Carcass cutting yields and meat quality of market gilts managed with immunological suppression of ovarian function and estrus.

Abstract

The objective of this study was to analyze the effects of immunological suppression of ovarian function and estrus (Improvest®; Zoetis Inc.) on carcass cutting yields and meat quality. A total of 1,080 gilts were allocated by weight and assigned to pens of 27 pigs/pen. Pens were then randomly selected to be managed with or without immunological suppression of ovarian function and estrus (IMP vs. CON). Improvest was administered to each IMP gilt on days 7 and 67 of the study. Pigs were marketed on day 89 (n = 8 heaviest gilts per pen), 103 (n = 8 next heaviest gilts per pen), and 117 (remaining pigs/pen) of the study. The heaviest 47 to 50 carcasses for each treatment from each marketing group were selected for carcass cutting tests and evaluation of meat quality the day following slaughter (approximately 32-h postmortem). A smaller subset of 18 to 20 pork loins per treatment from each marketing group were selected for meat quality evaluation following 14 d of postmortem storage. Carcasses were fabricated according to institutional meat purchase specifications (IMPS) and meat quality analyses included pH and instrumental color at 32-h postmortem and purge loss, pH, instrumental color, intramuscular fat (IMF), cooking loss, and star probe following 14 d of postmortem storage. Live performance data were analyzed using the pen as the experimental unit, while carcass data were analyzed using the individual carcass as the experimental unit. During the post-second dose period (measured from days 70 to 85), IMP gilts consumed 10.8% more feed (P < 0.01) and grew 13.5% faster (P < 0.01) compared with CON gilts. Hot carcass weight (HCW), and the weights of many cuts, were significantly influenced by the interaction of Improvest management and marketing group. Therefore, the focus was directed toward primal weights and merchandized cut weights when expressed as a percentage of HCW. When expressed as a percentage of HCW, primal-cut yield and merchandized-cut yield calculations were not different (P = 0.33 and P = 0.65, respectively) between CON and IMP gilts. Meat quality traits did not differ (P > 0.05) between CON and IMP gilts, with the exception of instrumental a* at 32-h postmortem which was 0.32 units greater for CON gilts compared with IMP gilts. In summary, managing market gilts with immunological suppression of ovarian function and estrus improves the rate of weight gain through increased feed intake; however, carcass-cutting yields were not significantly changed.