In Research: Update on Castration of Non-Breeding-Potential Bulls Research

By: Maggie Stephens, Graduate Student, Kansas State University, Beef Cattle Institute

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 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 happens. Surgical castration involves the physical removal of the testes.

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 at 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 implications of this procedure at this time in their 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 versus 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 callicrate 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 d 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 abattoir. Carcass characteristics were recorded and steak samples were obtained.

Cattle in BULL treatment tended to have a higher ADG (3.08 vs 2.31 lb; P < 0.10 ) and tended to have 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. Both treatments averaged choice quality grade, and yield grade were similar for both treatments, YG 2 for BULL and YG 3 for STR groups.

There was no difference between treatments for hot carcass weight, 963 vs. 943 lb for BULL and STR treatments, respectively Back fat thickness, was not different (0.41 +/- 0.008 in) and dressing percent (63.7%) between treatments. Longissimus muscle area (LMA) was greater in BULL compared to STR (15.5 in 2 vs 13.8 in2 ; P < 0.05 ). Steak tenderness measured by Warner Bratzler shear force (WBSF) was similar (P < 0.10) 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, W BSF, and sensory panel items compared to steers administered growth promotion technology 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.

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