Early Life Events and Long-term Effects on Future Calf Perfomance
Your cows have the best chance of reaching their genetic potential for lifetime milk yield if you ensure they get plenty of high-quality nutrition as heifer calves during the first few weeks after they are born, research shows.
In recent years, the dairy research community has focused attention on intensified milk feeding. Studies have included how to best manage a calf's nutrition, nutrient intake and weaning. Consensus among researchers puts value on supplying more nutrients from milk or milk replacer. There are also arguments for improving welfare status by following the same concept.
Improving nutrition suggests feeding calves for a much higher specific rate of daily gain than previously considered.
Research by Cornell University scientists bears this out. Published earlier this year in the Dairy Science Journal, their findings are based on data from 1,900 heifers collected over a 10-year period from two different herds.
In both herds, heifer calves received large quantities of high-quality milk replacer. Milk replacers used during the observation period were both commercially available with 28 per cent crude protein from milk sources and either 15 or 20 per cent fat. The overall objective of the calf nutrition program in the two herds was to double the birth weight of calves by weaning at around 56 days of age.
Among several recorded parameters were: birth weight; date of birth; average daily gain; health; treatment; weaning weight; age at first calving; and milk production for first and subsequent lactations. Data analysis accommodated conditions varying from herd to herd and from environment to environment, and changing over time within a herd.
In one herd, pre-weaning average daily gain was 820 grams. Data analysis showed that for every kilogram of pre-weaning average daily gain, heifers, on average, produced 850 kg more milk during their first lactation. In the second herd, for every kg of pre-weaning average daily gain, milk yield increased by 1,113 kg in the first lactation.
These results indicate increased growth rate improves how well an animal achieves its genetic potential. Although more research will be needed to clarify how this mechanism works, increased nutrition in the first few weeks of a heifer's life improves her lifetime lactation milk yield.
This study identifies nutrition and management of the pre-weaned calf as major environmental factors influencing expression of the animal's genetic potential-at least for milk yield. Previous research postulated some biologically active factors present in whole milk might be responsible for the improved performance. Increased milk production was observed solely in the heifers fed whole milk but not calves fed a milk replacer.
In the Cornell study, both herds were fed a high-quality milk replacer. It showed enhancing growth through increased milk replacer intake could also support improved milk yield in future lactations.
The key here is the milk replacer's density and nutrient quality. Study data indicate the milk replacer's digestibility, protein quality and protein level, along with total energy intake, appear critical to generate the milk response.
On the two farms involved in this study, calves born during winter produced, on average, less milk during their first lactation than calves born during summer. Considering calves were fed constant levels of milk replacer throughout the year, these observations might be related to energy intake above maintenance.
This is why your calves can benefit during colder months if you compensate for their increased energy needs. Other research shows calves respond best when they get a higher volume of a balanced milk replacer supplying calories from protein, fat and lactose rather than from just one nutrient.
Minimizing anything that reduces a calf's ability to achieve superior average daily gains, especially before weaning, can enhance future performance. This study shows how you can potentially profit by spending more time and resources on heifers at this early stage of life.
To positively influence lifetime performance:
Mario S. Mongeon is OMAFRA's livestock specialist at the Alfred Resource Centre, Alfred, Ont. Reference: Pre-weaning milk replacer intake and effects on long-term productivity of dairy calves. J F. Soberon , E. Raffrenato , R. W. Everett ,1 and M. E. Van Amburgh. Journal of Dairy Science 95 :783-793.
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