LUBBOCK, Texas — Nutrition and a clean, comfortable environment affect a dairy cow’s average daily gain.
“Nutrition and environment are both important, and we need to do both well,” says Michael Barrow, dean and professor at the Texas Tech University College of Veterinary Medicine, “but often we get more improvement by improving the environment than by improving nutrition.”
When it comes to feed milk solids, the data shows that for every litre increase above four litres a day, dairy farmers can expect to increase their calf’s average daily weight gain by 12, 25 or 45 grams, Ballou said during a webinar hosted by the Dairy Cattle Breeding Council.
“That means a 1.5, 3.1 or 5.6 pound improvement in weaning weight,” he said. “If you’re feeding six quarts of milk instead of four, you can expect to see a 3 to 8 pound improvement in weaning weight.”
Most dairy farmers understand the importance of colostrum management.
“The average daily weight gain of calves increased by about 44 grams per day when they were given good quality colostrum versus no colostrum,” Ballou said. “Delaying the introduction of colostrum by six hours reduced the average daily weight gain by 24 grams.”
When the researchers evaluated calves with a temperature humidity index (THI) below 50 and raised it to 69, average weight gain decreased by about 50 grams per day, the university professor said.
“When temperatures were between 50 and 70 degrees, average daily gain increased as calves moved from cooler temperatures to warmer, more thermally neutral temperatures,” he said.
One study evaluated coop litter containing sand, straw, and shavings versus no litter.
“Without bedding or sand, average daily gain during the winter was significantly reduced compared to when straw or shavings were used,” Ballou said.
Calf nutrition, including starter intake, has a long-term effect on the cow’s milk production.
“Comparing high and low starter intake, this study shows a difference of 1,140 pounds in lifetime milk production,” Ballou said.
“Every additional pound of dry matter intake at weaning increases an animal’s lifetime milk production by approximately 500 pounds,” the university professor said.
“There’s considerable evidence that animals that gain weight in the first six months of life are less likely to be removed from the herd,” he said.
“Calfs with low average daily gain are 3.4 times more likely to be removed from the herd, and calves with medium average daily gain are 2.4 times more likely to be removed.”
Body structure is important for dairy cows at an early age.
“This has a significant impact on lactation performance and survival of the herd,” says Ballou. “Starter intake at weaning is related to average daily gain as well as lactation performance.”
It’s not just a matter of the pre-weaning period, Ballou says.
“The time from birth to puberty is key, so not only do we need to maximise average daily gain in the rearing pen, but we also need to maximise the transition from milk to starter to grower feed,” he said.
A study conducted at Michigan State University looked at three treatments: feeding calves milk replacer, transition milk, or a transitional formula that contained milk replacer and colostrum replacer. These three treatments were offered to calves on days 2 through 4.
“Calves fed transitional milk or conditioned transitional milk had reduced ptosis scores and less inflammation,” Ballou says. “Calves in both groups gained about seven pounds at weaning.”
In one study, calves were fed high concentrations of starch derived from ground corn and oats or whole corn, oats, and cottonseed hulls.
“The ground diet was 43 percent starch, which was reduced to 35 percent in the second diet,” Barrow says.
“The calves fed the ground feed consumed approximately 3.1 pounds of dry matter compared to 4.6 pounds of dry matter for the calves fed the other feed,” he said. “Weaning weights of the calves fed the second feed improved dramatically.”
The researchers captured the animals to observe the ruminal lesions.
“The calves that were fed the ground diet had more severe ruminal lesions than the calves that were fed the second diet,” Ballou said. “To improve this, we need to feed them whole grains, less starch and more easily digestible fiber to reduce ruminal acidosis.”
In a study aimed at improving ruminal pH, calves were fed a control diet, a diet containing live yeast, or a diet containing live yeast with probiotics.
“We found that feeding live yeast improved ruminal pH because live yeast can use lactic acid as an energy source,” Barrow says.
“Fermentable carbohydrates stimulate ruminal development, but they must be done wisely,” he said. “When ruminal acidosis occurs, starter intake declines and average daily gain is suppressed.”
