A researcher at the University of Calgary has found a simple way to test for calf vigour — look for calves that suck.
“Suckle reflex is a really promising indicator of a calf’s ability to consume colostrum,” said Dr. Elizabeth Homerosky, who presented at the 2015 UCVM Beef Cattle Conference.
Colostrum consumption is one of the most important factors affecting pre-weaning health and mortality in beef calves, she said, but a 2009 study estimated that one-third of beef calves in Alberta and Saskatchewan have “suboptimal immunity.”
A calf’s ability to consume colostrum on its own depends on its vigour at birth, which can be impacted by things like dam age, temperature, and calving ease.
“We wanted to develop an on-farm assessment tool that’s really quick and easy — something that you guys can use that’s more accurate and predictive of a calf’s ability to consume colostrum.”
Homerosky tested her assessment tool on 77 calves at a commercial operation in southern Alberta last year. In addition to looking for physical signs of vigour, including the calves’ ability to stand up and consume colostrum on their own, she looked at the calves’ reflexes and gum colour; measured their heart rate, respiratory rate, and temperature; and took blood samples.
During the four-hour monitoring period, about 64 per cent of the calves in the trial stood up and sucked on their own, while 17 per cent sucked when the research team assisted them in finding the udder. The remaining 20 per cent were bottle fed or tube fed.
Calving ease was a pretty good indicator of which category the calves would fall into.
“When we looked at calves that were an easy pull, about 60 per cent sucked on their own,” said Homerosky. “It dropped down to about 35 per cent in calves that were hard pulls, with an increasing proportion that needed to be tube fed or bottle fed.”
But calving ease alone wasn’t the best indicator of calf vigour, she said. Reflexes like suckle strength were “significantly associated” with colostrum consumption.
“Of all the calves in the trial, 37 had a strong suckle reflex, regardless of what their calving ease was, and about 85 per cent stood up and sucked on their own,” she said.
“Twenty-six calves had a moderate suckle reflex, and about 60 per cent of those stood up and sucked on their own, regardless of calving ease.”
But Homerosky “really saw a difference” in calves with a weak suckle reflex.
“Only one calf out of those 14 sucked on its own. We can conclude that calves with a weak suckle reflex were 83 times less likely to suck on their own, as compared with calves that had a strong suckle reflex.”
Calves with a weak suckle reflex “are at a disadvantage” and will likely require intervention, she said.
“From a management standpoint, it’s probably a good idea to go ahead and start thinking about how you’re going to get colostrum into that calf prior to six hours. That’s something you can start doing on farm right away.”