Abstract

Records of first calving age and total milk yield in the first lactation of Local Indian Dairy (Zebu) and Holstein Friesian purebred cows and the various crosses between them from a single farm was studied. Heterosis in the F^ generation was 27.60 % for milk yield and -7.86 % for first calving age. Milk yield dropped by 3 8 . 9 ^ from F^ to F generations based on unadjusted data. When least square estimates for both the traits were regressed on proportion of Holstein Friesian level of inheritance , a curvilinear equation best fitted the relationship. Both traits improved with increasing Holstein Friesian inheritance in the crosses up to 77 % and declined beyond this level . Based on a marginal analysis, the optimum range of Holstein Friesian inheritance was between 58 % and 77%

S. Sivarajasingam, A. R Kumar

Proceedings of the World Congress on Genetics Applied to Livestock Production, Volume XI. Genetics of reproduction, lactation, growth, adaptation, disease, and parasite resistance., , 529–534, 1986
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