The objective was to determine the optimum percentage of Bos taurus (BT) genes on age at first-calving (AFC), days to first postpartum service (DFPS), days open (DO), and calving interval (CI) of Zebu cows and their crosses with European breeds. Calving records (n=1,704) from 570 cows with percentage of BT genes ranging from zero to 100, were collected from a commercial farm in tropical Mexico. The cows' AFC had a quadratic effect (P<0.05) as the percentage of BT genes increased and reached a minimum (31 mo) at 49% of BT genes. The cow's DFPS (143 d), DO (196 d), and CI (15.7 months) reached a minimum at 0% of BT genes and increased linearly (P<0.05) as the percentage of BT increased. The inclusion of BT genes at around 50% improved AFC; however, any percentage of BT genes beyond 0% increased DFPS, DO, and CI.

M. Diaz, J. G Garcia, R. Nunez, R. Lopez, P. A Martinez

Proceedings of the World Congress on Genetics Applied to Livestock Production, Volume , , 01.67, 2006
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