In Research: Non-Breeding Potential Bulls Castration Research

By Maggie Stephens, graduate studies, BCI

Castration is one of the beef industry’s most common management practices. Reasons for castrating male cattle include the improvement of carcass quality and aggressive behavior issues. In recent years, painful surgical procedures such as castration have become animal welfare concerns. The most common methods of

Castration Research

Bull castrated at 15 months of age.

castration are banding or surgical removal of the testicles. Castration via banding involves the use of a rubber elastic ring that can be tightened down and due to the loss of blood flow, eventually the necrosis of the scrotum and testicles ensues. Surgical castration involves the physical removal of the testies. The timing of castration is among the animal welfare concerns. As the animal ages and matures castration can become a very painful and stressful procedure. Most male cattle are castrated at birth, weaning or upon entry into a feedlot. Another class of male cattle is castrated at about a year of age; a portion of yearling bulls raised for breeding purposes fail the breeding soundness exam, and are routinely castrated. Many if not all bulls that fail the final breeding exam are over a year of age and are sexually mature. The implication of this procedure at this stage in life is of great animal welfare concern.


Research conducted at the Beef Cattle Institute compared the effects on performance, carcass characteristics and meat quality of intact male cattle verses castrated male yearling cattle that were administered growth promotion technology. Sixteen month old Angus bulls (n = 24; 1,331 + 81.4 lbs.) were stratified by weight and randomly assigned to one of two treatments: uncastrated control (BULL) and castrated via calacrate banding technique and given growth promotion technology (STR). Cattle assigned to STR treatment were implanted with 120 mg trenbolone acetate and 24 mg estradiol on day 0, and fed ractopamine hydrochloride 300mg/d the last 28 days of the feeding period. Cattle were fed a rolled corn based finishing ration with a NEg of 0.64 Mcal/lb for 62 d (final wt = 1496 +/-81.4 lb) then harvested at a commercial packing plant. Carcass characteristics were recorded and steak samples were obtained.

During the 62 day experiment, which were the final days of the feeding period, cattle in the BULL treatment tended to have a higher ADG (3.08 vs. 2.31 lb.; P < 0.10) and had tendencies for increased feed efficiency (10.6 vs 14.3 lbs.; P < 0.10). Feed intake for BULLS and STR (32.7 vs 33.1 lbs. P > 0.20) was not different. No difference was found in quality grade between treatments (choice). Yield grades were 2.7 and 3.1 for BULL and STR, respectively. However, they were not statistically different. There was no difference between treatments

Castration Research

Bull castrated via callicrate band.

for hot carcass weight 963 vs. 943 lb. for BULL and STR treatments respectively. Back fat thickness was not different between treatments (0.41 in.), and neither was dressing percentage (63.7%). Longissimus muscle area (LMA) was greater in BULL compared to STR (15.5 in2 vs. 13.8 in2; P< 0.05). Steak tenderness measured by Warner Bratzler shear force (WBSF) was similar (P < 0.05) between treatments. There was no difference for the subjective sensory panel evaluation (1 to 8 scale, 8 = extremely desirable) for the six categories; myofibrillar tenderness (5.24 vs 5.43), connective tissue (5.97 vs 6.26) overall tenderness (5.34 vs 5.58), juiciness, beef flavor intensity and, off flavor intensity. Fed bulls had improved performance with similar carcass characteristics, WBSF and sensory panel items compared to steers administered growth promotion technology.

In summary, feeding bulls could eliminate an animal welfare concern while removing the cost and management of growth promotion technology use. This study suggests that castration is an unnecessary procedure for this age group of bulls.