Grazing and feedlot performance, and carcass quality measurements of beef cattle surgically castrated at different stages of maturity with or without analgesia

Abstract Text: Castration is a common and justifiable management practice used by beef cattleproducers; however, itmay expose calves to both stress and pain, which may negatively affect animal performance. The objective was to determine the effects of surgical castration at birth or weaning with or without oral analgesic ongrowth performance and carcass quality. This abstract summarizes grazing and feedlot performance, and carcass measurement. Bull calves (n = 60) from the University of Arkansas cow/calf unit were allocated randomly near birth to 1 of 4 castration methods, consisting of surgical castration near birth or at weaning with or without oral administration of meloicam (1 mg/kg BW).  After a 56 d weaning period, calves were transported to West Texas A&M University (WTAMU) for the grazing and feedlot phases.  Body weight was determined upon arrivaland at the end of the grazing phase (start of feedlot phase) and end of the feedlot phase. Calves were allocated to a heavy and low weight group within each treatment upon arrival of the feedlot phase. During the 110 d grazing phase,steers were grazed a single group and had access to sorghum × sudan and native pastures consisting of buffalograss(Buchloedactyloides) and bluegrama grass (Boutelouagracilis).Throughout the finishing period steers werefed a common feedlot ration. When steers were determined to have reached a suitable degree of finish (1.27 cm backfat), they were harvested at a commercial plant and carcass data were recorded by personnel from the WTAMU Beef Carcass Research Center.  Performance and carcass measurements were analyzed using PROC MIXED of SAS and quality grades were analyzed using Chi-square.Starting (270, 273, 276 and 270 kg, respectively)and ending BW (381, 378, 383 and 374 kg, respectively), ADG,and total gain during the grazing phase did not differ (P≥0.42) across the 4 castration treatments. Ending BW (619, 624, 630 and 618 kg, respectively), ADG, total gain during the feedlot phase, and d on feed did not differ (P≥0.50) between treatments. Carcass weight, fat thickness, color, ribeye area, internal fat, preliminary yield grade, yield grade, and quality grade did not differ (P≥0.17) across treatments. Therefore, surgical castration performed at either birthor weaning with or without oral analgesia did not affectcalf performance during the grazing and feedlot phases and did not affect carcass quality measurements.

Keywords: castration timing, performance, carcass quality