Lecture 19 Beef 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 MIDWEST Cows Calves Months Management Nutrition Management Nutrition Feb– Apr Cows calve Fed stored feeds (Hay & supplements) Mineral/vitamin supplement free-choice Born Suckle cows AprOct Cows bred in late May – July Graze pasture Mineral supplement freechoice Mg in mineral in Apr-May & Sept-Oct Calves at cow side Suckle cows May be creep fed in Aug-Oct OctDec Late lactation & midgestation 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 DecFeb 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 scores Production stage Desired body condition score (9-point scale) Initiation of breeding season 5 Calving 5 If extra energy not offered post-calving 4 If energy supplied prebreeding is 30% greater than requirements • Never have cows at BCS < 4 or > 6 • Breeding problems • Calving difficulties • Expense Comment FEED INTAKE OF BEEF COWS • Normal amounts of feed consumption Daily DMI, % body wt – Dry, pregnant cows – Lactating cows 2.0 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 36 1200 lb cow w/20 lb peak milk DMI, lb/day 34 1400 lb cow w/30 lb peak milk 32 30 28 26 24 22 20 1 2 3 4 5 6 7 8 9 Month post-calving 10 11 12 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 Modifier 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 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%) • 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 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 NE reqt., Mcal/day 25 February calving April calving August calving 20 15 Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Months 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 – – – – Feed cost Inefficient weight gains (10 lb grain/1 lb BW gain) Reduced market price of feeder calves/lb Excessively fat replacement heifers • Limitations 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 grasslegume 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