In the quest to boost nutrition – and subsequent lifetime performance – of preweaned dairy calves, one strategy is to add milk replacer powder to enhance pasteurized whole milk.
Previous efforts to employ this strategy have shown improved preweaning average daily gain (ADG), but raised concerns about suppressing starter grain intake both pre- and post-weaning. Also of concern is the possibility of raising total solids to osmolality levels that cause digestive imbalances and diarrhea.
A team of researchers at the University of Illinois recently conducted a study to discern the best amount milk replacer to use when fortifying whole milk, and the ideal timeframe in which to do so. A total of 45 calves were fed a liquid ration for 59 days in three different feeding groups:
- No supplement – 5 liters of pasteurized whole milk with no added milk replacer powder from days 3-56, followed by a step-down to 2.5 liters per day for days 57-59. Total solids: 31.9 kg.
- Short-term supplement – 5 liters of pasteurized whole milk for days 3-9; an added supplement of milk replacer powder for days 10-41; and removal of the supplement from days 42-56; and a step-down to 2.5 liters per day, also with no supplement, for days 57-59. Total solids: 42.3 kg.
- Long-term supplement -5 liters of pasteurized whole milk for days 3-9; an added supplement of milk replacer powder for days 10-56; and a step-down to 2.5 liters per day that included the added milk replacer powder. Total solids: 47.7 kg.
All calves were weaned on day 60 and the study concluded on day 75. When milk replacer was added, the amount was based off of previous research indicating that 18% solids was the “safe” upper bound without issues related to osmolality. So, milk replacer solids were added to the pasteurized whole milk, to achieve a total solids limit of 18%.
Throughout the study, calves had free-choice access to a starter total mixed ration formulated using a base of corn, barley, soybean meal, and fish meal, combined with 8% chopped second-cutting alfalfa hay. The diet was formulated for calves with a birthweight of 60-70 kg. to achieve a target ADG of 0.75 kg. per day.
The results, published in the Journal of Dairy Science, showed:
- Starter feed intake was significantly higher in the preweaning period for calves that received no supplement, but did not vary significantly between the three groups in the postweaning period.
- Calves that received the long-term supplement showed significantly lower starter intake at weaning time, but only for the first week, from days 56-62.
- Total dry matter intake throughout the milk-feeding period was lowest in the non-supplemented group.
- Calves with no supplement had the lowest weaning bodyweight, overall hip height, and final bodyweight.
- The long-term supplemented calves had fewer health-related issues throughout the study.
The researchers concluded that while supplementing with milk replacer until the end of the milk-feeding period resulted in lower starter intake around the time of weaning, overall it was the most beneficial approach in terms of calf growth and health. Removing milk replacer supplementation midway through the preweaning phase, or not using it at all, decreased the ADG of calves.
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