Estimation of Genetic Gain on Growth and Carcass Traits over Direct and Index Selection for Growth and Feed Efficiency of Japanese Black Cattle by computer simulation(Animal Production Science Animal Breeding and Genetics)

概要

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A simulation study was performed for performance traits on 740 bulls and carcass traits on 1,774 progeny in Japanese Black cattle to compare the efficiency of direct and index selection. Performance traits included average daily gain (ADG), final body weight (BWF), metabolic body weight (MWT), feed intake (FI), feed conversion ratio (FCR) and residual feed intake (RFI). Progeny traits were carcass weight (CWT), rib eye area (REA), rib thickness (RBT), subcutaneous fat thickness (SFT), marbling score (MSR), meat quality grade (MQG), meat color (MCL) and fat color (FCL). Direct selection for BWF has resulted larger increase in ADG than direct selection for ADG itself. Correlated responses in CWT, REA, RBT and MSR were higher, while in SFT was lower over selection against RFI than those against FCR. Improvement in ADG or BWF resulting positive correlated responses in MSR and SFT, indicating that selection for rapid gain may favor fatter animals. This study provides evidence that selection against RFI might be better than that of FCR for getting better responses in carcass traits. On the other hand, BWF was better than ADG to be included in selection program for either in aggregate index (economic) selection or single trait selection to achieve better correlated responses.