9 minute read
Research
Beefing up options
By Samantha Tennent
Research shows there are various factors to consider when choosing bulls to use over the herd and should be selected based on traits the farmer is targeting.
Research has shown that not every dairy cow needs to be mated to a genetically superior dairy sire, since roughly only 25% of calves born each season are required as replacements. And although dairy farmers have been using beef bulls for decades, there has been little work to identify which bulls will perform the best.
Dr Lucy Coleman has spent the past five years trying to identify what makes a good beef bull for a dairy cow.
“The dairy farmer and beef farmer have different considerations so, in my research, I was looking at it from both perspectives,” Coleman explains.
“Dairy farmers want a bull that won’t impact the health and production of the cow or heifer, so they are interested in the calving difficulty and birth weight of the calf, as well as the gestation length.
“Where the beef producer is interested in, is how the calf will perform in a beef rearing system.”
Beef bull estimated breeding values are only relative within breeds, so it can be hard to predict the likely impacts when they are used across dairy cows.
Coleman’s work with Massey University has been part of the Beef + Lamb NZ
Genetics Dairy Beef Progeny Test.
“A lot of the earlier work on beef bulls and what people bred beef bulls for focuses on the beef production system, and there are plenty of dairy farmers who can be cautious because they have heard about some of the risks and that has put them off,” she says.
“But as we know with dairy bulls, there are good bulls within breeds; one bull isn’t equal to another.”
She looked at a comparison of birth weight, gestation length and preweaning growth of calves from mixed-aged dairy cows that were artificially bred to a selection of Angus and Hereford bulls from the lighter end of the scale. And she found there was little impact from the variation in birth weight on calving difficulty.
“Less than 1% of the cows needed assistance at calving, although there was a negative correlation between birth weight and gestation length with age at weaning,” she says.
“So, when choosing a bull with very light birth weight there may be a tradeoff to the growth of the calf.”
This means when choosing Angus and Hereford bulls to use over dairy cows, farmers should firstly be looking for bulls with low enough birth weights to reduce the risk of calving difficulty, but also emphasise gestation length and preweaning growth.
“They do need to be conscious of the tradeoffs between calving traits and growth traits, but should relate them specifically to the objectives of the herd and how important the growth traits are to their system,” she says.
“The goal should be to produce calves that are born without assistance that strike the right balance between income from calf sales and income from extra days in milk.”
She also uncovered there were no negative effects on milk production or rebreeding success of the cow bred to the different Angus and Hereford bulls.
Another novel trait she looked at in her research was tongue colour, hoping to determine whether it could be a useful predictor of the breed of newborn Angus-cross-dairy and dairy crossbred calves, when their similar coat colour makes it difficult.
“Holstein-Friesian cattle have a white spotting gene that causes nonpigmentation in their coat colour and
Lucy Coleman’s research has shown that dairy farmers look for certain traits when selecting bulls so their progeny carry desirable traits.
Farmers should be aiming to select bulls that produce calves that are born without assistance and strike the right balance between income from calf sales and income from extra days in milk.
consequently a pink-coloured tongue, where Angus cattle have black tongues. And Jersey calves can have either or a combination,” she says.
They were hoping that the Anguscross calves being more likely to have black tongues and less likely to have pink tongues than dairy calves that the black tongue would be a tell-tale sign.
“Unfortunately, we found a high incidence of all breeds of calves having spotted tongues which means there is a risk of keeping or culling falsely identified calves. So it isn’t a reliable sole indicator,” she says.
At the same time, she recorded which calves were polled and which had horn buds at birth, and found there was no chance of a dairy farmer accidentally keeping an Angus-cross if they picked replacements with horn buds. Conversely, if a beef producer purchased only the polled calves with a black tongue, 97% of the time they were the Angus-cross they were after.
“So when tongue colour is combined with other visual assessments it could help make decisions whether to cull or keep calves,” she says.
“And identification is more obvious at weaning for those few misidentified at birth.”
Now that they have a good idea of what makes a good bull, the wider Dairy Beef Progeny Test programme is continuing to work on identifying individual bulls and help share the information with the dairy sector to help with breeding decisions.
Before her PhD, Coleman was involved in other projects surrounding dairy beef too. She had spent time looking at the carcase characteristics and meat quality in steers and heifers from Hereford and Charolais bulls born to pure Angus cows and Angus-cross-dairy cows. Finding that utilising beef-cross-dairy cows for beef breeding could be a useful way to utilise surplus animals.
“There were slight differences in the weaning weights and because of the milk attributes from the dairy cross cows and the growing strength of Angus, by the time they were being killed they had caught up. There were minimal differences in the carcase weights and the meat quality was very similar,” she says.
“But the one difference we did note was the fat colour. Meat that comes from Jersey cows tends to have yellower fat and beef producers worry about being penalised.
“But that wasn’t the case, there wasn’t enough for the meat to be downgraded. So it’s reassuring for the beef market.” n
Lucy Coleman has spent the past five years researching the use of beef bulls over the dairy herd.
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Agreeing on animal welfare
By Samantha Tennent
Transparency around the use of animals in research and teaching is part of a new agreement.
Expect to see clearer information about the use of animals in research and teaching within New Zealand thanks to a newly established openness agreement.
Twenty-one universities, institutes of technology, non-profits, Crown Research
Institutes, government organisations, umbrella bodies, research funding organisations and learned societies have all committed to communicating openly about animal use.
NZ will be the first country outside Europe with an animal research openness agreement, which was launched in July in Queenstown at the Australian and NZ Council for the Care of Animals in Research and Teaching (ANZCCART) 2021 conference.
“Public confidence in animal research depends on the scientific community taking part in an ongoing conversation about why, and how animals are used,” NZ ANZCCART board chairperson and acting deputy vice-chancellor (Academic) of the University of Otago Professor Pat Cragg says.
“Through signing this openness agreement, the signatory organisations have committed to having this conversation with the public.
“Being open about why and how we use animals in research and teaching is just so important.”
Maintaining and improving high standards of animal welfare has been a longstanding commitment in NZ, as well as undertaking world-leading research and teaching using animals, controlled
The use of animals in research and education remains vital to scientific, medical and veterinary progress, but now there will be more transparency about why and how they are used.
under the Animal Welfare Act 1999. The scientific community in NZ recognises the importance of demonstrating and promoting values that contribute to these animal welfare standards.
“The objective of the agreement is to ensure that the public is well-informed about animal research, including the benefits, harms, and limitations,” he says.
“Topics such as the role animal research plays in the process of scientific discovery, how research is regulated in New Zealand and what researchers and animal care staff do to promote positive animal welfare should be addressed.
“And communication should be realistic about the ethical considerations involved, including that of the 3Rs of Replacement, Reduction and Refinement. Research is done that aims to benefit humans, animals and the environment.”
The agreement has been modelled on the 2014 groundbreaking Concordat on openness on animal research led by Understanding Animal Research in the United Kingdom. Similar agreements have followed in Spain, Portugal, Belgium and France, with the assistance of the European Animal Research Association.
A working group of 13 organisations chaired by Dr Jodi Salinsky, animal welfare officer and University Veterinarian at the University of Auckland, prepared the agreement and reviews were provided by the ANZCCART NZ board and through public consultation.
“The judicious use of animals in research remains vital to scientific, medical and veterinary progress,” Salinsky says.
“The agreement will help organisations that conduct, fund or support animal research communicate about the crucial work that is being done on the public’s behalf, by dedicated researchers, technicians and animal care staff.
“The current pandemic provides an ideal time to help our community understand the important contribution of this work. We look forward to the day when animals are no longer needed and honour the animals for the advances made that allow treatments, vaccinations and cures for diseases to be found.” n
Pat Cragg
NZ ANZCCART board chairperson and acting deputy vice-chancellor (Academic) of the University of Otago Professor Pat Cragg says an animal research openness agreement will help the public in its understanding of how and why animals are used. Heat & health drafting
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