Growth promotant effects on performance, composition, and palatability of steers with known parentage

Consumer demands for consistent, high quality beef dictate that superior sires be identified that produce efficient offspring with high quality, palatable meat. The objective of this project was to determine the effect of sire and implant treatment on the performance, carcass composition, and palatability traits of 330 progeny of 24 sires of Simbrah, Simmental and Hotlander breeding. The progeny were randomly assigned to three implant treatments: control (N), no implants given; double Synovex-S (SS) and Synovex-S followed by Revalor S (SR). Steaks were aged 3, 7, 14, or 21 d at 3°C . Sire effect was significant (P < .05) for final weight, calpastatin, |a-calpain, m-calpain, 3-h temperature, 48-h pH and temperature, and USDA quality grade traits. A sire effect also was found for USDA yield grade factors, yield grade and crest height. Warner Bratzler Shear (WBS) force and all sensory traits except initial and sustained juiciness were affected by sire (P < .05). Implant treatment significantly increased final weight, calpastatin activity, hot carcass weight, ribeye area and crest height over controls. A sire by implant treatment interaction existed for ADG. Of the 24 sire groups represented, 17 showed no response to implant treatment, while SS increased ADG in two sire progeny groups and SR increased ADG of three sire groups. Eleven sire progeny groups had a WBS force greater than 3.9 kg at 3 d of age but by 21 d of aging, only two sire groups had WBS force means greater than 3.9. Eight of the sire groups had at least 25% of the progeny with WBS force values greater than 3.9 kg after 21-d of age. Eliminating the less desirable sires would improve the consistency and palatability of beef.