| Popis: |
Variance components due to direct and maternal effects were estimated using data recorded on 740 Japanese Black cattle during the period from 1971-2003. Traits studied were feed intake (FI), feed conversion ratio (FCR), residual feed intake (RFI), average daily gain (ADG), metabolic body weight (MWT) at the mid point of the test period, and body weight (BWT) at the finish of the test (345 days). Data were analyzed using six alternative animal models (direct and including or excluding associated maternal effects). Direct heritability estimates from the model including direct and all the maternal effects were 0.21±0.03 for FI, 0.16±0.05 for FCR, 0.15±0.05 for RFI, 0.18±0.09 for ADG, 0.45±0.03 for MWT and 0.36±0.02 for BWT. Maternal heritability estimates were small and significantly different from zero for only RFI (0.03±0.01), MWT (0.03±0.01) and BWT (0.08±0.04). Antagonistic relationships were observed between direct and maternal genetic effects for FCR and growth traits. The estimates of direct heritability for feed efficiency traits were reduced up to 37% when maternal genetic and maternal environmental effects were considered in the model. The results showed that an antagonistic relationship existed between direct and maternal genetic effect for FCR and growth traits, which indicates that maternal effects should be accounted for these traits in genetic evaluation system. |
