Bio-availability of Minerals in Livestock Feeds and Feed

supplements

K.GURU MOHAN REDDY

TVM/2016-13

DEPARTMENT OF ANIMAL NUTRTION

COLLEGE OF VETERINARY SCIENCE, TIRUPATI

SRI VENKATESWARA VETERINARY UNIVERSITY

INTRODUCTION

• Nutritional status of animals reflects the productive and reproductive

functions

• Animals in the tropics suffer from mineral imbalances or deficiencies

(McDowell et al., 1993)

• In India livestock are maintained on grazing with little or no

supplementation of mineral mixture, except common salt (Garg et al.,

2005).

• Locally available feeds and fodder vary in mineral content and mineral

deficiency is an area specific problem

• Bioavailability of Mineral supplements is essential

• Mineral content in green vegetation depends on physical and chemical

properties of soil, soil erosion, cropping pattern, fertilizers and chemicals

application, species and genetic differences among plants, stage of growth,

presence of other minerals etc

• Availability of minerals also decreases with maturity of fodder

• Changing availability of feed and fodder resources and deterioration

condition of grazing lands, evaluation of the mineral content of feeds and

fodders is required for assessing the deficiency/ excess and development of

suitable area specific supplementation.

• The term “bioavailability” has been defined as the degree to which

an ingested nutrient in a particular source is absorbed in a form that

the nutrient is “available” at the tissue level rather than just at the

dietary level.

• Bioavailability should not be considered as an inherent property or

characteristic of the material being assayed, but, rather, an

experimentally determined estimate which reflects the absorption

and utilization under conditions of the test

ABSORPTION OF MINERALS

• Before absorption by the absorbing enterocytes from the gastrointestinal tract

can take place, the minerals must become available in ionic form (as cations and

anions), which is suitable for uptake and transport.

• In principal, the trans-epithelial transport consists of both, an active trans-

cellular component which can be regulated and/or a passive para-cellular

component which depends on chemical and electrical gradients existing across

the intestinal wall (Nys and Mongin, 1980; Schröder et al., 1996; Jongbloed and

Mroz, 1997).

• Passive transport through the gut wall, mediated by hormonal control that

is primarily based on their concentration in the extra cellular fluid.

• Before absorption by the absorbing enterocytes from the gastrointestinal

tract, the minerals must become available in ionic form (as cations and

anions), which is suitable for uptake and transport.

• Several interactions among various minerals (e.g. calcium and phosphorus;

calcium and zinc; copper and zinc; copper, molybdenum and sulphur)

BIOAVAILABILITY• The percentage of mineral absorbed as related to the amount fed to animal

• No nutrient is absorbed and utilized to the full extent that it is fed

• When 2.5 lbs. of protein fed per day. Digestibility is only 65 percent,

actually received is about 1.625 lbs. The same is true with minerals.

• As the genetic progress of the herd improves

forage mineral bioavailability

mineral interactions

stage of production

breed

• Bioavailability of one mineral is influenced by the concentration of other

minerals in the diet

• Ex: high levels of sulphur or molybdenum interfere with copper absorption

• Practical determination of animal’s mineral status is often very difficult.

• Blood analysis is a poor indication of mineral status for many of the

minerals.

• Liver biopsy may be required to determine the mineral status of animal

Methods for evaluating the bioavailability of minerals

• In vivo techniques, which are expensive

• In vitro techniques, which are relatively cheap

• Semi In Vivo Techniques, cell cultures and tissues

• Using chamber, adopted from rumen absorption studies (Schroder et al., 1995).

• Closely linked with those biological parameters and inexpensive

• Lead to tabulated values that can easily be applied in practice, or fit in an existing

evaluation system.

In vivo experiments

• Animal performance (average daily gain, feed intake, feed conversion

ratio, reproduction characteristics);

• Digestion/absorption coefficients;

• Concentrations in several tissues (bone and organs, such as liver,

kidneys, muscle, spleen);

• Total mineral content in the animal's body;

• Morphological characteristics in several tissues;

• Blood parameters (concentrations of the minerals, enzyme activities,

hormones);

• Concentrations in secretory fluids (bile, pancreatic fluid);

• Concentrations in urine.

In vitro techniques

• This approach has not resulted in satisfactory results

• Difficult to simulate the gastric and intestinal conditions properly

• Guéguen (1976, 1977) developed the citric acid solubility of

phosphorus sources

• Solubility in water and solubility in 2% citric acid were not

discriminative (Kemme et al., 1993)

• TNO Intestinal Model (TIM) that simulates gastro-intestinal

conditions (Havenaar et al., 1995)

Terms used to express the bioavailability of minerals

• Digestibility/absorbability- gastrointestinal tract

(feed - faeces).

• (Bio) availability or bio efficacy- retained in the body

[feed - (faeces + urine)] (Partridge, 1980)

• Compared with a reference that is assumed to be 100% available

(NRC, 1998)

Absorbability:

• Absorbed from the intestinal tract - terms absorption and

digestion can be used

• Scientific point of view - fraction that is absorbed from the

gastrointestinal tract, in this case, digestibility is not the right term

when related to minerals

• Availability should also not be used

Availability

• Measures not related to disappearance of minerals from the

gastrointestinal tract

• Nutritive value of a mineral is related to a reference mineral, the

term relative (bio) availability should be used

• Reference and response parameter should be indicated

Factors affecting mineral content of forages

• Soil

• Plant species

• Stage of maturity

• Yield

• Pasture management

• Climate

• Young and alkaline geological formations more abundant in most

trace elements than the older, more acid, coarse, sandy formations.

• Leaching and weathering of soils in tropical regions, under conditions of

heavy rainfall and high temperature, accentuate mineral deficiencies

• Legumes are richer in a number of minerals than are grasses

• As plants mature, mineral content declines due to the natural dilution

processes and translocation of nutrients to the root system

• Micro mineral concentration of forages across growing seasons is generally

less variable than macro mineral concentrations

• Mineral content in soil keeps on changing due to pressure on land for

maximum crop production, fertilizer application and natural

calamities, which may alter the nutrient contents in feeds and fodders

thereby affecting the mineral status of animals.

• Knowledge of the level of minerals in feeds and fodders of a particular

area is essential for balancing dietary mineral requirements and

formulating the area specific mineral mixture, which will be practical

as well as cost effective

Macro and Micro mineral profile in Soils and Waters

Item Calcium Phosp Magnes Zinc Ferrous Copper Cobalt Mangan Selenium

-------------- % ------------- ----------------------------- ppm -----------------------------

Soils 0.24 0.01 0.06 2.67 223 1.06 0.31 81.22 2.17

Critical

level*

<0.10 <0.005 <0.012 <1.50 <20.00 <1.00 - <5.00 -

Water 7.01 0.27 15.63 0.39 0.48 0.02 0.03 0.25 -

Critical

level**

- - 30 5 0.3 0.05 - - -

*Jackson (1973) **APHA (1996)

Macro and Micro mineral profile in soils and water

Feedstuffs Ca P Mg Zn Fe Cu Co Mn Se

---------------- % -------------- ---------------------------- ppm -----------------------------------

Concentrate Feed Ingredient

Soybean cake 0.42 0.39 0.11 55.28 262 13.00 0.31 49.96 0.14

Mustard cake 0.40 0.46 0.12 56.52 302 7.20 0.30 50.65 0.09

Pellet 0.40 0.47 0.11 50.92 304 6.05 0.16 111.7 -

Lahi 0.39 0.35 0.11 63.47 270 6.20 0.39 48.62 0.10

Complete Feed block 0.41 0.35 0.12 54.33 291 6.23 0.10 72.99 -

Wheat Bran 0.30 0.40 0.11 59.41 228 8.71 0.51 72.86 0.31

Gram Chuni 0.38 0.20 0.11 41.18 274 7.26 0.30 83.11 0.19

Grain- Lahi mixture 0.37 0.29 0.10 49.34 311 6.53 0.31 41.10 0.10

Average 0.38 0.36 0.11 53.77 279 7.74 0.31 65.93 0.15

Dry and Green Roughages

Green fodder 0.32 0.26 0.11 64.01 317 6.69 0.79 60.45 0.22

Wheat straw 0.40 0.14 0.10 43.00 271 3.44 0.19 33.58 0.13

Average 0.36 0.20 0.10 53.50 297 5.06 0.49 47.01 0.18

Critical Level* <0.30 <0.25 <0.20 <30.0 <50.0 <8.00 <0.10 <40.0 <0.06

*Critical level=Concentration below which are considered deficient (McDowell et al., 1993),

Based on requirements of cattle (NRC, 2001)

Bioavailability of calcium

• Present in bone tissue as the hydroxyapatite form of calcium phosphate

(99%) and Soft tissues of the body (1%)

• Bioavailability - vitamin D concentration, Ca/P-ratio, phytate or oxalate

complexes, anion/cation-ratio, dietary magnesium and aluminium, particle

size, etc

• Sources - calcium carbonate, limestone, oyster shells, calcium phosphates,

calcium sulphate and bone and meat meals

• Particle size of calcium sources has a distinct influence on the rate of

solubility of the calcium

Bioavailability of magnesium

• Structural role in the skeleton associated with hydroxyapatite crystals (60

to 70% of total magnesium of the body)

• Functional roles such as nerve function and muscular contraction.

• Component of several enzymes implicated in the metabolism of

carbohydrates, lipids and proteins

• In ruminants, magnesium absorption occurs predominantly in the reticulo-

rumen section of the gut

• Usual recommendation is to provide dairy cows with additional 25 g

magnesium a day

Bioavailability of sodium

• Sodium (and chlorine) maintain osmotic pressure, regulate acid-base

equilibrium and control water metabolism in the body

• Addition of salt to a feed replete with sodium can lower feed intake

• According to the type of diet, practical diets require less or more

supplementary sodium

• Common salt (NaCl) is mostly used for sodium supplementation, although

for regulating acid-base balance and to optimise chlorine levels sodium

bicarbonate is used.

• Other sources of sodium are sodium-containing phosphates and sodium

sulphate

• No publications suitable for the study of sodium bioavailability of

ruminants

Bioavailability of phosphorus

• Present in the skeleton (80%)

• Nucleotides, such as ATP, nucleic acids, phospholipids, and many

other phosphorylated compounds(20%)

• Absorption takes place predominantly in the small intestine

• Large differences in absorption and utilisation of phosphorus can be

found, depending on the nutritional status of the animal

• Factors - intake level, age of the animal, levels of dietary mineral

compounds, e.g., calcium, phytic acid and phytase, magnesium and

intestinal pH.

• Phosphate sources include dicalcium phosphate (anhydrous or

hydrated), monocalcium phosphate, or mono-dicalcium phosphate

• Lactating animals have higher levels of addition of phosphorus in

their diets compared with pregnant animals

Bioavailability of cobalt

• Component of vitamin B12

• Vitamin B12, also known as cobalamin contains about 4.5% cobalt

• Cobalt deficiency leads to "wasting diseases" as a result of inadequate

synthesis of vitamin B12 from dietary cobalt

• Deficiency - particularly in grazing animals

• Distributed throughout the body with high concentrations in liver,

bone and kidney. Supplemented as cobalt sulphate

Bioavailability of copper

• Essential component of several metallo enzymes.

• Copper deficiency is a serious problem for grazing ruminants in many

countries of the world.

• Due to both low concentrations of the element in forage as well as to

elevated amounts of molybdenum and sulphur, which interfere with

copper utilisation. Supplemented in the range of 10 to 30 mg/kg

Bioavailability of iron

• key role in many biochemical reactions

• all of the iron in the animal's body is organic in nature and only a very

small percentage is found as free inorganic ions

• Haemoglobin (blood) iron (60%)

• Myoglobin (3%)

• Iron content of the body varies with species, age, sex, nutrition and

state of health and is controlled by adjustment in absorption rate

• Ruminant diets are usually not supplemented with iron, because

roughage contains already a high amount of iron due to

contamination with soil particles.

• Supplemented as ferrous sulphate heptahydrate (FeSO4·7H2O) in

animal diets.

• No publications suitable for the study of iron bioavailability of

ruminants

Bioavailability of iodine

• Tissues concentration - 0.1 μg/g body weight

• Thyroid gland - 400 μg/g body weight

• Integral part of the thyroid hormones thyroxin (tetraiodothyronine)

(T4) and triiodothyronine (T3)

• Plants, water or other animal feedstuffs have highly variable

concentrations of iodine.

• Differences in species and strains, climatic and seasonal conditions,

the type of soil, the fertiliser treatment or possible interactions

• Thyroid gland - up to 90 % of the iodine is captured by a

Na/K-dependent ATP-ase.

• Predominant sources are calcium iodate and ethyl diamine hydro

iodide (EDDI) or organic forms of iodine Potassium or sodium iodide

are less stable sources

Bioavailability of manganese

• Important function in blood clotting and lipid and carbohydrate

metabolism

• Deficiency lowers the activity of the manganese superoxide

dismutases

• Abnormal male and female reproductive functions

• Absorption is affected by manganese source, dietary antagonists (fibre,

phytate, high levels of calcium and phosphorus, iron, magnesium) and

depends on the concentration in the diet

• Most diets for ruminants are likely to be deficient in manganese

• Supplemented as manganese sulphate, manganese oxide or various

organic forms

Bioavailability of molybdenum

• Considered as a toxic element because of its interference with the

copper metabolism in ruminants.

• As a component of the enzymes xanthine oxidase, aldehyde oxidase

and sulphite oxidase.

• Xanthine oxidase and aldehyde oxidase - electron transport chain

• Aldehyde oxidase - niacin metabolism

• Sulphite oxidase - sulphite to sulphate conversion for excretion in

urine.

• No evidence of characteristic symptoms of molybdenum deficiency in

ruminants.

• Supplementation of ruminant diets is not usual for molybdenum but

added to counteract toxicity risk due to high levels of copper supply.

Bioavailability of selenium

• Toxic element causing the lost of hair, nails and hooves.

• Chronic selenium toxicity have been related to consuming selenium-

accumulating plant.

• Chronic toxicity from (mg/kg)

• Acute toxicity needs a much higher selenium level in the diet

• Main constituent of glutathione peroxidase which, associated with

vitaminE plays a role of “cellular scavenger” protecting cellular membranes

from oxidative effects (peroxides and free radicals)

• Concentration depends on the soil concentration of selenium

• Seeds and by-products have generally higher selenium content than

forages

• Animal by-products including fish meals, but with the exception of milk

products have high concentration of selenium.

• supplemented as sodium selenite.

Bioavailability of zinc

• Activates several enzymes and is a component of metalloenzymes

• Most abundant intracellular trace mineral in animals

• Primarily absorbed from the small intestine

• Animal diets require supplementation with zinc because of either low

dietary levels or the presence of dietary factors that decrease

bioavailability of the mineral (e.g. phytic acid)

• Supplemented in diets for all species of livestock in the range of

30 to 250 mg/kg to cover their requirements

• Supplemented as zinc sulphate (ZnSO4·xH2O) or as zinc oxide

Factors affecting Trace Mineral Bioavailability in Ruminants

• Dietary factors that affect bioavailability of minerals differ greatly

between ruminants and non-ruminants.

• In ruminants, microbial digestion in the rumen and reticulum

precedes mammalian digestion in the abomasum and small intestine.

• Ruminant diets are usually high in fibre, and considerable digestion of

fibre occurs via microbial fermentation in the rumen.

• The pH in the rumen environment is only slightly acidic (6.0–6.8), and

in the rumen, many trace minerals exist largely in an insoluble form

Conclusion

• Locally available feeds and fodder are varying in mineral content and

mineral deficiency is an area specific problem.

• Mineral status of locally available feedstuffs is essential.

• Mineral content dependent on the soil, which nourishes the plants

• Availability decreases with maturity of fodder

• Agro-climatic conditions - mineral content in green vegetation

depends on physical and chemical properties of soil, soil erosion,

cropping pattern, fertilizers and chemicals application, species and

genetic differences among plants, stage of growth, presence of other

minerals etc

• Understanding the bioavailability of various mineral sources effective

mineral mixture supplementation can be provided

REFERENCES

• Assessing bioavailability of essential trace minerals in animal nutrition-Wilhelm

Windisch

• Bioavailability of iron, zinc, and other trace minerals fromvegetarian diets1–4--

Janet R Hunt

• Bioavailability of minerals in legumes-Ann-Sofie Sandberg

• Bioavailability and Antagonists of Trace Minerals in Ruminant Metabolism --

David R. Ledoux1 and Marcia C. Shannon

• Minerals from Drinking Water: Bioavailability for Various WorldPopulations and

Health Implications-- Choon Nam Ong

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