Fat retention from the basal diet was quite

low at only 55.71%. These results are inconsistent with Al-Hozab's

(1985) results in that the retentions of saturated fatty acids were

significantly improved with 6% tallow in some feedstuffs. Both mono­

and poly-unsaturated fatty acid retentions were significantly increased

with each tallow increment up to 8%. Maximum oleic (CI8:l) and

linoleic (Cl8:2) acid retentions also occurred with 8% tallow. Tallow

supplementation up to 8% decreased stearic (CI8:0) acid retention.

34

Tab Ie 8. Effect of tallow supplementation on average amino acid retention by laying hens (Experiment 1)

" "d 1 Supplemental Tallow (%)

Aml.no Acl. s 0 2 4 6 8 10

-------------------- (% ) --------------------Arginine 94.30 92.22 91.44 93.43 90.19 92.05

Lysine 68.24 69.47 75.05 78.62 63.54 73.90

Methionine 91.86 87.40 90.60 89.87 89.26 87.45

Cystine 59.22 77.85 56.19 -0.81 31.39 71.80

Phenylalanine 71.94 69.86 79.04 77 .41 80.40 80.39

Tyrosine 92.14 89.41 90.16 91.61 88.39 89.51

Valine 89.62 86.10 87.25 88.75 87.23 86.76

Leucine 91.47 89.00 89.06 78.69 89.73 89.45

Isoleucine 88.84 90.37 87.65 88.78 86.80 87.03

Threonine 86.82 83.34 84.30 85.88 83.46 83.54

Histidine 91.95 89.36 89.35 92.00 88.09 89.22

1 Means of periods 2, 4, 6 and 8

35

Table 9. Effect of tallow supplementation on average fatty acid retention by laying hens (Experiment 1)

'd 1 Supplemental Tallow (%)

Fatty Acl. s 0 2 4 6 8 10

-------------------- (%) ---------------------C16:0 57.80 58.99 64.64 62.41 60.92 64.12

C18:0 52.50 67.65 51.12 46.42 38.56 40.25

C18:1 49.73d 76.62 c 80.32bc 85.34ab 89.26 a 88.68a

C18:2 60.67c 81. 54ab 74.37ab 79.00ab 89.06 a 88.42a

C18:3 70.66c 85.22ab 78.18bc 77.99bc 85. 94ab 86.53a

Saturated 51.84 59.83 61.56 58.58 55.03 58.07

Mono-unsaturated 50.25d 76.29c 81.08bc 85.79ab 89.36 a 88.90 a

Poly-unsaturated 60.15 c 79.88ab 74.43b 78.87ab 88.08a 87.87 a

Total fat 55.71 b 7l.09a 71.64 a 73.12 a 75.22 a 75.99 a

1 Means of periods 2, 4, 6 and 8

a-d , h' h . . Means Wl.t l.n a row not aVl.ng common letter superscrl.pts are significantly different (P<.05)

36

Increased ME levels in laying hen diets resulted in

significantly higher body weights for all birds fed tallow supplemented

diets. An inverse relationship was found between body weight and egg

production by the end of the production periods. Younger hens utilized

fat more efficiently than those at the end of the laying cycle. Also,

at the end of the laying cycle fat deposition is favored over egg

production when fat level or the ratio of energy to protein increases

in the diet. Supplementing fat up to 8 or 10% resulted in low protein,

TSAA and Lys intakes. Thus, it 1S recommended that dietary protein,

TSAA and Lys levels be increased with high fat levels.

Summary

This experiment was conducted to evaluate the effects of

added tallow on nutrient utilization in laying hens. Tallow increased

fat retention significantly while both protein and starch retentions

were only marginally affected by tallow. Egg production and egg mass

were not significantly affected by dietary tallow level. Body weight,

and feed conversion reached maximum levels with a tallow level of 6%

and decreased as tallow levels increased above 6%. Feed intake

remained relatively constant at about 104 gld through tallow levels of

4 and 6%, and decreased to about 98 gld with the 10% tallow diet. ME

consumption and energy balance increased with tallow levels up to 6%.

Higher tallow ME values were obtained from calorimetry data

than from digestibility measurements due to the beneficial effects of

tallow on the digestibilities of fat and protein in the basal diet.

37

Tallow ME obtained from regression analyses and digestibility

decreased significantly with age of bird. The decreases in the ME of

tallow obtained as the hens became older suggests that the best use of

tallow would be in the diet of young birds during the early stages of

production.

CHAPTER 4

EFFECTS OF TALLOW SUPPLEMENTATION

IN MINIMAL AMINO ACID DIETS

Introduction

One of the more severe problems facing the poultry industry

is reduced performance during adverse hot weather conditions when feed

intakes are normally reduced and the rate of gain or egg output decline

due to reduced metabolizable energy (ME) intakes above maintenance

available for production. A number of dietary manipulations are often

made at these times in attempts to overcome the reduction in hen

performance. One of the most common practices is the adjustment of

dietary protein and amino acid levels. A newer method of adjusting

diets involves formulation to amino acid requirements without regard to

total dietary protein level. Diets of this type are lower in total

protein, but still meet the essential amino acid needs of the animal.

Such diets should result in lower heat production than those formulated

along more traditional lines.

Brown, Waring and Squance (1965) demonstrated that the

optimum calorie:protein ratio for egg production, expressed as

kcal/kg:percent crude protein, was in the region of 170:1. They

concluded that when designing high-energy diets for layers an attempt

should be made to keep the calorie:protein ratio close to ~his figure.

However, more recent studies concerning amino acid requirements of

38

laying hens express the am~no acid requirement in relation to the

energy content of the diet.

39

Adams and associates (1962a) examined the use of increased

dietary energy and protein levels to overcome the adverse effect of

high environmental temperatures on the performance of chicks.

Increased dietary energy level improved the rate of gain regardless of

environmental temperature, while increased protein failed to overcome

the adverse effects of increased environmental temperature.

Reid and Maiorino (1984) examined the effects of total

sulfur-containing amino acids (TSAA) levels on energy utilization of

laying hens as influenced by environmental temperature. Hens were

maintained at 15.6 and 32.2°C and fed diets containing .47, .49, .51

and 3.47% TSAA. Maintenance ME requirements were found to be the same

at each temperature for diets containing .51% TSAA. A level of .50%

TSAA in the diet was adequate to support optimum energy'balance in

laying hens.

Protein requirements for hybrid pullets have been evaluated

to be around 14-15 gld by Thayer et~. (1974); while others have

found that around 17 gld was needed for optimum performance of laying

hens (Aitken ~ al., 1973; Reid, 1976). These variations in

protein requirement can be interpreted on the basis of dietary

essential amino acid levels. A diet containing adequate lysine (Lys)

and methionine (Met), but relatively low (13%) protein, was found to be

as effective as diets containing 15, 17 or 18% protein for maintaining

egg production and size (Fernandez ~ al., 1973).

40

Reid (1984) studied the interaction between Lys and added

tallow. Supplemental tallow levels of 0, 2 and 4% were fed with

dietary Lys ranging from .6 to .84%. Best egg production was obtained

when the Lys level in the diet was .75% or above.

This experiment was conducted to evaluate the effects of

added tallow in diets containing minimal amounts of protein, but

designed to meet the essential amino acid needs ·of the laying hen.

Experimental Procedure

Three hundred and eighty-four White Leghorn hens (Shaver

288A) of similar age and weight were divided into 16 groups at 26 weeks

of age. Each experimental diet was fed to 24 birds (3 replications of

8 birds/treatment) in each of two houses for ten 28-day periods. Hens

were housed four birds/cage in either a conventional house with open

sides (House 10) or in an insulated, evaporatively cooled house (House

11). Temperature means during the experiment are shown in Table 10.

During the initial seven months of the study temperatures in the

insulated house (House 11) were higher than those in the conventional

cage house (House 10). With the onset of hot weather, the evaporative

cooling in House 11 resulted in temperatures which were around 2°C

cooler than House 10.

Experimental diet compositions are shown in Table 11. The

first four experimental diets were formulated by a least cost linear

program. Diet 1 was designed to satisfy both protein (15%) and

essential amino acid requirements of the laying hen according to the

National Research Council (NRC, 1984). Diet 2 was formulated to

41

Table 10. Temperature means during experimental periods (Experimen t 2)

House 101 House 112 Periods

°c of °c of

1. Nov. 11.7 53.1 17.9 64.2 2. Dec. 12.2 54.0 17.8 64.0 3. Jan. 10.3 50.5 16.9 62.4 4. Feb. 11.8 53.2 17.7 63.9 5. Mar. 15.7 60.3 20.5 69.0 6. Apr. 18.2 64.8 21.3 70.3 7. May 22.3 72.1 24.0 75.2 8. June 28.1 82.6 25.9 78.6 9. July 29.7 85.5 27.0 80.6

10. Aug. 29.9 85.8 27.0 80.6

Means 19.0 66.2 21.6 70.9

1 House 10 - conventional system

2House 11 - evaporated system

Table 11. Composition of experimental diets (Experiment 2)

Ingredient

Ground milo Soybean meal Dehy. alfalfa meal Ground limestone Dicalcium phosphate DL-Methionine

S~lt. . 1 V 1. tam1.n m1.X T . I· 2 race m1.nera m1.X Diet 1 Diet 2 Diet 3 Diet 4 Tallow

1

66.66 16.20 5.00 9.02 1.61

.06

.35 1.00

.10

Calculated Nutrient Composition

Protein, % ME, kcal/g Met + Cys, % Lysine, % Calcium, % Avail. phosphorus, %

15.00 2.73

.50

.72 4.00

.39

2

70.04 12.74 5.00 9.00 1.67

.10

.35 1.00

.10

13.62 2.75

.50

.62 4.00

.40

3

66.54 16.22 5.00 9.02 1.61

.16

.35 1.00

.10

15.00 2.72

.60

.72 4.00

.40

Diet Number

4

61.68 21.24 5.00 9.05 1.51

.07

.35 1.00

.10

17.00 2.68

.57

.87 4.00

.38

5

97.00

3.00

14.55 2.89

.49

.70 3.88

.38

6

97.00

3.00

13.21 2.91

.49

.60 3.88

.39

7

97.00

3.00

14.55 2.88

.58

.70 3.88

.39

8

97.00 3.00

16.49 2.84

.55

.84 3.88

.37

Isupplied the following per kg of diet: 3,966 IU vitamin A, 615 ICU vitamin D3

, 1.78 mg riboflavin, 11.2 mg niacin, 4.5 mg calcium pantothenate, 5.3 pg vitamin B12 , 2.2 IU d-alpha tocopheryl acetate, .88 mg menadione sodium bisulfite, 175 mg chol1.ne chloride and 50 mg ethoxyquin

2supplied the following (ppm): 20 Fe, 60 Zn, 60 Mn, 4 CU and 1 Mo .po N

satisfy the essential amino acids at a lower protein level (13.6%).

Diet 3 was the same as Diet 1 with additional Met. Diet 4 was

formulated at 17% protein to provide a high protein level (Table 12).

Each of diet was supplemented with 3% tallow to provide the eight

experimental diets fed in each of the two houses used in the study.

Feed and tap water were supplied ad libitum.

43

Egg production, body weight, egg weight and feed consumption

data were recorded and summarized every 28 days throughout the

experiment. Feed and excreta samples collected during the second

experimental period were analyzed as described for the first experiment

and nutrient retentions were calculated using the inert marker

(chromium oxide) technique. Statistical significance was determined by

analyses of variance and the means separated at P<.05 using LSD (Iman

and Conover, 1983).

Results and Discussion

Significantly higher egg production and egg mass were

obtained in the insulated and cooled house (House 11) in comparison

with those obtained in the open conventional cage house (House 10)

(Table 13). The insulated house was warmer in the cooler months of the

study and cooler during the hotter periods, thus providing a more

uniform temperature throughout the experiment.

In the conventional cage house (House 10), the NRC basal diet

(Diet 1) supported an egg production rate of 73.9% (Table 13).

Reducing the total protein level to 13.6% (Diet 2) resulted in a

significant decrease in egg production to 69.5%. Diet 3, with a higher

Table 12. Tallow, protein and amino acid composition of experimental diets (Experiment 2)

Dietary Treatment

1. Basal NRC Diet 2. NRC-AA Restricted 3. Basal NRC + .1% Met 4. 17% Protein Diet

5. Basal NRC Diet 6. NRC-AA Restricted 7. Basal NRC + .1% Met 8. 17% Protein Diet

Protein (%)

15.0 13.6 15.0 17.0

14.6 13.2 14.6 16.5

TSAA (%)

.50

.50

.60

.57

.49

.49

.58

.55

Lys Tallow (%) (%)

.73

.62 • 72 .87

.70

.60

.70

.84

0.0 0.0 0.0 0.0

3.0 3.0 3.0 3.0

44

Table 13. Effects of experimental diets on performance of laying hens housed at different temperatures (Experiment 2)

Basal NRC Basal 17% Basal NRC Basal 17% NRC AA NRC + Protein NRC AA NRC + Protein

Diet Rest. .1% Met Diet Diet Rest. .1% Met Diet

------------- Without Tallow -------------- ------------- With 3% Tallow -------------Egg Production (%)

73.9de 69.5 f 82.1 a 75.9cd 71.5ef 74.Ide 73.Idef 81.8a House 10 (I9.0°C)

House 11 (21.6°C) 79.9abc 76.3bcd 80.2ab 78.3abc 79.0

abc 79.1

abc 79.6abc 76.5bcd

Egg Mass (g/d) 43.3fg 40.2h 48.1 ab 45.1 cdefg 42.6gh 43.1 fg 44.0efg 48.7a House 10 (I9.0°C)

House 11 (2I.6°C) 47.4abc 44.1 defg 46.7 abc 46.6abcd 46.7 abc 45.8bcde 47.5 abc 45.2cdef

Feed Conversion (kg/dz) 1.87ab 1.87s 1. 65 efg 1.85abc 1. 76cd 1. 78sbcd 1. 77bcd 1.61 g House 10 (I9.0°C)

House 11 (2I.6°C) 1. 72def 1.77abcd I.62g 1. 74de 1. 63 fg 1. 63 fg 1.61 g 1. 73def

Bod~ Weight (kg) 1. 85cde 1. 79 f I.84e I.88bcd 1. 85de 1.83e 1.89abc 1.91 ab House 10 (19.0°C)

House 11 (21.6°C) 1.85de 1.83e 1. 77£ 1.85cde 1.89ab 1. 78 f 1. 84de I.92a

Protein Intake (g) 16.5d 14.2h 16.7d 19.3a 15.0fg 14.3h 15.3f 17.9c House 10 (I9.0°C)

House 11 (21.6°C) 16.9d 14.8g 16.0e 18.8

b 15.3

fg 14.0h 15.1 fg 17.4c

TSAA Intake (mg) 553.6ef

521.8g

667.0a

649.8b

503.Ih

523.3g

611.5c

601. 3cd

House 10 (19.0°C)

House 11 (2I.6°C) 567.7e 544.9f 638.9

b 633.7b

512.6g 513.4gh

601. 8cd 586.3d

Lysine Intake (mg) 792.4e 643.9 i 803.0e 987.2a 720.1g 645.7 i 736.3g 913.5c House 10 (I9.0°C)

House 11 (21.6°C) S12.6e 672.4h 769.2 f 962.Sb 733.7g 633.5 i 724.6g 890.7d

a-k, X-Y . h' h . .. 'f' I d'ff ( < 05) Means W1t 1n a parameter not aV1ng common letter superscr1pts are s1gn1 1cant y 1 erent P.

Means

75.3Y

78.6X

44.4Y

46.3X

1. 77X

1.68Y

1.85

1.84

16.2

16.1

578.9

574.9

780.2

774.9

.p­V1

46

TSAA level than that recommended by NRC (1984), supported an egg

production level of 82.1% which was the highest obtained in this house.

Tallow supplementation to the NRC basal diet (Diet 1) did not

significantly affect egg production rate (Table 13). At the lower

protein level (Diet 2), tallow produced a significant increase in egg

production to 74.1% in comparison with 69.5% production in the absence

of tallow. A significant improvement in egg production rate was also

obtained with the addition of tallow to the high protein diet (Diet 4)

in this house; while tallow supplementation reduced egg production for

hens fed the NRC basal diet supplemented with Met (Diet 3). Highest

egg production rates in the open house (House 10) were obtained with

the Met supplemented basal diet (Diet 3) and the 17% protein diet (Diet

4) with added tallow.

A different response pattern occurred in the insulated and

evaporatively cooled house (House 11). Significantly higher egg

production was obtained with the NRC basal diet (Diet 1) in this house

in comparison with the same diet in the open house (Table 13).

Lowering the total protein level to 13.6% from 15%, with the same amino

acid levels (Diet 2), did not significantly affect egg production in

this house. Neither increasing the TSAA level in the NRC basal diet

(Diet 3) nor increasing the total protein level to 17% (Diet 4) had any

significant effect on egg production rate. Tallow supplementation also

did not significantly affect egg production with any of the diets in

this house. Overall egg production in House 11 was significantly

better than in House 10 (78.6 vs. 75.3%).

47

Egg mass followed patterns similar to egg production in the

two houses and with the various experimental diets, indicating that the

parameters studied did not significantly affect egg weight. Hens fed

the Met supplemented basal diet (Diet 3) had a higher egg mass than

hens fed other diets without tallow at both temperatures (Table 13).

Egg mass for birds at 21.6°C (House 11) was significantly higher than

for birds housed at 19.0°C (House 10). At 19.0°C (House 10) fat

addition increased egg mass significantly from 40.2 to 43.1 g egg/d for

birds fed Diet 2 and from 45.1 to 48.7 g egg/d for birds fed the

regular diet (Diet 4); while tallow supplementation did not

significantly affect egg mass for any diet at 21.6°C (House 11).

Body weight of hens fed the low protein diet (Diet 2) and the

Met supplemented basal diet (Diet 3) at 19.0°C (House 10) were

significantly increased due to 3% fat addition (Table 13). At 21.6°C

(House 11) tallow supplementation significantly decreased body weight

of birds fed the 13.6% protein diet (Diet 2) and significanly increased

body weight with all other diets.

Significant differences in feed conversion occurred due to

temperature. Birds at 19.0°C (House 10) had a poorer feed conversion

than those at 21.6°C (House 11). It is expected that birds at low

environmental temperatures would have poorer feed conversions than

those at thermoneutral temperatures. Feed is converted to heat to

maintain body temperature rather than to net energy (NE) for

production. Low feed conversions were obtained at both temperatures

when the Met supplemented diet (Diet 3) without tallow was fed. This

is an indicator of the importance of TSAA levels on laying hen

48

performance. Fat addition to this diet did not result in improved feed

conversion. Feed converS10n was improved with tallow supplementation

to the 17% protein diet (Diet 4) at 19.0°C (House 10) and to the 13.6%

protein diet (Diet 2) at 21.6°C (House 11). Tallow supplementation of

the NRC basal diet (Diet 1) resulted in improved feed conversion in

both houses, while other diets did not show any significant improvement

with tallow at either temperature.

Protein intake was significantly higher with the 17% protein

diet (Diet 4) at both temperatures. Except the 13.6% protein diet at

19.0°C, protein intakes for all diets at both temperatures decreased

significantly due to fat addition. However, protein intakes for birds

housed at 21.6°C were not significantly higher than those at 19.0°C.

As expected, TSAA intake increased significantly with the Met

supplemented basal diet (Diet 3) at both temperatures in comparison

with the NRC basal diet (Diet 1). Fat supplementation resulted in

significant decreases in TSAA intake for all diets at both

temperatures, except for the 13.6% protein diet at 19.0°C. At the

lower environmental temperature (19.0°C) TSAA intake was not

significantly higher than at 21.6°C. Lys intake followed the same

pattern as TSAA, except high Lys intake occurred with the 17% protein

diet (Diet 4) at both temperatures (Table 13). These results indicate

that fat supplementation decreased both protein and amino acid intakes;

therefore, it is important to adjust dietary protein and amino acid

levels with both fat addition and environmental temperature.

Effects of dietary tallow supplementation on energy

utilization by laying hens are shown in Table 14. ME intakes were

Table 14. Experimental diet effects on energy utilization by laying hens housed at different temperatures (Experimen t 2)

Basal NRC Basal 17% Basal NRC Basal 17% NRC AA NRC + Protein NRC AA NRC + Protein Means

Diet Rest. .1% Met Diet Diet Rest. .1% Met Diet

------------- Without Tallow -------------- ------------- With 3% Tallow -------------Dietarr HE ekcal/g)

House 10 (19.0°C) 2.78 2.86 2.78 2.70 3.02 2.98 3.09 2.87 2.89

House 11 (21.6°C) 2.73 2.71 2.74 2.60 2.89 2.89 3.01 2.82 2.80

HE Intake ekcal/d) 306.2cd 298.6def 306.1 cd 321.1 ab ;11.3X House 10 (19.0°C) 310.4c 311. Sc 32S.Sa 310.8c

House 11 e21.6·C) 308.0c 295.1 efg 293.0fg 288.2g 303.4cde 30S.4cd 312.3bc 298.4def 300.SY

Energl Balance ekcal/d) 72.Sde 68.8e 81.0ab 77.6abcd 74.1 cde 73.0de 76.4bcd 83.3a 7S.8Y House 10 e19.0°C)

House 11 (21.6°C) 79.4abc 7S.Sbcd 7S.6abcd SO.2abc 79.9abc 77.7abcd S1.0ab 80.0abc 79.0X

Gross Energetic Eff. (%) 23.6de 23.1e 26.0ab 2S.4bcd 23.7 cde 23.4e 26.7ab 24.3Y House 10 eI9.0°C) 22.7e

House 11 e21.6°C) 2S.7b 25.5bc 26.8ab 27.7a 26.2ab 2S.3bcd 25.9b 26.7ab 26.2X

Maint. Energl (kcal/d) 203.7bc 199.Sbcde 197.8cdef 201. Sbcd 20S.3b 214.3a 199.2bcde 204 .• 2X House 10 e19.0·C) 212.2a

House 11 e21.6°C) 196.9def 191.8f 184.7g 184.4g 19S.2ef 193.gef 19S.3cde 193.7ef 192.4Y

ME Cons. > Maint. ekcal/d) f House 10 e19.0·C) 102.Se 99.1 f li2.6ab 104.6cdef 106.2bcdef 109.0abcde 111.2abcd 111.6abc 107.1

House 11 (21.6·C) 111.1 abcd 103.3ef I08.3abcde 103.7def 108.2abcde 111.6abc 114.0a 104.7cdef 10S.1

Net Energetic Eff. e%) House 10 (19.0·C) 70.S fghi 69.6hi 71.Sefg 73.2cde 69.9ghi 66.9 j 68.7 ij 74.6bc 70.7Y

House 11 e21.6·C) 71.Sefgh 72.7cdef 72.4def 76.Sa 74.2bcd 69.4hi 70.9fgh 76.2sb 73.0X

HI + Activitl (kcal/d) 90.4cd 92.8c 88.0cde 82.8def 94.8bc 107.2a 102.6ab 79.5 f 92.3X House 10 (19.0°C)

House II (21.6°C) S8.3cde 80.gef 81.2ef 67.3h 79.1 fg 93.8c 91.4c 71.3gh 81. 7Y

a-j,X-YM ' h' h ' •. 'f' d'ff ( < OS) eans W1t 1n a parameter not aV1ng common letter super9cr1pts are 91gn1 1cantly 1 erent P.

.j::-\D

50

increased significantly for both the low protein and Met supplemented

diets (Diets 2 and 3) due to fat supplementation at both temperatures.

In the case of hens fed the 13.6% protein diet (Diet 2), this

improvement in ME intake with tallow supplementation may account for

the increases in egg production through higher amounts of ME available

for production. However, the extra ME consumed by hens fed the Met

supplemented basal diet appeared primarily as gains in body weight.

Average ME intakes for birds housed at 19.0°C were significantly

higher than those at 21.6°C, suggesting that birds housed at 19.0°C

needed around 3% more energy to maintain their body temperature than

those at 21.6°c.

In the conventional cage house (House 10), energy balance was

significantly higher for birds fed the Met supplemented basal diet

(Diet 3) than for those fed the NRC basal diet (Diet 1), indicating a

higher requirement for TSAA under these conditions. Energy balance was

not significantly affected by tallow supplementation in either house

nor by both diet in the insulated and evaporatively cooled house (House

11) (Table 14). Average energy balance was significantly higher at

21.6°C (House 11) than at 19.0°C (House 10).

Gross energetic efficiency dropped significantly from 26 to

23.4% when fat was added to the Met supplemented basal diet (Diet 3) at

19.0°C (House 10) and no significant differences occurred with the

other diets at either temperature. Hens housed at 21.6°C (House 11)

had higher gross energetic efficiencies than those at 19.0°C (House

10). Net energetic efficiency followed the same trend as gross

energetic efficiency.

51

The average maintenance energy requirement of birds housed at

19.0°C (House 10) was 204.2 kcal/d, while those at 21.6°C (House 11)

had a maintenance requirement of. 192.4 kcal/d, about 5.8% less. ME

consumption above maintenance did not differ significantly due to

housing temperature.

No change in starch retention was observed due to diet, fat

addition, or to housing. Protein retention decreased slightly from

27.7 to 25% as fat was added to the diets. On the other hand, fat

retention increased significantly from 58.9 to 73.9% with tallow

supplementation.

Summary

An experiment was conducted to evaluate the effects of

dietary formulation and tallow supplementation on laying hen

performance in two types of housing. Although there are economic

benefits which may be realized from feeding low dietary protein levels,

the results of this study show that reducing the total protein level

below that recommended by the NRC (1984) produced a significant

reduction in egg production in birds housed in a conventional open cage

house (House 10). Met supplementation to provide a total of .60% TSAA

was required for maximum egg production for hens housed in the open

house. A significant increase in egg production was obtained with the

low protein diet (Diet 2) when 3% tallow was added, suggesting that

lower protein levels may be used for laying hens under some conditions

if fat is incorporated in the diet. However, the level of egg

production supported by this combination was significantly below that

obtained with the 17% protein diet (Diet 4), either with or without

added tallow. The limiting nutrient in all of the diets, other than

the 17% protein formulation, appeared to be Lys. The highest egg

production rates were associated with the highest intakes of Lys and

the response appeared to be limited by TSAA intakes iu some of the

diets.

52

For birds housed in the insulated and evaporatively cooled

house (House 11) the diet based on the NRC amino acid requirements

(Diet 2) appeared to be optimal for performance even with a lower

protein level. No additional benefits were obtained in egg production

with the feeding of 3% tallow in any of the diets under these housing

conditions. The main effects of added tallow were improved feed

conversions which, of course, reduce feed costs of producins eggs.

The results of this study indicate that formulation of laying

hen diets based on amino acid requirements without consideration of

total protein level may be used to reduce feed costs of egg production

provided care is taken to maintain adequate intake levels of amino

acids with variation in environmental temperature. The impFovement in

production with added tallow in the conventional house suggests the

need for further research to determine an explanation. TSAA and lysine

intake did not increase as the environmental temperature increased.

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Adams, R. L., F. N. Andrews. J. C. RogIer, and C. W. Carrick, 1962b. The sulfur amino acid requirement of the chick from 4 to 8 weeks of age as affected by temperature. Poultry Sci. 41:1801-1806. .

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Association of Official Analytical Chemists, 1980. Official Methods of Analysis. 13th ed. W. Horwitz, ed. Association of Official Analytical Chemists, Washington, DC.

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