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

The productive performance of first-lactation cows is a crucial indicator of their overall productive potential and health. This is also linked to milk production in subsequent lactations and the cow’s productive performance, longevity, and ability to live a long life. One of the affecting factors is optimal calf rearing where optimal growth and development should be ensured, as this influences subsequent reproductive performance, such as services per conception, age at first breeding or calving, and lifetime productive performance. Average daily weight gain (ADG) and feed intake of pre-weaning calves is a focus area, as they are crucial indicators of animal growth and development. These factors have great consequences on the subsequent production performance. However, existing studies regarding the precise relationship between ADG and feed intake of pre-weaning calves and their production performance is inconclusive. It has been demonstrated by several studies that enhancing the ADG of pre-weaning calves can have a substantial effect on first-lactation performance. In contrast, other studies have demonstrated that such increases in daily weight gain does not necessarily lead to marked improvements in first-lactation performance. To take this further, the cited study aimed to investigate the effects of daily weight gain and feed intake of calves on first-lactation milk yield and composition using the convincing statistics of a meta-analysis.

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 yield data to gain insight into the effects of pre-weaning 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/day. 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 modelling of milk protein yield revealed that ADG and LDMI exerted a significant influence, whereas the effect of SDMI remained insignificant.

Conclusions: The study confirmed the important influence of ADG on the future lactation performance of calves and indicated that this positive correlation persisted without an evident plateau within the observed range of the study. Moreover, the study indicates that LDMI could enhance first-lactation production performance, particularly when it is within a specific range (here, pre-weaning LDMI of 0.79–0.80 kg/day) to achieve the highest production performance. Further multivariate modelling analyses revealed that ADG is pivotal in regulating production performance during the first-lactation period, exerting a more significant influence than feed intake alone. Thus, the precise regulation of ADG and LDMI levels can enhance production performance during the first-lactation period, which should be the focus of further research.