Genetic and environmental influences on beef cattle production in Zambia 2. Live weights for age of purebred and reciprocally crossbred progeny

Abstract

Live weights from birth to 3·5 years are reported for beef cattle reared under ranching conditions in Zambia. The 809 cattle were purebred Africanders, Angonis, Barotses and Borans and the reciprocal crossbreds of the latter three breeds born in 2 years. All animals born in the 1st year and half the males born in the 2nd year grazed natural grassland. The remaining males and all females born in the 2nd year received, in addition, dry season supplementary feed from 1·5 years of age.The interaction of genotype with year-of-birth was important but not the interactions of genotype with management or sex. Purebred progeny of the introduced Africander breed were heavier than the progeny of the indigenous Angoni and Barotse breeds in both year-of-birth groups, but only heavier than progeny of the introduced Boran breed in the first group. On average, the Africander progeny had live-weight advantages of about 16% and 10%, and the Boran progeny advantages of about 12·5% and 5·5% over the purebred Angoni and Barotse progeny respectively. Heterosis estimates tended to increase with age, reaching levels of about 5 to 6% in the Barotse/Boran crosses at and after 1·5 years. Heterosis was not shown by the other crosses. The Barotse and Boran breeds had similar maternal effects which were superior to those of the Angoni breed.

Genetic and environmental influences on beef cattle production in Zambia 4. Weaner production from purebred and reciprocally crossbred dams

“…Thorpe, Cruickshank and Thompson (1979) have shown that Bos taurus-sired F, progeny had relatively greater live and carcass weight advantages over purebred Angoni, Barotse and Boran progeny than did the crossbred progeny of these breeds (Thorpe et al, 1980b;Thorpe, Cruickshank and Thompson, 1980c). Hence, to utilize heterosis fully, Bos taurus crossbreeding should be considered in Zambia.…”

Genetic and environmental influences on beef cattle production in Zambia 3. Carcass characteristics of purebred and reciprocally crossbred castrated males

“…Details of the origins of the data, routine management practices and the environment at the Central Research Station, Mazabuka, have been given by Thorpe et al (1980a) and the specific management of the castrated males (steers) used in this study by Thorpe et al (1980b). The data are records for purebred steers of the Africander, Angoni, Barotse and Boran breeds, and the reciprocal crossbreds of the latter three breeds, born in 1967 and 1969.…”

“…INTRODUCTION PREVIOUS papers in this series have reported the influence of breed and environmental effects on weaner production (Thorpe, Cruickshank and Thompson, 1980a) and have given live weight-for-age estimates for young stock of the indigenous breeds, Angoni and Barotse, the imported breeds Boran and Africander, and the reciprocal crossbreds of the first three breeds (Thorpe, Cruickshank and Thompson, 1980b). This paper reports the carcass characteristics of male castrates of these breed and crossbred types.…”

L'amélioration génétique animale

“…Vaccaro a par ailleurs montré que des vaches importées de race européenne pure produisaient en moyenne, en conditions tropicales, seulement 0,74 génisse de renouvellement (femelles encore en vie au moment de leur première mise bas) au cours de toute leur existence, tandis que des vaches de race européenne pure nées sur place en produisaient 0,98. Thorpe et al (1980 ;1981). La laine angora, ou mohair, est recherchée pour la longueur et la finesse de ses fibres.…”