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Trends in the timing of castration

Bruce Derksen for Progressive Cattleman Published on 25 March 2019
Castrating and branding

Reasons for bull calf castration stretch beyond reducing sexual activity and reproduction. Bulls are naturally aggressive and as such, castration becomes necessary for the welfare of the herd and the protection of those who work with them.

Considering carcass values and grades, bulls exhibit a lower-quality, inconsistent, tougher, less-marbled carcass than steers, along with delivering a much larger number of “dark cutters” due to higher pH levels in the muscle, producing a visually unappealing dark red or purple-colored beef. Prices also reflect that steer calves should and almost always do command higher prices than bull calves at market.

Dr. Trevor Hook, veterinarian at Ponoka, Alberta, Central Veterinarian Clinic, when asked about bull calves and age at time of castration says, “Our opinion here at Central Vet is that it’s better to do them earlier, in the first week of life, although that can be challenging as the testicles are small, and banding is probably the way to go when you are doing them at that age.” He went on to say that newborn calves tend to carry on with normal activities after the initial procedure is completed.

Many cow-calf producers do not castrate early because they are afraid steers will not wean as heavy as bull calves, even though research has proven this to be untrue. In a study at Oklahoma State University in 2001, no advantage was found in the growth rate of bulls before weaning compared with bulls that were castrated (by any method) at 2 to 3 months of age and given an implant.

W. Mark Hilton, DVM, and clinical professor of beef production medicine in the Purdue University School of Veterinary Medicine, West Lafayette, Indiana, states in nearly every case, when intact bulls are compared to implanted steers, virtually no difference in weaning weight is shown. He explains that a bull calf has a relatively modest increase in testosterone production up to about 7 months of age, so any “testosterone advantage” is minimal to that point. Minor benefits will almost always be outweighed by the negatives results of late castration.

Research studies comparing age and size at time of castration in relation to sickness trends are also available. Michelle Arnold, a large-ruminant extension veterinarian at University of Kentucky states one research study shows a potential doubling of the sickness rate in comparison to steers, with an average of 28 percent on incoming steers compared to 60 percent in calves castrated at that age.

A 2010 department of clinical sciences study by Oklahoma State University confirmed increased plasma cortisol concentrations in older bulls at time of castration, and given the immunosuppressive nature of these high levels, proposed a greater risk of bovine respiratory disease (BRD) for these animals.

In 2014, the department of animal science, University of Arkansas Division of Agriculture, studied the effects of castration method and timing on performance and morbidity of 271 newly arrived beef stockers, finding that if calves were castrated before arrival at the feedlot, morbidity was reduced. Fifty-one percent of the calves that arrived as steers were treated for BRD compared with 78 percent that arrived as bulls.

When bull calves castrated at weaning are compared to steers castrated early in life, studies confirm an enhanced marbling and tenderness in carcass qualities for the earlier-cut steers. Hilton also believes bulls heavier than 500 pounds at castration have less marbling than those castrated earlier. Tenderness ratings decrease the heavier the animal when castrated, becoming very pronounced with bulls weighing more than 900 pounds.

A Beef Cattle Research Council study done with University of Alberta and agencies throughout the province discussed dark cutting and its representation in the Canadian grading system. Severe penalties for Canadian beef quality grade B4 can amount to a $0.50-per- pound discount, or up to $300 in reduced value per animal. Bulls are cited as a main contributor in these “dark cutter” carcasses, with late castration producing bullish or stag males that will develop and retain the characteristics and conformation of bulls, subsequently contributing to the higher numbers of B4 grades in comparison to calves castrated early.

Finally, price reflections between steer calves and bull calves should always show steers commanding higher prices at market. A study of Kentucky auction markets from 2010 to 2017 found that 550-pound steers outsold similar weight bull calves by an average of $11 per hundredweight (cwt).

In 2010, 14 Arkansas auction barns were the source of a study done by University of Arkansas researchers who collected data on 79,822 head in 38,346 lots, reporting that steers sold for $6.31 more per cwt than bulls.

Castration early in a calf’s life is ideal in terms of physiology in that it lowers stress and results in improved weight gains and better health in the feedlot. Carcass value and grades exhibit enhanced marbling and tenderness. Instigating a proactive approach of routine castration early in a newborn calf’s life will help standardize the efficiency and financial benefits of sound animal welfare practice.  end mark

PHOTO: Steers castrated early in life have been shown to see enhanced marbling and tenderness in carcass quality. Photo by Mike Dixon.

Bruce Derksen is a freelance writer based in Lacombe, Alberta, Canada.