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The effects of supplemental Zn within steroidal implant strategy on performance, carcass characteristics, trace mineral status, and muscle gene expression were tested in a 59-d study using 128 Angus-crossbred steers (492 ± 29 kg) in a 2 × 4 complete randomized design. Implant strategies included no implant (NoIMP) or Component TE-200 (TE200 ; Elanco, Greenfield, IN) administered on day 0. Zinc was supplemented at 0, 30, 100, or 150 mg Zn/kg dry matter (Zn0 , Zn30 , Zn100 , Zn150 , respectively) from ZnSO4. Steers were stratified by body weight (BW) to pens (n  = 5 or 6 steers/pen) equipped with GrowSafe bunks (GrowSafe Systems Ltd. Airdrie, AB, Canada) and assigned treatments (n  = 15, 16, or 17 steers/treatment). Cattle were weighed on days −1, 0, 18, and 59 with blood collected on days −1, 18, 40, and 59. Muscle samples were collected from the longissimus thoracis on day 11 and liver samples were collected on day 55 or 56. Data were analyzed using the Mixed Procedure of SAS via contrast statements testing the linear and quadratic response to Zn supplementation within implant treatment and NoIMP vs. TE200 for performance, carcass, blood, and liver parameters. Specific contrast statements were formed for the analysis of gene expression in muscle including: Zn0 vs. Zn150 within NoIMP and TE200, NoIMP vs. TE200 (Zn0 and Zn150 only), and the linear effect of supplementing Zn0, Zn100, and Zn150 within TE200. Steer was the experimental unit. Day 18 BW and days 0 to 18 average daily gain (ADG) were linearly increased due to Zn supplementation within TE200 (P  ≤ 0.002) in conjunction with a linear increase from Zn in day 11 muscle epidermal growth factor receptor, matrix metalloproteinase 2, and phosphodiesterase 4B gene expression of TE200 steers (P  ≤ 0.05). Plasma Zn on days 18 and 40 linearly increased with increasing Zn supplementation regardless of implant treatment (P  ≤ 0.03) and was lesser for TE200 than NoIMP steers on day 18 (P  = 0.001). Day 59 BW and hot carcass weight (HCW) were greater for TE200 vs. NoIMP (P  ≤ 0.002) and HCW of implanted steers tended to linearly increase with increasing Zn supplementation (P  = 0.09). No effects of Zn supplementation were observed in NoIMP for HCW, BW, or ADG (P  ≥ 0.17). Yield grade and 12th rib fat tended to quadratically decrease within NoIMP (P  ≤ 0.09), with Zn100 being the most lean. These data indicate increasing supplemental Zn influences steroidal implant signaling machinery while increasing the Zn status and implant-induced growth of feedlot cattle. [ABSTRACT FROM AUTHOR]

Ninety-two Angus-crossbred steers (424 ± 28.3 kg initial body weight) were used in a 98-d study to assess the effects of increasing Zn supplementation on cattle performance, liver and plasma trace mineral concentrations, blood metabolites, and carcass characteristics. All steers were implanted with a Component TE-200 (200 mg trenbolone acetate + 20 mg estradiol; Elanco Animal Health, Greenfield, IN) on d 0 and fed 300 mg‧steer−1‧d−1 of ractopamine hydrochloride (Zoetis, Parsippany, NJ) from d 70 to 98. Cattle were fed via GrowSafe bunks (GrowSafe Systems Ltd. Airdrie, AB, Canada), and steer served as the experimental unit (n  = 22 or 23 steers/treatment). Supplemental Zn was administered through the diet at 0, 100, 150, or 180 mg Zn/kg on a dry matter basis from ZnSO4 (Zn0, Zn100, Zn150, or Zn180, respectively). Cattle were weighed on d −1, 0, 9/10, 20, 41, 59, 69, 70, 78/79, 97, and 98. Blood was collected on d 0, 9/10, 69, 78/79, and 97, and liver biopsies on d 9/10 and 78/79 (n  = 12 steers/treatment). Data were analyzed as a complete randomized design. Contrast statements were formed to test the linear, quadratic, and cubic effects of Zn supplementation and test Zn0 vs. Zn supplementation. Day 10 and 70 body weight (BW) and d 0 to 10 and 0 to 70 average daily gain were linearly increased with Zn supplementation (P  ≤ 0.05), and greater for Zn supplemented steers (P  ≤ 0.03). No effects of Zn supplementation were observed on final BW, dressing percentage, ribeye area, 12th rib fat, or marbling (P  ≥ 0.11). Hot carcass weight tended to be 7 kg greater for Zn supplemented steers than Zn0 (P  = 0.07), and yield grade linearly increased with increasing Zn supplementation (P  = 0.02). Day 10 liver Mn concentrations tended to quadratically decrease (P  = 0.08) with increasing Zn supplementation, though d 79 liver Mn concentrations and arginase activity were not influenced by Zn (P  ≥ 0.28). Day 10 liver arginase activity tended to be (r  = 0.27; P  = 0.07) and d 10 serum urea nitrogen was correlated with d 10 liver Mn (r  = 0.55; P  < 0.0001). Zinc supplementation linearly increased d 10 liver Zn and d 10, 69, 79, and 97 plasma Zn concentrations (P  ≤ 0.05). A cubic effect of Zn was observed on d 79 liver Zn (P  = 0.01) with lesser liver Zn in Zn0 and Zn150 steers. These data suggest increasing dietary Zn improves growth directly following the administration of a steroidal implant and that steroidal implants and beta agonists differ in their effects on protein metabolism. [ABSTRACT FROM AUTHOR]

The article focuses on study of performance, lipolytic rate of beef steers and carcass characteristics affected by dietary copper supplementation of beef steers fed ractopamine hydrochloride. Topics discussed include intracellular signaling pathways activated by beta agonists to increase muscle accretion, cattle stratified to treatment by initial liver concentration, and performance of beta agonist-fed steers influenced by supplemental concentrations.

To assess plasma trace mineral (TM) concentrations, the acute phase protein response, and behavior in response to a lipopolysaccharide (LPS) challenge, 96 Angus cross steers (average initial body weight [BW]: 285 ± 14.4 kg) were sorted into two groups by BW (heavy and light; n = 48/group), fitted with an ear-tag–based accelerometer (CowManager SensOor; Agis, Harmelen, Netherlands), and stagger started 14 d apart. Consecutive day BW was recorded to start the 24-d trial (days −1 and 0). Dietary treatments began on day 0: common diet with either 30 (Zn30) or 100 (Zn100) mg supplemental Zn/kg DM (ZnSO4 ). On day 17, steers received one of the following injection treatments intravenously to complete the 2 × 3 factorial: 1) SALINE (~2–3 mL of physiological saline), 2) LOWLPS: 0.25 µg LPS/kg BW, or 3) HIGHLPS: 0.375 µg LPS/kg BW. Blood, rectal temperature (RT), and BW were recorded on day 16 (−24 h relative to injection), and BW was used to assign injection treatment. Approximately 6, 24 (day 18), and 48 (day 19) h after treatment, BW, RT, and blood were collected, and final BW recorded on day 24. Data were analyzed in Proc Mixed of SAS with fixed effects of diet, injection, diet × injection; for BW, RT, dry matter intake (DMI), plasma TM, and haptoglobin-repeated measures analysis were used to evaluate effects over time. Area under the curve analysis determined by GraphPad Prism was used for analysis of accelerometer data. Body weight was unaffected by diet or injection (P ≥ 0.16), but there was an injection × time effect for DMI and RT (P < 0.05), where DMI decreased in both LPS treatments on day 16, but recovered by day 17, and RT was increased in LPS treatments 6 h post-injection. Steers receiving LPS spent less time highly active and eating than SALINE (P < 0.01). Steers in HIGHLPS spent lesser time ruminating, followed by LOWLPS and then SALINE (P < 0.001). An injection × time effect (P < 0.001) for plasma Zn showed decreased concentrations within 6 h of injection and remained decreased through 24 h before recovering by 48 h. A tendency for a diet × time effect (P = 0.06) on plasma Zn suggests plasma Zn repletion occurred at a greater rate in Zn100 compared to Zn30. These results suggest that increased supplemental Zn may alter the rate of recovery of Zn status from an acute inflammatory event. Additionally, ear-tag–based accelerometers used in this study were effective at detecting sickness behavior in feedlot steers, and rumination may be more sensitive than other variables. [ABSTRACT FROM AUTHOR]

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 days 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 days −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 day 126 body weight with no effects of Zn within NoIMP, whereas 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 day 120 (IMP × Day; P = 0.02). Within IS/200, ZnG tended to have greater muscle Zn than ZnS, whereas 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 that implants improve growth and influence Zn metabolism. Future work should examine Zn sources and supplementation alongside implant strategies. [ABSTRACT FROM AUTHOR]

Two hundred 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, and 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 day 0 (REV-XH; 20 mg estradiol + 200 mg trenbolone acetate) containing four uncoated pellets and six coated pellets or the uncoated implant Revalor-200 on day 0 and again on day 91 (REV-200; 20 mg estradiol + 200 mg trenbolone acetate). Heifers were blocked by weight within source to pens of five or six heifers per pen (nine pens per treatment). A corn silage-based diet was fed during the growing period (days 0–55) followed by transition to a corn-based finishing diet. Weights were taken consecutively on days −1/0, 55/56, and 167/168. Liver and muscle from the longissimus thoracis were collected from one heifer per pen on days −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, days 0–28 and 91–120 ADG were greatest for REV-200, whereas REV-XH numerically peaked during days 56–91 (IMP × Period; P = 0.02). Day 91 IND body weight tended to be heavier (P = 0.06) and day 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 day 164 was greater (P = 0.05) in IND than NRC. Liver Mn concentrations decreased by day 14 regardless of implant, though days 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, days 0–168 DM intake, hot carcass weight, or ribeye area (P ≥ 0.11). The nominal differences in performance between implant strategies suggest that extended-release implants may be an effective implant strategy to replace re-implant programs in heifers, whereas 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. [ABSTRACT FROM AUTHOR]

To determine the effect of various trace mineral-containing products on trace mineral status of cattle 56 Angus-cross steers (303 ± 15 kg; n = 8 per treatment) were blocked by BW and administered a trace mineral treatment on d-0: injectable saline (CON), injectable Multimin®90 (ITM), MineralMax drench (MMD), MineralMax paste (MMP), Starting Fluid Drench (SFD), Se365 bolus (Se365), or Reloader250 bolus (Rel250). Steers received a common diet (silage-based d 0–49; corn-based d 50–122) via bunks capable of measuring individual feed disappearance. Plasma (0, 8, 24, and 48-h) and liver (-7, 2, 15, 29, 49, 65, 91, and 120-d) samples were obtained for analysis of Cu, Mn, Se, and Zn. Data were analyzed as repeated measures with effects of treatment, time, and treatment×time, with initial mineral concentration as covariate. Plasma Zn, Mn, and Se concentrations were affected by treatment×time (P = 0.001) where ITM was greater through 8-h for Zn and through 24-h for Mn and Se over all other treatments. Liver Se concentration was greater in ITM vs. other treatments through d-15 and Rel250 was greater than ITM and MMP on d-91 and greater than CON, MMD, MMP, and SFD on d-120 (treatment×time; P ≤ 0.001). Plasma Cu, and liver Cu, Mn, and Zn concentrations were unchanged by treatment (P ≥ 0.05). Liver Mn concentrations were least on d-2 and generally increased over time (P ≤ 0.001), while liver Zn concentrations were greatest on d-2 and least from d-29 onward (time; P ≤ 0.001). Liver Cu concentrations were greatest on d-15 and d-29 vs. other days (time; P ≤ 0.001). Overall, use of injectable trace mineral rapidly increased plasma Mn, Se and Zn, and liver Se concentrations. Oral treatments tested here exerted no effect on plasma or liver concentrations, while the multi-element bolus, Rel250, increased liver Se after 91-d. [ABSTRACT FROM AUTHOR]

Simple Summary: This review addresses the physiological and biochemical connections between steroidal implants and Zn and their interaction to influence growth in beef cattle. Steroidal implants have been widely accepted as a growth-promoting technology that provides an unmatched economic return to the producer and improves beef production's environmental sustainability. Likewise, decades of research have indicated Zn is vital for skeletal muscle growth. Considering Zn is an essential trace mineral, strategic Zn supplementation to implanted cattle may optimize beef production. Although many interrelationships between steroidal implants and Zn are new and forthcoming, the literature reviewed hereafter indicates roles for Zn in a multitude of growth processes pertinent to steroidal implant-induced growth and uncover changes in Zn metabolism due to steroidal implant use. Growth-promoting technologies such as steroidal implants have been utilized in the beef industry for over 60 years and remain an indispensable tool for improving economic returns through consistently improved average daily gain via increased skeletal muscle hypertrophy. Zinc has been implicated in skeletal muscle growth through protein synthesis, satellite cell function, and many other growth processes. Therefore, the objective of this review was to present the available literature linking Zn to steroidal implant-induced protein synthesis and other metabolic processes. Herein, steroidal implants and their mode of action, the biological importance of Zn, and several connections between steroidal implants and Zn related to growth processes are discussed. These include the influence of Zn on hormone receptor signaling, circulating insulin-like growth factor-1 concentrations, glucose metabolism, protein synthesis via mTOR, and satellite cell proliferation and differentiation. Supplemental Zn has also been implicated in improved growth rates of cattle utilizing growth-promoting technologies, and steroidal implants appear to alter liver and circulating Zn concentrations. Therefore, this review provides evidence of the role of Zn in steroidal implant-induced growth yet reveals gaps in the current knowledge base related to optimizing Zn supplementation strategies to best capture growth performance improvements offered through steroidal implants. [ABSTRACT FROM AUTHOR]