How milk allowance affects milk and starter intake, behaviour and weight gain in dairy calves
If conventional milk feeding rates of 10% of a calf’s birth weight are still being used with an aim to stimulate solid feed intake, calves are likely to experience hunger and lower growth rates. Dairy farms are increasingly choosing to feed calves higher planes of pre-weaning nutrition to support greater growth. If these higher feeding planes are combined with additional management to increase starter intake prior to weaning, such as using gradual weaning methods and social housing, they will result in improved weight gains and better calf welfare.
In their research entitled, “The effect of milk allowance on behavior and weight gain in dairy calves,” Rosenberger, et al. studied the short- and long-term effects of a variety of milk allowances on feed intake, behaviour and body weight. They also reviewed calf management interventions required if higher planes of pre-weaning nutrition are being applied.
Key takeaways from the research
Milk intake of dairy calves fed ad libitum increases with milk allowance.
Calves on restricted feeding schedules exhibit signs of hunger and stress both prior to and during weaning.
Calf starter intakes are higher in calves allowed less milk, but with proper weaning management, calves fed higher planes of nutrition can have a smooth weaning transition.
Calves fed higher planes of pre-weaning nutrition gain more weight and this higher body weight can be maintained after weaning with proper management.
Fifty-six Holstein calves were randomly assigned to 1 of 4 feeding treatments (6, 8, 10 or 12 L/d) of whole milk. At day 42, their milk allowance was reduced by half, followed by an additional reduction of 20% per day, beginning at day 50. All calves were were fully weaned by day 55. Throughout the study, calves had ad libitum acces to both hay and starter feed.
Body weights were measured bween 2 and 10 weeks of age. Daily intakes of milk and starter were recorded, and unrewarded trips to the automated feeder were counted as well. Average daily gain, feed ratio and body weight were recorded throughout the study and weekly health checks were performed.
Milk consumption: Milk intake did increase with milk allowance, although none of the calves consumed to the limit of their allowance. For example, on average, 5.66L p/d was consumed by the 6L calves and 9.4L p/d was consumed by the 12L calves, prior to beginning step-down weaning.
Average milk consumption of dairy calves prior to step-down weaning
Rewarded and unrewarded visits to the feeder: Calves allowed less milk had more unrewarded visits to the feeder than those with a higher milk allowance (averaging 11.1 p/d for the 6L calves compared with 0.4 p/d for the 12L calves, pre-weaning). These unrewarded visits are indicative of hunger, which is a finding supported by previous studies. While unrewarded visits did increase during weaning for all treatments, calves with a higher milk allowance still had fewer unrewarded visits.
Calf starter intakes: Prior to weaning, intake of calf starter was higher for calves fed less milk. For example, the 6L calves consumed 0.25 kg/d whereas the 12L calves consumed only 0.05 kg/d. While differences in starter consumption between the treatments continued during weaning (6L calves averaged 1.15 kg/d compared to the 12L calves at 0.54 kg/d), there was no difference in starter consumption after weaning, with all treatments consuming almost 3 kg/d. As consuming more starter prior to weaning can ease the transition from milk to solid feed, management is required to stimulate interest in solid feed. The present study utilised several techniques to do so including using a step-down weaning process, providing access to forage, and housing calves socially. Socially housed calves have less phobia of new foods and tend to have higher pre-weaning starter intakes.
Average starter intake in calves fed different amounts of milk
Growth in the short- and long-term: Average daily gain was higher in calves fed more milk, with the 6L calves averaging 770 g/d compared to the 12L calves at 900 g/d. The benefits of feeding more milk persisted so over the course of the entire study, average daily gain was higher in calves fed more milk. This is consistent with previous studies. Due to appropriate weaning management, the body weight advantage of the 12L calves remained both during and after weaning. Additionally, feeding higher amounts of milk may have positive effects on both long-term production and reproduction.
Body weight in claves fed different amounts of milk
This study confirms that calves given ad libitum access to milk can indeed consume very high quantities. The high number of unrewarded trips to the feeder for calves with lower milk rations shows that calves fed restricted amounts of milk experience hunger throughout both the pre-weaning and weaning periods. This has serious implications for calf welfare. To decrease stress at weaning for calves fed higher amounts of milk, management techniques to smoothen the transition are important. If managed properly however, the higher average daily gain resulting from a higher pre-weaning plane of nutrition can persist long after weaning.
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