Effects of Sex Class, a Combined Androgen and Estrogen Implant, and Pasture Supplementation on Growth and Carcass Performance and Meat Quality of Zebu-Type Grass-Fed Cattle

Forty-seven Zebu calves were used to determine the effects of class (bull or steer), supplementation (SUPPL, a poultry litter-based supplement or mineral supplementation), and implant (20 mg estradiol combined with 120 mg of trenbolone acetate or no implant) on growth and carcass performance and beef eating quality. The average daily gain (ADG) of implanted cattle significantly increased for steers, but not for bulls. The SUPPL treatment increased ADG by 8.63% from day 0 to end, and shortened in 73.3 d the time to reach 480 kg BW (p < 0.01). Compared to bulls, the steer carcasses exhibited more desirable maturity and finish scores, thicker back fat (p < 0.05), and yielded greater (p < 0.01) percentages of high-value boneless subprimals (HVBLS) (+1.64%) and total cuts (1.35%). The SUPPL bulls dressed 2.63 and 1.63% greater than non-supplemented bulls and SUPPL steers, respectively (p < 0.05). Meat sensory quality was subtly affected (p < 0.05) by sex class or supplementation. The implant did not affect (p > 0.05) shear force or sensory ratings. The supplementation improved key growth performance traits while it adversely affected tenderness-related sensory traits. The implant enhanced the rate of gain of steers only, without improving cut-out yields or inducing adverse effects on palatability traits in both steers and bulls.

Effect of zinc source and implant strategy on performance, carcass characteristics, and trace mineral concentrations in finishing feedlot steers

Seventy-two Angus-crossbred steers (411 ± 16 kg) were assigned to a 2 × 3 factorial arrangement of treatments to examine the effects of blended Zn source supplementation on performance, carcass characteristics, and trace mineral parameters of steers administered no implant or a two-implant program. Factors included implant (IMP) strategies and Zn supplementation. During the 126-d study steers were either not implanted (NoIMP) or implanted (IS/200; Elanco, Greenfield, IN) on d 0 (Component TE-IS; 80 mg trenbolone acetate + 16 mg estradiol) and 57 (Component TE-200; 200 mg trenbolone acetate + 20 mg estradiol). All steers were fed 70 mg Zn/kg on a dry matter (DM) basis from ZnSO4 + 30 mg Zn/kg DM from either basic ZnCl (Vistore Zn, Phibro Animal Health, Teaneck, NJ), Zn glycinate (Gemstone Zn, Phibro Animal Health), or ZnSO4 (ZnB, ZnG, or ZnS, respectively). Steers were blocked by weight into pens of 6 and fed a dry rolled corn-based diet via GrowSafe bunks (GrowSafe Systems Ltd.; Airdrie, AB, Canada). Data were analyzed using the Mixed Procedure of SAS, with fixed effects of Zn, IMP, and the interaction. Steer was the experimental unit (n = 12 steers/treatment). Liver and muscle collected on d -5, 14, 71, and 120 were analyzed for Zn concentration, and data were analyzed as repeated measures (repeated effect = Day). An IMP × Zn tendency (P = 0.07) was observed for d 126 body weight with no effects of Zn within NoIMP while ZnS tended to be heavier than ZnB with ZnG intermediate within IS/200. Carcass-adjusted overall feed efficiency (G:F) was greatest for ZnS (Zn; P = 0.02). Implanted cattle had greater DM intake, G:F, and carcass-adjusted performance (P ≤ 0.01). Liver Zn concentrations were greater for IS/200 by d 120 (IMP × Day; P = 0.02). Within IS/200, ZnG tended to have greater muscle Zn than ZnS while ZnB was intermediate (Zn × IMP; P = 0.09). No Zn or IMP × Zn (P ≥ 0.12) effects were observed for carcass data. However, IS/200 had greater hot carcass weight, dressing percentage, and ribeye area than NoIMP (P ≤ 0.001). These data suggest implants improve growth and influence Zn metabolism. Future work should examine Zn sources and supplementation alongside implant strategies.

PSX-B-5 Effect of replacement of dry-rolled corn with un-processed rye on growth performance, efficiency of dietary net energy utilization, and carcass traits of finishing heifers

Continental × British beef heifers were used in a randomized complete block design experiment to evaluate the effects of replacing dry-rolled corn with unprocessed rye on growth performance, efficiency of dietary net energy (NE) utilization, and carcass trait responses in finishing heifers. Heifers (n = 56; 433 ± 34.0 kg) were transported 241 km from a regional sale barn to the Ruminant Nutrition Center in Brookings, SD. Heifers were blocked by weight grouping and then allotted to pens (n = 7 heifers/pen and 4 pens/treatment). Treatments included a finishing diet that contained 60% grain (DM basis) as dry-rolled corn (DRC) or unprocessed rye grain (RYE). On d 14, heifers were consuming the final diet and were implanted with 200 mg of trenbolone acetate and 28 mg of estradiol benzoate (Synovex-Plus, Zoetis, Parsippany, NJ). RYE heifers had decreased (P ≤ 0.01) final body weight, average daily gain, and gain efficiency; but tended (P = 0.08) to have a greater dry matter intake compared to DRC. RYE had decreased (P ≤ 0.01) observed dietary NE and decreased (P ≤ 0.01) observed-to-expected dietary NE ratio for maintenance and gain compared to DRC. Dressing percentage, 12th rib fat thickness, ribeye area, and the distribution of USDA yield and quality grades were not altered (P ≥ 0.12) by diet. Hot carcass weight, yield grade, estimated empty body fat (EBF), and body weight at 28% EBF decreased (P ≤ 0.02) and retail yield increased (P= 0.01) in RYE compared to DRC. These data indicate that unprocessed rye is a palatable feed ingredient for inclusion in finishing diets for beef cattle and that rye inclusion only minimally influences carcass quality. The feeding value of unprocessed rye is considerably less (21.4%) than that of dry-rolled corn using current standards and approximately 91% of the NE value of processed rye.

Determination of Eleven Veterinary Drugs in Chicken Meat and Liver

Brazil chicken production is around 13 million tons and about a third is exported to over 150 countries, placing Brazil as the world largest chicken meat producer, and therefore it is crucial to follow the legislation of all importer markets. This study conducted a survey by chance in 45 meat industries able to export. Therefore, 2580 chicken meat samples were collected and submitted to 11 analyte extraction and chromatographic verification of compliance in an accredited laboratory. Ten chemical residues (amoxicillin, bacitracin, colistin, dinitolmide + zoalene, spectinomycin, roxarsone, tiamulin, tylosin, trenbolone acetate and virginiamycin) were investigated in chicken meat and one (halofuginone hydrobromide) in chicken liver. The results showed that no compound exceeded the maximum residue limits established by seven legislations. All residue concentrations found were below the method quantification limit, thereby confirming the capability of Brazilian chicken meat industries in complying to foreign markets.

Zinc supplementation strategies in feedlot heifers receiving an extended-release implant or an aggressive re-implant program

Two-hundred and eight Angus-crossbred heifers (291 ± 23 kg) from four sources were used in a randomized complete block design. The objective of the study was to determine the effects of implant strategy and Zn supplementation on performance, carcass characteristics, muscle fiber diameter, and mineral status of heifers. Heifers were assigned to a 2 × 2 factorial study for 168 d, factors included Zn and implant (IMP). Heifers were supplemented Zn (mg/kg dry matter [DM]; ZnSO4) at national (30; NRC) or industry (100; IND) recommendations. Implant strategies (Merck Animal Health, Madison, NJ) included extended-release Revalor-XH on d 0 (REV-XH; 20 mg estradiol + 200 mg trenbolone acetate) containing 4 uncoated pellets and 6 coated pellets or the uncoated implant Revalor-200 on d 0 and again on d 91 (REV-200; 20 mg estradiol + 200 mg trenbolone acetate). Heifers were blocked by weight within source to pens of 5 or 6 heifers per pen (9 pens per treatment). A corn silage-based diet was fed during the growing period (d 0-55) followed by transition to a corn-based finishing diet. Weights were taken consecutively on d -1/0, 55/56, and 167/168. Liver and muscle from the longissimus thoracis were collected from one heifer per pen on d -5, 14, 105, and 164. Data were analyzed via Mixed Procedure of SAS. Average daily gain (ADG) and liver mineral used Period as the repeated effect. Corresponding to periods of high hormone payout from each implant, d 0-28 and 91-120 ADG were greatest for REV-200, while REV-XH numerically peaked during d 56-91 (IMP × Period; P = 0.02). Day 91 IND body weight tended to be heavier (P = 0.06) and d 120 body weight was heavier (P = 0.05) than NRC heifers. No effect of Zn or IMP on final body weight was observed (P ≥ 0.21). Muscle fiber cross-sectional diameter on d 164 was greater (P = 0.05) in IND than NRC. Liver Mn concentrations decreased by d 14 regardless of implant, though d 105 and 164 concentrations were lesser for REV-200 than REV-XH (IMP × Period; P = 0.02). No effects of Zn, IMP, or the interaction were observed for carcass-adjusted gain to feed, d 0-168 DM intake, hot carcass weight, or ribeye area (P ≥ 0.11). The nominal differences in performance between implant strategies suggests extended-release implants may be an effective implant strategy to replace re-implant programs in heifers, while the improved performance of heifers fed IND vs. NRC during times of peak hormone payout suggests a role for Zn in periods of rapid growth.

Anabolic Implants Varying in Hormone Type and Concentration Influence Performance, Feeding Behavior, Carcass Characteristics, Plasma Trace Mineral Concentrations, and Liver Trace Mineral Concentrations of Angus Sired Steers

Fifty Angus-sired steers were utilized to evaluate the effects of anabolic implants varying in hormone type and concentration on performance, carcass traits, and plasma and liver trace mineral concentrations over 129 d. Steers were stratified by weight into one of four (n = 12 or 13/treatment) implant treatments: (1) estradiol (E2; 25.7 mg E2; Compudose, Elanco Animal Health, Greenfield, IN, USA), (2) trenbolone acetate (TBA; 200 mg TBA; Finaplix-H, Merck Animal Health, Madison, NJ, USA), (3) combination implant (ETBA; 120 mg TBA + 24 mg E2; Revalor-S, Merck Animal Health), or (4) no implant (CON). Steers were randomly assigned to pens equipped with GrowSafe bunks and fed a corn and barley-based finishing ration. Overall average daily gain and body weight were greater for ETBA and TBA than CON (p ≤ 0.04), but not E2 (p ≥ 0.12). Feed efficiency and hot carcass weight were only greater than CON for ETBA (p ≤ 0.03). Plasma and d 2 liver Zn concentrations were lesser for ETBA than CON (p ≤ 0.01) and d 10 liver Mn was lesser (p = 0.0003) for TBA than CON. These data indicate that implants containing TBA influence growth and trace mineral parameters, though more work investigating this relationship is necessary.

Determination of Eleven Veterinary Drugs in Chicken Meat and Liver

Brazil chicken production is around 13 million tons and about a third is exported to over 150 countries, placing Brazil as the world largest chicken meat producer, and therefore it is crucial to follow the legislation of all importer markets. This study aimed at evaluating ten chemical residues (amoxicillin, bacitracin, colistin, dinitolmide + zoalene, spectinomycin, roxarsone, tiamulin, tylosin, trenbolone acetate and virginiamycin) in chicken breast and one (halofuginone hydrobromide) in chicken liver. Most of these compounds are not covered by National Residues and Contaminants Control Plan (PNCRC), although they are mandatory to export chicken meat worldwide. A total of 2580 samples were collected from 45 industries and submitted to analyte extraction and chromatographic verification of compliance in an accredited laboratory. The results showed that no compound exceeded the maximum residue limits established by worldwide legislation. All results were below the method detection limit, thereby confirming the capability of Brazilian chicken meat plants in complying to foreign markets. Our results can provide occurrence trends of veterinary drug from poultry products in Brazil.

Effect of trenbolone acetate, melengestrol acetate, and ractopamine hydrochloride on the growth performance of beef cattle

The effect of trenbolone acetate+estradiol implants (TBA), melengestrol acetate (MGA), and ractopamine hydrochloride+TBA (RAC+TBA) on growth performance and carcass characteristics in beef cattle (n=680; 279±10.1 kg) fed barley grain/corn silage was examined in a 4-yr study (4 pens/treatment/yr; 262 ±8 d feeding period). In the first 2 yrs, treatments were: 1) control heifers (H-CON; no growth promoters (GP), 2) TBA implanted heifers (H-TBA), 3) MGA heifers (H-MGA), 4) control steers (S-CON; no GP), and 5) TBA implanted steers (S-TBA). A sixth treatment 6) RAC+TBA steers (RAC+TBA) was included in yrs 3 and 4. Overall DMI of heifers was increased (P<0.001) by TBA, but not MGA. Compared to H-CONs, H-TBA had greater ADG (P <0.001), G:F (P < 0.001), and carcass weight (P < 0.001), whereas S-TBA had increased ADG (P < 0.001), G:F (P< 0.001), and carcass weight (P< 0.001) compared to S-CON. Compared to H-CON, H-MGA had increased (P< 0.01) ADG, G:F and carcass weight. The RAC+TBA had increased (P< 0.01) ADG and carcass weight (3.2%), but not G:F or DMI compared to S-TBA. This 4 yr study showed a consistent positive impact of growth-enhancing technologies on the performance of Canadian feedlot cattle.