ANSC 318 1st Edition Lecture 19 Outline of Last Lecture I Nutrient Requirements Body Condition Scores and TDN CP Ratio in Breeding Cattle Outline of Current Lecture II Grow Finishing Beef Cattle Production a Management Options for Weaned Beef Calves b Background for Growing Programs for Beef Cattle c Impacts of Production Systems on Slaughter Weights d Effects of Age and Frame Size on Carcass Weight III Factors Affecting NE Requirements for Maintenance a Factors Affecting NEg Requirements i Effects of Sex and Rate of Gain ii Effects of Implants iii Impact of Compensatory Growth iv Effects of Background Program and Frame Size IV Protein Requirements for Growing and Finishing Cattle a Factors Affecting Protein Requirements in Feedlots b Utilizing NPN to Meet Protein Requirement i Avoid Toxicity Problems c Use of UIP in Growing and Finishing Diets i Effects of Bypass Protein on Growth Rates in Growing Bulls V Macromineral Requirements for Feedlot Cattle a Impact of Potassium on Performance Level VI Micromineral Requirements for Feedlot Cattle Current Lecture Beef Cattle Nutrition and Feeding Growing and Finishing Cattle Nutrition and Management Texas and Nebraska are the top 2 beef producers in the US Management Options for Weaned Beef Cattle Weaned Calves steers heifers 7 8 months Feedyard calves finished on high grain diets Calf wintered stock pasture high roughage diet limit fed high grain diet Feedyard short yearlings finished on high grain diet Yearling summer stockers pasture high roughage diet Feedyard long yearlings finished on high grain diet These notes represent a detailed interpretation of the professor s lecture GradeBuddy is best used as a supplement to your own notes not as a substitute In the US about 95 of cattle go through a feedlot before slaughter Background for Growing Programs for Beef Cattle Growing Programs Cool season pastures wheat ryegrass etc stockpiled forage poor quality corn silage feedlots limit feeding of high grain diets feedlots corn stalks Impact of Production Systems on Slaughter Weights High grain diets from fed to calves from the beginning cause continuous growth and cattle reach choice quality at 500 lbs in around 200 days Those started on high roughage or restricted diets and finished on high grain diets gain more quickly compensatory growth when switched to high grain and tend to be leaner take longer to reach select or choice quality Effects of Age and Frame Size on Carcass Weight Item Days on Feed Slaughter Wt lb Carcass Wt lb Age Class Calf 251 1134 712 Short yearling 166 1181 737 Long yearling 98 1301 816 Frame Size Large 214 1421 897 Medium 163 1176 739 Small 139 1024 631 Factors Affecting NE Requirements for Maintenance Body Weight NEm Mcal day 0 077 BW 75 Breed or genetics dairy breeds 1 2X beef bos Taurus breeds 1 0X beef bos indicus breeds 0 9X Environment Cold Stress and heat stress increase NEm requirements Factors Affecting NE Requirements for Growth in Beef Cattle NEg requirements reflect the rate and composition of growth Factors that increase fat tissue deposition will increase NEg requirements Factors Affecting Higher of fat growth Higher of Muscle growth NEg Requirements increase NEg decrease NEg Body Weight 800 lb 600 lb 400 lb Gender Heifers Steers Bulls Mature Body Small mature size Large mature size Size Hereford Charlais Anabolic Non implanted Steers Implanted Steers Implants Compensatory Calf feds Short yearlings Long yearlings Growth 95 of cattle in the US are implanted cattle can be implanted more than once Effects of Sex and Rate of Gain on NEg Requirements NEg requirements for medium frame cattle weighing 700 lb Heifers Steers Bulls Effects of Implant and Frame Size on NEg Requirements NEg requirements for cattle weighing 700 lb and gaining 3 3 lb day No implant estrogen implant revalor implant Impact of Compensatory Growth on NEg Requirements cattle will compensate for previous periods of growth restriction by growing faster and more efficiently during refeeding composition of growth is usually leaner during this period Effects of Background Program and Frame Size on NEg Requirement NEg requirements for cattle weighing 700 lb and gaining 3 3 lb day Calves short yearlings long yearlings Protein Requirements for Growing and Finishing Cattle Protein is needed for rumen microbes maintenance of host animal and growth of host animal Factors Affecting Protein Requirements in Feedlot Cattle Protein requirements reflect the rate and composition of growth factors that increase lean tissue deposition will increase protein requirements opposite of how fat effects NEg requirements Utilizing Nonprotein Nitrogen to Meet Protein Requirements urea is most commonly used as a commercial source of NPN Urea is 45 N which equates 281 CP equivalents 45 x 6 25 2 81 1 lb of urea can be converted to 2 81 lb microbial protein NPN sources are rapidly hydrolyzed in the rumen to ammonia for ruminal bacteria For effective use NPN sources need to be fed with readily available starch CHO high grain NPN Source Nitrogen Content Protein Equivalent Ammonium Acetate 18 112 Ammonium Carbonate 36 225 Biuret 35 219 Urea 45 281 NPN sources are best utilized for beef cattle when urea is added to high grain diets urea less effectively used in high roughage urea included in short or long yearling cattle compared to diets for calves urea included in diets with high concentration of protein feeds high in UIP Utilizing NPN Avoid Toxicity Problems to prevent urea toxicity mix diets well adapt cattle to urea based diets slowly 2 3 weeks limit urea to 1 3 of total dietary protein for diet will 12 CP 1 urea 2 81 CPE safe Use of UIP in Growing and Finishing Diets 2 sources of metabolizable protein microbial protein and UIP protein UIP protein is protein that escapes rumen digestion all feeds have some UIP protein some more than others animal protein sources are higher in UIP protein soybean meal is low in UIP protein Cattle that have higher rates of protein deposition require more metabolizable protein and thus will require more UIP protein to maximize their growth potential Cattle that may require more UIP protein newly weaned calves vs yearling calves large frame vs small frame revalor implanted vs nonimplanted calves Effects of Bypass Protein on Growth Rates in Growing Bulls Item Low UIP protein diet High UIP protein diet Corn Silage 50 0 50 0 Corn Grain 28 5 30 4 Fish Meal 0 0 3 0 Sunflower Meal 3 5 0 0 ADG lb per day 2 87 3 18 Macromineral Requirements in