Submitted to: American Society of Animal Science Southern Section Meeting
Publication Type: Abstract Only
Publication Acceptance Date: 10/28/2004
Publication Date: 2/5/2005
Citation: Looper, M.L., Burke, J.M., Mcbeth, L.J., Krehbiel, C.R., Flores, R., Rosenkrans, Jr, C.F., Aiken, G.E. 2005. Effects of time of castration on growth, feedlot performance, and carcass characteristics of Angus and Charolais-sired calves. American Society of Animal Science Southern Section Meeting. Journal of Animal Science 83(Suppl. 2):32. Interpretive Summary:
Technical Abstract: Spring-born Angus and Charolais-sired calves (n = 54) were utilized to determine the effects of time of castration on growth, feedlot performance, and carcass characteristics. Calves were surgically castrated at birth (CB; n = 25; within 24 h) or at weaning (CW; n = 29; mean age = 197 ± 2 d). After weaning, all steers were supplemented with 2.7 kg/d of a corn:soybean meal ration (CP = 12%) for 124 d, and then grazed Elbon rye (Secale cereale) for 112 d until transport to feedlot. Steers were weighed at weaning, initiation and termination of grazing rye, and at 28-d intervals in the feedlot. Carcass characteristics collected included hot carcass weight (HCW), fat thickness (FT), longissimus muscle area (LMA), marbling score (MARB), yield grade (YG), and quality grade. Adjusted 205-d weaning weights were similar (P > 0.10) between CB and CW steers. Average daily gain during rye grazing was not different (P > 0.10) between castration treatments. For the first 56 d of the feedlot phase, CW steers (3.0 ± 0.1 kg/d) gained more (P < 0.05) than CB steers (2.7 ± 0.1 kg/d). However, feedlot performance during the entire feeding period and carcass characteristics were similar (P > 0.10) between castration treatments. Angus-sired steers had increased (P < 0.05) FT, MARB, and YG than Charolais-sired steers. Charolais-sired steers had a larger (P < 0.05) LMA than Angus-sired steers. Percentage of steers with Choice carcasses was similar (P > 0.10) between castration treatments. Angus-sired steers (54%) had more (P < 0.05) Choice carcasses than Charolais (21%). Castration at either birth or weaning did not alter overall growth, feedlot performance, or carcass characteristics of Angus and Charolais-sired steers.