Management opportunities can reduce feed costs and the cost of excess nutrient waste outputs. The key to controlling excess nutrient output is controlling nutrient intakes. The question becomes whether nutrient excretion can be reduced without negatively impacting animal performance

Johnson, Brad

Walker, Julie

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South Dakota State UniversityOpen PRAIRIE: Open Public Research Access InstitutionalRepository and Information ExchangeSDSU Extension Extra SDSU Extension8-1-2001Managing Feedlot Cattle to Reduce NutrientWasteJulie WalkerDept. of Animal and Range Sciences, South Dakota State Univ., Brookings, julie.walker@sdstate.eduBrad JohnsonSouth Dakota State UniversityFollow this and additional works at: http://openprairie.sdstate.edu/extension_extraThis Other is brought to you for free and open access by the SDSU Extension at Open PRAIRIE: Open Public Research Access InstitutionalRepository and Information Exchange. It has been accepted for inclusion in SDSU Extension Extra by an authorized administrator of Open PRAIRIE:Open Public Research Access Institutional Repository and Information Exchange. For more information, please contact michael.biondo@sdstate.edu.Recommended CitationWalker, Julie and Johnson, Brad, "Managing Feedlot Cattle to Reduce Nutrient Waste" (2001). SDSU Extension Extra. Paper 54.http://openprairie.sdstate.edu/extension_extra/54ExEx 2029August 2001Animal & Range SciencesManaging Feedlot Cattle to Reduce Nutrient Wasteby Julie Walker, area beef Extension specialist, andBrad Johnson,1 Extension ruminant nutrition and beef feedlot specialist,SDSU Animal & Range Sciences DepartmentCOLLEGE OF AGRICULTURE & BIOLOGICAL SCIENCES / SOUTH DAKOTA STATE UNIVERSITY / USDAExtensionExtraManagement opportunities can reduce feed costs and the costof excess nutrient waste outputs.  The key to controlling excessnutrient output is controlling nutrient intakes.  The questionbecomes whether nutrient excretion can be reduced withoutnegatively impacting animal performance?Balanced RationsNitrogen and phosphorus are the primary nutrients consideredin nutrient waste management systems.  Excess nutrient excretioncan be controlled by properly balancing diets according tonutrient requirements for production.   The maintenance recommendations for phosphorus (NRC1996) have been reduced by approximately 43% from 1984NRC recommendations.  The new recommendation is 0.22% Pto meet nutrient needs for maintenance and gain of an 800 lbsteer on a finishing diet.  Erickson et al. (1998) conducted anexperiment to evaluate animal performance across various levels(0.14 -0.34%) of P intake.  Steer performance was measuredas average daily gain (ADG), dry matter intake (DMI), andfeed efficiency. These variables were not affected by P levelin the diet.  This suggests that when steer diets are balanced,producers can lower the P levels in the diet to the 1996 NRCrecommendations without negatively affecting performance.Most corn-based diets average 0.28 - 0.32 % P, exceeding therequirement for an 800 lb steer.  The challenge then becomeslowering the phosphorus concentration of a corn-based diet.Typically feedstuffs other than corn are needed to lower thephosphorus concentration of the diet.  Comparing phosphorousbook values of whole grains (barley, oats, sorghum, andwheat), corn has the lowest phosphorus level.  Therefore, thebest possible management alternative is to minimize additionalsupplementation of phosphorus.  Forages are typically lower in phosphorus than concentrates.However, lowering the ration P concentration by increasinglevels of forage has the disadvantage of decreasing gains.  Protein (nitrogen) requirements can be divided into twosegments, protein needed by the microbial population inthe rumen and protein needed by the animal.  Degradableintake protein (DIP) is the protein used to meet the microbialrequirement and the animal requirement can be met bymicrobial protein leaving the rumen and by undegradableintake protein (UIP).  Excess DIP is converted to ammoniaand excreted in the urine.Protein requirements change as the animal grows.  There isan opportunity to reduce crude protein level of the diet. Whena ration is balanced using DIP and UIP, usually the crudeprotein of the ration is lower than when balanced with crudeprotein levels.  11 Department of Animal Science and Industry, 126 Call Hall, KansasState University, Manhattan, KS 665062Feedstuffs vary in the amount of protein degraded in the rumen(DIP) versus small intestine (UIP).  For example, dry-rolledcorn is 40% DIP and high-moisture corn is 60% DIP with thesame amount of crude protein (8-10%). Protein sources also vary in DIP percentages, such as soybeanmeal 65%, cottonseed meal 57%, feathermeal 30% and fishmeal40%.  By using a variety of feedstuffs, UIP, and DIP requirementscan be met at lower crude protein levels in the diet, thus reducingnitrogen excretion.Phase Feeding Phase feeding is a systematic method for adjusting the animal'sdiet during the feeding period to meet its nutrient requirements.Since nutrient requirements change as cattle grow, protein andphosphorus requirements can be reduced as an animal matures.This suggests the opportunity to reduce nitrogen and phosphorusintakes and excretion.  An experiment was conducted by the University of Nebraskato evaluate phase feeding with yearlings and calves.  Theconcentrate portion of the diets was comprised of dry rolledcorn, high moisture corn, or corn bran. Control (CON) steersconsumed a diet of 13.6% CP, 4.48% UIP, and .34% P comparedto a balanced (BAL) yearling diet that was systematically reducedduring the feeding period from 11.9 -11.2 % CP, 3.67% UIP,and .24-.22 % P.  Yearlings fed the balanced diet consumedless dry matter than the control steers (Table 1).  However, nodifferences in ADG, feed efficiency, or carcass characteristics(data not shown) were found.  The second experiment involved calves.  The control diet was13.4% CP, 5.16% UIP, .35% P compared to the balanced diet(12.7-10.8% CP, 5.51-3.02% UIP, and .26-.20% P), which wasphase-fed in 8 finishing diets.  Calves fed the balanced diethad similar DMI, ADG, and feed efficiency as control calves(Table 1).Table 1. Feedlot performance for yearlings andcalves fed control or balanced rations.Phase feeding yearling steers reduced N and P excretion by 16and 44% respectively (Table 2).  This indicates improvednutrient output (i.e. lower N and P excretion) can be achievedwithout compromising animal performance.  Table 2. Nitrogen and Phosphorus Balance for yearlings.Phase feeding allows nutritionists to more effectively optimizeperformance without overfeeding. This improvement wasdemonstrated by reducing intake thus reducing potential feedcosts.  Additional cost savings could be realized by reducingthe amount of nutrients excreted in animal waste.A practical disadvantage of phase feeding is constantly changingdiets.  Phase feeding increases management requirements toensure proper delivery of the correct diet.  The risk of metabolicdisorders that could occur with improper diet changes isincreased in these systems.   ImplantsAnabolic growth-promoting agents, commonly referred to asimplants, are approved for use in steers and heifers targeted forharvesting.  Characteristics of implanted cattle are enhancedgrowth rate, feed efficiency, and lean tissue accretion.  Implantingsteers on finishing diets has improved gains by 8-20% and feedefficiency by 5-15%.  With implanted heifers, gains wereincreased 10-20% and feed conversion improved by 7-12%.  The increased tissue accretion suggests the possibility of reducednutrient excretions.  An example from Johnson et al. (1996)showed that the animals implanted with trenbolone acetate(TBA) + estradiol (E2) increased ADG by 18% (Table 3) duringthe 40 day period, suggesting that nitrogen and phosphorusretention would be higher in the implanted animals.  Table 4shows that the amount of nitrogen retained in the carcass wasincreased by 82% during the first 40 days for implanted animals.Similar intakes were observed in this study; therefore, the amountof nitrogen excreted would be less from implanted animalscompared to control animals. Table 5 illustrates calculatedestimates for reducing phosphorus excretion by implanting duringthe first 40 days.  Phosphorus is needed for both maintenance    ITEMInitial Wt., lbFinal Wt., lbDMI, lbADG, lbF/GErickson et al., 1998* P < .05CON539124520.63.665.72CON652124926.24.066.45BAL660124925.04.016.21BAL542124720.53.655.64YEARLING CALVES*    IntakeRetentionExcretedErickson et al., 1998* P < .01CON12.522.0510.47CON.56  .06  .50  BAL.47  .06  42  BAL7.90 2.03 5.87 NITROGEN   PHOSPHORUS**** Lbs/hd/d                                      Lbs/hd  (Pm) and gain (Pg).  Since the maintenance requirement iscalculated from body weight, implanted animals have a slightlyhigher requirement.  Phosphorus for gain is calculated as 3.9 gof P per 100 g of protein gain or 5.54 g P/d and 10.10 g P/d forcontrol and implanted animals, respectively.  Since true absorption of phosphorus is 68%, 18.3 g P/d and25.1 g P/d were needed by the control and implanted steers tomeet their phosphorus requirements for maintenance and gain.The phosphorus balance calculations indicate potential forreduced phosphorus excretion.  Table 3. Feedlot Performance for initial 40 days offinishing periodTable 4.  Effect of TBA + E2 on Carcass NitrogenTable 5. Phosphorus Balance for first 40 days SummaryRation balancing allows producers to manage the nutrient intakefor optimum performance and minimizing nutrient output.Adjusting rations throughout the feeding period reduces potentialof overfeeding of nutrient such as nitrogen and phosphorus.  Useof implant and other growth enhancers permits for improvementsnutrient retention, thus reducing nutrient output.  ReferenceErickson, G., M. Klemesrud, T. Milton, and T. Klopfenstein.1998. Phosphorus Requirement of Finishing Yearlings.Nebraska Beef Report: 78-80.Erickson, G., T. Milton, and T. Klopfenstein. 1998. Evaluationof 1996 NRC for Protein and Phosphorus Requirements ofFinishing Cattle.  Nebraska Beef Report: 84-85.Johnson, B.J., P.T. Anderson, J.C. Meiske, and W.R. Dayton.1996. Effect of a Combined Trenbolone Acetate and EstradiolImplant on Feedlot Performance, Carcass Characteristics, andCarcass Composition of Feedlot Steers. J. Anim. Sci. 74:363-371.Issued in furtherance of Cooperative Extension work, Acts of May 8 and June 30, 1914, in cooperation with the USDA.  Larry Tidemann, Director of Extension, AssociateDean, College of Agriculture & Biological Sciences, South Dakota State University, Brookings.  SDSU is an Affirmative Action/Equal Opportunity Employer (Male/Female)and offers all benefits, services, and educational and employment opportunities without regard for ancestry, age, race, citizenship, color, creed, religion, gender, disability,national origin, sexual preference, or Vietnam Era veteran status.  ExEx 2029: 150 copies printed by CES at a cost of 9 cents each.   August  2001.    ITEMInitial Wt., lbDays 0-40    ADG, lb    F/G    DMI, lbP Intake, g/dJohnson et al., 1996* P < .058694.584.8322.227.198693.895.4721.326.14CONTROL                       IMPLANTED **  ITEMDays 0-40Days 0-115 Days 0-143 Days 41-115 Days 116-143Johnson et al., 1996** P < .01* P < .1018619217919321020118.218.918.219.511.533.125.322.720.318.2823425458CTL       IMP CTL       IMP  ****%ResponseCarcass Ngain, g/dN Intake, g/d    ITEMP Intake, g/dPm, g/dWhole Body Protein Gain, g/dPg, g/dP Excreted, g/dEstimated requirement, g/dP Excess, g/dCalculated from Johnson et al. 1996 data.27.196.9925910.1017.0925.12.0926.146.891425.5420.618.37.8CONTROL           IMPLANTED 

Managing Feedlot Cattle to Reduce Nutrient Waste

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Managing Feedlot Cattle to Reduce Nutrient Waste

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