Lecture 19Beef Cow Nutrition

Reading: pp 401-408

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

TRADITIONAL BEEF COW MANAGEMENT IN MIDWESTCows Calves

Months Management Nutrition 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-

choiceMg 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

Fed stored feeds (Hay & supplements)

Mineral/vitamin supplement free-choice

USE OF CONDITION SCORING TO MAINTAIN REPRODUCTION IN BEEF COWS

• Condition scores for beef cows Empty body fat, %

– Condition score 1 – Emaciated 0

– Condition score 2 – Very thin 4

– Condition score 3 – Thin 8

– Condition score 4 – Borderline 12

– Condition score 5 – Moderate 16

– Condition score 6 – Good 20

– Condition score 7 – Very good 24

– Condition score 8 – Fat 28

– Condition score 9 – Very fat 32

BODY CONDITION SCORE GOALS FOR FEEDING BEEF COWS

• Desired body condition scoresProduction stage Desired body condition

score (9-point scale)Comment

Initiation of breeding season

5

Calving 5 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

FEED INTAKE OF BEEF COWS

• Normal amounts of feed consumption Daily DMI, % body wt– Dry, pregnant cows 2.0– Lactating cows 2.5 – 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

1 2 3 4 5 6 7 8 9 10 11 1220

22

24

26

28

30

32

34

36 1200 lb cow w/20 lb peak milk

1400 lb cow w/30 lb peak milk

Month post-calving

DM

I, lb

/da

y

ENERGY REQUIREMENTS FOR BEEF COWS

• Maintenance– 70% of the requirement– Needed for basal metabolism, activity, and body

temperature regulation• Pregnancy• Growth• Lactation

• Maintenance energy requirement of beef cows– NEm, Mcal/day = .077BW.75

– Modified by a large number of factors

– Maintenance ModifiersModifier 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 Increase by 20%

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

Increase by 15%

(Include temp, wind, BCS, hide & coat thickness, coat cover and heat increment)

Cold temp, dry coat, BCS 4

Increase by 20%

Cold temp, snowy coat, BCS 5

Increase by 96%

Energy Requirements for Pregnancy and Lactation• Pregnancy

– 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%)

Daily NEm REQT OF BEEF COWS IN RELATION TO PHYSIOLOGICAL STATE

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

COMPARISON OF THE NEm REQT OF BEEF COWS TO THE NEm CONCENTRATION OF

SOME COMMON FEEDS

SEASONAL ENERGY REQUIREMENTS WILL VARY WITH CALVING DATE

Months

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

NE

re

qt.

, M

ca

l/d

ay

15

20

25February calvingApril calving August calving

MATCHING COW ENERGY REQUIREMENTS WITH FORAGE SUPPLIES FOR GRAZING

• 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

• 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

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

PROTEIN REQT OF BEEF COWS• Protein requirement of ruminants is for

metabolizable protein• Metabolizable protein supply dependent on:

– Ruminally undegraded protein – Microbial protein synthesis

• 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)

CRUDE PROTEIN REQUIREMENT OF BEEF COWS IN RELATION TO CALVING

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

• 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

• 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

• Protein block or tubs– 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

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

RELATION OF P REQT OF BEEF COWS IN COMPARISON TO THE P CONCENTRATION OF

COMMON FORAGES

• 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

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