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 Productiona. Management Options for Weaned Beef Calvesb. Background for Growing Programs for Beef Cattlec. Impacts of Production Systems on Slaughter Weightsd. Effects of Age and Frame Size on Carcass WeightIII. Factors Affecting NE Requirements for Maintenancea. Factors Affecting NEg Requirements i. Effects of Sex and Rate of Gainii. Effects of Implantsiii. Impact of Compensatory Growthiv. Effects of Background Program and Frame SizeIV. Protein Requirements for Growing and Finishing Cattle a. Factors Affecting Protein Requirements in Feedlotsb. Utilizing NPN to Meet Protein Requirementi. Avoid Toxicity Problemsc. Use of UIP in Growing and Finishing Dietsi. Effects of Bypass Protein on Growth Rates in Growing BullsV. Macromineral Requirements for Feedlot Cattlea. Impact of Potassium on Performance LevelVI. Micromineral Requirements for Feedlot CattleCurrent LectureBeef Cattle Nutrition and Feeding: Growing and Finishing Cattle Nutrition and Management•Texas and Nebraska are the top 2 beef producers in the USManagement 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 dietThese 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 slaughterBackground 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 cattlereach choice quality at 500 lbs in around 200 days•Those started on high roughage or restricted diets and finished on high-grain diets gain morequickly (compensatory growth) when switched to high-grain and tend to be leaner; take longer to reach select or choice qualityEffects of Age and Frame Size on Carcass WeightItem Days on Feed Slaughter Wt, lb Carcass Wt, lbAge Class:Calf 251 1134 712Short yearling 166 1181 737Long yearling 98 1301 816Frame Size:Large 214 1421 897Medium 163 1176 739Small 139 1024 631Factors 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 requirementsFactors 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 requirementsFactors Affecting Higher % of fat growth Higher % of Muscle growthNEg Requirements (increase NEg) (decrease NEg)Body Weight 800 lb 600 lb 400 lbGender Heifers Steers BullsMature Body Size Small-mature size Large-mature size (Hereford) (Charlais)Anabolic Implants Non-implanted Steers Implanted SteersCompensatory GrowthCalf feds Short yearlings Long yearlings•95% of cattle in the US are implanted•cattle can be implanted more than onceEffects of Sex and Rate of Gain on NEg Requirements•NEg requirements for medium-frame cattle weighing 700 lb-Heifers>Steers>BullsEffects 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 implantImpact of Compensatory Growth on NEg Requirements•cattle will compensate for previous periods of growth restriction by growing faster and moreefficiently during refeeding•composition of growth is usually leaner during this periodEffects 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 yearlingsProtein Requirements for Growing and Finishing Cattle•Protein is needed for  rumen microbes, maintenance of host animal, and growth of hostanimalFactors 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 requirementsUtilizing 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 112Ammonium Carbonate 36 225Biuret 35 219Urea 45 281NPN 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 UIPUtilizing 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