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Effect of castration method and analgesia on growth performance and carcass traits in feedlot cattle
Castration is a painful, yet routine management practice within the U.S. that is known to transiently decrease performance but the method of castration, provision of analgesia, or both may impact growth in feedlot cattle. Our objective was to determine the effect of castration timing (birth vs. feedlot entry), method (surgical vs. banding) and use of the analgesic meloxicam (MEL) on performance and carcass traits in feedlot cattle. This study was a randomized complete block design conducted over a 3-year period. Single-source Angus × Hereford steer (n = 42) and bull (n = 152) calves were randomized at birth to 1 of 5 treatments arranged as a 2 × 2 + 1 factorial: 1) steers castrated near birth (CON), 2) bulls surgically castrated without MEL (SUR), 3) bulls surgically castrated with MEL (SUR+MEL), 4) bulls band castrated without MEL (BAN), and 5) bulls band castrated with MEL (BAN+MEL). Upon feedlot arrival (d -10), animals were blocked by initial BW (224 ± 4.5 kg) and assigned randomly to treatment pens (n = 6 pens/treatment). Oral MEL was administered at 1 mg/kg BW concurrent with castration on d 0. Individual BW was collected at weaning, d 0, 7, 14, 32, re-implant and upon finishing to determine interim and overall ADG. Although BW was not affected by castration method or MEL, there was a tendency (P = 0.10) for CON animals to be heavier at d 32 and re-implant. From d 0 to 7, ADG was reduced for surgical (-0.42 kg/d) compared to band (0.43 kg/d) castration. Conversely, ADG was increased for surgical (1.74 kg/d) vs. band (1.46 kg/d) castration from d 14 to 32. Daily gain was increased for CON compared to castrated for all interim periods (P ≤ 0.02) except re-implant to final (P = 0.90). There was also an overall improvement in ADG for CON (P = 0.04) and MEL (P < 0.01), but this was not influenced by method (P = 0.80). The CON had increased marbling score (P = 0.03) compared to castrated; whereas, backfat thickness was increased (P < 0.05) in SUR+M, but did not differ from CON (P = 0.15). Administration of MEL tended (P = 0.08) to increase yield grade. Castration near birth had long-term performance benefits compared to castration upon feedlot arrival. Castration, regardless of method, transiently reduced ADG, but MEL administration improved overall ADG for both methods.
Keywords:
analgesia, beef cattle, castration