Effects of anti-gonadotropin-releasing factor vaccination and administration age on the meat characteristics of pork loins from finishing gilts

This pilot study evaluated the effects of anti-gonadotropin-releasing factor (anti-GnRF) vaccination and administration age on gilts (female pigs), with a specific focus on meat characteristics, including nutritional composition, meat quality, and the muscle histology of pork loins. A total of 66 Duroc × (Landrace × Large White) gilts were randomly assigned to three experimental groups: (1) intact gilts; (2) immunized gilts receiving a typical vaccination at 12 and 16 weeks of age; and (3) immunized gilts receiving early vaccination at 9 and 13 weeks of age, which is the earliest schedule recommended by the manufacturer. The pigs were slaughtered at the market age of 24 weeks, with meat samples collected from all of the groups for analysis, including meat samples from intact gilts (MIG), meat from gilts vaccinated at 12 and 16 weeks (MV12/16), and meat from gilts vaccinated at 9 and 13 weeks (MV9/13). Meat from the immunized gilts had significantly higher intramuscular fat (IMF) content than MIG (P < 0.05), accompanied by changes in the fatty acid profile—excluding polyunsaturated fatty acid—without adverse effects on meat quality or muscle histology. No significant differences were observed between the MV12/16 and MV9/13 samples. These findings suggest that anti-GnRF vaccination enhances the IMF content in pork without affecting meat quality or muscle structure. In addition, the administration age did not influence the chemical composition, meat quality, or muscle histology. An early vaccination schedule provides a practical approach to improve gilt production management, facilitating easier pig handling, efficient vaccination administration, and enhanced IMF deposition.