Richard Rennie spoke to a researcher who has come up with a deceivingly simple solution to calf selection over the busy spring period, helping both commercial rearers and dairy farmers make the right choice.
A test developed by Massey University research student Lucy Coleman’s gives farmers a simple way of deciding the fate of their calves.
It involves looking at a calf’s tongue and checking its head for horn buds.
The results determine if it is an Angus-dairy cross suitable for beef rearing or a Friesian-Jersey crossbred that’s heading to the bobby calf truck or to become a heifer replacement.
Coleman’s test is part of her work on the Beef + Lamb New Zealand Genetics dairy-beef progeny test looking at the post-calving performance of dairy cows and the effects of different bull genetics on calving outcomes.
Her research was prompted by an Angus breeder who noticed his Angus calves always had black tongues and wondered if it could be a good marker when the breed was crossed with others.
Coleman had spent plenty of time at spring calving on Limestone Downs near Port Waikato where her research is based so was familiar with trying to match up mothers to calves and often being frustrated.
“I had struggled at times, as most farmers do, on busy days when we were having to tag calves and match them to their mums.
“Even though we had the mating records there are also times when the cows don’t pick the right calf as theirs.”
The use of DNA, while accurate, brings end-of-season delays, slowing record-keeping when farmers might want to keep calving records updated daily under a deluge of newborns.
It seemed the Angus breeder was onto something.
“Angus cattle have a gene which causes the black coat and a black tongue, Holstein-Friesian cattle possess a gene causing the white patches in the coat and a pink coloured tongue.
“So we wanted to see if the tongue colour could be an indicator of breed.”
The research put Coleman up close and personal with more than 1000 calves.
Her initial study of the tongue colour of 476 dairy and Angus-cross-dairy calves shortly after birth showed identifying breed solely on having a black tongue was correct for 73% of the Angus-cross calves and 90% for the dairy breed.
The less than 100% accuracy was also compromised by some having spotted tongues, raising the question about whether to sell the calf or to keep it.
Another genetic trait Coleman incorporated into her study to improve the accuracy was the presence of horns or whether the animal was hornless (polled).
“The poll gene is a dominant gene in cattle and Angus cattle are homozygous polled so their offspring will also be polled even if the other parent is horned.”
Adding that trait to her decision tree significantly improved the odds of making the right choice with each calf.
“We conducted a second study the following year and recorded the presence of horns and tongue colour of 418 dairy and Angus-cross-dairy calves after birth. Ninety five percent of dairy calves had horn buds present at birth while none of the Angus-cross calves had horn buds, confirming that the buds are exclusive to dairy breed calves.”
The work has resulted in a useful take-home rule for both dairy farmers and calf rearers wanting to be sure they are buying calves with Angus beef genetics.
The recommendation for calf rearers is to buy only calves that are polled (no buds) and with a black tongue, which greatly reduces any risk they are buying a dairy calf.
For dairy farmers the simple test is to keep only calves with horn buds present by four days old as replacements.
Coleman cautions about 5% of dairy calves will not have developed horn buds by four days of age, which is the time calves are required to be reared before being transported off the farm.
“The beauty of this is that it’s something farmers can pick up and run with straight away.
“There is no investment or tech needed with it.
“Calving time is really busy and farmers want something that is quick and easy for making what is a really important decision – if it takes too long or involves having to have another person they would be less likely to do it.”
The dairy/beef test is just a small part of Coleman’s research and the B+LNZ genetics programme provides rich pickings for future work.
Coleman is also heartened by efforts across both sectors to rear better calves and believes farmers are starting to appreciate the major developmental changes that happen with young calves that can significantly affect their future productivity.
“Everyone has a different way of rearing calves and different systems work better on different farms but it’s a case of having someone who is really invested in looking after them and paying attention to them.”
