Evaluating effects of Zinpro Performance MineralsRTM on performance and carcass characteristics of steers fed finishing diets designed for natural beef production

Scope and Method of Study. One hundred sixteen steers, (harvest 1, n = 42 and harvest 2, n = 38, and harvest 3, n = 36, respectively) were used to evaluate the effect of organic Zinpro Performance Minerals RTM on performance, carcass characteristics, tenderness and retail-case life of longissimus steaks. Steers were blocked by initial weight and assigned one of two treatment groups, inorganic (ING) or Zinpro (ZPM) trace mineral supplements, at weaning. Each group was fed to a compositional endpoint and harvested at a commercial facility. Strip loins (IMPS ;Findings and Conclusions. In group one, carcass adjusted average daily gain (ADG) and dry matter intake (DMI) were greater (P < 0.05) for ING steers and gain to feed (G:F) tended to be greater (P = 0.06) for the entire trial period compared to ZPM steers. In harvest group two, body weight (BW), ADG, DMI and G:F were similar among treatments; however, ING steers tended to gain more efficiently (P = 0.07) than ZPM steers. Only DMI tended to be greater (P = 0.09) in ING steers for the entire trial period with all other measurements being similar (P > 0.05). No differences (P > 0.05) were observed between treatment groups for strip loin steak WBS and cooking loss percentage. In harvest group one, ING had significantly (P < 0.05) greater hot carcass weights (HCW) and tended to have more 12 th rib fat (P = 0.07) than ZPM. Kidney, pelvic and heart fat percentage (KPH) tended to be lower (P = 0.07) in ING compared to ZPM. All carcass traits were similar in harvest group three. No differences (P > 0.05) were found for the subjective color evaluation or a* and b* values between treatments. Steers in ING initial harvest group had higher (P < 0.05) L* values than the organic contemporaries. Trace mineral analysis revealed no differences (P > 0.05) between treatments for Ca, Na, Fe, Cu, or Mn content. In harvest group one, Zn content tended to be greater (P = 0.07) and Ni was greater (P < 0.05) in ING. For harvest group two, S, Mg, K and P were greater (P < 0.05) for ING compared with ZPM.