Influence of non-genetic factors on growth traits of Horro (Zebu) and their crosses with Holstein Friesian and Jersey cattle

Abstract

The present study was carried out to estimate genetic parameters of pre-weaning weight (birth, weaning and pre-weaning weight gains) of Horro cattle and their crosses (Horro-Friesian (HF) and Horro-Jersey (HJ)) at Bako Agricultural Research Center. The data used in the study included pedigree and weight records of animals born between 1980 and 2008. Genetic parameters were estimated by ASREML. Direct heritability estimates from univariate analyses of the best model for each trait were: 0.68 ± 0.09 for BW, 0.53 ± 0.097 for WW and 0.29 ± 0.08 for DG, respectively. Direct maternal heritability estimates were BW (0.12 ± 0.10), WW (0.21 ± 0.08) and DG (0.21 ± 0.07), respectively. The ratio of permanent maternal environment was 0.17 to 0.18 for BW, 0.018 to 0.03 for WW, 0.016 to 0.023 for DG, respectively. Direct- maternal genetic correlations were: -0.76, -0.71 and -0.89, for BW, WW and DG, respectively. High direct heritability estimates observed for birth weight indicated that in Horro and their crosses faster genetic improvement through selection is possible for this trait. However, the results suggested that both the direct and maternal effect should be taken into account simultaneously during selection because of the high negative direct and maternal genetic correlation. From this study, it was suggested that estimation of genetic parameters for pre-weaning growth traits should be carried out separately for Horro and their crosses