A comparison of slaughter performance and meat quality of pigs immunised with a gonadotrophin-releasing factor vaccine against boar taint with physically castrated pigs

The objective of this study was to evaluate the effect of vaccination against gonadotropin-releasing factor (GnRF) on carcass characteristics and meat quality and back fat quality. In total, 400 healthy male pigs were randomly assigned into two treatment groups: physically castrated males (CM) and vaccinated males (IM). CM pigs were physically castrated within 3 days of age. IM pigs received the GnRF vaccine twice, at 14 and 21 weeks of age. At the end of the experiment, 20 pigs of each treatment were weighed individually and slaughtered at 25 weeks of age. The longissimus muscle was collected to evaluate the meat quality including pH, drip loss, shear force, cooking loss, intramuscular fat, fatty acid composition and inosine monophosphate. Subcutaneous fat was sampled to evaluate fatty acid composition. IM pigs had a lower dressing percentage and were leaner (P < 0.01). The inosine monophosphate content was higher in pork from IM pigs than from CM pigs (P < 0.05). IM pigs had a higher content of polyunsaturated fatty acids in longissimus muscles than CM pigs (P < 0.01), mostly because of the higher linoleic acid content (P < 0.01). IM pigs had higher levels of unsaturated fatty acids in subcutaneous fat than CM pigs (P < 0.01), mostly because of the higher linoleic acid and linolenic acid (P < 0.01) and the lower myristic acid content (P < 0.01). There were no adverse effects of the GnRF vaccine on slaughter performance and meat quality of pigs. These results suggest that GnRF vaccine administered to pigs increases the inosine monophosphate content in longissimus muscles and the content of polyunsaturated fatty acids in longissimus muscles and back fat. Consequently, vaccination with Improvac for boar taint control will provide a good alternative to physical castration of male pigs.