Casey, H

Coertze, RJ

Kreiner, HA

van Zly, JGE

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S.Afr.J.Anim.Sci.,  199 l ,  2I(4) 201Growth and efficiency of young Brahman,Bonsmara and Drakensberger bullsH.A. Kreiner, N"H. Casey,. J.G.E. van Zyl andR.J. CoertzeDepartment of Livestock Science, Faculty of Agriculture,University of Pretoria, Pretoria 0002, Republic of South Africa* Author to whom correspondence should be addressedReceived 14 September 1990; accepted 12 April 199)Growth and individual cumulative feed intakes (cumF[) of 15Brahman" 12 Bonsmara and 14 Drakensberger bulls, randomlyacquired from various herds, were r@orded in a 140-day post-weaning feedlot trial. Of the linear and quadratic regressions fittedto the data of each animal, the quadratic expression showed thebest fit. Average daily gain (ADG), average daily feed intake(ADFD and average feed conversion efficiency (FCE) wereobtained from differentials of the resultant equations, Conected"pooled means of performance traits for the Brahman, Bonsmaraand Drakensberger were (P < 0,05) initial mass: 2ll', 230', and236'; final mass: 352",442b, and 403b; cumFl:876', 1164b, and1243b; ADG: 1,01',  1,51b, and 1,20';  ADFI: 6,26',  8,31b, and8,88b; FCE: 6,36"b, 5,57", nd 7,42b. The conclusion is that asubstantial genetic basis exists for variation in ADF[, gain andFCE for bulls on postweaning performance tests.Groei en kumulatiewe voerinnames (KVI) van 15 Brahman-, 12Bonsmara- en 14 Drakensbergerbulle, afkomstig van verskillendekuddes, is in 'n 140-dae intensiewe naspeense groeifase gemeet.Van die lineOre en kwadratiese regressies wat op die data gepas is,het die kwadratiese regressie die beste passing getoon. Gemiddel-de daaglilae toename (GDT), gemiddelde daaglikse voerinname(GDVD en gemiddelde daaglikse voeromset (GVO) is d.m.v. diedifferensiaal van die vergelykings bereken. Gekorrigeerde"gepoelde gemiddeldes van preslasie-eienskappe van die Brahman-,Bonsmara- en Drakensbergerbulle was (P < 0,05) aanvangsmassa:2I1", 230^, en 236': finale massa: 352', Mzb, en 403b; KVI:876',  1164b, en 1243b; GDT 1,01", 1,5lb, en 1,20';  GDVI: 6,26',8 ,31b,  en 8,88b;  GVO:6,36 'b ,5 ,57 ' ,  en7,42b.  Die  gevolgrekk ingis dat daar 'n aansienlike genetiese basis bestaan vir variasie inGDVI, GDT en CVO vir bulle op naspeense groeitoetse.Keywords: Bulls, efficienry, feedlot, growth performance.The more recent studies on postweaning gains of beef cattlehave included direct measluements of feed consumption andindividual feed conversion ratios. These indicate that efficie.ncyof feed utilization varies between brecds (Smith et al., L976;Cundiff et a|",1981; Chewning et al", 1990). Efficiency of feedusage is not a directly measurable trait, but must be computedas a function of feed consumed, gain in body mass, bodycomposition and time. In order to evaluate growth and efficien-cy reliably at any point or interval, a mathematical model isrequired that suitably approximates to a set of growth andintake data.This study investigates the growth and efficiency ofBrahman, Bonsmara and Drakensberger bulls in a post-weaning feedlot period using simple, suitable mathematicalmodels to describe and analyse growth and fe€d conversionefficiencv.Individual growth and feed intake data were obtained from15 Brahman, 12 Bonsmara and 14 Drakensberger bulls in a140-day feedlot trial. The bulls were acquired at random fromvarious herds and those of the same breed were not siblings.The animals were penned after weaning at approximately eightmonths of age and were fitted with neckbands holding ele<;tro-magnetic transponders, which activated an automatic feedstation. An adaptation period of 21 days was allowed, afterwhich individual daily feed intakes were recorded. The n.tionwas similar to that used in Phase C of the Bull PerformmceTesting Scheme, containing 10,79 MJ ME/kg DM (BeefCattle Performance Testing Scheme). Body mass was recordedevery 14 days following overnight withdrawal of feed andwater.Linear and quadratic regressions were fitted to the measuredcumulative feed intake (cumFl) (y) versus days (x) and mass(y) versus days (x). Mass (y) was also regressed by linear andquadratic functions on cumulative feed intake (x). The func-tions used were defined as follows: linear: y = a + bx andquadratic: y = a + bx + cx2•ADO, ADFI and FCE for the total feeding period werecalculated by linear regressions. Analyses of variance by least-square means were carried out to quantify breed differenc,~singrowth rate, feed intake and efficiency of feed utilization on amonthly basis and for the total feeding period.Differentials of the quadratic equations were used to calcu-late average daily feed intakes (ADFI), average daily gains(ADO) and feed conversion efficiency (FCE) at Days 1, 28,56, 84, 112 and 140 of the test period. The inverse of thedifferential of the quadratic function relating body mass to feedintake describes feed efficiency, being the amount of feedconsumed per unit gain, at any stage.The results of the linear and quadratic regressions for eachbreed are given in Table 1. The coefficients of determination(r2) indicate that the quadratic regressions most accuratelydescribed the increase in mass over the time observed. CumFlis described well by both the linear and quadratic regressions.The relationship between cumFI and mass was best describedby a quadratic function in all three breeds. In both the linearand quadratic regressions the increasing variance of y, as agiven x moves away from the mean, results in a diminishingaccuracy of the estimate, yielding either an over- or an under-estimate of y. For this reason, estimates of efficienciesobtained from the differentials of the quadratic equations atDays 1 and 140 may deviate from expectation. The cumFl,mass, ADO, ADFI and FCE as calculated from the quadraticregressions at 28-day intervals are presented in Table 2.Table 1 Pooled parameters and r2 values of regression equationsLinear QuadraticRegression a b r2 a b c r2Brahmanmass: days 216,7 1,0256 0,9693 209,7 1,3471 -0,00233 0,9813mass: cumFI 223,5 0,1593 0,9615 216,6 0,2189 -0,000093 0,9809cumA : days -40,4 6,4136 0,9951 -26,4 5,7368 0,00507 0,9971Bonsmaramass: days 236,7 1,5327 0,9758 228,7 1,9219 -0,00283 0,9823mass: cumA 250,6 0,1796 0,9701 236,9 0,2677 OO85סס,0- 0,9911cumA : days -63,4 7,8211 0,9924 -30,3 6,4429 0,01505 0,9973Drakensbergermass: days 245,3 1,2089 0,9665 233,9 1,7436 -0,00380 0,9851mass: cumFl 247,1 0,1791 0,9812 242,7 0,2240 -0,000060 0,9965cumFi : days -50,4 7,8211 0,9891 -11,2 5,0940 0,02762 0,9988Table 2 Cumulative feed intake (cumFI), mass, aVElragedaily gain (ADG), average daily feed intake (ADFI) and feedconversion efficiency (FCE) of Brahman, Bonsmara and Drakensberger bulls on 140-day postweaning feedlot growth at28-day intervalsBrahman Bonsmara DrakensbergerDays infeedlot cumFI Mass ADG ADA FCE cumA Mass ADG ADFI FeE cumFI Mass ADG ADA FCE1 0 211 1,34& 5,75&b 4,57 0 230 1,91 b 6,47" 3,74 0 236 1,74&b 5,15b 4,4628 138& 246 1,21& 6,Or 5,18& 162b 280 1,76b 7,28b 4,16b 153 &b 280 1,53&b 6,64& 4,86&b56 311& 277& 1,09& 6,30& 6,21& 377b 327b 1,61 b 8,11 b 4,91& 361 &b 320&b 1,32& 8,19b 5,53&b84 491& 306& 0,95& 6,59& 7,84& 616b 370b 1,45b 8,95b 6,14b 611b 354b 1,01& 9,73b 6,64&b112 680' 330& 0,82& 6,87& 10,82& 879b 408b 1,28b 9,79b 8,46b 906b 381b 0,89& 11,28b 8,67b140 876& 352& 0,69& 7,16& 17,87& 1164b 442b 1,13b lO,62b 14,32b 1243b 403b 0,68& 12,83b 13,36b•.b Differing superscripts of traits in rows differ at P < 0,05.The initial mass did not differ significantly (P < 0,05)between the three breeds, although the Bonsmara and Drakens-berger tended to be heavier than the Brahman. The initial ADOdiffered (P < 0,05), with the Bonsmara having the highest, theDrakensberger intermediate and the Brahman the lowest ADO.After approximately 50 days, the ADOs of the Brahman andDrakensberger were not significantly different, but were signi-ficantly (P < 0,05) lower than that of the Bonsmara. This wastrue up to the end of the feeding period.The Bonsmara had the highest ADFI at the start of the trial,with the Brahman intermediate and the Drakensberger thelowest ADFI. At day 28, ADFI of the Bonsmara was signifi-cantly (P < 0,05) higher than that of the Drakensberger as wellas of the Brahman. From approximately Day 40 onwards,ADFI of the Brahman was significantly lower than that of boththe Bonsmara and Drakensberger. The final mass of theBrahman was significantly (P < 0,05) lower than the final massof Bonsmara and Drakensberger. The Bonsmara tended to beheavier than the Drakensberger, although not significantly.The Bonsmara tended throughout the feeding period to bethe most efficient feed converters (FCE). There was, however,no significant difference between the Bonsmara and Drakens-berger, but the Brahman was significantly (P < 0,05) lessefficient. These results support the assertions of Koch et ai.(1963), Smith et ai. (1976), Cundiff et ai. (1984), Thiessen etai. (1985) and Brown et ai. (1986), that the fastest growinganimals are the most efficient feed converters within age-constant intervals in spite of heavier weights maintained.The decreased efficiency of feed utilization during thefeeding period observed within breed groups would suggestthat the faster gaining breed groups could have been aided byleaner composition of their gain. Carcass composition was,however, impossible to determine in this trial.Means of performance traits for the entire feeding period ascalculated by linear regressions, are presented in Table 3.These analyses indicate the Bonsmara to have maintained agrowth rate significantly higher than that of both the Brahmanand Drakensberger breeds. Brahman had significantly lowerADFI than Bonsmara and Drakensberger. Bonsmara usedsignificantly less feed per unit gain than Brahman andDrakensberger. Brahman tended to be more efficient thanDrakensberger, but the faster growing Bonsmara tended to bemore efficient feed converters than the Drakensberger andBrahman.Table 3 Initial mass, final mass, cumulative feed intake(cumFI), average daily gain (ADG), average daily feed intake(ADFI) and feed conversion efficiency (FeE) of Brahman,Bonsmara and Drakensberger bulls as calculated by linearregressionsInitial Finalmass mass cumFl ADG ADFI FCEBrahman 211- 352- 876- 1,01- 6,26- 6,36-bBonsmara 230- 442b 1164 b 1,51 b 8,31 b 5,57-Drakensberger 236- 403b 1243b 1,20- 8,88b 7,42b•• b Differing superscripts of traits in columns differ at P < 0,05.Frisch & Vercoe (1977) found that Brahman-cross steers hada lower voluntary food intake per kilogram live mass, as wellas a lower fasting metabolism per kilogram live mass, com-pare:d to Bos taurus steers. Furthermore, Bos indicus breedsshow a better growth rate on roughage than Bos taurus breeds(Fri:>eh, 1976). The conclusion drawn by Frisch & Vercoe(1977) was that Bos indicus breeds, having evolved under poornutritional conditions, have a low fasting metabolism and acomparatively low growth rate under optimal conditions. Thismay well apply to the Drakensberger breed, although moredetailed research would be required.Monteiro (1975) suggested that the different efficienciesover a same age interval found in breed groups most likelycorrespond to breed characteristics of size, degree of maturity,and to breed differences in some intrinsic appetite parameters.Bro'NIl et ai. (1986) suggested that the feed intake and gaindifferences between breeds were more likely the result of appe-tite and feed capacity than intrinsic efficiency or compositionof gains. Chewning et ai. (1990) concluded that differences doexist between breeds in ADO, feed efficiency and daily feedintake, which are important parameters for cattle producers tomake sound economic decisions. The conclusion drawn fromthes,e results is that a substantial genetic basis exists forvariation in feed consumption, gain and the ratio of gain tofeed (efficiency) for bulls on postweaning performance tests.Ack,nowledgementsThe authors acknowledge Prof. H.T. Oroeneveldt, Departmentof Statistics, University of Pretoria, for his assistance with thestatistical analyses.ReflerencesBEEF CATTLE PERFORMANCE TESTING SCHEME. Administered bythe Director, Animal and Dairy Science Research Institute, Departmentof Agricultural Development. Private Bag X2, Irene 1675, Republic ofSouth Africa.BROWN, C.l, JOHNSON, Z. & BROWN, A.A., 1986. Some genetica:;pects of feed intake, gain and feed conversion of young bulls onp~stweaning gain test. In Proceedings, 3rd World Congress onGenetics applied to Livestock Production (Madrid) Xl: 291-294.CHEWNING, J.1., BROWN, A.H. (Jr.), JOHNSON, Z.B. & BROWN,C.1., 1990. Breed means for average daily gain, feed conversion andintake of beef bulls during postweaning feedlot performance tests.J, Anim. Sci. 68, 1500.CUNDIFF, L.V., KOCH, R.M., GREGORY, K.E. & SMITH, G.M., 1981.Characterization eX biological types eX cattle - cycle II. IV Postweaninggrowth and feed efficiency of steers. J. Anim. Sci. 53, 332CUNDIFF, L.V., KOCH, R.M. & GREGORY, K.E., 1984.Characterization of biological types of cattle - cycle Ill. IVP~stweaning growth and efficiency. J. Anim. Sci. 58, 312.FRISCH, lE., 1976. A model for reasons for breed differences in growthnLte of cattle in the tropics. Proc. Aust. Soc. Anim. Prod. II, 85.FRISCH, J.E. & VERCOE, J.E., 1977. Food intake, eating rate, weightgains, metabolic rate and efficiency of feed utilization in Bos taurusand Bos indicus crossbred cattle. Anim. Prod. 25, 343.KOCH, R.M., SWIGERS, L.M., CHAMBERS, D. & GREGORY, K.E.,1963. Efficiency of feed use in beef cattle. J. Anim. Sci. 22,486.MO/ITEIRO, L.S., 1975. Food efficiency in relation to estimated growthof body components in cattle. Anim. Prod. 20, 315.SMI1l1, G.M., FITZHUGH, H.A.(Jr.), CUNDIFF, L.V., CAR1WRIGHT,T.C. & GREGORY, K.E., 1976. A genetic analysis of maturingpatterns in straightbred and crossbred Hereford, Angus and Shorthorncattle. J. Anim. Sci. 21, 588.THIESSEN, R.B., TAYLOR, St.C.S. & MURRAY, l, 1985. Multibredcomparisons of British cattle. Variation in relative growth rate, relativefcod intake and food conversion efficiency. Anim. Prod. 41, 193.

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Growth and efficiency of young Brahman, Bonsmara and Drakensberger bulls

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Growth and efficiency of young Brahman, Bonsmara and Drakensberger bulls

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