THE INFLUENCE OF PORCINE GROWTH-HORMONE ON MUSCLE-FIBER CHARACTERISTICS, METABOLIC POTENTIAL AND MEAT QUALITY

Treatment of lean female pigs with porcine growth hormone (placebo or 80 mug pGH per kg body weight per day) for 6 weeks from 50 kg to 86 kg body weight did not change the frequency and the percentage area of m uscle fibre types (ST, FTa and FTb fibres) and muscle capillarity of M . longissimus dorsi, M. gluteus medius and M. psoas major. The mean fi bre cross-sectional area increased 5.3%, albeit nonsignificantly, corr esponding to a 6.6% increase in carcass meat. The muscles contained sl ightly less dry matter and protein, and the lipid content of M. longis simus dorsi decreased 19% after pGH treatment. In the backfat the fatt y acid composition changed towards a higher ratio of polyunsaturated t o saturated fatty acids. The pH(u) of M. longissimus dorsi was unalter ed, while the pH45 was reduced by pGH. The muscle glycogen level and t he activity of lactate dehydrogenase (LDH), citrate synthetase (CS), a nd 3-OH-acyl-CoA-dehydrogenase (HAD) of M. longissimus dorsi were unch anged by pGH. The haem pigment, shear force, sarcomere length and eati ng quality of loin chops, were unaffected by pGH treatment. The result s show that pGH treatment did not change the muscle characteristics in a way that affects the meat quality of M. longissimus dorsi in lean f emale pigs.