1. Lecture 24 Beef Cow Nutrition
Reading: pp

2. GOALS OF FEEDING BEEF BREEDING HERDS
Optimize cow reproduction
1 calf every 365 days
Optimize calf production
Acceptable weaning weight
Acceptable quality
Minimize feed costs
Minimize stored feeds fed
Maintain forage and natural resources

3. TRADITIONAL BEEF COW MANAGEMENT IN MIDWEST
Cows
Calves
Months
Management
Nutrition
Feb–Apr
Cows calve
Fed stored feeds (Hay & supplements)
Mineral/vitamin supplement free-choice
Born
Suckle cows
Apr-Oct
Cows bred in late May – July
Graze pasture
Mineral supplement free-choice
Mg in mineral in Apr-May & Sept-Oct
Calves at cow side
Suckle cows May be creep fed in Aug-Oct
Oct-Dec
Late lactation & mid-gestation
Graze corn stalks with protein supplement. Mineral/vitamin supplement free-choice
Calves weaned Placed in feedlot or in a backgrounding program
Started on high grain or left on mixed forage/grain diet
Dec-Feb
Late gestation

4. USE OF CONDITION SCORING TO MAINTAIN REPRODUCTION IN BEEF COWS
Condition scores for beef cows Empty body fat, %
Condition score 1 – Emaciated
Condition score 2 – Very thin
Condition score 3 – Thin
Condition score 4 – Borderline
Condition score 5 – Moderate
Condition score 6 – Good
Condition score 7 – Very good
Condition score 8 – Fat
Condition score 9 – Very fat

5. BODY CONDITION SCORE GOALS FOR FEEDING BEEF COWS
Desired body condition scores
Production stage
Desired body condition score (9-point scale)
Comment
Initiation of breeding season 5
Calving
If extra energy not offered post-calving 4
If energy supplied pre-breeding is 30% greater than requirements
Never have cows at BCS < 4 or > 6
Breeding problems
Calving difficulties
Expense

6. FEED INTAKE OF BEEF COWS
Normal amounts of feed consumption
Daily DMI, % body wt
Dry, pregnant cows
Lactating cows – 3.0
Factors reducing feed intake
High levels of NDF
High energy concentration
Short sward height
At less than 8 inches
At less than 1 ton/ac

7. ENERGY REQUIREMENTS FOR BEEF COWS
Maintenance
70% of the requirement
Needed for basal metabolism, activity, and body temperature regulation
Pregnancy
Growth
Lactation

8. Maintenance energy requirement of beef cows
NEm, Mcal/day = .077BW.75
Modified by a large number of factors

9. Maintenance Modifiers
Modification
Change in NEm reqt.
Breed
Beef breed
Base
Dairy breed
Increase by 20%
Brahman breed
Decrease by 10%
Sex
Bull
Increase by 15%
Lactation
Lactating
Previous nutrition
BCS<5
Decrease by 5%/BCS unit
BCS>5
Increase by 5%/BCS unit
Grazing
Hill, poor pasture yield and digestibility
Increase by 30%
Environmental stress
Cold temp, dry coat, BCS 5
(Include temp, wind, BCS, hide & coat thickness, coat cover and heat increment)
Cold temp, dry coat, BCS 4
Cold temp, snowy coat, BCS 5
Increase by 96%

10. Energy Requirements for Pregnancy and Lactation
Increases energy requirement during last trimester by 80%
Lactation
Energy requirement affected by daily milk production
Peak requirement occurs at approximately 8 weeks post-calving
NE requirements for pregnancy and lactation are added to NEm requirement
Variation in requirement associated with these processes after the seasonal energy requirements of beef cows
Increase in NEm reqt, Mcal/d (%)
Peak milk, lb/d
8 wk post-calving
25 wk post-calving 20
6.7 (72%)
2.5 (27%) 30
10.1 (108%)
3.8 (40%)

11. Daily NEm REQT OF BEEF COWS IN RELATION TO PHYSIOLOGICAL STATE

12. REQUIRED NEm CONCENTRATION OF DIET FOR BEEF COW IN RELATION TO CALVING

13. COMPARISON OF THE NEm REQT OF BEEF COWS TO THE NEm CONCENTRATION OF SOME COMMON FEEDS

14. SEASONAL ENERGY REQUIREMENTS WILL VARY WITH CALVING DATE

15. MATCHING COW ENERGY REQUIREMENTS WITH FORAGE SUPPLIES FOR GRAZING

16. Management implications of variations in energy requirements of beef cows
Use of large, dairy breeds for beef production should be restricted to operations with ample forage supplies.
Match cow type to nutritional environment
Match calving season with availability of forages for grazing
Energy requirements in late winter increase because of cold stress, pregnancy and early lactation
Save best forage late winter
Early weaning may be used to reduce cow energy requirements if feed resources are limiting.
Will improve rebreeding efficiency
Corn silage and other high quality stored forages should be limit-fed if used for beef cows
Allowing cow body condition to decrease to 4 early in gestation will decrease energy needs late in gestation.
Maintaining good pasture yield and quality will reduce energy requirements while increasing forage energy concentration

17. Risk management for energy deficiency (Quantity or Concentration)
Supplement cows with feedstuff with higher energy concentration to obtain a BCS of 5
Higher quality forage
Grain
Grain byproducts
Do not rely on protein blocks for energy source
Wean calves to reduce energy requirement
Creep feed calves

18. CREEP FEEDING OF CALVES
Feeding a supplement that is high in energy and protein in a feeder that only calves can access
Common composition
Grain (Corn, oats etc)
Grain by-products (DDGS, corn gluten feed etc)
Protein supplements (Soybean meal, corn gluten meal etc)
No NPN
Mineral and fat-soluble vitamin supplements
Desire consumption of 3 to 4 lb/day
May be controlled by salt concentration
Advantages
Increased weaning weights
Feeder calves adapted to grain
Increase carrying capacity of pastures
Maintain cow reproduction if forage is limiting
Limitations
Feed cost
Inefficient weight gains (10 lb grain/1 lb BW gain)
Reduced market price of feeder calves/lb
Excessively fat replacement heifers

19. PROTEIN REQT OF BEEF COWS
Protein requirement of ruminants is for metabolizable protein
Metabolizable protein supply dependent on:
Ruminally undegraded protein
Microbial protein synthesis

20. Microbial protein synthesis is adequate to meet the metabolizable protein requirement of mature beef cows
Implications
The protein requirement of mature beef cows is a requirement for ruminal degradable protein
Rumen undegradable protein needed for replacement heifers
The protein requirement of beef cows can be expressed as crude protein
The protein requirement of beef cows can be met by:
True protein sources
Generally from plant sources
NPN sources (usually urea)
Should not supply greater than 1/3 of the crude protein in diet
Should not comprise greater than 1% of the diet DM
Should be supplied with an energy source (grain, grain byproducts, molasses)

21. CRUDE PROTEIN REQUIREMENT OF BEEF COWS IN RELATION TO CALVING

22. COMPARISON OF CP REQT OF BEEF COWS AND CP CONCENTRATION OF COMMON FORAGES

23. Implications
Protein supplementation not needed for beef cows grazing or fed:
Well-managed cool season grass and grass-legume pastures
Medium to high quality cool season grass and grass-legume hay
Protein supplementation needed for beef cows grazing or fed:
Mature warm season grasses
Corn stalks
Mature cool season grass hay

24. Protein supplementation systems
Hand-feeding
1 ½ to 2 lb of a supplement containing 40 – 44% protein
Requires feeder to prevent waste
Can feed supplement as cubes on ground
Can be offered every 2 or 3 days
Liquid supplements
Mixtures of molasses, NPN source (urea), true protein source (whey, corn steep water), phosphoric acid, soluble forms of trace minerals and vitamins A, D, and E, and possibly fat and propylene glycol
Contain 24 to 40% CP
As much as 100% from NPN
Fed free choice in a lick wheel feeder tank (150 – 250 gal)
25 cows/wheel
Desire 1 to 5 lb of consumption/day
Observe consumption
Do not use if forage quantity is inadequate
Keep feeder full

25. Protein block or tubs Total mixed ration
Mixtures of true protein sources (Soybean meal, cottonseed meal, DDGS), molasses, urea, calcium and phosphorus sources, salt, trace mineral and vitamin A and D supplements, and binder (lignin sulfonate, cement)
Blocks may be 50 to 500 lb
Supply 1 block/10 to 20 cows
Contain 15 to 40% CP
0 to 50% from NPN (urea)
Desire 1 to 2 lb consumption
Controlled by hardness, salt content, or positioning of block
May be difficult for old cows
Do not feed if forage quantity is inadequate
Weather losses may occur
Avoid sheep from consuming block
Total mixed ration
Protein supplement mixed into ground forage
Ensures diet is balanced
Minimizes waste
Requires grinding, mixing, daily feeding, and feed bunk

26. MINERAL SUPPLEMENTATION OF BEEF COWS
Traditional system
Free choice feed a 1:1 mixture of dicalcium phosphate (or bone meal) and trace mineral salt
Problem
Forages contain adequate P if forage is immature and grown on soil with adequate P
Expensive
Environmental load
Recommended system
Test forage for P and supplement P ONLY if forage is mature, weathered, and/or grown on low P soil

27. RELATION OF P REQT OF BEEF COWS IN COMPARISON TO THE P CONCENTRATION OF COMMON FORAGES

28. Magnesium should be supplemented when cows are grazing lush pastures in spring and fall
Prevention of grass tetany
Supplementation
0.6 oz Mg/day
Forms
MgO (1 oz/day)
MgSO4 (3 oz/day)
Do not feed dolomitic limestone
If part of a complete mineral mix, must adjust intake to attain 0.6 oz Mg/day
Can be included in part of free choice mineral mix
Loose mineral better than block
Trace minerals
Cu, Zn, Fe, Mn, Co, I, Se
Cu has been a problem in the Midwest because of borderline soils, increasing soil pH, and increasing Mo and S in forages
Included in free choice mineral mix
Organic forms of trace minerals may improve absorption, but their use is not economical
Cafeteria mineral feeding of trace minerals is not effective

29. VITAMIN SUPPLEMENTATION OF BEEF COWS
Vitamin A
Only needed when consuming crop residues and stored forages
Need 30,000 IU/d when pregnant and 45,000 IU/d during lactation
May be supplied in complete supplement, in a free choice vitamin-mineral supplement (500,000 IU/lb), or by intramuscular injection (1 million IU/28 days)
Vitamin D
Not needed when cattle maintained outdoors
Vitamin E
Not needed
B vitamins not needed by forage fed cattle