Impact of selection of dual purpose cattle on secondary traits
2001
Pribyl, J. | Pribylova, J. (Vyzkumny Ustav Zivocisne Vyroby, Prague-Uhrineves (Czech Republic))
The selection of dual purpose cattle is simulated by selection indices. It includes milk (amount of milk, milk protein) and beef production (daily gain, valuable meat cuts, growth capacity, feed conversion) and secondary traits (fertility, longevity, mastitis, calving difficulty). Partial breeding values for traits are combined into selection indices. Economic values of 1, 1.5, 2 and 4 multiples of results of the profit function are assigned to secondary traits in the indices. In the case of basic variant, the genetic gain of milk production is 58 kg and effects of selection on milk and beef production and secondary traits are at a ratio 81 : 20 : -1. The most important traits in the indices are amount of milk, feed conversion, milk protein content and daily gain. Most secondary traits show worse values. In the case of 1.5 multiple overevaluation of secondary traits, the genetic gain is 51 kg of milk and ratios of selection are 72 : 19 : 9. In the case of 2 multiple overevaluation the genetic gain of milk is 43 kg and ratios of effects for groups of traits are 59 : 18 : 23. In the case of 4 multiple overevaluation the genetic gain is 15 kg and the ratios are 17 : 10 : 73. With overevaluation of secondary traits, the ratio of milk to beef production is decreased.
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