Genetic and environmental influences on beef cattle production in Zambia 1. Factors affecting weaner production from Angoni, Barotse and Boran dams

Thorpe, W.R.; Cruickshank, D. K. R.; Thompson, R.

doi:10.1017/s0003356100024004

Cited by 13 publications

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“…Differences in the reproductive performance of these breeds have been shown . Similar observations have been made by other workers in southern Africa (Steenkamp, van der Horst and Andrew, 1975;Thorpe, Cruickshank and Thompson, 1980). Calving rates (number of calves born as a proportion of the number of cows exposed to the male) of heifers and non-lactating cows were satisfactory but reconception was depressed in lactating cows, particularly if their calves were born late in the calving season.…”

Section: Introductionsupporting

confidence: 88%

Breed and environmental factors affecting the reconception of indigenous beef cows in Botswana

Buck

Light

1982

Anim. Sci.

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The breeding records of 2710 lactating cows, of the Africander (1208), Tswana (542) and Tuli (960) breeds, were analysed to examine the effects of breed and environment on reconception. The reconception rate of Africander cows (0-56) was significantly lower than that of Tswana and Tuli cows (0-80 and 0-81 respectively) (P<0-01). The environmental effects of ranch, calving year, calving period and age/parity all had significant effects on reconception (Z'<0-01). Interactions between breed and the other main effects were all significant.The Africander is considered to be a breed of lower fertility than the other two Sanga breeds, the Tswana and Tuli, in Botswana. The results are discussed with respect to determining management interventions to improve cow reproductive performance.

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Section: Introductionsupporting

confidence: 88%

Breed and environmental factors affecting the reconception of indigenous beef cows in Botswana

Buck

Light

1982

Anim. Sci.

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“…O efeito desse longo Tabela 1 -Estatística descritiva das variáveis independentes data juliana de parto (DJ), peso do bezerro ao nascer (PN), ordem de parto (OP), altura (H), peso no início do acasalamento (PI), escore de condição corporal no início do acasalamento (ECCI), ganho diário médio durante o acasalamento (GDA) e peso de desmame ajustado (PAJ205) Os resultados obtidos corroboram os encontrados por Teixeira et al (2000), que avaliaram mais de 48.000 parições, em Valparaíso -SP, e observaram os maiores índices de repetição de cria (80%) nas vacas que pariram mais cedo dentro do ano. De acordo com Thorpe et al (1980) e Barcellos et al (1999), vacas que parem no início da estação de parição possuem vantagens em relação às que parem no final, apresentando maiores chances de repetição de cria.…”

Section: Resultsunclassified

Taxa de prenhez de vacas Nelore x Hereford em ambiente subtropical sob restrição alimentar

et al. 2006

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RESUMO -Foi desenvolvido um experimento para identificar os efeitos que influenciam a taxa de prenhez de 117 vacas de corte Nelore x Hereford aos 2 e 20 anos de idade e com diferentes frações gênicas de Nelore (25,0; 37,5; 50,0 e 100,0%), paridas no período de 11/08/03 a 23/12/03 e acasaladas, por monta natural, entre 10/12/03 e 12/03/04. Foram avaliados os efeitos dos fatores data juliana de parto (DJ), peso ao nascer (PN), sexo do bezerro (S) do parto anterior, ordem de parto (OP), altura de garupa (H), peso ao início do acasalamento (PI), escore de condição corporal ao início do acasalamento (ECCI), ganho diário médio de peso durante o acasalamento (GDA), fração gênica de Nelore (FGN) e peso ao desmame ajustado (PAJ205) do parto anterior sobre a probabilidade de prenhez e de concepção. Os dados foram submetidos à análise de regressão logística, por meio do procedimento LOGISTIC do pacote computacional SAS, para identificar os efeitos de cada variável. A média da taxa de prenhez foi de 43,2%. A probabilidade de prenhez e as chances de concepção foram explicadas pelas variações de DJ, PI, ECCI e GDA. A mudança na chance de prenhez para cada acréscimo na variável regressora foi estimada com base na estatística da razão entre chances (odds ratio), determinada por OR = exp(b k ), considerando que chance é a razão entre a probabilidade de o evento ocorrer e a de não ocorrer. Não foram observados efeitos significativos de PN, S, OP, H, FGN e PAJ205. Portanto, para aumentar as taxas de prenhez de vacas de corte, são necessárias melhorias no escore de condição corporal (ECC) no início do acasalamento e no ganho de peso (GP) durante a estação de monta, ambos decorrentes de adequada nutrição pré e pós-parto. Key Words: body condition, calving date, logistic regression, feed restriction IntroduçãoA reestruturação ocorrida nos últimos anos quanto à ocupação dos territórios agrícolas conduziu a pecuária de corte para áreas marginais de exploração. Estas áreas, com limitações de solo e vegetação, têm sido destinadas à bovinocultura de corte por questões econômicas, uma vez que os cultivos de grãos têm sido mais eficientes e rentáveis nestas áreas.

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“…As reproductive and calf live-weight records were available for the dams of these breeding females (Thorpe, Cruickshank and Thompson, 1980a), it was possible to estimate dam/daughter regressions for calving rate and calf weights. The analyses provided estimates of environmental effects for these traits and relationships were derived between subsequent calving rate, and dam live weights and live-weight changes.…”

Section: Introductionmentioning

confidence: 99%

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

Thorpe¹,

Cruickshank²,

Thompson

1981

Anim. Sci.

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Estimates of dam reproductive performance are reported for purebred Africander, Angoni, Barotse and Boran dams, and the reciprocal crossbreds of the latter three breeds, under ranching conditions in Zambia.Mean performances based on a maximum of 1996 records collected over six parities were: calving rate, 65-6%; weaning rate, 62-8%; calf birth weight, 26-6kg; calf weaning weight, 163-6kg; and dam live weight at weaning, 363 0 kg.Purebred Africander and Barotse dams had significantly poorer calving rates, 542 and 57-6% respectively, than the purebred dams of the Angoni and Boran breeds, 69 1 and 66 0% respectively. Reciprocal crossbred dams of the latter two breeds had the highest calving rates, 71-2 and 744%. Heterosis estimates for calving rate were 0-8% for Angoni/Barotse crosses, 7-8% for Angoni/Boran crosses and 10-3% for Barotse/Boran crosses and, for weaning rate, 3-7, 6-7 and 11 5% respectively. There were no differences between reciprocal crossbred dams for calving and weaning percentages. The mortality rate of calves born to crossbred dams was 4 0 % and that of the calves born to purebred dams of the same breeds 4-7 %. Dam status at mating had an important effect on fertility with the calving rate of dams dry at mating, 89-1 %, contrasting with a rate of 39-8% for those dams that were lactating at mating and that had calved late in the season.There were large differences between breeds for calf weights but heterosis estimates were small and nonsignificant. There were no differences between the progeny weights of reciprocal crossbred dams. Sex, date and period of birth, and dam status had significant effects on calf weights.Africander dams had the heaviest, and Angoni dams the lightest, live weights at weaning, 421 1 and 320-7 kg respectively. Heterosis estimates for dam live weights were small and non-significant, and reciprocal crossbred differences were unimportant. Dams which lost most live weight during the dry season, that had extremely light live weights at the beginning of the breeding season or that gained little weight during the breeding season had significantly poorer fertility than other dams.Overall estimates of heritability derived by dam/daughter regression were 0-20 for calving percentage, 0-76 for calf birth weight and 0-72 for calf weaning weight.

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Genetic and environmental influences on beef cattle production in Zambia 1. Factors affecting weaner production from Angoni, Barotse and Boran dams

Cited by 13 publications

References 13 publications

Breed and environmental factors affecting the reconception of indigenous beef cows in Botswana

Breed and environmental factors affecting the reconception of indigenous beef cows in Botswana

Taxa de prenhez de vacas Nelore x Hereford em ambiente subtropical sob restrição alimentar

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

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