Britt Hicks, OSU Extension Area Livestock Specialist, recently offered a good discussion of when to castrate bull calves and I wanted to share it.

Beef Quality Assurance Guidelines recommend that bull calves that are not herd sire prospects be castrated as early in life as possible (preferably, between birth and four months of age).  It has been speculated that delaying castration until weaning may improve performance since intact bull calves may grow more rapidly than steer calves.  However, several studies suggest that there is no lifetime performance advantage to waiting to castrate calves until weaning.  In fact, most research show that late castration (at weaning) decreases feedlot arrival gains and increases morbidity (sickness).

In 2011, University of Florida research investigated whether timing of castration in nursing calves affected calf performance and weaning weight.  In this study, 93 Angus and Brangus calves were either surgically castrated early (average age of 36 days) or late (average age of 131 days).  The age of the early castrated calves ranged from 3 to 73 days and the age of the late castrated calves ranged from 84 to 180 days.  At the time of castration, the average body weight of the late castrated calves was 356 lb.  Actual weaning weight (456 vs. 452 lb), adjusted 205-day weaning weight (512 vs. 504 lb), and average daily gain from birth to weaning (2.00 vs. 1.92 lb) were all similar between early and late castrate treatments, respectively.  These researchers concluded that this data indicates that producers have some degree of flexibility in determining when to implement castration.  The data showed that castration at or near birth did not have a detrimental effect on calf performance or weaning weight.  These authors also suggested that producers should realize that delaying castration until calves are approximately 131 days old will not bring added weight at weaning despite some producer philosophies and marketing claims that endorse such management practices.

In 2015, joint research between the University of Arkansas and West Texas A&M University (WTAMU) evaluated the effect of castration timing (near birth or at weaning) on lifetime growth performance and carcass quality of beef calves.  In this study, calves were surgically castrated near birth or at weaning.  All calves were weaned at day 214 of the study to undergo a 56-day weaning period.  For the first 28 days after weaning, the calves were fed hay ad libitum and a supplemental ration intended to achieve approximately 1.5 lb of gain per day.  After 28 days, the calves were moved to a mixed-grass pasture to be maintained for an additional 28-day period to complete the 56-day weaning phase of the study.  After this weaning phase, the calves were shipped 480 miles to the WTAMU Nance Ranch and grazed on native grass and sorghum-Sudan grass for a 111-day backgrounding period until entry into the adjacent WTAMU Research Feedlot.  The calves were fed a common feedlot ration throughout the finishing period (average length of 128 days) and harvested at a commercial processing plant.

These researchers reported that average daily gain from birth to weaning (214 days) was similar between treatments (1.81 vs. 1.85 lb/day for steers and bull calves, respectively).  Furthermore, there was no difference in weaning weight between the bulls left intact (483 lb) or the non-implanted steers castrated near birth (475 lb).  These authors suggest that this observation indicates that testosterone-enhanced growth in bulls vs. steer cohorts is not realized until bulls reach ages beyond the typical weaning age.  However, during the 56 day weaning period, calves castrated near birth gained faster than calves castrate at weaning (2.25 vs. 2.04 lb/day, P = 0.04).  Summer grazing and feedlot finishing performance and carcass measurements did not differ between treatments.  Theses researchers concluded that the results of this study indicate that castration procedures should be performed as early in life as possible to minimize performance loss.

Research from Nebraska (2005) has shown that as age of castration increases, weight loss resulting from the procedure increases (Figure 1).  In addition, reviews of marketing data show that bull calves marketed through conventional channels have historically suffered a price discount of ~5% compared to steer calves (~$5.00 to $7.00/cwt discounts) since surgical castration of calves after arrival at a feedlot decreases daily gains and increases morbidity.

Research conducted at the University of California, Davis (2017) assessed the effect of age on healing and pain sensitivity after surgical castration of beef calves.  In this study, beef calves were surgically castrated at 3 days of age (range of 0 to 8 days) or 73 days of age (range of 69 to 80 days).  The results of this study showed that calves castrated soon after birth experienced more tissue swelling and showed more signs of pain, but their incisions healed sooner (39 vs. 61 days) and their weight gain 77 days after castration was greater (1.54 vs. 0.66 lb/day), when compared to animals castrated around 73 days of age.

Collectively, these studies suggest that there is no lifetime performance advantage to waiting to castrate calves until weaning, but there is a high probability of receiving lower prices when marketing intact calves through conventional channels. When considering how age at castration affects animal welfare, the consensus is that the younger the calf is at time of castration, the less impact castration has on its welfare and performance.

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