Estimation of the Genetic and Phenotypic Parameters of Preweaning Growth Traits in the Japanese

Abstract

Preweaning growth traits should be recognized as one of the most important factors in genetic improvement of beef cattle in Japan as well as in USA, Canada, and so on. The genetic and phenotypic parameters of weights and gains from birth to weaning were estimated from 1, 046 records obtained from 1960 to 1976 on the Japanese Black calves in the Tottori National Livestock Breeding Station. The calves were born from 221 dams and 22 sires. The average calving number per dam was 4.7±2.6. The method of analysis of variance used was based on Method III of HENDERSON (1953). The six classifications; sire, dam, sex, age of dam, year and season, and sex by season interaction, were taken into account here. The calculation was done using the program; LSML76, for least-squares analysis written by HARVEY (1976). The results are as follows; 1) The precision in estimation of heritability and repeatability using the whole records from sires having more than 5 calves was higher than that using records from sires having more than either 10 or 20 calves, in terms of the residual variance, and the relative size of the standard error to heritability and repeatability estimate. 2) In the case of the adjusted 30-day weight and the average daily gain (DG) until 30 days, sire component of variance was very small (3.6% and 1.2%, respectively), while the dam component of variance was large (34.0% and 34.3%, respectively). 3) Heritability estimates obtained from paternal half-sib analyses and repeatability estimates from maternal half-sib were 0.43 and 0.26 for birth weight; 0.15 and 0.34 for adjusted 30-day weight; 0.30 and 0.26 for adjusted 180-day weight; 0.05 and 0.34 for DG until 30 days; 0.25 and 0.25 for preweaning DG; 0.27 and 0.18 for DG after 30 days, respectively. 4) Genetic correlations among all weights and gains were very high and positive, 0.67 to 0.99, except for DG until 30 days. It is concluded that the DG until 30 days appears to be a good criterion for selection for maternal ability of dams, while either the adjusted 180-day weight or the preweaning DG is for selection for both growth of calves themselves or sires and meternal ability of dams.