Selection for lean growth efficiency in Duroc pigs influences pork quality

A unique line of Duroc pigs was established by intensive selection for incr eased lean growth efficiency. The objective of this study was to determine the influence of this selection strategy on fresh pork quality traits. Two lines of Duroc pigs originating from the same foundation herd were evaluate d. One line was selected for lean growth efficiency over five generations ( Select line), and the other was a contemporary line maintained from the fou ndation herd (Control line). All pigs in the trial tested negative for the halothane gene. Selection for lean growth efficiency resulted in improved l ean gain, carcass lean, increased loin eye area, and less overall carcass f at. The Select line had significantly lower subjective firmness scores in l ongissimus and significantly greater amounts of moisture and protein lost a s measurable drip in longissimus, semimembranosus, and semitendinosus. Ther e were no differences in subjective color scores or in Hunter L, a, and b v alues between lines. No selection line differences were observed in glycoly tic potential or ultimate pH. The longissimus and the semitendinosus exhibi ted significantly lower early postmortem pH values in Select line pigs. War ner-Bratzler shear values were higher for Select line longissimus chops. De gradation of troponin-T was decreased in the Select line longissimus sample s. This result suggests that reduced degradation of myofibrillar proteins m ay be associated with increased moisture and protein lost during storage. T his research points out that elimination of the halothane gene will solve s ome but not all of the genetically influenced pork quality problems faced b y the industry. The Select line of pigs appears to be more prone to produci ng pork that is soft and exudative, indicating a link between soft and exud ative pork and some genetic selection strategies may exist. Therefore, it a ppears that selection for some economically important traits, such as feed efficiency or increased lean growth in the absence of the halothane gene, m ay compromise pork quality.