Effects of sexual condition and ractopamine supplementation on the proteomic profile of pork meat

Pork is one of the most consumed meats worldwide, yet, pork quality remains an issue for the industry, mainly because of flavour, colour and water holding capacity instabilities. Castration techniques combined with dietary supplementation with ractopamine hydrochloride (RAC) seem to be a tangible solution to deal with these issues. There is a lack of knowledge of how these techniques will impact the proteomic profile and, consequently, the meat quality. The main goal of this work was to study the proteomic profile of non-aged pork meat under different sexual conditions and RAC dietary supplementation, and how the combination of these two factors impacts meat quality attributes. Forty-eight animals were distributed in six treatments, three sexual conditions (females; surgically castrated males; immune castrated males) and two diets (with RAC inclusion or without). For proteomic analysis, a sample of the Longissimus dorsi muscle was collected 24 h after slaughter and analysed using one-dimensional SDS/PAGE. The ultimate pH and colour (L*, a*, b*) were measured in the carcasses after 24 h, then meat samples were collected to measure drip, cooking and thawing losses, as well as the shear force. The interaction between gender and diet affected the ultimate pH and the L* parameter. Meat tenderness was only influenced by diet. Twenty-seven protein bands were revealed by SDS/PAGE, six of them with the protein abundance affected by diet. In conclusion, the inclusion of dietary RAC caused differences in the pork meat proteome, and more studies are necessary to fully explore the proteins involved in these changes.