A group of researchers with the Provimi nutrition and research center collaborated on a study with a team from the University of New Hampshire in the US looking at the use of differing levels of milk replacer in calf diets, and then evaluating growth before and after weaning and digestion.
The researchers were trying to better understand why digestion and rumen development are delayed in calves getting a diet with high quantities of milk replacer, said corresponding author Mark Hill, ruminant nutritionist at Provimi.
“One of the things that is troubling is that logic would say as you feed more milk the calf will grow faster and it does,” he told FeedNavigator. “But why does the growth slow down?”
Adding more milk replacer to calf diets means they will grow more quickly during the pre-weaning phase, he said. However, the growth slows in the point weaning period and the diets are more expensive.
It appears with the addition of more milk to the diet that the rumen develops more slowly, meaning the calf has a harder time digesting its food post-weaning, said the researchers.
However, the group found that a more moderate milk replacer feeding program may offer the most promise to producers.
“With an aggressive program, the growth of those animals will slow down after weaning but if you [measure] the growth to four months of age they’ll be larger than the conventional calves – they grow so much larger pre-weaning they’re still ahead,” said Hill. “The calves on the moderate program appear to be just as large.”
The study
In the trial, 96 male calves were given one of three milk-replacer-based diets for a period of 42-49 days, said the researchers.
The diets included a control (CON) of 0.44kg of dry matter (DM), 21% crude protein (CP) and 21% fat powder for 39 days which was halved for days 40-42; a moderate diet (MOD) of 0.66kg DM, 27% CP, 17% fat powder for 39 days, which was reduced to 0.33kg DM for days 40-42; and an aggressive (AGG) diet of 0.66kg DM for five days then 0.87kg, 27% CP and 17% fat powder through day 42 when the diet was reduced to 0.43kg DM for days 43-49.
Calves also were given a textured starter diet of 20% crude protein and ad libitum water for the entire 56 days, said the researchers.
Body weight was taken initially and every seven days, hip widths were measured and a body condition score (BCS) was given at the start and every 14 days, they said. BCS was scored from one to five, with one being emaciated and five obese.
Manure was evaluated for consistency daily and fecal samples were collected from sample cows during days 51-56 and analyzed for digestibility, they said.
Results
Calves getting the control diet had the worst performance in terms of average daily gain (ADG), feed efficiency and hip width change, said the researchers. Calves getting the largest amount of milk replacer ate the least starter, had the best ADG and saw the largest change in BCS.
However, calves on the aggressive management plan also had the lowest digestibility of organic matter and neutral detergent fiber, they said. Post-weaning, calves getting the largest amount of milk replacer had a digestion performance that was less than optimal and resulted in slower growth post-weaning than those calves getting the CON or MOD diets.
“When we’re reducing the milk [the calf] is not digesting the starter it is eating, so it’s having some effect there,” said Hill.
Despite the drop in post-weaning digestive ability the calves getting the supplemented amounts of milk replacer remain heavier and larger than the control group calves, he said. However, they are not statistically larger in hip width or weight than the calves getting the moderate diet.
What’s next?
The group is continuing work with milk replacer diets and calf growth said Hill. It is looking to better understand what is happening in the calf’s digestive system.
“There are some ideas that if you weaned the calf slowly over two or three weeks that would allow us to have better growth,” he said. “It appears to work to some degree.”
But not all the inefficiencies have been captured during that weaning process, he said. Their follow-up research will look at the interaction between calf growth, milk replacer use and digestion.
“What we’ve done with those is we’ve looked at digestibility of the diet at multiple points pre-weaning and post-weaning between the moderate and aggressive program,” said Hill. “We’re trying to characterize what that digestibility looks like at different ages and especially in the post weaning calf.”
Source: Journal of Dairy Science
Title: Effect of milk replacer program on calf performance and digestion of nutrients with age of the dairy calf
Authors: C. Chapman, P. Erickson, J. Quigley, T Hill, H. Bateman, F. Suarez-Mena, R. Schlotterbeck