Impact of health management, health treatments, and zilpaterol hydrochloride supplementation on carcass quality, color, and palatability traits in heifers.

Two hundred sixty-eight strip loins were collected from heifers fed at Oklahoma State University in Stillwater, OK. In Exp. 1, heifers (n = 127) were assigned to 1 of 3 health management treatment groups: antimicrobial administrations were given based on standard feedlot protocol (SFP) or ruminal temperature (RT) or given a metaphylactic treatment of tulathromycin (MT) followed by visual assessment (VA). In Exp. 2, heifers (n = 155) were assigned to the same treatment groups as above and were supplemented zilpaterol hydrochloride (ZH) or control (CON). Three steaks were collected from each strip loin, 1 each for retail display, sensory evaluation, and Warner-Bratzler shear force (WBSF). Color was evaluated from the retail display steak using a trained color panel and objectively using a HunterLab Miniscan XE. An Instron Universal Testing Machine with a Warner-Bratzler head was used for evaluation of instrumental tenderness, and a trained sensory panel was used to assess palatability traits. Heifers treated by VA had the least number of antimicrobial administrations and lowest yield grade and also had the lightest HCW (P < 0.05) compared with the heifers treated by the other health management protocols. There were no subjective color attribute differences or sensory panel differences (P > 0.05) across all health management systems or antimicrobial administrations. There were no differences in carcass and performance traits for any antimicrobial administrations treatment groups (P > 0.05). Heifers who had 0 or 1 antimicrobial administrations had lower (P < 0.05) a* (redness/greenness: positive values = red and negative values = green), and b* (yellowness/blueness: positive values = yellow and negative values = blue) values compared with those who had 2 antimicrobial administrations. In Exp. 2, heifers treated by VA had the least number (P < 0.05) of antimicrobial administrations when compared with MT and RT. Health management group did not have any other effects on carcass, sensory, or color attributes. Zilpaterol hydrochloride supplementation caused a decrease (P < 0.05) in internal fat and yield grade, but no interactions were observed between the number of antimicrobial administrations and ZH supplementation. With the supplementation of ZH, WBSF significantly increased (P < 0.05). At the end of retail display, the control group had a greater (P < 0.05) surface discoloration when compared with the ZH group. Treatment and detection of bovine respiratory diseases (BRD) is critical to the industry economically and results from this study show that different methods can be used to detect BRD without dramatically impacting carcass, sensory, and retail case life characteristics.

Effects of vitamin E on color stability and palatability of strip loin steaks from cattle fed distillers grains.

The objective of this study was to determine the effect of preslaughter antioxidant supplementation to cattle fed wet distillers grains on carcass yield and quality grade, and on the color stability and consumer acceptability of steaks. Two hundred five crossbred steers were fed 35% wet distillers grains with the supplementation of 4 different levels of α-tocopheryl acetate: 0, 125, 250, and 500 IU•animal(-1)•d(-1) for 97 d. Chuck rolls (n = 69) and strip loins (n = 185) were collected and processed at 4 and 7 d postslaughter, respectively. Chucks were ground and separated into 0.23-kg samples. Strip loins were faced and cut into 2.54-cm steaks and packaged in a polyvinyl chloride overwrapped (PVC) package, a vacuum package, or modified atmosphere packages (MAP) for further color, α-tocopherol, objective tenderness, palatability, and proximate analysis. Color was measured objectively using a HunterLab Miniscan XE spectrophotometer (HunterLab Associates Inc., Reston, VA) and subjectively by a trained color panel, and a consumer panel was used to indicate which treatments affected retail acceptability and purchase decisions. Warner-Bratzler shear force measurements were used for objective tenderness, and a trained panel assessed subjective palatability characteristics. Instrumental color measurements revealed little difference for ground beef in both PVC and MAP packages, but diets with 500 and 250 IU•animal(-1)•d(-1) of vitamin E had a longer (P < 0.05) retention of redness and yellowness in steaks as compared with steaks from animals receiving less vitamin E. Subjective color evaluation for strip steaks indicated that greater vitamin E was more likely (P < 0.05) to maintain color stability, overall acceptability, and consumer purchase preference while decreasing percentage of discoloration. No significant differences (P > 0.10) were observed for objective tenderness and sensory attributes of strip steaks, and no differences (P > 0.10) were observed in protein, fat, and moisture percentages of ground beef. Lipid oxidation analysis indicated that steaks packaged in PVC for 7 d and MAP for 1, 3, and 7 d, and ground beef packaged in MAP and PVC for 0 and 7 d of retail display required greater inclusion of vitamin E (500 and 250 IU•animal(-1)•d(-1)) to remain below the 2.28 mg of malonaldehyde/kg threshold. Ultimately, 500 IU•animal(-1)•d(-1) of vitamin E should be supplemented to cattle fed wet distillers grain-based diets when products are packaged in MAP to maximize retail shelf life.