Cattle handling technique can induce fatigued cattle syndrome in cattle not fed a beta adrenergic agonist.

Angus crossbred steers (n = 40; 563 ± 44 kg) were used to examine the effects of handling method and fat thickness on the blood chemistry and physiology of market steers. Steers were blocked by backfat (BF) thickness and were randomly assigned to treatment groups: low-stress handling (LSH) and aggressive handling (AH). Cattle were then ran¬domly assigned to one of 5 blocks containing 4 steers from the LSH and AH treatments. Steers in the LSH treatment were walked and AH cattle were run through a course of 1,540 m. Blood samples were obtained via jugular venipuncture before handling (BASE), at 770 m (LAP1), at 1,540 m (LAP2), and at1 h (1H) and 2 h (2H) after finishing the course. Blood samples were analyzed for plasma lactate (LAC), creatinine kinase (CK), base excess (BE), blood pH (pH), serum cortisol (CORT) concentrations, and venous carbon dioxide (PvCO2) and oxygen (PvO2) pressures. Heart rate (HR), respiratory rate (RR), and rectal temperature (TEMP) were measured at the same intervals. Cattle in the AH treatment had greater ( < 0.05) LAC than those in LSH at BASE (4.1 vs. 3.0 mmol/L), LAP1 (16.5 vs. 2.3 mmol/L), LAP2 (22.3 vs. 2.4 mmol/L), 1H (7.2 vs. 2.7 mmol/L), and 2H (4.0 vs. 2.5 mmol/L), respectively. Creatinine kinase and RR were not different (P > 0.14). Blood pH in AH cattle was decreased compared with that in LSH cattle ( < 0.05) at LAP1 (7.25 vs. 7.45) and LAP2 (7.19 vs. 7.48) but was not different ( > 0.13) at BASE, 1H, or 2H. Heart rate and TEMP were increased in AH cattle compared to LSH ( > 0.01). Serum cortisol was increased ( < 0.05) in AH compared to that in LSH cattle at LAP1 (87.5 vs. 58.9 nmol/L), LAP2 (144.4 vs. 93.1 nmol/L), and 1H (113.5 vs. 53.1 nmol/L). Although RR was not differ¬ent between LSH and AH, PvCO2 was decreased in AH compared to that in LSH ( < 0.05) at LAP2 (30.6 vs. 39.3 mmHg) and PvO2 was increased at LAP1 (42.7 vs. 33.5 mmHg) and at LAP2 (51.5 vs. 36.6 mmHg). Lactate was increased in AH cattle in the thicker BF group at 1H ( < 0.05), and blood pH was decreased at LAP1, LAP2, and 1H ( < 0.05) compared to the thinner BF cohorts. Four AH steers became exhausted (EXH) and did not complete the course. Increased CK, decreased PvCO2, and muscle tremors occurred in EXH steers compared to non-exhausted AH cohorts. Results of this study show that AH causes physiologic and blood chemistry changes in steers, which can be potentially detrimental to cattle, emphasizing the need for low-stress handling practices.

Implant program effects on performance and carcass quality of steer calves finished for 212 days.

We compared the effects of seven implant treatments combining use of Ralgro (RAL), Synovex-S (SYN), and Revalor-S (REV) on performance and beef quality traits of crossbred steer calves (n = 560) finished for 212 d. A randomized complete block design was used to compare treatments consisting of 1) non-implanted control (CON); 2) RAL on d 0, SYN on d 60, and REV on d 130 (RALSYNREV); 3) RAL on d 0, REV on d 60, and REV on d 130 (RALREVREV); 4) SYN on d 30 and REV on d 130 (SYNREV); 5) REV on d 30 and REV on d 130 (REVREV); 6) REV on d 0, REV on d 75, and REV on d 150, 12.5% crude protein diet (REV3X-12.5); and 7) REV on d 0, REV on d 75, and REV on d 150, 14.5% crude protein diet (REV3X-14.5). All implant groups had higher ADG and gained more efficiently (ADG: feed intake) than the CON group. No distinct performance advantages were noted for particular implant schemes. Implant treatments did not (P > .05) affect dressing percentage, carcass weight, or KPH fat percentage. Fat thickness did not differ (P > .05) for implanted vs CON steers; however, REVREV, SYNREV, and RALREVREV steers produced fatter carcasses than did REV3X-12.5 and RALSYNREV steers. The REV3X-12.5 and REV3X-14.5 treatments increased longissimus muscle area compared with CON; longissimus muscle areas for all other treatments did not differ (P > .05) from CON. No reduction in percentage of Choice and Prime carcasses occurred with use of SYNREV or REVREV; however, all treatments receiving three successive implants had lower (P < .05) percentages of Choice and Prime carcasses than the CON group. Increasing dietary crude protein seemed to lessen the detrimental effect of three successive REV implants on percentages of Choice and Prime carcasses. Loin steaks from REVREV, REV3X-12.5, and REV3X-14.5 steers had higher (P < .05) shear force values than steaks from CON steers.

Comparative effects of supplementing beef steers with zilpaterol hydrochloride, ractopamine hydrochloride, or no beta agonist on strip loin composition, raw and cooked color properties, shear force, and consumer assessment of steaks aged for fourteen or twenty-one days postmortem.

Beef steers (n = 1,914) were assigned to 1 of 3 ß-adrenergic agonist (ßAA) supplementation treatments-zilpaterol hydrochloride (ZH; 8.3 mg/kg of DM for 20 d with 3-d withdrawal), ractopamine hydrochloride (RH; 308 mg·head(-1)·d(-1) for 28 d), or no ßAA (CON)-to determine the effects on consumer eating quality. Strip loins (n = 1,101; CON = 400, RH = 355, and ZH = 346) were obtained and fabricated into 2.5-cm-thick steaks for proximate, Warner-Bratzler shear force (WBSF), slice shear force (SSF), and consumer analyses; steaks were aged until 14 or 21 d postmortem. Fat and moisture contents were not affected by ßAA supplementation (P > 0.05), but strip steaks from steers fed ZH had more protein (P < 0.01) than those from steers fed CON or RH, which were similar. An interaction between ßAA and aging was observed (P < 0.01) for WBSF but not SSF. Within steaks aged 14 d, ZH steaks required the most force to shear, RH steaks were intermediate, and CON steaks had the lowest WBSF values; however, RH steaks had a stronger response to aging than CON or ZH steaks, resulting in the lowest WBSF values at 21 d. Slice shear force values were greater (P < 0.01) in steaks from steers fed ZH than in steaks from steers fed CON or RH, which did not differ. Following shear force analyses, steaks within 2 SD of each treatment mean for WBSF were selected randomly for consumer assessment of eating quality. Consumer testing (n = 400; 200/postmortem aging period) was arranged in a 3 × 3 factorial representing 3 quality grades (Select, Low Choice, and Premium Choice) and 3 treatments (ZH, RH, and CON). In steaks aged 14 d, ßAA supplementation affected (P < 0.01) tenderness, flavor, and overall liking and tenderness acceptability, resulting in lower consumer scores for ZH than CON and RH; however, juiciness, flavor, and overall acceptability were similar (P > 0.05). In steaks aged 21 d, feeding ßAA influenced (P < 0.01) only tenderness and juiciness scores. Despite these differences, ßAA did not affect (P > 0.05) acceptability. Quality grade impacted (P < 0.01) all traits and acceptability in steaks aged 14 and 21 d. In 14-d steaks, Premium Choice typically was scored higher than Low Choice or Select; however, consumers rated 21-d Low Choice and Premium Choice similarly-both receiving greater scores than Select. Consumers detected several differences in eating quality at 14 d because of ßAA supplementation. Increasing aging from 14 to 21 d mitigated differences in shear force and tenderness scores because of feeding ZH, so that tenderness and overall acceptability were similar between ZH, RH, and CON.

Feeding performance, carcass characteristics, and tenderness attributes of steers sorted by the Igenity tenderness panel and fed zilpaterol hydrochloride.

Steers (n = 560; initial BW = 420 ± 26 kg) were selected from a pool of 1,040, using the IGENITY Profile DNA test for tenderness, sorted into 1 of 4 tenderness genotype (TG) groups [140 tough (TUF), 140 intermediate (INT), 140 tender (TEND), or 140 mixed (MXD)], and subsequently allocated into 56 pens at random, of which one-half (28 pens, 7 pens from each TG) were supplemented the ß-adrenergic agonist zilpaterol hydrochloride (ZH) and the balance fed a control ration. No TG × ZH interaction (P ≥ 0.15) occurred for any measured trait. Cattle from INT TG had less (P < 0.05) DMI during pretreatment (d 0 to 118) and entire trial (d 0 to 143) periods than other TG. Cattle fed ZH had greater (P < 0.01) ADG and G:F, and decreased (P < 0.01) DMI during the treatment period (d 119 to 143). Cattle from the TEND group had greater (P < 0.01) marbling scores, increased (P < 0.02) calculated USDA yield grades (YG), and more (P < 0.02) calculated empty body fat (EBF) than TUF cattle. Cattle receiving ZH during the treatment period had increased (P < 0.01) HCW, dressed yield, and LM area. Additionally, cattle fed ZH exhibited decreased (P < 0.01) EBF, marbling, KPH, and calculated USDA YG. No difference (P > 0.06) in YG distributions were detected among TG, yet TEND cattle were represented by a greater (P < 0.01) proportion of Prime and premium Choice carcasses. Cattle fed ZH exhibited increased (P < 0.01) frequencies of YG 2 carcasses and fewer (P < 0.01) YG 3, 4, and 5 carcasses concurrent with an increase (P < 0.04) in the percentage of Select carcasses. Longissimus steaks from TUF cattle had greater (P < 0.03) Warner-Bratzler Shear Force (WBSF) values at 7 and 14 d postmortem than steaks from INT or TEND cattle. Furthermore, ZH-fed cattle had increased (P < 0.01) WBSF values for all aging periods compared with control cattle. Frequency of steaks with WBSF values <3.9 kg (certified tender) were less (P < 0.05) for the TUF group. Feeding ZH resulted in fewer longissimus steaks (P < 0.01) with WBSF values <3.0 kg (guaranteed tender) across all aging periods; however, no difference in the frequency of steaks with WBSF values <3.9 kg was found after 21 d of aging. Igenity Profile tenderness scores were correlated (P < 0.05) to carcass finish attributes and WBSF values. Commercially available tenderness panels may have the potential to allow for antemortem sorting of cattle into expected tenderness groupings, which could augment feeding management strategies and ultimately lead to increased marketing value for the beef system.

Effects of zilpaterol hydrochloride and days on the finishing diet on feedlot performance, carcass characteristics, and tenderness in beef heifers.

British × Continental heifers (n = 3,382; initial BW = 307 kg) were serially slaughtered to determine if increasing days on the finishing diet (DOF) mitigates negative consequences of zilpaterol HCl (ZH) on quality grade and tenderness of beef. A 2 × 3 factorial arrangement of treatments in a completely randomized block design (36 pens; 6 pens/treatment) was used. Zilpaterol HCl (8.33 mg/kg DM) was fed 0 and 20 to 22 d before slaughter plus a 3 to 5 d withdrawal to heifers spending 127, 148, and 167 DOF. Feedlot and carcass performance data were analyzed with pen as the experimental unit. Three hundred sixty carcasses (60 carcasses/treatment) were randomly subsampled, and strip loin steaks were aged for 7, 14, and 21 d for assessment of Warner-Bratzler shear force (WBSF) and slice shear force (SSF) with carcass serving as the experimental unit for analysis. No relevant ZH × DOF interactions were detected (P > 0.05). Feeding ZH during the treatment period increased ADG by 9.5%, G:F by 12.5%, carcass ADG by 33.6%, carcass G:F by 35.9%, carcass ADG:live ADG by 15.6%, HCW by 3.2% (345 vs. 356 kg), dressing percent by 1.5%, and LM area by 6.5% and decreased 12th-rib fat by 5.2% and yield grade (YG) by 0.27 units (P < 0.01). Feeding ZH tended to decrease marbling score (437 vs. 442 units; P = 0.10) and increased WBSF at 7 (4.25 vs. 3.47 kg; P < 0.01), 14 (3.57 vs. 3.05 kg; P < 0.01), and 21 d (3.50 vs. 3.03 kg; P < 0.01). Feeding ZH decreased empty body fat percentage (EBF; 29.7% vs. 30.3%; P < 0.01) and increased 28% EBF adjusted final BW (473.4 vs. 449.8 kg; P < 0.01). Analysis of interactive means indicated that the ZH × 148 DOF group had a similar percentage of USDA Prime, Premium Choice, Low Choice, and YG 1, 2, 3, 4, and 5 carcasses (P > 0.10) and decreased percentage of Select (30.4 vs. 36.6%; P = 0.03) and Standard (0.2 vs. 0.9%; P = 0.05) carcasses compared with the control × 127 DOF group. As a result of ZH shifting body composition, extending the DOF of beef heifers is an effective feeding strategy to equalize carcass grade distributions. This can be accomplished along with sustaining the ZH mediated advantages in feedlot and carcass weight gain.

Dose and release pattern of anabolic implants affects growth of finishing beef steers across days on feed.

Four experiments evaluated the effect of implant dose and release pattern on performance and carcass traits of crossbred beef steers. In Exp. 1, steers (4 to 7 pens/treatment; initial BW = 315 kg) were fed an average of 174 d. Treatments were 1) no implant (NI); 2) Revalor-S [120 mg of trenbolone acetate (TBA) and 24 mg of estradiol 17ß (E(2)); REV-S]; 3) Revalor-IS followed by REV-S (cumulatively 200 mg of TBA and 40 mg of E(2); reimplanted at 68 to 74 d; REV-IS/S); and 4) Revalor-XS (200 mg of TBA and 40 mg of E(2); REV-X). Carcass-adjusted final BW was greater (P < 0.05) for REV-X and REV-IS/S than for REV-S (610, 609, and 598 kg, respectively). Daily DMI did not differ (P > 0.10) among the 3 implants, but carcass-adjusted G:F was greater (P < 0.05) for REV-X and REV-IS/S than for REV-S (0.197 and 0.195 vs. 0.188). Both HCW and LM area were greater (P < 0.05) for REV-X and REV-IS/S than for REV-S. Marbling scores were greatest (P < 0.05) for REV-S and least (P < 0.05) for REV-IS/S; REV-X was intermediate to NI and REV-IS/S. In Exp. 2, steers (10 pens/treatment; initial BW = 391 kg) were fed 131 d, with treatments of REV-S, REV-IS/S (reimplanted at 44 to 47 d), and REV-X. Carcass-adjusted final BW (598 kg), ADG (1.6 kg), DMI (9.4 kg), G:F (0.17), and HCW did not differ (P > 0.10) among treatments. The percentage of Choice was less (P < 0.05) and percentage of Select greater (P < 0.05) for REV-IS/S than for REV-S and REV-X. In Exp. 3, steers (10 pens/treatment; initial BW = 277 kg) were fed 197 d and received either REV-IS/S (reimplanted at 90 to 103 d) or REV-X. Carcass-adjusted final BW (625 vs. 633 kg) and ADG (1.81 vs. 1.76 kg) were greater (P < 0.05) for REV-X-implanted steers. Daily DMI did not differ, but G:F tended (P < 0.10) to be increased and HCW was greater (P < 0.05) for REV-X than for REV-IS/S. In Exp. 4, steers (8 pens/treatment; initial BW = 238 kg) were fed 243 d and received either REV-IS/S (reimplanted at 68 to 71 d) or REV-X. Carcass-adjusted final BW (612 kg), ADG (1.54 kg), DMI (7.55), and G:F (0.21) did not differ (P > 0.10) for REV-IS/S and REV-X-implanted steers. Carcass traits did not differ among implants, but the percentage of Choice carcasses was greater (P < 0.05) and percentage of Select was less (P < 0.05) for REV-X than for REV-IS/S. These data indicate that when TBA/E(2) dose is equal, the altered release rate of REV-X can improve performance and quality grade, but these effects depend on duration of the feeding period and timing of initial and terminal implants.

Characterization of estrogen-trenbolone acetate implants on tenderness and consumer acceptability of beef under the effect of 2 aging times.

Anabolic steroid implants are commonly used to increase growth performance and carcass leanness. The objective of this study was to determine the effects of various trenbolone acetate implants on Warner-Bratzler shear force (WBSF), slice shear force, and consumer palatability ratings for USDA Choice and Select beef strip steaks aged for 14 and 21 d from cattle implanted before slaughter. Beef steers (n = 1,740) were subjected to the following treatments: 1) nonimplanted control (CON); 2) Revalor-IS on d 0 and Revalor-S on d 70 (IS/S); or 3) Revalor-XS (RXS) on d 0, and were randomly assigned to pens within blocks. A subsample of USDA Choice (n = 82) and USDA Select (n = 81) carcasses was selected. Strip loins from these carcasses were collected, and steaks measuring 2.54 cm were fabricated and aged for 14 or 21 d postmortem. Select steaks aged 14 d from RXS cattle had decreased (P < 0.05) WBSF values compared with IS/S steaks, but CON steaks did not differ from either implant treatment. Warner-Bratzler shear force did not differ among treatments (P > 0.05) from USDA Choice steaks aged 14 and 21 d or from Select steaks aged 21 d. Consumer scores for flavor and overall liking for USDA Choice 14-d aged RXS steaks were less (P < 0.05) than CON steaks; however, there were no differences between RXS, IS/S, and CON for tenderness or juiciness, or for tenderness and overall acceptability. Select steaks aged 14 d from IS/S cattle had less (P < 0.05) tenderness, tenderness acceptability, overall acceptability, overall liking, juiciness, and flavor scores than RXS and CON steaks; however, consumers also rated RXS steaks less for tenderness, juiciness, and tenderness acceptability when compared with CON steaks. Consumer scores for overall liking, flavor, and tenderness for USDA Choice steaks aged 21 d from RXS, IS/S, and CON did not differ. However, implant affected (P < 0.05) overall liking, flavor, juiciness, and tenderness for USDA Select steaks aged 21 d. Even so, there were no differences between RXS, IS/S, and CON steaks for tenderness or overall acceptability for steaks aged 21 d, regardless of quality grade. Results indicated that tenderness differences exist among implant strategies when strip steaks were aged 14 d; however, tenderness and overall consumer acceptability were only influenced by implant in Select steaks aged 14 d. Furthermore, aging for 21 d can minimize and even eliminate implant differences in WBSF and slice shear force, as well as tenderness and overall consumer acceptability.

Technical note: feeding zilpaterol hydrochloride to calf-fed Holstein steers improves muscle conformation of top loin steaks.

The objective of this research was to evaluate changes in the muscle conformation of subprimal top-loins (M. longissimus lumborum) from calf-fed Holstein steers fed zilpaterol hydrochloride (ZH). Top-loins (n = 100) were transversely cut into 2.54 cm-thick steaks, weighed, and objectively evaluated via image analysis software for muscle area, width, and length traits. Top-loin steaks from steers fed ZH were heavier (P< 0.01; 367 vs. 337 g) and average muscle area per steak was greater (P < 0.05; 80.9 vs. 77.2 cm(2)) as compared to steaks from control steers. Muscle width (medial-lateral) was not different (P = 0.23) between control steers and those fed ZH. However, steaks from steers fed ZH had greater (P < 0.05) depth (dorsal-ventral) than steaks from control steers throughout the top-loin. The increased muscle depth of top-loins from calf-fed Holstein steers fed ZH may improve the center-of-the-plate salability of a cut that has traditionally suffered from poor muscling.

Zilpaterol hydrochloride supplementation has no effect on the shelf life of ground beef.

The objective of this study was to determine the effect of feeding zilpaterol hydrochloride (ZH) on the shelf life and stability of ground beef. Beef knuckles and plates were obtained from USDA Select beef heifer carcasses from control (CON) animals or those supplemented with ZH (8.33 mg/kg of dietary DM basis) for the last 20 d of the finishing period. Subprimals were coarsely ground and blended to produce an 80% lean product. The mixture was vacuum-stuffed into chubs and placed in dark storage at 2 to 4°C for 7, 14, or 21 d before fine grinding. Each week, the finely ground samples were packaged on expanded polystyrene trays overwrapped with polyvinyl chloride film and placed in refrigerated retail cases (0 to 2°C) under continuous fluorescent lighting to simulate retail display. Samples were subjected to a variety of analyses at different time intervals (h) during simulated display, including composition analysis, thiobarbituric acid-reacting substance analysis (TBA), sensory color, instrumental color, and aerobic plate count. Data analysis revealed trained sensory color and discoloration scores were similar between CON and ZH-treated samples. Instrumental L* and b* values for CON and ZH-treated samples did not differ (P = 0.13 and 0.19, respectively). Instrumental a* values declined (P < 0.05) over the display period for CON and ZH ground beef. However, a* values for ZH ground beef stored for 7 d were greater (P < 0.05) than CON values at 18 through 72 h of display. There was a treatment × storage day interaction (P < 0.001) for TBA values with ZH having smaller TBA values than CON after 7 d of dark storage. There was no difference (P = 0.21) in aerobic plate count between ZH and CON ground beef samples. Overall, ground beef from cattle supplemented with ZH was equal to or better than CON for sensory color and discoloration, instrumental color, and stability variables, including TBA reactive substances and aerobic plate counts.

Additive effects of a steroidal implant and zilpaterol hydrochloride on feedlot performance, carcass characteristics, and skeletal muscle messenger ribonucleic acid abundance in finishing steers.

This experiment investigated the effects of zilpaterol hydrochloride (ZH) and the steroidal implant Revalor-S (RS; 120 mg of trenbolone acetate and 24 mg of estradiol-17beta) on finishing steer performance and the mRNA concentration of beta-adrenergic receptors (beta-AR) types I and II, and types I, IIA, and IIX myosin heavy chain (MHC) isoforms. A total of 2,279 feedlot steers weighing 426 +/- 6.4 kg were administered no implant or RS on d 0, and fed 0 or 8.3 mg of ZH/kg of diet DM during the last 30 d with a 3-d withdrawal. Treatments were randomly assigned to 24 pens (n = 6 pens/treatment). At slaughter, semimembranosus muscle tissue was excised for RNA isolation from 4 carcasses per pen. No interactions were detected for any of the variables measured in the experiment. Administration of ZH during the last 30 d of the feeding period increased (P < 0.01) ADG, G:F, HCW, and LM area; decreased (P < 0.01) 12th-rib fat depth and marbling; and improved (P < 0.01) yield grade. Treatment had no effect on beta1-AR mRNA levels, but there was an increase (P = 0.01) in beta(2)-AR mRNA levels due to ZH inclusion. Myosin heavy chain-I (MHC-I) mRNA levels were unaffected by treatment. For MHC-IIA mRNA concentrations, administration of RS tended (P = 0.08) to increase mRNA levels, whereas ZH feeding the last 30 d tended (P = 0.08) to decrease mRNA levels for this isoform of myosin. Feeding ZH the last 30 d before slaughter increased (P < 0.01) mRNA concentrations of MHC-IIX in semimembranosus muscle of steers. These data indicate the combined use of ZH and RS additively contributes to BW and carcass gain in finishing feedlot steers and decreases marbling scores and USDA quality grades. The LM area increased and fat thickness decreased. In addition, ZH feeding changes the mRNA levels of MHC isoforms to a faster, more glycolytic fiber type in bovine skeletal muscle. These changes in mRNA concentrations of MHC isoforms, due to ZH feeding, could be affecting skeletal muscle hypertrophy.

Predicting red meat yields in carcasses from beef-type and calf-fed Holstein steers using the United States Department of Agriculture calculated yield grade.

Analyses were conducted to evaluate the ability of the USDA yield grade equation to detect differences in subprimal yield of beef-type steers and calf-fed Holstein steers that had been fed zilpaterol hydrochloride (ZH; Intervet Inc., Millsboro, DE) as well as those that had not been fed ZH. Beef-type steer (n = 801) and calf-fed Holstein steer (n = 235) carcasses were fabricated into subprimal cuts and trim. Simple correlations between calculated yield grades and total red meat yields ranged from -0.56 to -0.62 for beef-type steers. Reliable correlations from calf-fed Holstein steers were unobtainable; the probability of a type I error met or exceeded 0.39. Linear models were developed for the beef-type steers to predict total red meat yield based on calculated USDA yield grade within each ZH duration. At an average calculated USDA yield grade of 2.9, beef-type steer carcasses that had not been fed ZH had an estimated 69.4% red meat yield, whereas those fed ZH had an estimated 70.7% red meat yield. These results indicate that feeding ZH increased red meat yield by 1.3% at a constant calculated yield grade. However, these data also suggest that the calculated USDA yield grade score is a poor and variable estimator (adjusted R(2) of 0.31 to 0.38) of total red meat yield of beef-type steer carcasses, regardless of ZH feeding. Moreover, no relationship existed (adjusted R(2) of 0.00 to 0.01) for calf-fed Holstein steer carcasses, suggesting the USDA yield grade is not a valid estimate of calf-fed Holstein red meat yield.

Effect of zilpaterol hydrochloride supplementation on cutability and subprimal yield of beef steer carcasses.

Beef steers (n = 11,877) from 7 studies were fed zilpaterol hydrochloride (ZH) for 0 or 20 to 40 d before slaughter to determine the effects of ZH on subprimal weight and yield. Carcasses were selected based on mean HCW of treatment groups for fabrication into boneless, closely trimmed, or denuded subprimals, lean, fat, and bone. Data from the 7 trials were pooled for statistical analysis. Feeding ZH increased (P < 0.05) weights of all major subprimals compared with steers not supplemented with ZH. Also, subprimals from the hindquarter, including valuable cuts like the tenderloin, strip loin, and top sirloin butt, increased (P < 0.05) as a percentage of cold carcass weight from steers fed ZH. The tenderloin was 0.06 percentage units greater (P < 0.05), the strip loin was 0.08 percentage units greater (P < 0.05), and the top sirloin butt was 0.11 percentage units greater (P < 0.05) in ZH-fed steers when compared with steers not fed ZH. Supplementation of ZH greatly increased (P < 0.05) total saleable carcass yield by 1.76 percentage units, whereas ZH inclusion decreased (P < 0.05) the percentage of fat trim and bone by 0.58 and 1.10 percentage units, respectively. Therefore, ZH can be utilized by the beef industry to improve red meat yield efficiency throughout the beef production chain.

Moisture enhancement and blade tenderization effects on the shear force and palatability of strip loin steaks from beef cattle fed zilpaterol hydrochloride.

Two trials investigated zilpaterol hydrochloride (ZH) feeding duration, enhancement, blade tenderization, and postmortem aging effect on Warner-Bratzler shear force (WBSF; trial 1) and consumer sensory ratings (trial 2). For trial 1, USDA Select beef strip loins were obtained from carcasses of beef steers fed ZH (6.8 g/t on 90% DM) the last 0, 20, 30, or 40 d of the feeding period. One-half of each strip loin was enhanced (110%) with a brine solution, whereas the remaining portion was not enhanced. Both pieces were portioned into steaks, which were aged 7, 14, or 21 d for WBSF analysis. For trial 2, paired USDA Select beef strip loins were obtained from carcasses of beef steers fed ZH the last 0 or 20 d of feeding. Paired strip loins were fabricated into 4 pieces and assigned to control, moisture enhanced, blade tenderized, and blade tenderized + moisture enhanced treatments. Strip loin pieces were then portioned into steaks that were aged 14 or 21 d postmortem. Consumers panelists (n = 458) indicated their like or dislike of tenderness, juiciness, flavor, and overall like of each sample using 8-point, verbally anchored scales, as well as tenderness and overall acceptability. With exception of 20 d ZH-treated steaks, results from trial 1 indicate WBSF values decreased (P < 0.05) with enhancement. Among enhanced steaks, steaks from cattle fed ZH for 20, 30, and 40 d had greater (P < 0.05) WBSF values than controls. Among nonenhanced steaks, 20 d ZH-treated steaks had WBSF values similar to 0, 30, and 40 d ZH-treated steaks, whereas 30 and 40 d ZH-treated steaks had greater (P < 0.05) WBSF values than controls. Postmortem aging for 21 d improved (P < 0.05) WBSF values for all ZH durations when compared with 7-d aging treatments. Results from trial 2 indicate ZH feeding for 20 d had no effect on flavor scores, decreased tenderness scores (P < 0.05), and tended (P < 0.10) to decrease juiciness and overall like scores when compared with controls for steaks aged 14 d. After 21 d aging, steaks from 20 d ZH-fed cattle had reduced (P < 0.05) tenderness, juiciness, and overall like scores and tended (P < 0.10) to have decreased flavor scores when compared with controls. These results indicate enhancement improved WBSF, but was not sufficient to overcome the detrimental effect of ZH feeding duration on WBSF until steaks were aged for 21 d postmortem. Consumer scores indicate 20 d ZH feeding had no effect on overall acceptability, but decreased tenderness and tenderness acceptability scores when compared with controls.

Effects of zilpaterol hydrochloride feeding duration on beef and calf-fed Holstein strip loin steak color.

Two studies using beef and calf-fed Holstein cattle were conducted to determine the effect of zilpaterol hydrochloride (ZH) supplementation on the color of strip loin steaks packaged in traditional and modified-atmosphere packaging. Select (USDA) strip loins were obtained from the carcasses of beef (n = 118) or calf-fed Holstein (n = 132) cattle fed ZH (6.8 g/ton on a 90% DM basis) for the last 0, 20, 30, or 40 d of feeding. One portion of the strip loin was moisture enhanced, cut into steaks, and packaged in an atmosphere containing 80% oxygen and 20% carbon dioxide. The remaining portion of the strip loin was vacuum-packaged until further processing. At 14 d postmortem, the vacuum-packaged loins were portioned and packaged in traditional retail packaging. Traditionally packaged and modified-atmosphere-packaged steaks were then placed in retail cases at -1 to 3 degrees C for 5 d and evaluated by both trained and consumer panelists. Instrumental color values and purge loss were also recorded. Zilpaterol hydrochloride duration had no effect on the color and purchase intention scores of consumer panelists for beef and calf-fed Holstein strip loin steaks. Zilpaterol hydrochloride feeding duration had no effect on the color or discoloration scores of trained panelists for enhanced, modified-atmosphere-packaged beef strip steaks. Traditionally packaged beef steaks from cattle treated with ZH for 20 d had more desirable (P < 0.05) lean color scores than steaks from cattle not treated with ZH on d 2, 3, and 4 of display and had similar discoloration scores on d 1, 2, and 3 of display. The color scores of trained panelists for enhanced calf-fed Holstein steaks were more desirable (P < 0.05) for steaks from cattle not treated with ZH than for steaks from cattle treated with ZH for 20 d on d 1, 2, 3, and 4 of display. However, the discoloration scores of trained panelists for enhanced and modified-atmosphere-packaged calf-fed Holstein steaks were similar for steaks from cattle treated with ZH for 0 and 20 d on d 1, 2, and 3 of display. The scores of trained panelists indicated that traditionally packaged steaks from calf-fed Holsteins treated with ZH for 0 d had a darker lean color (P < 0.05) than steaks from ZH-treated cattle on d 1 of display, whereas the lean color scores for ZH treatments of all durations were similar on d 4 of display. The scores of trained panelists indicated that ZH treatment had no effect on the discoloration of traditionally packaged, nonenhanced strip steaks from calf-fed Holsteins. Therefore, feeding ZH to beef or calf-fed Holstein steers had no detrimental effect on the lean color or color stability of strip loin steaks subjected to enhancement, packaged in modified-atmosphere or traditional packaging, and displayed under simulated retail conditions.

Effect of extended withdrawal of zilpaterol hydrochloride on performance and carcass traits in finishing beef steers.

The objective was to evaluate the effects of an extended withdrawal period after feeding the beta-adrenergic agonist zilpaterol hydrochloride (ZH) for 20 d at the end of the feeding period. Three hundred eighty-four crossbred beef steers were blocked by BW and randomly allocated into 64 pens (6 steers/pen). Pens were assigned to treatments in a 2 x 4 factorial arrangement in a randomized complete block design. Main effects were the addition of 0 (control) or 8.3 mg/kg of ZH (DM basis) to the finishing diet for 20 d before estimated average slaughter date and paired withdrawal periods of 3, 10, 17, or 24 d before slaughter. Individual BW were measured initially, 1 d before ZH feeding, and 1 d before slaughter. The ZH feeding period was initiated so that control cattle in the 3-d withdrawal group would be expected to average 65% USDA Choice Quality grade and have 1.27 cm of 12th-rib fat based on visual appraisal. Carcass data were collected at slaughter. For the 3-d withdrawal steers, 2 steers from each pen were selected to determine visceral organ and total offal mass at slaughter. The ZH x withdrawal day interaction was not significant (P > 0.10) for the majority of variables. There was no difference (P > or = 0.12) due to ZH feeding for final BW, carcass-adjusted final BW, or ADG. However, DMI was decreased (P = 0.02) and G:F increased (P = 0.01) in steers fed ZH vs. control steers. As day after withdrawal of ZH increased, there was a linear increase (P < 0.001) in final BW and carcass-adjusted final BW, but a linear decrease (P < 0.001) in ADG over the finishing period and over the ZH plus withdrawal period. Overall, HCW was 380 and 369 kg (P < 0.001) for ZH and control steers, respectively. However, the difference between ZH and control was 14, 17, 5, and 6 kg with 3, 10, 17, and 24 d withdrawal, respectively (ZH x withdrawal day, P = 0.09). Feeding ZH increased dressing percentage (65.8 vs. 64.6%; P < 0.001) and LM area (94.8 vs. 89.7 cm(2); P < 0.001), and decreased calculated yield grade (2.69 vs. 2.91; P = 0.03) and percentage of cattle grading USDA Choice (31.1 vs. 42.3%; P = 0.03) compared with controls. Small intestinal mass (g/kg of empty BW) was greater (P = 0.03) for steers fed ZH compared with controls. There were no other differences (P > or = 0.11) in mass of body components, expressed in kilograms or as a fraction of empty BW. In this experiment, improvements in animal performance and HCW due to feeding ZH were generally maintained when withdrawal was extended through 10 d.

Effects of supplementing feedlot steers and heifers with zilpaterol hydrochloride on Warner-Bratzler shear force interrelationships of steer and heifer longissimus lumborum and heifer triceps brachii and gluteus medius muscles aged for 7, 14 and 21d.

Longissimus lumborum (LL) muscles from 117 steers plus LL, gluteus medius (GM), and triceps brachii (TB) muscles from 132 heifers were evaluated for effects of feeding duration of zilpaterol hydrochloride (Zilmax(R); ZH; 7.56g/907kg on a dry matter basis) and aging time on tenderness. Both genders were blocked by initial weight into six blocks of four pens. Pens were assigned to treatments of control (C), or 20, 30 or 40days on ZH, with a 3day withdrawal. Steaks from each subprimal were vacuum aged individually for 7, 14 or 21days, frozen, thawed, and cooked to 71 degrees C for Warner-Bratzler shear force (WBSF). All muscles from steers and heifers from ZH30 and ZH40 treatments had higher (P<0.05) WBSF than those of C. The WBSF of steer LL and heifer TB from the ZH20 treatment was higher (P<0.05) than C. There was a treatment by aging interaction (P>0.05) for WBSF of GM steaks from heifers. Percentage of intramuscular fat had little effect on tenderness. Percentages of steer LL and heifer TB steaks with WBSF values below thresholds of either 5.0 or 4.6kg from the ZH20 treatment were quite high, whereas percentages of heifer LL and GM muscles below 5.0kg (67%) and 4.6kg (57%) were low. Feeding ZH20days generally increased WBSF values, but mean WBSF values for steer LL and heifer TB were below 4.6kg. Feeding ZH 20days resulted in>40% of GM steaks with WBSF values above 4.6kg.

Effect of feeding zilpaterol hydrochloride to beef and calf-fed Holstein cattle on consumer palatability ratings.

The need to provide consumer data for beef steak tenderness, juiciness, flavor, and overall palatability ratings from zilpaterol hydrochloride (ZH) beef to the processor, retailers, restaurants, and consumers is paramount. Consumer palatability responses were studied for 14- and 21-d aged USDA Choice and USDA Select quality grade beef and USDA Choice calf-fed Holstein New York Strip steaks from cattle that had been fed ZH for 0, 20, and 30 d before slaughter. Strip loins were cut into 2.54-cm-thick New York strip steaks and assigned to a 14- or 21-d aging treatment. The first and fourth steaks were assigned for 14- or 21-d WBSF analysis, and the second, third, fifth, and sixth steaks were reserved for consumer sensory panel evaluation. Warner-Bratzler shear force (WBSF) analysis was conducted at Texas Tech University (TTU, Lubbock), Kansas State University (Manhattan), Oklahoma State University (Stillwater), and West Texas A&M University (Canyon) with values used to sort steaks for consumer evaluation. Slice shear force analysis was performed at TTU on available paired consumer steaks. Consumers (n = 3,007) in 4 metropolitan areas (Baltimore, MD/Washington, DC; Chicago, IL; Los Angeles, CA; and Lubbock, TX) were asked to rate tenderness, juiciness, flavor, and overall acceptability. Consumers were selected to represent a wide range of income, education, and ethnicity at each city. Steaks were cooked to a medium degree of doneness (71 degrees C), cut into 1 cm(3) pieces, and served warm to consumers. Consumers tasted samples from each of 3 separate steaks from each ZH treatment (0, 20, and 30 d) and within each USDA quality grade and within the 14- and 21-d aging treatments. Steaks were selected to represent the distribution of tenderness for the first, second, and third SD either side of the mean for each treatment. A second calf-fed Holstein consumer study (n = 240) was conducted with consumers eating USDA Choice 14- and 21-d aged steaks from Holstein cattle fed ZH for 0 or 20 d. Steaks from 0- and 20-d ZH treatments were different for tenderness for the 14-d aged USDA Choice and the calf-fed Holstein study groups. No differences were shown for all other 0- and 20-d ZH treatments for tenderness. The 21-d aged USDA Select steaks were improved with aging, which aided in removing the effects of ZH treatment. The ZH treatment of 30 d before slaughter resulted in increased WBSF values and decreased consumer tenderness, juiciness, and overall palatability ratings for 14-d-aged USDA Choice. No differences were shown for tenderness, juiciness, flavor, and overall palatability consumer ratings for 0- and 20-d steaks from 21-d Choice and 14- and 21-d Select quality and aging periods. Overall, USDA Choice Holstein steaks aged 14 and 21 d had differences in tenderness with ZH.

Effect of zilpaterol hydrochloride supplementation of beef steers and calf-fed Holstein steers on the color stability of top sirloin butt steaks.

Top sirloin butt steaks were used to determine the effects on color stability of supplementing zilpaterol hydrochloride (ZH) to beef and calf-fed Holstein steers. This study compared the effects of dietary ZH supplementation for 0, 20, 30, or 40 d on feed. One-half of the top sirloin butts were enhanced and packaged in modified-atmosphere packaging (MAP); the remaining one-half were packaged in polyvinylchloride (PVC) film. Beef steaks packaged with PVC from cattle supplemented for 30 d had a tendency (P = 0.07) to produce a redder (a* = 18.31) steak than the control cattle (a* = 17.00) or cattle supplemented for 40 d (a* = 17.05). In beef steaks, ZH had no effect on subjective visual color (P = 0.15 to 0.27) and discoloration (P = 0.10 to 0.59) of steaks packaged with PVC when stratified by day of display, with the exception of visual color on d 5. Beef steaks under MAP from cattle supplemented for 20 d were redder (a* = 19.50, P < 0.05) than those from cattle supplemented for 30 (a* = 18.07) or 40 d (a* = 17.57), but were similar to the control steaks (a* = 18.68). There was no effect (P > 0.05) of retail display day and day of supplementation on objective or subjective color of calf-fed Holstein steaks packaged with PVC. Dietary supplementation for 20 d produced a greater (P < 0.05) b* value on d 1 of display in MAP-packaged steaks from calf-fed Holsteins. If recommending a period of dietary supplementation, 20 to 30 d would be suggested to result in, on average, the brightest, reddest sirloin butt steaks.

Effects of zilpaterol hydrochloride with or without an estrogen-trenbolone acetate terminal implant on carcass traits, retail cutout, tenderness, and muscle fiber diameter in finishing steers.

Our objective was to determine the effects of feeding zilpaterol hydrochloride (ZH), a beta-agonist, for the final 30 d of the feeding period, with or without a terminal estrogen + trenbolone acetate (TBA) implant (Revalor-S; 24 mg of estradiol-17beta and 120 mg of TBA; REV) on meat tenderness and carcass cutout yields. Crossbred steers (n = 2,279) were divided into 6 BW blocks and 24 pens. Within each block, pens were assigned randomly to 1 of 4 treatments: 1) no terminal implant (control); 2) a terminal REV given 91 d before slaughter; 3) no terminal implant plus ZH; and 4) a terminal REV implant plus ZH (REV+ZH). All cattle received Component TE-IS (16 mg of estradiol and 80 mg of TBA) on d - 61 of the feeding period [corrected]. Zilpaterol hydrochloride was added to the diets at a concentration of 8.38 mg/kg (DM basis) during the final 30 d of the feeding period, followed by a 3-d period before slaughter in which ZH was withdrawn from the diet. Carcasses (n = 30/treatment) were selected from the 2,279 cattle and fabricated into subprimal cuts as per Institutional Meat Purchase Specifications. Strip loins were collected, cut into 2.54-cm steaks, and aged 7, 14, and 21 d, after which Warner-Bratzler shear force (WBSF), collagen content, desmin degradation, and muscle fiber diameter measurements were determined. Feeding ZH increased (P < 0.05) yield of the #112A ribeye roll, #116B chuck mock tender, #167A peeled knuckle, #169 top inside round, #171B outside round, #171C eye of round, #180 strip loin, #184 top sirloin butt, and #189A full tenderloin for ZH treatment. Longissimus muscle WBSF at 7, 14, and 21 d postmortem was increased (P < 0.001) with ZH supplementation. Desmin degradation at 7, 14, and 21 d postmortem was not affected with REV or ZH supplementation compared with controls. Zilpaterol hydrochloride had an additive effect with REV on increasing LM fiber diameter (P < 0.001). When fed to cattle that received a terminal implant of REV, ZH potentially increased LM WBSF as a result of induced muscle hypertrophy. During the 21-d aging period, WBSF decreased with aging, suggesting that carcasses from cattle supplemented with ZH might require longer aging time to ensure that acceptable levels of tenderness are reached.

Effects of duration of zilpaterol hydrochloride and days on the finishing diet on carcass cutability, composition, tenderness, and skeletal muscle gene expression in feedlot steers.

Preselected carcasses (n = 112) from feedlot steers fed zilpaterol hydrochloride (ZH; 8.33 mg/kg, DM basis) in a serial slaughter experiment were evaluated to determine the effects of ZH upon carcass cutability, composition, and tenderness. A 4 x 4 factorial arrangement of treatments in a completely random design was used with days on ZH (0, 20, 30, and 40 d before slaughter with a 3-d withdrawal) and days on the finishing diet (DOF; 136, 157, 177, and 198 d). No relevant ZH duration x slaughter group interactions were detected (P > 0.05) for carcass cutability, composition, or tenderness data. Exposure to ZH increased the lean yield of 22 of the 33 subprimals evaluated with every subprimal within the round showing increased cutability (P < or = 0.04). Carcass fat was decreased, whereas carcass protein and moisture were increased due to ZH (P < 0.01). Lengthening the ZH feeding period did not result in additive gains in subprimal yield or chemical composition (P > 0.05). Warner-Bratzler shear force analysis of the LM indicated that ZH caused a toughening effect (P < 0.01) regardless of the length of the aging period (7, 14, or 21 d). Extending the ZH dose duration caused a linear increase in Warner-Bratzler shear force at 7 (P = 0.06) and 21 d (P < 0.01) of aging. Within 10 min postmortem, samples (n = 48) were collected from the semimembranosus muscle for RNA isolation from 4 randomly selected steers from each treatment within the 157, 177, and 198 d slaughter groups. Feeding ZH did not alter beta1- or beta2-adrenergic receptor (AR), calpastatin (CAL), IGF-I, or myosin heavy chain (MHC) isoform I mRNA abundance (P > 0.10). There was a ZH duration x DOF interaction (P < 0.01) for the expression of MHC-IIa and -IIx. Expression of MHC-IIa was decreased in every ZH treatment within the 177 and 198 DOF groups (P < 0.02). Expression of MHC-IIx was increased in the 20-d ZH group in the 157 DOF group (P = 0.03), and the 40-d ZH group in the 177 (P = 0.10) and 198 (P = 0.03) DOF groups. There was a tendency for a linear decrease in CAL mRNA abundance as ZH duration increased (P = 0.07), and there was a linear increase in beta2-AR (P = 0.03) and CAL (P < 0.01) mRNA abundance as DOF increased. Collectively, the data indicate that ZH may influence net protein turnover by decreasing MHC-IIa mRNA transcription and possibly increasing MHC-IIx. Furthermore, a ZH feeding duration of 20 d appeared to be adequate for capturing lean yield benefits while limiting tenderness losses.