Report on visit to East and Southern Africa. April 4 - June 14, 1986

The three aspects of breed performance assessment considered evaluation as purebreds, evaluation of (F1) crosses with other breeds and evaluation as part of composite breeds. Performance evaluation were made for the indigenous African breeds, via Boran, Angoni, Tuli, Africander, Mashona and Tswana in Kenya, Uganda, Zimbabwe, Botswana and Zambia. The objective of the visit was to make recommendations on the need for future breed evaluation studies in Africa and on the scope of greater utilization of indigenous breeds

Comparative productivity of the Brahman and some indigenous Sanga and Bos indicus breeds of East and Southern Africa

Major evaluation studies involving cattle breeds indigenous to eastern and southern Africa and their crosses are summarised. Comparative productivity of the Boran, Mashona, Tuli, Barotse, Angoni and Africander relative to the Brahman in designated high- and low-performance environments free of the tsetse fly were derived. In general, the indigenous breeds are highly productive, largely due to high reproductive rates. The most productive breeds in the high- and low-performance environments were the Tuli and Mashona, respectively. The Africander was the least productive breed in both environments. Breed-environment interactions were apparent. Crossing between indigenous breeds and Bos taurus or Brahman did not improve maternal performance above the most productive indigenous breeds. However, the growth rate of progeny increased. Thus crossbreeding programmes using the superior indigenous breeds as dams and exotic Bos taurus or Bos indicus as terminal sire breeds are recommended where controlled mating is feasible. The development of a composite breed is currently being evaluated in Botswana. There is a need to evaluate crosses between the most productive Sanga breeds, e.g. Tuli and Mashona, and Bos indicus breeds, e.g. Brahman and Boran, especially in stressful environments where better adaptation is advantageous. Furthermore, it is suggested that future evaluations should include not only production traits but also adaptive traits such as parasite resistance and heat tolerance, and ideally should incorporate several nutritional levels, so that results can be extrapolated more readily to other environments

The cosmid CSSM25 assigns syntenic group U2 to bovine Chromosome 9 and is localized to ovine Chromosome 8

The cosmid-derived microsatellite CSSM 25 has previously been shown to map to bovine syntenic group U2 by link-age and hybrid somatic cell analysis. We have mapped the cosmid by fluorescent in situ hybridization to bovine Chromosome (Chr) 9q17-21 and ovine Chr 8q17-21 and hence assign U2 to Chr 9 in cattle. Bovine Chr 9 and ovine Chr 8 show strong banding pattern homology, and the localization of CSSM 25 to the same region confirms the strong conservation of gene locations on these chromosomes

Biochemical Genetics of Glycogenosis Type II in Brahman Cattle

Glycogenosis type II is an inherited lysosomal storage disorder caused by acid α-glucosidase deficiency. The disorder is inbred in Brahman cattle, and the incidence of carriers in Australian herds averages 15%. Affected animals are lethargic and die typically in the eighth or ninth month after birth, A complete lack of acid α-glucosidase synthesis was demonstrated in cultured fibroblasts and muscle tissue of affected animals. Moreover, the tissue was found to be devoid of acid α-glucosidase mRNA. Gross abnormalities of the acid α-glucosidase gene itself were not detected by Southern blot analysis. These results suggest Brahman glycogenosis type II to be caused by a point mutation or a micro deletion/insertion in the acid α-glucosidase gene