Upregulated heat shock protein beta-1 associated with caloric restriction and high feed efficiency in longissimus dorsi muscle of steer

The objective of this study was to identify myogenic proteins associated with caloric restriction and feed efficiency in bovine longissimus dorsi muscle. Thirty-one Korean native steers were allocated to 100% ad libitum (n = 16) or 80% of ad libitum (n = 15) groups. Regardless of nutritional level, a subset of these animals were assigned to groups with high or low feed efficiency (n = 5) at a later time point based on feed efficiency. A total of 7 differentially expressed proteins were found between groups with different nutrition levels while a total of 12 differentially expressed proteins were found between groups with different feed efficiencies. Interestingly, heat shock protein beta-1 (HSPB1) was a differentially expressed protein that showed up in both results (nutrition level and feed efficiency). It was up-regulated in both the 80% ad libitum group and the high feed efficiency group. In in vitro study, mRNA expression level of HSPB1 was increased (P < 0.05) after myogenic differentiation. Results of this study suggest that HSPB1 might be a myogenic protein involved in response to caloric restriction and feed efficiency in longissimus dorsi muscle of Korean native steer.