Relationships of Growth Rate with Milk Production and Factors Influencing Some Economic Traits in First Lactation of Canadian Holstein Cattle

Abstract

Study on some economic traits of 200 Canadian Holstein female calves was carry out. Data were collected from the herd maintained at Chiang Mai Livestock Research and Breeding Center, born during period of 1991 to 1997. Average daily gain from birth to 3 months (ADGI) positively influenced weaning weight at 3 months (W3) (r = 0.92, P<0.01). Average daily gain after 3 months to 12 months (ADG2) positively influenced weight at 12 months (W12) (r = 0.93, P<0.01). Prediction equation ADG1 and ADG2 were 9.327W3-194.512 and 2.260W12-156.265, respectively. Relationships of weight at 12 months with first lactation 305-d milk yield (305-d MY) was not significant (r = 0.22, P>0.05). The effect of seasons of birth on 305-d milk yield in first lactation were found to be signicant (P<0.05). Years of birth had significant (P<0.01) effects on ADG1, ADG2 and 305-d milk yield. Age at first of calving (AFC) was also significantly influenced (P<0.05) by years of birth.