135 Effects of intratesticular injectable zinc as an alternative castration method compared to banding one week post weaning in beef bulls: effects on health, inflammation, behavior, and growth during the backgrounding period

Abstract

Abstract Castration is a widely practiced management strategy that results in temporary pain with adverse effects on growth performance. Therefore, humane alternatives must be investigated. Male beef calves (n = 81) were stratified by weaning weight and allocated to 1 of 8 pens. Pens were assigned randomly to treatment: 1) banded (B; n = 42) or 2) a 1 mL intratesticular Zn (100 mg Zn) injection (Z; n = 39). Two pens from each treatment were selected for blood collection (B, n = 22; Z, n = 19); the alternative pens were assigned to behavior measurements (5 calves/pen; B, n = 10; Z, n = 10). Behavior data were collected for 1 wk post-castration using accelerometers (HOBOware Lite software). Blood was collected daily on d 0 through d 7 post-castration, and every 28 d for the remainder of the backgrounding phase for complete blood cell counts, serum haptoglobin (Hp), and serum testosterone. Testicular width and BW were also measured. All blood and growth parameters were analyzed using the MIXED procedures of SAS while GLIMMIX was used for behavioral analysis. Body weights did not differ due to treatment throughout the 140-d backgrounding phase (P ≥ 0.39). Overall ADG was greater for Z calves compared with B calves (P = 0.05). Serum testosterone concentrations were greater in Z calves compared with B calves throughout the 140-d trial (P ≤ 0.02). Testicular width in Z calves peaked numerically on d 3 and declined to baseline measurements by d 113 (P = 0.67). Intratesticular Zn castrated calves spent more time lying flat on their side compared with B calves 1 d post-castration (P = 0.03) until d 3 and 4 where B calves spent more time lying on their side compared with Z calves (P ≤ 0.02). Banded calves spent more time standing the first 2 d post-castration compared with Z calves (P ≤ 0.01). On d 3, 4, 5, and 6, Z calves spent more time standing (P ≤ 0.01) while B calves spent more time laying on their sternum (P ≤ 0.03). Banded calves had decreased Hp concentrations on d 1, 2, 3, 7, and 28 compared with Z calves (P ≤ 0.01). Total white blood cell concentrations, both proportion and concentration of neutrophils, and proportion of lymphocytes were greater in Z calves compared with B calves on d 1, 2, and 3 (P ≤ 0.01). Although growth performance was not hindered by the Zn intratesticular injection castration method, it did cause behaviors indicative of pain and resulted in an acute inflammatory and immune response compared with banded calves. Therefore, castrating with an intratesticular injection of Zn may not be a sufficient alternative to conventional methods.