Beef cattle producers with long calving seasons could see an increased risk of calf mortality, according to a recent study from the University of Calgary.
“We looked at the correlation between the length of the calving season and mortality, and for every extra day, the mortality between a week of age and weaning went up by half a per cent,” said Dr. Claire Windeyer, who began surveying calf management practices in more than 250 cow-calf herds last summer.
“It does have impacts on your bottom line at the end of the day.”
The risk is a small one, though. In the herds surveyed, calf mortality rates were between one and two per cent.
“A half a per cent of that is a very small increment,” she said.
But longer calving seasons have other implications on calf performance that can’t be ignored, said Windeyer. Most producers had a six- to 12-week calving season, but some calved over the course of six months, leading to “exhaustion of the environment.”
“If you’re calving into the same area over a six-month period, you’re going to have buildup of manure, waste feed, and mud, especially this time of the year. You really start working that environment quite hard.”
In that environment, calves have increased exposure to pathogens, such as the bugs that cause scours, and that can lead to significant financial losses.
“If you have a newborn calf being born into a pasture that’s had calves on it for the last three to six months, that cow is going to be exposed to a lot more pathogens than the first calf born,” she said. “You get more and more challenges in the environment the longer that season goes on.”
Timing of calving also played a role in the risk of calf mortality, depending on location, facilities, and weather, she said.
Timing of calving is also key and Windeyer found March was the worst time for bovine respiratory disease.
Producers who calved in that month had six per cent more respiratory disease in their herds compared to ranches that calved in January and February. The lowest incidence of respiratory disease was during May and June calving.
“In March, you don’t know what the weather is going to do. In January and February, at least you can anticipate some cold, dry weather,” she said.
“It’s all about having the appropriate facilities to be able to manage… the weather that does arise in the season that you’re calving.”
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Colostrum also key
Colostrum is also critical for calf performance, said Windeyer.
“We all know they’re born naive and relatively unprotected, and that colostrum contains not only important antibodies but also good calories, minerals, vitamins, and other immunity components.”
Producers who checked their cows’ udders to make sure the calves were feeding saw a 35 per cent decrease in mortality in the first seven days of life, while those who provided colostrum to calves saw a 24 per cent decrease in mortality between one week to weaning.
Frozen beef cow colostrum can be a good alternative to fresh for producers who need to supplement their calves’ diets, but Windeyer cautions against dairy colostrum and other supplemental products.
“The quality of good dairy colostrum is usually poorer than beef colostrum,” she said. “It’s much more dilute than what our beef cows produce, so if you’re using dairy colostrum, you need to get a lot more to get enough antibodies in it.”
And for some replacement products, calves need to drink up to 16 litres to gain the right amount of necessary antibodies.
“No beef calf is going to drink 16 litres in the first 24 hours.”
Veterinarians can check the quality of the colostrum to make sure it meets the nutritional needs of newborn calves.
“Not all colostrum is created equal, and you can’t always tell just by looking at it. If it’s more thick, it tends to be better quality, but that’s not always the case.”
Producers should have replacement colostrum products on hand and “be wary” of their storage methods for frozen colostrum.
“If it sits on the counter for half a day and then you stick it in the freezer, the quality of that colostrum has gone down substantially,” said Windeyer. “After about two hours, the bacterial growth in that colostrum really ramps up. If you’re going to store colostrum, put it in the freezer as quickly as possible.”
Producers who used frozen colostrum from off their farm saw a 68 per cent increase in calf mortality within the first 24 hours — likely a result of scrambling to find a source of colostrum, said Windeyer.
“By the time you get it into the calf, that calf is probably quite a bit older than it should have been when it got its first dose of colostrum,” she said.
“Their guts start closing within four hours, and within 24 hours, they’re not absorbing any antibodies. The sooner you can get it in them, the better.”