concepts in beef cow nutrition aaron stalker university of nebraska-lincoln
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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
0
50
100
150
200
250
300
350
400
450
500
An
nu
al C
ost
s ($
)
Other
Vet and Medicine
Pasture
Purchased andHarvested Feeds
USDA, Economic Research Service, 2002
$419
Annual operating costs per cow Northern Great Plains
0
50
100
150
200
250
300
350
400
450
500
An
nu
al C
ost
s ($
)
Other
Vet and Medicine
Pasture
Purchased andHarvested Feeds
USDA, Economic Research Service, 2002
$419
46%
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
RUMEN
Dietary Protein
SMALL INTESTINE
Dietary Protein
SMALL INTESTINE
Degradable Intake Protein
Dietary Protein
SMALL INTESTINE
Degradable Intake Protein
Dietary Protein
SMALL INTESTINE
Degradable Intake Protein
Dietary Protein
SMALL INTESTINE
Degradable Intake Protein
Dietary Protein
SMALL INTESTINE
Degradable Intake Protein
Undegraded Intake Protein
aka Bypass or Escape
Dietary Protein
SMALL INTESTINE
Degradable Intake Protein
Undegraded Intake Protein
aka Bypass or Escape
Metabolizable Protein
Dietary Protein
SMALL INTESTINE
Degradable Intake Protein
Dietary Protein
SMALL INTESTINE
Degradable Intake Protein
Dietary Protein
SMALL INTESTINE
Degradable Intake Protein
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
0
200
400
600
800
1000
Mar Apr May Jun Jul Aug Sep Oct Nov Dec Jan Feb
MP
(g
/day
)
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
0
200
400
600
800
1000
Mar Apr May Jun Jul Aug Sep Oct Nov Dec Jan Feb
MP
(g
/day
)
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
0
200
400
600
800
1000
Mar Apr May Jun Jul Aug Sep Oct Nov Dec Jan Feb
MP
(g
/day
)
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
0
200
400
600
800
1000
Jun July Aug Sep Oct Nov Dec Jan Feb Mar Apr May
MP
(g
/day
)
Protein Supply Cow Requirement
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
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
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.
Seasonal price index of 227-271 kg steer calves 1993-2003
94
96
98
100
102
104
106
Jan Feb Mar Apr May Jun July Aug Sep Oct Nov Dec
Ind
ex
5 Year Average 10 Year Average
Source: USDA, Agricultural Marketing Service, western Nebraska-eastern Wyoming market 1993-1997, Nebraska auction markets 1998-2003.
94
96
98
100
102
104
106
Jan Feb Mar Apr May Jun July Aug Sep Oct Nov Dec
Ind
ex
5 Year Average 10 Year Average
Seasonal price index of 227-271 kg steer calves 1993-2003
Source: USDA, Agricultural Marketing Service, western Nebraska-eastern Wyoming market 1993-1997, Nebraska auction markets 1998-2003.
94
96
98
100
102
104
106
Jan Feb Mar Apr May Jun July Aug Sep Oct Nov Dec
Ind
ex
5 Year Average 10 Year Average
Seasonal price index of 227-271 kg steer calves 1993-2003
Source: USDA, Agricultural Marketing Service, western Nebraska-eastern Wyoming market 1993-1997, Nebraska auction markets 1998-2003.
Steer calf price 1998-2003
80
85
90
95
100
105
110
115
120
Jan Feb Mar Apr May Jun July Aug Sep Oct Nov Dec
$/0.
45 k
g
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
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.
Sale price 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.
Average resource use for Traditional and Extended Grazing cows over 4 years
Item Traditional Extended Grazing
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 resource use for Traditional and Extended Grazing cows over 4 years
Item Traditional Extended Grazing
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 resource use for Traditional and Extended Grazing cows over 4 years
Item Traditional Extended Grazing
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 resource use for Traditional and Extended Grazing cows over 4 years
Item Traditional Extended Grazing
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 resource use for Traditional and Extended Grazing cows over 4 years
Item Traditional Extended Grazing
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
Item Traditional Extended Grazing
Feeding labor, hour/head - 0.15
Hay fed, kg - 200
Commercial Supplement, kg - 47.6
Grazing days 21 -
Average post-weaning resource use for March and June born calves over 4 years
Item Traditional Extended Grazing
Feeding labor, hour/head - 0.15
Hay fed, kg - 200
Commercial Supplement, kg - 47.6
Grazing days 21 -
Average post-weaning resource use for March and June born calves over 4 years
Item Traditional Extended Grazing
Feeding labor, hour/head - 0.15
Hay fed, kg - 200
Commercial Supplement, kg - 47.6
Grazing days 21 -
Average post-weaning resource use for March and June born calves over 4 years
Item Traditional Extended Grazing
Feeding labor, hour/head - 0.15
Hay fed, kg - 200
Commercial Supplement, kg - 47.6
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
• Traditional vs. Extended Grazing system
– Weaned calf
– Approximately equivalent value
• Seasonal price
• Price slide
Conclusions
• Traditional vs. Extended Grazing system
– 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
Metabolizable Protein Requirement of a 1200lb March-Calving Cow, 20 lb milk
0
200
400
600
800
1000
Mar Apr May Jun Jul Aug Sep Oct Nov Dec Jan Feb
MP
(g
/day
)
Cow Requirement
Peak Lactation
Weaning
Fetal Growth
National Research Council, Nutrient Requirements of Beef Cattle, 1996
Metabolizable Protein Requirement of a 1200lb March-Calving Cow, 20 lb milk
0
200
400
600
800
1000
Mar Apr May Jun Jul Aug Sep Oct Nov Dec Jan Feb
MP
(g
/day
)
Cow Requirement
Peak Lactation
Weaning
Fetal Growth
National Research Council, Nutrient Requirements of Beef Cattle, 1996
Metabolizable Protein Requirement of a March-Calving Cow and Forage Supply
0
200
400
600
800
1000
Mar Apr May Jun Jul Aug Sep Oct Nov Dec Jan Feb
MP
(g
/day
)
Protein Supply Cow Requirement
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
Date
Cha
nge
in B
ody
Con
diti
on
Scor
e
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
4.0
4.3
4.5
4.8
5.0
5.3
5.5
5.8
6.0
Jun. Aug. Nov. Dec. Mar.
BC
S
August
November
Effect of weaning date on pregnancy rate
96.5 94.2
0
10
20
30
40
50
60
70
80
90
100
Pre
gn
an
cy
ra
te (
%)
August
November
P = 0.56
Effect of weaning date on weaning weight
391
513
0
100
200
300
400
500
We
an
ing
we
igh
t, l
bs
August
November
P = <0.001
Effect of weaning date on carcass weight
788 780
0
100
200
300
400
500
600
700
800
Ca
rca
ss
wt,
lb
s
August
November
P = 0.56
Effect of supplement on cow body condition score
4.0
4.3
4.5
4.8
5.0
5.3
5.5
5.8
6.0
Dec. Mar. Jun. Aug. Nov.
BC
S
Supplement
No Supplement
Effect of supplement on pregnancy rate
95.4 96.9
0
10
20
30
40
50
60
70
80
90
100
Pre
gn
an
cy
ra
te (
%)
Supplement
No Supplement
P = 0.27
Effect of supplement on weaning weight
463441
0
100
200
300
400
500
We
an
ing
we
igh
t, l
bs
Supplement
No Supplement
P = <0.001
Effect of supplement on carcass weight
804764
0
100
200
300
400
500
600
700
800
Ca
rca
ss
wt,
lb
s
Supplement
No Supplement
P = 0.04
Effect of supplement on cow body condition score
4.0
4.3
4.5
4.8
5.0
5.3
5.5
5.8
6.0
Dec. Mar. Jun. Aug. Nov.
BC
S
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
Hay
Effect of supplement on cow body condition score
4.0
4.3
4.5
4.8
5.0
5.3
5.5
Dec Mar May June Oct
BC
S
Sup
No Sup
******
**
Effect of supplement on pregnancy rate
90.393.2
0
10
20
30
40
50
60
70
80
90
100
Pre
gn
an
cy
ra
te (
%)
Sup
No Sup
P = 0.46
Effect of supplement on percentage of live calves at weaning
9499
0
10
20
30
40
50
60
70
80
90
100
110
Pre
gn
an
cy
ra
te (
%)
Sup
No Sup
P = 0.02
Effect of supplement on calf weight
479
81
466
80
0
100
200
300
400
500
600
Birth Wean
Ca
lf w
eig
ht
(lb
s)
Sup
No Sup
P = 0.29
P = 0.02
Effect of supplement on carcass weight
801813
0
100
200
300
400
500
600
700
800
900
1000
Ca
rca
ss
we
igh
t (l
bs
)
Sup
No Sup
P = 0.23
Effect of meadow grazing on cow body condition score
4.0
4.3
4.5
4.8
5.0
5.3
5.5
Dec Mar May June Oct
BC
S
Meadow
Hay
***
Effect of meadow grazing on pregnancy rate
91.492.0
0
10
20
30
40
50
60
70
80
90
100
Pre
gn
an
cy
ra
te (
%)
Meadow
Hay
P = 0.88
94.7 97.5
0
10
20
30
40
50
60
70
80
90
100
110
Pre
gn
an
cy
ra
te (
%)
Meadow
Hay
P = 0.15
Effect of meadow grazing on percentage of live calves at weaning
Effect of meadow grazing on calf weight
479
79
466
81
0
100
200
300
400
500
600
Birth Wean
Ca
lf w
eig
ht
(lb
s)
Meadow
Hay
P = 0.20
P = 0.01
Effect of meadow grazing on carcass weight
805809
0
100
200
300
400
500
600
700
800
900
1000
Ca
rca
ss
we
igh
t (l
bs
)
Meadow
Hay
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•
How much supplemental protein?
• Cows grazing native winter range, Nebraska Sandhills:
• 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)
How much supplemental protein?
• Cows grazing native winter range, Nebraska Sandhills:
• 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.