University of Nebraska - LincolnDigitalCommons@University of Nebraska - LincolnRoman L. Hruska U.S. Meat Animal ResearchCenter

U.S. Department of Agriculture: AgriculturalResearch Service, Lincoln, Nebraska

1993

Estimates of Mature Weights and Maturing Ratesfor Breed CrossesThomas G. JenkinsProduction Systems Research Unit, U.S. Meat Animal Research Center

Miroslav Kaps

Larry V. CundiffU.S. Meat Animal Research Center, Larry.Cundiff@ars.usda.gov

Calvin L. FerrellNutrition Research Unit, U.S. Meat Animal Research Center

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Jenkins, Thomas G.; Kaps, Miroslav; Cundiff, Larry V.; and Ferrell, Calvin L., "Estimates of Mature Weights and Maturing Rates forBreed Crosses" (1993). Roman L. Hruska U.S. Meat Animal Research Center. 331.http://digitalcommons.unl.edu/hruskareports/331

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Estimates of MatureWeights and MaturingRates for Breed CrossesThomas G. Jenkins, Mlroslav Kaps, Larry V.Cundiff, and Calvin. L. Ferrell'

Introduction

Recent attempts to increase weight of product marketedfor a cow herd have emphasized increasing the weights ofprogeny that are to be sold. Previous investigations haveidentified sufficient variation between and within breeds ofcattle to enable the producer to set the desired level ofgenetic potential for size in the cow herd and rate of growthin the progeny. The assumption has been that a positiverelationship exists between mature size and productivity.Researchers are beginning to question if this assumption iscorrect. It has been reported that mature size is negativelyrelated to productivity. However, higher productivity hasbeen related to faster maturing rate (the rate at which ananimal attains its mature body mass). Breeds of cattlewould be expected to vary with regard to the combination ofmaturing rate or mature weight that would be most benefi-cial for production. With the diversity in genetic potential forweights available, today's producers should be able to setthe optimum mature weights and maturing rates for theirproduction goals within a defined production environment.Exploitation of genetic differences among the breeds forthese traits has been suggested as a way that beef produc-tion efficiency could be improved. Exploitation of these dif-ferences requires characterization of measures of growththrough maturity for a large number of breeds or otheruniquely defined populations of cattle. Estimates of growthparameters from birth through 15-18 months are readilyobtainable. Estimates of mature weights and rates ofmaturing for diverse populations are limited. The objectiveof the present investigation was to estimate means forbreeds for several measures of growth through maturity,thus providing an information base characterizing diversebreeds of cattle with regard to mature weights, rates ofmaturing, and heights.

Procedure

Data that were analyzed for this report were collected aspart of the Germ Plasm Evaluation Program conducted atMARC,a comprehensive investigation conducted to charac-terize production performance for diverse breeds of cattle.The data for weight, height and condition scores of F1females from the first three cycles were produced from 1970through 1976. The F1 females used in the study were pro-duced by artificially inseminating either Angus or Herefordcows with semen from Angus, Brahman, Brown Swiss(European and American), Charolais, Chianina, Gelbvieh,Hereford, Jersey, Limousin, Maine Anjou, Pinzgauer, RedPoll, Sahiwal, Simmental, South Devon and Tarentaisebulls. More detailed information describing how sires fromthe different breeds were identified for use has been previ-ously reported. Weights were recorded at birth, weaning, at28-day intervals from weaning to approximately 24 mo ofage and then twice yearly until a cow was removed from theproject. Postweaning, heights at the hip, and body condi-tion scores (9 point; 1 = extremely emaciated, 9 = extremelyobese) were recorded at each weighing. Calves born intothe project were raised on pasture with their dams andweaned at approximately 200 days of age. Following wean-

'Jenkins is a research animal scientist, Production Systems ResearchUnit, MARC; Kaps was a visiting scientist from Yugoslavia; Cundiff isthe research leader, Genetics and Breeding Research Unit; and Ferrellis the research leader, Nutrition Research Unit, MARC.

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ing, the heifers were maintained in a drylot for approxi-mately 168 days. Multiparous cows were sustained oncool- and warm-season grass pastures during the summermonths. During the winter, legume and grass hay was pro-vided to the cows. Weight, height and condition measure-ments were recorded prior to initiation of the breeding sea-son and at time of weaning. Records from individuals thatwere open two consecutive years were removed from theevaluation. Animals dying prior to accumulating a minimumof 24 measurements of weight were deleted from the dataset. Animals were not removed based upon a growth crite-rion. These edits resulted in a set of records collected from1577 individuals that were used for analyses. The numberof sires for each of the breeds were: Angus 32; Brahman17; Brown Swiss 11; Charolais 25; Chianina 17; Gelbvieh11; Hereford 32; Jersey 32; Limousin 12; Maine Anjou 15;Pinzgauer 9; Red Poll 16; Sahiwal 6; Simmental 26; SouthDevon 29 and Tarentaise 6; respectively. For greater detailconcerning management protocol of cattle assigned to theGerm Plasm Evaluation Program, see previous progressreports.

Breeds included in the project were identified for evalua-tion to characterize the diversity in potential for productiontraits such as growth rate, age at puberty, and milk produc-ing ability. To minimize the effect of variation in body condi-tion on weights of animals within each breed attributable toindividual animal differences in milk production, weight mea-surements recorded after 20 mo of age were adjusted to aconstant condition score. Growth curves (weight-age rela-tionship) were estimated for the individual animals using therecorded weights. Nonlinear regression was used to fit ani-mal weights to a growth function commonly referred to asthe Brody growth model. An assumption associated withthis model is that the rate of growth along the growth curveis proportional to the amount of growth remaining to beattained. Parameters of interest estimated from this modelinclude the asymptote of the curve (A) and the rate constant(k), respectively, which previously have been used todescribe mature weight and rate of approach to matureweight of living organisms.

Results

Improvement in production characteristics measured byweight may result from selection within breeds or by usingbreed substitution to exploit direct genetic variation amongbreeds. Based upon previous research, immediateimprovement could be realized by breed substitution.However, within breed selection represents the beneficialcourse of action to maintain genetic diversity among ourcattle breed populations. Breed means and characterizingtraits of interest are reported in Table 1. Information suchas this can be used to identify the breed resources for themost appropriate breeding program. In addition to matureweights, maturing rate and height at maturity, weights atbirth, 200 day, 365 day, and 500 day are reported for the 16sire breeds. Weights for the traits averaged over breeds ofsire were 77, 427, 645, 741, 1140 Ib for birthweight, wean-ing weight, yearling weight and 500 day weight. The aver-age weight of maturing was 5.6% and the average height atmaturity was 50 in. Cows sired by Chianina bulls and thosesired by Maine Anjou bulls exhibited heavier mature weightsand attained these weights at relatively slow rates (maturing

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rates approximately 16% less than the average of the 16 tion with results from other studies, producers should bebreeds). The mature weight average of the Jersey sired able to identify breeds of animals which are most suited tocows was approximately 18% less than the pooled breed serve a paternal, maternal, or general purpose role in theaverage and, as indicated by their maturing rate, they beef industry today. The ability to exploit differences amongattained their mature weight rapidly. The Brahman, breeds to establish desired mature sizes or rates of matur-Hereford, Sahiwal and Tarentaise sired females grew to a ing is evident from the diversity among the sire breedsheavier mature weight than the Jersey sired female but the reported in this study. Using mating systems to effectivelymaturing rate averages for these breeds were similar to that use this genetic diversity should provide the producer anof the Jersey. Using information from this study in combina- effective means to improve the efficiency of beef production.

Table 1- Mature weight, maturing rate, height at maturity, and weights at various ages by sire breed

Weight (Ib).Maturing Heightat

Sirebreed N Birth 200d 365d 500d Maturity rate. maturity(in)(k*100)

Angus 122 75 394 613 715 1126 96.4 49.2Brown Swiss 107 84 427 638 743 1144 98.2 50.4Brahman 94 81 462 715 823 1210 108.9 52.0Charolais 100 81 451 651 750 1219 89.0 50.8Chianina 67 87 429 653 770 1296 83.9 53.5Gelbvieh 65 84 440 649 761 1185 94.6 50.4Hereford 173 73 431 653 737 1100 107.1 48.4

Jersey 99 62 376 552 634 935 108.9 48.4Limousin 136 75 422 618 704 1135 89.3 50.4

Maine Anjou 67 90 429 667 779 1283 87.5 51.2

Pinzgauer 85 92 451 719 805 1155 117.8 50.4Red Poll 81 81 403 592 695 1124 87.5 49.2Sahiwal 83 75 431 658 748 1069 110.7 50.0Simmental 132 81 444 661 752 1131 101.2 50.8South Devon 93 77 416 627 719 1126 96.4 52.0Tarentaise 73 75 442 701 783 1142 112.5 49.6

Pooled 1577 77 427 645 741 1409 5.6 50.0

.Maturing rate of each sire breed is expressed relative to the pooled estimate of 5.6.