Meat quality traits and the expression of tenderness-related genes in the loins of young goats at different ages.

Goat meat is considered healthy because of its low fat content, but it is often rather tough. Tenderness is the most important attribute of quality during meat consumption and there is scarce information about the expression of genes involved in the meat tenderization process in goats. The aim of this trial was to assess certain meat quality traits and the expression, at the messenger RNA (mRNA) and protein levels, of specific genes involved in the tenderization process of the longissimus lumborum (LL) in young male goats (Capra hircus) at different ages. Samples of LL were collected at slaughter from 32 Alpine goats that were divided into three categories: 9 suckling kids (Sk) at 5.4±0.15 weeks of age, 16 chevons (Ch) at 17.1±0.55 weeks of age and 7 post-puberal goats (Pu) at 34.3±2.5 weeks of age. Animal and carcass variables (live weight gain, live weight, carcass weight and fat deposits) and quality traits of meat (lipid content, ultimate pH, color parameters, cooking loss and shear force) were determined. The mRNA abundances of calpain-1 (Capn1), calpain-2 (Capn2), calpastatin (Cast), caspase 3 (Casp3), caspase 9 (Casp9), αB-crystallin (Cryab), heat shock protein 27 (Hsp27), heat shock protein 40 (Hsp40) and heat shock protein 70 (Hsp70) were detected by quantitative PCR. Capn1, Cast, Cryab and Hsp27 protein expression was investigated by ELISA. The Sk group had the leanest carcasses. The meat of the Pu group was the darkest (P<0.05) and the toughest (P<0.05). The redness of meat increased with the age of the goats. The Sk group showed lower mRNA abundances for the Capn2/Cast ratio, Casp3, Cryab, Hsp27, Hsp40 and Hsp70 than the Pu group (P<0.05). Intermediate values were found for the Ch group. Similar results were highlighted for the protein expression of Cryab and Hsp27. The experiment acknowledged a differentiation of the experimental groups based on performance, carcass and meat characteristics, and the genes considered. Moreover, Sk and Pu groups, characterized by a different tenderness of their meat, were clearly discriminated by a different expression of the Hsp.