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Vitamin D3 (D3) supplementation may be used to increase tenderness in beef from cattle fed zilpaterol hydrochloride (ZH). The study was arranged as a 2 × 2 factorial with fixed effects of ZH (no ZH or ZH fed at 8.3 mg/kg DM for 20 d with a 3-d withdrawal) and D3 (no D3 or 500,000 IU D3∙steer-1∙d-1 for 10 d prior to harvest). Cattle (n = 466) were harvested in 2 blocks on the basis of BW with subsequent collection of carcass data. Full loins and inside rounds (n = 144 of each subprimal) were collected for fabrication of 5 steaks from the longissimus lumborum (LL), gluteus medius (GM), and semimembranosus (SM), which were aged for 7, 14, 21, 28, or 35 d. Warner-Bratzler shear force (WBSF) was used to evaluate mechanical tenderness of LL, GM, and SM steaks at all aging periods. Slice shear force (SSF) analysis was conducted on only 14- and 21-d LL steaks. No interactions (P > 0.05) between ZH and D3 occurred throughout the entire study. Supplementing ZH resulted in increased HCW (P < 0.01), larger LM area (P < 0.01), and improved calculated yield grades (P < 0.01) with decreases in fat thickness (P = 0.02) and marbling scores (P = 0.05). Supplementation with D3 increased calculated yield grade (P < 0.01) and decreased (P = 0.01) rib eye area. Feeding ZH increased (P ≤ 0.05) WBSF of LL steaks at each postmortem age interval, whereas D3 had no effect (P > 0.05) on WBSF or SSF of LL steaks. Like for WBSF, ZH supplementation increased SSF values at 14 and 21 d postmortem (P < 0.01) compared with those for non-ZH steaks. There was an interaction between ZH and postmortem age (P < 0.01) for WBSF of LL steaks. At 7 d LL steaks from ZH steers sheared over 0.6 kg greater than non-ZH steaks; however, by 21 d this difference was reduced to an average of 0.2 kg. Differences in distribution between LL steaks below 3.0 kg from non-ZH and ZH-fed cattle were also notable (P ≤ 0.05) through 21 d of aging. At 35 d postmortem a high proportion of LL steaks (68.5%) from ZH-fed steers required less than 3.0 kg to shear. Supplementation with ZH and D3 had no impact (P > 0.05) on WBSF values of GM steaks. Feeding ZH did not alter WBSF of SM steaks, but at 28 d D3 increased (P = 0.04) WBSF values. Shear force in ZH steaks was not effectively reduced by feeding D3 for 10 d to steers prior to harvest. Aging, however, was an effective method of reducing initially greater shear force values in LL steaks and, to a lesser degree, GM steaks from ZH-fed cattle. [ABSTRACT FROM AUTHOR]

Interest in low-fat diets coupled with attention for novel and locally-produced foods has led to a resurgence in rabbit meat consumption in the United States. Psyllium seed husks (PSH) from the Plantago ovata plant have been touted as a livestock nutritional enhancement designed to clean digestive tracts, improve performance and feed efficiency, and lower production costs; however, PSH has not been fully investigated in rabbit diets. Therefore, intact male and female New Zealand fryers (n = 44) were used to examine effects of diets with PSH or without (C) on carcass composition, fatty acid profile, and cholesterol of rabbits. Rabbit fryers (2.3 ± 0.54 kg BW) were sourced from 2 producers, and transported from southwest Missouri to the University of Arkansas abattoir, where they were humanely harvested. After harvest, carcass measurements were collected and LM samples were obtained for fatty acid analysis and cholesterol determination. Rabbits fed PSH had greater (P < 0.01) final B W, HCW, cold CW, and DP than rabbits fed C. Even though LM color and cooking losses did not differ (P ≥ 0.34) between treatments, LM from PSH-fed rabbits had greater (P < 0.01) shear force values than that from C-fed rabbits. Cholesterol content tended to be greater (P ≤ 0.07) in the LM of C than PSH rabbits. Among the various SFA, mg of C 10:0 was higher (P ≤ 0.01) in the LM of C-fed rabbits, whereas, LM concentrations of C14:0 was greater (P ≤ 0.04) in PSH-fed rabbits. All other SFA examined did not differ (P ≥ 0.26) between treatments. For MUFA, only C18:1t was found to be greater (P ≤ 0.03) in PSH-fed than C-fed rabbits; all other MUFA were similar (P ≥ 0.26) between treatments. Polyunsaturated fatty acids, C20:4n-6, C22:5, and C22:6 were greater (P ≤ 0.03) in PSH than C rabbits. Fatty acid C20:2 tended (P ≤ 0.07) to be higher in C vs. PSH. All other PUFA were similar (P ≥ 0.12) between dietary treatments. Total mg of FA found in LM of PSH- and C-fed rabbits did not differ (P ≥ 0.65). Weights and dressing percentages of rabbit fryers fed psyllium seed husks were improved relative to control rabbits sourced and harvested at the same time; however, shear force values were lower in control rabbits in this trial. Cholesterol tended to be lower and various differences were observed in the fatty acid profle of rabbits fed psyllium seed husks. [ABSTRACT FROM AUTHOR]