Effects of preweaning calf daily gain and feed intake on first-lactation performance: A metaanalysis

This study aimed to investigate the effects of daily weight gain and feed intake of calves on first-lactation milk yield and composition using a metaanalysis. A total of 57 treatments from 18 studies were included in the study. Univariate and multivariate mixed models were constructed for calf ADG, liquid DMI (LDMI), starter DMI (SDMI), 305-d milk, milk fat, and protein yields data to gain insight into the effects of preweaning calf daily gain and feed intake on first-lactation performance. Univariate mixed models revealed ADG was significantly positively correlated with 305-d milk, milk fat, and protein yields during the first-lactation period. This indicates that ADG is a significant determinant of enhanced production performance during the first-lactation period. Furthermore, a significant quadratic correlation was observed between LDMI and 305-d milk, milk fat, and protein yields during the first-lactation period. The optimal performance during the first lactation was achieved when LDMI was maintained at 0.79 to 0.80 kg/d. In contrast, no significant association was observed between SDMI and production performance during the first-lactation period. Further multivariate mixed model analyses demonstrated that, when the effects of the 3 independent variables were considered collectively, only ADG exhibited a significant positive effect on 305-d milk yield and fat production during the first-lactation period. However, the modeling of milk protein yield revealed that ADG and LDMI exerted a significant influence, whereas the effect of SDMI remained insignificant. This study emphasized the significant effect of ADG and LDMI in optimizing the future lactation performance of calves, providing a crucial foundation for the development of scientific feeding management strategies.