Crossbreeding beef cattle in Western Uganda 3. Genetic analysis of body weight

Abstract

SUMMARYGenetic influences on body weights, taken at three-monthly intervals from birth to two years, were measured in the progeny of Angus, Boran and Red Poll bulls mated to Ankole, Boran and local Zebu cows. At two years old, progeny of Angus and Red Poll sires were 9% heavier than progeny of Boran sires. Progeny of Boran dams were 15% heavier than progeny of Zebu dams and 8% heavier than progeny of Ankole dams at two years. Differential performance by progeny of Ankole dams in different years suggested that genetic × environment interaction might be of some importance, and indicated the necessity of testing breed types over several years. Low and variable heritability estimates of weight-for-age up to two years old, and significant hybrid vigour effects on weight, indicated that in this environment, exploitation of hybrid vigour could be of great importance. Repeatability estimates for calf pre-weaning weights averaged 0·42.

Crossbreeding beef cattle in Western Uganda 6. A note on hybrid vigour in Red Poll–Boran crosses

“…The estimates of hybrid vigour effects on early weights support the previous indirect evidence (Trail et al, 1971a) that hybrid vigour was of importance in this environment. In his review of hybrid vigour in beef cattle, Mason (1966) noted that, in the experiments on crosses between Brahman and British beef breeds in southern U.S.A., the advantage of the crosses in weaning weight was 10 to 16%.…”

“…RECENT work in south-west Uganda (Trail, Sacker and Fisher, 1971a) involved the use of Angus, Boran and Red Poll bulls on Ankole, Boran and Zebu cows. The difference between the weight-for-age of Boran purebreds and that of all other combinations suggested hybrid vigour to be of importance in this environment.…”

Quantitative genetics and the evolution of ontogeny: I. Ontogenetic changes in quantitative genetic variance components in randombred mice

“…Atchley & Rutledge (1980) also found no significant age-related increase in sex-corrected heritability for trunk circumference while tail length's heritability was significantly positively correlated with age. Agricultural genetic studies of weight in cattle (Mavrogenis, Dillard & Robison, 1978;Trail, Sacker & Fisher, 1971), sheep (Dzakuma, Nielsen & Doane, 1978;Mavrogenis etal. 1980;Martin e<a£.…”

Crossbreeding beef cattle in Western Uganda 4. Calving percentage and mothering ability

“…Indications of the influence of hybrid vigour on pre-weaning weights of progeny of F x dams were calculated by the method described by Trail, Sacker and Fisher (1971b), and are shown in Table 3. Effect as % of mean -11-6 2-5 4 1 6-2 5-4 8-2…”