Abstract: p94 or calpain3a, a Ca2+-dependent protease expressed mainly in skeletal muscle, is highly correlated with muscle growth and meat tenderness. Somatostatin (SS) is the major inhibitory factor for growth hormone secretion and has also been reported to attenuate the expression and activity of calpains. Cysteamine (CS) can deplete the endogenous SS and thus is expected to have influence on animal growth and meat tenderness. To test this hypothesis, 60 healthy fattening goats with average body weight of 15±1 kg were employed and evenly divided into two groups (groupⅠandⅡ) at random. GroupⅠwas fed with a basal diet and groupⅡwith basal diet supplemented with 900mg•kg-1 CS. Goats were slaughtered after 60 days. Blood was collected to detect the serum levels of T3 and T4, the longissimus dorsi and semitendinosus muscles were sampled to investigate the shear force and the expression of p94 mRNA. The results showed that dietary supplementation of CS significantly accelerates body weight gain (p<0.05) and improves the tenderness of semitendinosus muscle of fattening goats (p<0.05), accompanied with increased expression of p94 mRNA (p<0.05). However, the serum levels of T3 and T4 and the tenderness of the longissimus dorsi were not affected by CS treatment (p>0.05). The results indicate that dietary supplementation of cysteamine can accelerate the growth of goats and meliorate the tenderness of semitendinosus muscle, which probably through up regulation of p94 mRNA expression in the muscle.

Key words: p94, calpain, cysteamine, meat tenderness