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LECTURE 20 FEEDLOT CATTLE NUTRITION. pp. 409-418. GOALS WHEN FEEDING FINISHING CATTLE. Maintain animal health Produce a desirable carcass Choice grade (5.0 to 8.5% intramuscular fat, 28% body fat) Body weight will vary with genetics, growth rate, and implants Yield grade 3 or less
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LECTURE 20FEEDLOT CATTLE NUTRITION pp. 409-418
GOALS WHEN FEEDING FINISHING CATTLE • Maintain animal health • Produce a desirable carcass • Choice grade (5.0 to 8.5% intramuscular fat, 28% body fat) • Body weight will vary with genetics, growth rate, and implants • Yield grade 3 or less • Acceptable maturity (< 30 months) • White fat and bright red muscle • Carcass weight between 600 and 900 lbs • Minimize production costs • Feed • Non-feed costs (Facility depreciation, Interest etc) • Minimize environmental impacts • Maximize feed efficiency
TRADITIONAL SYSTEM OF FEEDLOT FINISHING OF BEEF CATTLE Feeder calf or yearling (600-900 lb) Implanted with estrogen w/ or w/o Trenbolone acetate Feed high grain diet (80-90% grain) with ionophore Gain 3-4 lb/day Feed/gain 6-7 Season prices: High in March and April Low in July Harvested at 1200 –1400 lb producing a carcass with a choice quality grade and a yield grade of 2 or 3
FEED INTAKE OF FEEDLOT CATTLE • Normal intake is 2 to 3% of body weight • Factors • Degree of finish as affected by body weight, cattle type, implants etc. • Feeding after a period of restricted gain (backgrounding or grazing) • Part of compensatory gain • Diet • Ionophores • Forage concentration • Fat concentration • Nutritional imbalance • Potassium deficiency • Environmental • Temperature (base is 15 to 25 C) • Decreases by 10 to 35% if temperature increases to 35C • Increases by 16% is temperature decreases to -5 to -15C • Mud • Decreases by 15% if mud depth is 4 to 8 inches
EFFECT OF BODY WEIGHT AND FATNESS ON FEED INTAKE Body fat DMI
Maintenance energy requirement of finishing beef cattle • NEm, Mcal/day = .077BW.75 • Modified by a large number of factors
EFFECTS OF BODYWEIGHT ON THE NEm and NEg REQUIREMENT TO GAIN 3.5 lb/day FOR STEERS AT EITHER AT FINISHED WEIGHT OF 1200 OR 1400 LB
ENERGY SOURCES FOR FEEDLOT DIETS • Grains • Fed at levels up to 95% of the diet • Usually are processed • Grinding, cracking or rolling • High moisture corn • Steam-flaking • Cattle must be properly adapted to diet • Limits
Grain processing byproducts • Fat supplements (Tallow, Vegetable-Animal Fat) • Increase energy concentration • Reduce dustiness • Limit to 5% of DM • Molasses • Increase energy concentration • Reduce dustiness • Increase palatability • Increase binding of pellets • Limit to 5% of DM
ADAPTATION TO HIGH GRAIN DIETS • Rumen microbial population must be slowly adapted to high grain diets to prevent: • Lactic acidosis • Founder • Polioencephalomalacia • Bloat • Systems • Hand feeding • Cattle fed forage for 4 to 7 days • Start feeding grain at 0.5% BW • Amount of grain increased at 1 lb/day to 1% of BW • Amount of grain increased at 1/2 lb/day to full feed • Decrease forage as grain increased • Feed bunks must be monitored to ensure feed consumption • If intake decreases or ceases, slow rate of increase
Self-feeding a mixed ration • Supplementing Vitamin A at 30,000 to 50,000 IU/hd/day and Vitamin E at 400 to 800 IU/hd/day can assist in managing stress
MEETING THE FIBER REQUIREMENTS OF FEEDLOT CATTLE • Need for fiber in ruminant diets • Stimulate rumination and saliva secretion • Prevents • Parakeratosis of rumen wall • Liver absess • Acidosis • Bloat • Requirement is for effective NDF (eNDF) • Includes fiber content and physical form of fiber • Requirements • 8% eNDF if: • Good bunk management, ionophore fed • 20% eNDF if: • Variable bunk management, no ionophore
eNDF concentrations of common feeds in feedlot diets • FeedeNDF, % of DM Ground corn stalks 65 Ground hay 51 Corn silage 33 Soy hulls 22 Corn gluten feed 13 Whole corn grain 10 Cracked corn 8 Ground corn 5 Distillers dried grains w/solubles 4 Soybean meal 3
Metabolizable protein supply dependent on: • Ruminally undegraded protein • Microbial protein synthesis
FACTORS AFFECTING THE PROTEIN REQUIREMENTS OF GROWING BEEF CATTLE • Animal age and weight • Compensatory gain • Use of hormone implants • Feed intake
PRACTICAL IMPLICATIONS OF MP REQTS. OF FINISHING BEEF CATTLE • Cattle at light weights relative to finishing weight will benefit from sources of rumen undegradable protein • Distillers grains w/solubles • Corn gluten meal • Expeller processed soybean meal • Blood meal • Cattle at moderate weights only need to be supplemented with rumen degradable protein sources • NPN • Recall rules for safe use of NPN • Cattle near finishing weights obtain adequate metabolizable protein from a corn-corn silage diet with no protein supplementation • If DDGS are fed at 20 to 40% of the DM at any time during feeding, no protein supplementation is necessary
MINERAL NUTRITION OF FEEDLOT CATTLE • Salt (NaCl) • Should be supplied at 0.25% of diet DM • Calcium and phosphorus • Feeds commonly used for feedlot diets contain low amounts of CA and adequate to high amounts of P • Add limestone to maintain Ca:P ratio of 2:1 • Prevents urinary calculi • Potassium • Borderline on high grain and corn silage diets • Monitor and supplement if: • Low feed intake • Heat stress
Sulfur • Toxic is fed at greater than 0.4% of diet • Causes polioencephalomalacia • Occurs at lower dietary levels of S if S content of water is high • May be a problem in diets containing high levels of Distillers dried grain w/ solubles • DDGS contain as much as 1.0% S • Management • Do not feed > 40% DDGS in cattle diets • Increase forage content of diet (15%) • Delay addition of high levels of DDGS until cattle adapted to grain • Use DDGS from plants that contain consistent levels of S • Supplement cattle fed DDGS with 150 – 200 mg thiamine/day • Trace minerals • Cu, Zn, Fe, Mn, Co, and Ishould be supplemented in a premix
VITAMIN NUTRITION OF FEEDLOT CATTLE • Vitamin A • Supplement at 30,000 – 50,000 IU/d during adjustment • Supplement at 20,000 – 30,000 IU/d after adjustment • Vitamin E • Supplement at 400 – 800 IU/d for first 30 days in feedlot • Supplement at 500 IU/d during last 100 days in feedlot will improve product shelf life • Vitamin D • No need for supplementation if exposed to sunlight • B vitamins • Thiamine supplementation at 150 – 200 mg/d may reduce the risk of polioencephalomalacia in cattle fed DDGS • Other B vitamins not needed