PSVII-1 Growth performance from 65 to 125 kg body weight, and carcass and meat composition of gilts, barrows, immunologically castrated pigs and entire males.

Abstract

The aim of this study was to evaluate growth performance, carcass and meat composition of T1) gilts, T2) barrows, T3) immunocastrated (IMC) and T4) entire male (EM) pigs. Twenty eight individually allocated Yorkshire-Landrace x Duroc-Pietrain pigs (68.8 ± 1.2 kg initial BW) were fed a sorghum-soybean meal-based diet (18.4% PC, 3.4 Mcal ME/kg), and water ad libitum. The IMC received two 2-mL subcutaneous injections of an antiGnRH immunological product (Improvac; Zoetis, Mexico) at 115 and 145 days of age. Body weight (BW), ADG, Feed Intake (ADFI), Feed efficiency (G:F) and hot carcass weight (HCW) were registered. Serum testosterone (TEST) was analyzed in blood samples taken at days 115, and 145 of age, and at slaughter, using a commercial ELISA kit (Mexlab, Mexico). Testicles and bulbourethral glands of IMC and EM pigs were weighed. Protein and fat contents were determined (AOAC, 2005) in Longissimus dorsi muscle (LM). Data were analyzed in a randomized block design with two blocks of contemporary pigs utilizing SPSS (v21), and means were compared with Tukey test (P < 0.05). ADFI was similar (P > 0.05) among treatments. Gilts had lower final BW (P < 0.05) than others (121.6 vs. 134.4 kg). IMC and EM had higher (P < 0.05) ADG (0.984 vs. 0.855 kg/d) and G:F (0.208 vs. 0.178 kg/kg) than gilts and barrows. TEST of gilts and barrows remained under 0.1 ng/mL (P < 0.05). At slaughter, IMC had less (P < 0.001) TEST (0.2 vs. 6.8 ng/mL), smaller testicles (0.276 vs. 0.702 kg; P < 0.002), and bulbourethral glands (0.075 vs. 0.202 kg; P < 0.002) than EM. Gilts had less HCW (P < 0.01) than others (99.6 vs. 109.7 kg). LM fat (2.80 ± 0.16%) and protein (22.6 ± 0.37%) content was similar (P > 0.05) among gender. In conclusion, immunologically castrated pigs had better ADG and G:F than barrows and gilts, however lower serum testosterone concentrations than EM pigs.