Lecture 24 Beef Cow Nutrition Reading: pp 373-381

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 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

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 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

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

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 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%

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%)

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

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 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

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