Immunocastration affects testicular mass, serum concentrations of testosterone, and average daily gain of boars

Abstract Text: The objective of this study was to determine the effects of an immunological castration product (Improvest, Zoetis) on reproductive steroid hormones, reproductive organs, and growth.  A total of 72 Landrace x Yorkshire boars (69 d of age, 22.76 ± 4.64 kg BW) were used in 2 successive replications. This study was a randomized design with three treatment groups: single injection (SI) of Improvest at 10 wk of age, double injection (DI) of Improvest at 10 and 15 wk of age, and intact controls (no Improvest; CNT) (n = 24 per group).  At wk 10, 15, 20 and 25, blood was collected and serum harvested to evaluate testosterone concentrations via RIA, and BW were determined.  At wk 25, 18 pigs (n = 6 per group) were sacrificed and testicles were removed, weighed, and measured for length, width, and circumference. Statistical analysis was performed using JMP Pro 10. Testosterone concentrations at wk 20 and 25 were less (P < 0.0001 and P = 0.0003, respectively) for DI (0.065 ng/mL and 1.178 ng/mL, respectively) compared to SI (1.589 ng/mL and 6.372 ng/mL, respectively) and CNT (1.356 ng/mL and 5.920 ng/mL, respectively).  Testosterone concentration for wk 10 and 15 were similar (P = 0.5332 and P = 0.7875, respectively) among the three treatments.  Body weights were greater (P = 0.017) for DI compared to CNT at wk 25 (122.0 kg and 117.6 kg, respectively), while SI (120.1 kg) was not different (P = 0.398) from DI and tended (P = 0.119) to be greater than CNT. The ADG from birth to the initiation of the treatments (10 wk of age) was not different (P = 0.7631) among treatments; ADG from 10 to 25 wk of age was greater (P = 0.0093) for DI compared to CNT and there was a tendency (P = 0.067) toward a greater ADG for SI compared to CNT.  Both left and right testicle length, width, and circumference were less (P < 0.0001) for DI compared to SI and CNT. Testicle wt (g/kg BW) was less (P < 0.0001) for both the left and right testicles for DI compared to SI and CNT.  The results of the current study indicate that immunological castration has a major impact on ADG and that a single injection tended to cause a greater ADG when compared to intact males

Keywords: Boars, Immunocastration, Swine