Concepts in Beef Cow Nutrition Aaron Stalker University of Nebraska-Lincoln

Concepts in Beef Cow Nutrition

Aaron Stalker

University of Nebraska-Lincoln

Introduction

• Feed costs – Major factor in economic efficiency

• Harvested forages– Majority of total feed costs

Annual operating costs per cow Northern Great Plains

Vet and Medicine

Pasture

Purchased andHarvested Feeds

USDA, Economic Research Service, 2002

Annual operating costs per cow Northern Great Plains

Vet and Medicine

Pasture

Purchased andHarvested Feeds

USDA, Economic Research Service, 2002

Biological Priority for Nutrients

Priority Function

1 Maintenance

2 Growth

3 Milk Production

4 Reproduction

Plant Cell

•PROTEIN•SUGARS•STARCH•PECTINS•FATS

PRIMARYWALL

SECONDARYWALL

CELL CONTENTS

CROSS SECTION

InsideSECONDARY WALL

PRIMARY WALL

CELLULOSE

HEMICELLULOSE

LIGNIN ACIDDETERGENTFIBER (ADF)

NEUTRALDETERGENTFIBER (NDF)

OUTSIDE

Ruminal Microorganisms Ferment Structural CarbohydratesFerment Structural Carbohydrates

Volatile Fatty AcidsVolatile Fatty AcidsAcetate, Propionate, ButyrateAcetate, Propionate, Butyrate

Microbial Crude ProteinMicrobial Crude Protein

What is MP? Metabolizable protein (MP) systemMetabolizable protein (MP) system

(1996 NRC)(1996 NRC)

Acknowledges ruminal microorganismsAcknowledges ruminal microorganismsProtein (nitrogen) requirementProtein (nitrogen) requirementSeparate from hostSeparate from host

Degradable intake protein (DIP)Degradable intake protein (DIP)Fraction of total protein degraded in rumenFraction of total protein degraded in rumen

Primary source of nitrogen for microorganismsPrimary source of nitrogen for microorganisms

What is MP? Metabolizable protein (MP) systemMetabolizable protein (MP) system

Undegradable intake protein (UIP)Undegradable intake protein (UIP)Fraction of total intake protein not degraded in Fraction of total intake protein not degraded in

rumenrumenPasses to small intestine Passes to small intestine

Metabolizable proteinMetabolizable proteinSum of digestible microbial protein and Sum of digestible microbial protein and

undegradable intake proteinundegradable intake protein

Dietary Protein

SMALL INTESTINE

Dietary Protein

SMALL INTESTINE

Dietary Protein

SMALL INTESTINE

Degradable Intake Protein

Dietary Protein

SMALL INTESTINE

Dietary Protein

SMALL INTESTINE

Dietary Protein

SMALL INTESTINE

Dietary Protein

SMALL INTESTINE

Undegraded Intake Protein

aka Bypass or Escape

Dietary Protein

SMALL INTESTINE

Undegraded Intake Protein

aka Bypass or Escape

Metabolizable Protein

Dietary Protein

SMALL INTESTINE

Dietary Protein

SMALL INTESTINE

Dietary Protein

SMALL INTESTINE

Dietary Protein

SMALL INTESTINE

• Demonstration of NRC software

Feed Costs

• Directly related to calving date

• Survey of cow calf producers– Western and North Central Nebraska

– 80% March-calving herd– Requires feeding hay

• 2427 kg per cow(Clark et al., 2004)

Reduce Harvested Forage

• Key Concepts

– Cow nutrient requirements

– Forage nutrient supply

Reduce Harvested Forage

• Key Concepts

– Cow nutrient requirements

– Forage nutrient supply

Metabolizable Protein Requirement of a 1200lb March-Calving Cow, 20 lb milk

Mar Apr May Jun Jul Aug Sep Oct Nov Dec Jan Feb

Cow Requirement

Peak Lactation

Weaning

Fetal Growth

National Research Council, Nutrient Requirements of Beef Cattle, 1996

Biological Priority for Nutrients

Priority Function

1 Maintenance

2 Growth

3 Milk Production

4 Reproduction

Potential metabolizable protein from native upland forage in Nebraska Sandhills

Protein Supply

Cow weighing 1200 lbs with 20 lbs peak milk, Adapted from Lardy et al., 2004

Metabolizable Protein Requirement of a March-Calving Cow and Forage Supply

Protein Supply Cow Requirement

March Calving Cow weighing 1200 lbs with 20 lb peak milk production

Metabolizable Protein Requirement of a June-Calving Cow and Forage Supply

Jun July Aug Sep Oct Nov Dec Jan Feb Mar Apr May

June Calving Cow weighing 1200 lbs with 20 lb peak milk production

Hypothesis

• June-Calving

– Annual operating costs decreased

• Extend grazing

• Limited Harvested Forage

• Match requirements with supply

Objectives

• Compare productivity

– Traditional: March-calving

– Extended Grazing: June-calving

• Develop net returns budgets

Study Site

Materials and Methods

• 195 cows– 75 March-calving: Traditional– 120 June-calving: Extended Grazing

• First two years not included

• 4 Years of data– 4 production cycles

Materials and Methods

• 195 cows– 75 March-calving: Traditional– 120 June-calving: Extended Grazing

• 60 breeding season on meadow• 60 breeding season on upland range

• 4 Years of data– 4 production cycles

Herd Management

• Traditional system– Fed hay mid-January through April

• Extended Grazing system– Fed supplement– Fed hay post-calving and winter storms

Weaning

• Calves weaned at 210 days of age– Traditional: March-born

• October

– Extended Grazing: June-born• January

• Pregnancy status determined

• Weaning rates

Post-weaning management

• Traditional: March-born – Grazed sub-irrigated meadow for 21 days

• Extended Grazing: June-born– Fed hay and supplement for 21 days

Economic analysis

• Budgets include actual costs of:– Harvesting hay– Purchased feed– Grazing

• Fence and water maintenance• Monitoring livestock

– Labor– Operating interest and overhead– Heifer replacement – Veterinary and medicine

Economic analysis (cont.)

• Budgets do not include costs of:– Land– Property taxes– Insurance – Buildings– Management

Statistical Analysis

• Experimental design– Completely randomized

• Experimental unit– Calving system

• Replication year

Statistical Analysis (cont.)

• Proc GLM SAS

• Single degree of freedom orthogonal contrasts: – Traditional vs. Extended Grazing

• All measured responses

– Range vs. Meadow within Extended system• Pregnancy rate• Weaning rate

Results and Discussion

Traditional Extended Grazing

Item Range Range Meadow

Pregnancy Rate, %ab 94.8 92.1 91.7

Weaning Rate, %ab 88.8 90.2 87.7

aMeans were similar (P>0.10) for Traditional vs. Extended Grazing.bMeans were similar (P>0.10) for Range vs. Meadow within Extended Grazing system.

Pregnancy and weaning rates of cows in Traditional and Extended Grazing systems

Traditional Extended Grazing

Item Range Range Meadow

Pregnancy Rate, %ab 94.8 92.1 91.7

Weaning Rate, %ab 88.8 90.2 87.7

aMeans were similar (P>0.10) for Traditional vs. Extended Grazing.bMeans were similar (P>0.10) for Range vs. Meadow within Extended Grazing system.

Weaning weight of calves in Traditional and Extended Grazing systems

Item Traditional Extended Grazing

Weaning weight, kg 220a 189b

Gross value, $ 439 428

Sale price, $/45 kg 90.51 102.72

Cow cost/weaned calf, $ 252 176

abMeans differ (P<0.05) for Traditional vs. Extended Grazing.

Gross value of calves in Traditional and Extended Grazing systems

Sale price, $/45 kg 90.51 102.72

Seasonal price index of 227-271 kg steer calves 1993-2003

Jan Feb Mar Apr May Jun July Aug Sep Oct Nov Dec

5 Year Average 10 Year Average

Source: USDA, Agricultural Marketing Service, western Nebraska-eastern Wyoming market 1993-1997, Nebraska auction markets 1998-2003.

Steer calf price 1998-2003

181-226 kg 227-271 kg 272-317 kg 318-362 kg

Source: USDA, Nebraska auction markets 1998-2003.

Sale price of calves in Traditional and Extended Grazing systems

Sale price, $/45 kg 90.51 102.72

Sale price of calves in Traditional and Extended Grazing systems

Sale price, $/45 kg 90.51 102.72

Average resource use for Traditional and Extended Grazing cows over 4 years

Hay fed, kg 1787 100

Commercial Supplement, kg 44 70

Grazing days 233 357

Feeding labor, hour/head 0.66 0.18

Calving labor, hour/head 0.57 0.30

Average post-weaning resource use for March and June born calves over 4 years

Feeding labor, hour/head - 0.15

Hay fed, kg - 200

Commercial Supplement, kg - 47.6

Grazing days 21 -

Hay fed, kg - 200

Grazing days 21 -

Hay fed, kg - 200

Grazing days 21 -

Hay fed, kg - 200

Grazing days 21 -

Summary of Traditional and Extended Grazing systems

ItemExtended Grazing Traditional Difference

Gross value, $ 428 439 -11

Cow cost, $ 176 252 76

Net returns per calf in Traditional and Extended Grazing systems

ItemExtended Grazing Traditional Difference

Gross value, $ 428 439 -11

Cow cost, $ 176 252 76

Net returns $252 $187 $65

Conclusions

• Traditional vs. Extended Grazing system

– Similar pregnancy rate

– Similar weaning rate

Conclusions

– Weaned calf

– Approximately equivalent value

• Seasonal price

• Price slide

Conclusions

– Extended Grazing

• Lower feed costs

• Greater net returns

Implications

• Changing calving date– Effective means of increasing net returns

• Match – Cow nutrient requirements– Forage nutrient supply

• Not March vs. June

Implications

• Date of calving varies

– Geographic location

– Forage resources

Cow Requirement

Peak Lactation

Weaning

Fetal Growth

Cow Requirement

Peak Lactation

Weaning

Fetal Growth

Metabolizable Protein Requirement of a March-Calving Cow and Forage Supply

March Calving Cow weighing 1200 lbs with 20 lb peak milk production

Weaning Dates

• 8 weaning dates:– August 18, 1999 to November 24, 1999– August 16, 2000 to November 22, 2000

(140 to 240 days after calving)

Effect of Weaning Date on Change in Cow Body Condition Score

-0.5-0.4-0.3-0.2-0.1

00.10.20.30.40.5

8/18 9/1 9/15 9/29 10/13 10/27 11/10 11/24

R2 = .95

August weaning

1. No protein supplement during winter grazing

2. Protein supplement during winter grazing

Weaning and Supplement Treatments for March Calving Cows

November weaning

1. No protein supplement during winter grazing

2. Protein supplement during winter grazing

Effect of weaning date on cow body condition score

Jun. Aug. Nov. Dec. Mar.

August

November

Effect of weaning date on pregnancy rate

96.5 94.2

August

November

P = 0.56

Effect of weaning date on weaning weight

August

November

P = <0.001

Effect of weaning date on carcass weight

788 780

August

November

P = 0.56

Effect of supplement on cow body condition score

Dec. Mar. Jun. Aug. Nov.

Supplement

No Supplement

Effect of supplement on pregnancy rate

95.4 96.9

Supplement

No Supplement

P = 0.27

Effect of supplement on weaning weight

463441

Supplement

No Supplement

P = <0.001

Effect of supplement on carcass weight

804764

Supplement

No Supplement

P = 0.04

Dec. Mar. Jun. Aug. Nov.

Supplement

No Supplement

Protein supplement during winter grazing

1. Graze meadow pre breeding

2. Feed hay pre breeding

No Protein supplement during winter grazing

1. Graze meadow pre breeding

2. Feed hay pre breeding

Follow up study

Winter

Protein Supplement

No Protein Supplement

SpringMeadow

Dec Mar May June Oct

No Sup

******

Effect of supplement on pregnancy rate

90.393.2

No Sup

P = 0.46

Effect of supplement on percentage of live calves at weaning

No Sup

P = 0.02

Effect of supplement on calf weight

Birth Wean

No Sup

P = 0.29

P = 0.02

Effect of supplement on carcass weight

801813

No Sup

P = 0.23

Effect of meadow grazing on cow body condition score

Dec Mar May June Oct

Meadow

Effect of meadow grazing on pregnancy rate

91.492.0

Meadow

P = 0.88

94.7 97.5

Meadow

P = 0.15

Effect of meadow grazing on percentage of live calves at weaning

Effect of meadow grazing on calf weight

Birth Wean

Meadow

P = 0.20

P = 0.01

Effect of meadow grazing on carcass weight

805809

Meadow

P = 0.67

How much supplemental protein?

• Cows grazing native winter range, Nebraska Sandhills:

• 0.4 lb CP mid-late gestation (Dec-Feb)•

• 0.6 lb CP 30 days pre-calving•

• 1.0 lb CP 30-45 days post calving•

• 0.4 lb CP mid-late gestation (Dec-Feb)• 1.5 lb DDG (as fed)

• 0.6 lb CP 30 days pre-calving• 2.2 lb DDG (as fed)

• 1.0 lb CP 30-45 days post calving• 3.0 lb DDG (as fed)

• 0.4 lb CP mid-late gestation (Dec-Feb)• 2.0 lb of CP in total diet

• 0.6 lb CP 30 days pre-calving• 2.2 lbs of CP in total diet

• 1.0 lb CP 30-45 days post calving• 2.6 lbs of CP in total diet

Price Shop Calculate the cost per unit of the nutrient(s) you need. Evaluate other factors. Purchase in most economical way.

EXAMPLE: $/Ton of Feed # of CP/Ton

$200/ton of DDG600# of CP/Ton DDG

= $/lb of CP

= $.33/lb of CP

Cost of Supplements

$/Ton % CP Cost of CPCottonseed Pellets 300 32 0.4720% Cube (AN) 265 20 0.6632% Liquid (16% NPN) 285 21 0.6812% Tub 600 12 2.5032% Cube 320 32 0.5019% Alf. Hay (Lg Rd. ) 110 19 0.3317% Alf. Hay 85 17 0.25

Feed Cost Calculator

• www.westcentral.unl.edu•Ag manager’s tool box

• A measure of energy reserves

• Influences animal– Reproduction/lactation– Feed efficiency/gain– Health– Maintenance requirements

• Scale 1 – 9 (emaciated to obese)

Body Condition Score

BCS 2Ribs and bone structure easily visible, but no signs of physical weakness.

BCS 3Very thin. No visible fat is on the ribs or brisket. Individual muscles in the hindquarters are easily visible and spinous processes are very apparent.

BCS 5There is less than 0.2 inches of fat over the ribeye. Last oneor two ribs may be apparent. No fat is present in the brisket.

BCS 6Appearance is smooth throughout. Some fat deposition is apparent in the brisket. Individual ribs are not visible.

BCS 7Brisket is full. Tail head and pin bones have protruding deposits of fat on them. Back appears square due to fat.

Concepts in Beef Cow Nutrition Aaron Stalker University of Nebraska-Lincoln

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