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Angus-cross steers (n = 144; 362 kg ± 20.4) were used to determine the effect of Zn and steroidal implants on performance, trace mineral status, circulating metabolites, and transcriptional changes occurring in skeletal muscle. Steers (n = 6 per pen) were stratified by body weight (BW) in a 3 × 2 factorial. GrowSafe bunks recorded individual feed intake (steer as experimental unit; n = 24 per treatment). Dietary treatments (ZINC; eight pens per treatment) included supplemental Zn as ZnSO4 at 1) 0 (analyzed 54 mg Zn/kg DM; Zn0); 2) 30 mg/kg DM (Zn30); 3) 100 mg Zn/kg DM (Zn100). After 60 d of Zn treatment, steers received a steroidal implant treatment (IMP) on day 0: 1) no implant; NO; or 2) high-potency combination implant (TE-200, Elanco, Greenfield, IN; 200 mg TBA, 20 mg E2; TE200). BWs were taken at days -60, 0, and in 28 d increments thereafter. Liver biopsies for TM analysis and blood for TM, serum glucose, insulin, nonesterified fatty acids (NEFA), urea-N, and IGF-1 analysis were collected on days 0, 20, 40, and 84. Glucose, NEFA, and insulin were used to calculate the revised quantitative insulin sensitivity check index (RQUICKI). Linear and quadratic effects of ZINC were evaluated in SAS 9.4. Means for IMP were separated using the LSMEANS statement with the PDIFF option. Day -60 BW was a covariate for performance and carcass data. Growth performance, plasma, liver, and metabolite data were analyzed as repeated measures. TE200 tended to decrease plasma Zn by 8.4% from days 0 to 20 while NO decreased by 3.6% (IMP × day; P = 0.08). A tendency for a ZINC × day effect on G:F was noted (P = 0.06) driven by Zn30 and Zn100 decreasing significantly from period 0-28 to period 28-56 while Zn0 was similar in both periods. An IMP × day effect was noted for RQUICKI where (P = 0.02) TE200 was greater on day 40 compared to NO cattle, but by day 84 RQUICKI was not different between TE200 and NO. On day 20, increasing Zn supplementation linearly increased mRNA abundance (P ≤ 0.09) of protein kinase B (AKT1), mammalian target of rapamycin (mTOR), matrix metalloproteinase 2 (MMP2), and myogenic factor 5 (MYF5). In this study, Zn and implants differentially affected genes related to energy metabolism, satellite cell function, and TM homeostasis on days 20 and 84 postimplant. These results suggest steroidal implants increase demand for Zn immediately following implant administration to support growth and may influence insulin sensitivity in finishing cattle., (© The Author(s) 2024. Published by Oxford University Press on behalf of the American Society of Animal Science.)

Angus-cross steers (n = 144; 359 kg ± 13.4) were used to assess the effect of dietary Mn and steroidal implants on performance, trace minerals (TM) status, hepatic enzyme activity, hepatic gene expression, and serum metabolites. Steers (n = 6/pen) were stratified by BW in a 3 × 2 factorial. GrowSafe bunks recorded individual feed intake (experimental unit = steer; n = 24/treatment). Dietary treatments included (MANG; 8 pens/treatment; Mn as MnSO4): (1) no supplemental Mn (analyzed 14 mg Mn/kg DM; Mn0); (2) 20 mg supplemental Mn/kg DM (Mn20); (3) 50 mg supplemental Mn/kg DM (Mn50). Within MANG, steers received a steroidal implant treatment (IMP) on day 0: (1) no implant; NO; or (2) combination implant (Revalor-200; REV). Liver biopsies for TM analysis and qPCR, and blood for serum glucose, insulin, non-esterified fatty acids, and urea-N (SUN) analysis were collected on days 0, 20, 40, and 77. Data were analyzed as a randomized complete block with a factorial arrangement of treatments including fixed effects of Mn treatment (MANG) and implant (IMP) using PROC MIXED of SAS 9.4 using initial BW as a covariate. Liver TM, serum metabolite, enzyme activity, and gene expression data were analyzed as repeated measures. No MANG × IMP effects were noted (P ≥ 0.12) for growth performance or carcass characteristic measures. Dietary Mn did not influence final body weight, overall ADG, or overall G:F (P ≥ 0.14). Liver Mn concentration increased with supplemental Mn concentration (MANG; P = 0.01). An IMP × DAY effect was noted for liver Mn (P = 0.01) where NO and REV were similar on day 0 but NO cattle increased liver Mn from days 0 to 20 while REV liver Mn decreased. Relative expression of MnSOD in the liver was greater in REV (P = 0.02) compared to NO and within a MANG × IMP effect (P = 0.01) REV increased liver MnSOD activity. These data indicate current NASEM Mn recommendations are adequate to meet the demands of finishing beef cattle given a steroidal implant. Despite the roles of Mn in metabolic pathways and antioxidant defense, a basal diet containing 14 mg Mn/kg DM was sufficient for the normal growth of finishing steers. This study also provided novel insight into how implants and supplemental Mn influence genes related to arginine metabolism, urea synthesis, antioxidant capacity, and TM homeostasis as well as arginase and MnSOD activity in hepatic tissue of beef steers., (© The Author(s) 2024. Published by Oxford University Press on behalf of the American Society of Animal Science.)

Low-risk, weaned Angus-crossbred steers (n = 72; 284 ± 25 kg) were used in a 42-d receiving study. Steers were housed in pens (n = 6 steers per pen) equipped with GrowSafe bunks for determination of individual animal feed disappearance. Dietary treatments (n = 24 steers per treatment) included: 1) trace minerals (TM) from an organic source (Availa4; Zinpro Corp., Eden Prairie, MN) at 7 g·steer-1·d-1; for 42 d (ORG); 2) ORG for entire 42-d plus AvailaZn (Zn amino acid complex, Zinpro Corp., Eden Prairie, MN) to provide 1,000 mg Zn·steer-1·d-1 for first 14 d (ORG+Z); 3) inorganic TM sources to supplemented at equivalent concentration as in ORG for 42-d (ING). Cattle were weighed on day -1, 0, 14, 41, and 42. Whole blood was collected (n = 72 steers) on day 0, 14, and 42. Liver biopsies were conducted (n = 36 steers; 3 steers per pen) on day 0, 14, and 42. Flow cytometry measures were conducted using whole blood on day 1, 14, and 42 for determination of circulating frequencies of immune cell populations. There was a tendency for improved overall average daily gain (P = 0.07) where both ORG and ORG+Z were greater than ING. Final body weight did not differ (P = 0.21) and overall dry matter intake was unaffected by dietary treatment (P ≥ 0.18). However, overall gain-to-feed ratio was improved (P = 0.01) in steers supplemented organic TM (ORG and ORG+Z) compared to ING. Plasma Zn concentration did not differ at any time point during the study (P ≥ 0.20). Liver Zn concentration did not differ between treatments on day 0 or 42; however, on day 14 ING tended (P = 0.09) to be greater than ORG+Z with ORG being intermediate. Plasma Cu was unaffected by dietary treatment (P ≥ 0.34) on day 0, 14, and 42. Plasma Fe did not differ on day 0 or 42 but tended to be greater in ORG and ORG+Z compared to ING (P = 0.08) on day 14. Dietary treatment did not alter (P ≥ 0.22) liver Fe or Mn concentration at any time point. Frequency of total circulating natural killer (NK) and CD8 T cells measured on day 0, 14, and 42 did not differ (P ≥ 0.07). However, cell surface markers of activation (CD16, CD44, and CD8) on NK cells measured on day 14 did differ because of treatment (P ≤ 0.05). Results presented herein indicate TM from an organic source supplemented to steers during receiving can positively influence growth rate and feed efficiency. Regardless of source, TM supplementation affected markers of immune function but did not influence the prevalence of circulating NK and CD8 T-cell populations., (© The Author(s) 2023. Published by Oxford University Press on behalf of the American Society of Animal Science.)

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., (© The Author(s) 2021. Published by Oxford University Press on behalf of the American Society of Animal Science.)

To assess the efficacy of bis-glycinate bound Zn, 36 crossbred wethers (34 ± 2 kg) were sorted by body weight into three groups and stagger started on a Zn-deficient diet (18 mg Zn/kg dry matter [DM]; 22.5% neutral detergent fiber [NDF]) for 45 d prior to a 15-d metabolism period (10 d adaptation and 5 d collection). On day 46, lambs were randomly assigned to dietary treatments (four lambs treatment-1group-1): no supplemental Zn (CON) or 15 mg supplemental Zn/kg DM (ZINC) as Zn sulfate (ZS) or bis-glycinate (GLY; Plexomin Zn, Phytobiotics). Blood was collected from all lambs on days 1, 44, 56, and 61. Liver, jejunum, and longissimus dorsi samples were collected after euthanasia on day 61. Gene expression was determined via quantitative real-time polymerase chain reaction. Data were analyzed using ProcMixed of SAS (experimental unit = lamb; fixed effects = treatment, group, and breed) and contrast statements assessed the effects of supplemental Zn concentration (ZINC vs. CON) and source (GLY vs. ZS). After 15 d of Zn supplementation, plasma Zn concentrations were greater for ZINC vs. CON and GLY vs. ZS (P ≤ 0.01); tissue Zn concentrations were unaffected (P ≥ 0.27). Liver Cu concentrations were lesser for ZINC vs. CON (P = 0.03). Longissimus dorsi Mn concentrations were greater for ZINC vs. CON (P = 0.05) and tended to be lesser for GLY vs. ZS (P = 0.09). Digestibility of DM, organic matter (OM), and NDF was lesser for ZINC vs. CON (P ≤ 0.05); acid detergent fiber digestibility tended to be greater for GLY vs. ZS (P = 0.06). Nitrogen retention (g/d) tended to be greater for GLY vs. ZS (P = 0.10), and N apparent absorption was lesser for ZINC vs. CON (P = 0.02). Zinc intake, fecal output, retention, and apparent absorption were greater for ZINC vs. CON (P ≤ 0.01). Apparent absorption of Zn was -5.1%, 12.8%, and 15.0% for CON, ZS, and GLY, respectively. Nitrogen and Zn retention and apparent absorption were not correlated for CON (P ≥ 0.14) but were positively correlated for ZINC (retention: P = 0.02, r = 0.52; apparent absorption: P < 0.01, r = 0.73). Intestinal expression of Zn transporter ZIP4 was lesser for ZINC vs. CON (P = 0.02). Liver expression of metallothionein-1 (MT1) tended to be greater for GLY vs. ZS (P = 0.07). Although Zn apparent absorption did not differ between sources (P = 0.71), differences in post-absorptive metabolism may be responsible for greater plasma Zn concentrations and liver MT1 expression for GLY-supplemented lambs, suggesting improved bioavailability of GLY relative to ZS., (© The Author(s) 2021. Published by Oxford University Press on behalf of the American Society of Animal Science.)

Trace mineral status is a critical component of bovine health. Impairment of physiological processes, caused by trace mineral toxicities or deficiencies, can be potential underlying factors of disease. Historically, the status of critical trace minerals, such as copper, manganese, selenium, and zinc, has been evaluated through the analysis of hepatic tissue. We assessed variation of these 4 elements between homogenized liver and samples of 0.02 g, 0.1 g, 0.5 g, and 1.0 g. We also evaluated concentration differences in copper, manganese, selenium, and zinc among samples stored under different durations. No differences in concentrations of copper, manganese, selenium, or zinc were observed among samples stored frozen for 3, 7, and 14 d post-collection. Statistical differences in concentrations of selenium and zinc were observed between 0.02-g biopsy samples and larger samples. Moisture content differed between 0.02-g biopsies and larger samples and over time. Results indicate that as little as 0.02 g of hepatic tissue dried to ~0.006 g is reliable for interpretation of trace mineral status and determination of toxicities and deficiencies in cattle pertaining to copper, manganese, selenium, and zinc, despite the small differences observed.

The objective of this study was to assess whether supplemental Zn source or concentration would affect ruminant Zn retention and nutrient digestibility. Thirty-six weaned crossbred Polypay wethers, were sorted by BW to 3 periods and stagger started on a common diet (22 mg Zn/kg DM) for a 52-d depletion period. Day 52 BW was used to assign Zn treatments (3 lambs/treatment/period): no supplemental Zn (CON), or supplemental Zn (40 mg Zn/d) from Zn sulfate (ING; Zinc Nacional, Monterrey, SA, Mexico), Zn methionine (ORG; Zinpro 120; Zinpro, Eden Prairie, MN), or Zn hydroxychloride (HYD; IntelliBond Z; Micronutrients USA LLC, Indianapolis, IN). On day 53 (day 1 of Zn treatments), lambs were moved to metabolism crates for 10 d of adaptation and 5 d of total fecal and urine collection. Blood for plasma Zn analysis was collected on day 52 and day 68. Data were analyzed as a randomized complete design with fixed effects of treatment, period and the interaction, which was significant (P ≥ 0.19) for day 68 plasma Zn but was removed for all other variables. Contrast statements were used to separate treatment means: CON vs. ZINC (ING, ORG, HYD), ING vs. HYD, and ORG vs. HYD. Day 52 plasma Zn concentrations were similar when CON was compared with ZINC (P = 0.84), and when ING and ORG were compared with HYD (P ≥ 0.19). Dry matter and neutral detergent fiber digestibility were lesser in ORG compared with HYD (P = 0.05) and organic matter and acid detergent fiber digestibility tended (P ≤ 0.08) to be lesser in ORG compared with HYD. Intake and fecal excretion of Zn was lesser, while apparent absorption of Zn was greater, in CON compared with ZINC (P ≤ 0.001). Zinc retained as a percent of Zn intake was greater in CON compared with ZINC (P = 0.001). Zinc retained (mg/d) was similar in CON compared with ZINC (P = 0.58) and when ING or ORG were compared with HYD (P ≥ 0.83). There was a treatment × period interaction for day 68 plasma Zn where treatments did not differ for periods 1 and 3 but ORG lambs had increased plasma Zn in period 2 compared with other treatments (P = 0.02). Lambs receiving no supplemental Zn had increased apparent absorption, suggesting Zn absorption may be upregulated in these lambs. Similarities in Zn retention across treatments suggests Zn requirements of these lambs were met regardless of supplementation concentration or source. Nutrient digestibility was improved in HYD lambs compared with ORG, and further work is needed to clarify the influence of supplemental Zn source on nutrient digestion.

The study objective was to determine whether N retention was improved with supplemental Zn above NRC concentrations with or without ractopamine hydrochloride inclusion. Angus crossbred steers (n = 32, 485 ± 26 kg BW) with Genemax gain scores of 4 or 5 were utilized in a 2 × 2 factorial arrangement (8 steers/treatment). Steers were blocked by BW to a finishing diet with 1 of 2 mineral supplementation strategies (ZNTRT), no supplemental Zn (analyzed 32 mg Zn/kg DM; CON) or supranutritional Zn (CON + 60 ppm ZnSO4 + 60 ppm Zn-amino acid complex; analyzed 145 mg Zn/kg DM; SUPZN), fed 56 days in pens equipped with GrowSafe bunks and assigned to β-agonist (BA) supplementation strategies of 0 (NON) or 300 mg steer-1 d-1 ractopamine hydrochloride (RAC) fed the last 30 d before harvest. Initial 56-d ADG was not affected by ZNTRT (P = 0.66), but DMI was greater in CON vs. SUPZN (P < 0.01). On day 56 (day 1 of BA supplementation), steers (4 groups; 8 steers/group; 2 steers/treatment) were moved to metabolism crates and adapted for 10 d, followed by 5 d of total fecal and urine collection. Total retention of Zn, Mn, Fe, Cu, and N were calculated. Data were analyzed as a 2 × 2 factorial arrangement, with group as a fixed effect and the 3-way interaction of ZNTRT × BA × group as random. No interactions between ZNTRT and BA were noted for any data (P ≥ 0.19). Collection DMI did not differ among treatments (P ≥ 0.23); however, Zn intake was lesser in CON vs. SUPZN (P < 0.01). Fecal and urinary Zn excretion and Zn and Mn retention were lesser in CON vs. SUPZN (P ≤ 0.03); however, Zn retention was not different between NON and RAC (P = 0.43). Retention of Cu and Fe was unaffected by strategies (P ≥ 0.49). Urine output and urine N excretion were greater in NON vs. RAC (P ≤ 0.05). Nitrogen retention (as percent of N intake) was lesser (P = 0.05) in CON (40.0%) vs. SUPZN (44.3%) and lesser (P = 0.02) in NON (39.5%) vs. RAC (44.8%). Zinc and N retention were found to be positively correlated (r = 0.46, P < 0.01). Average daily gain and G:F across the 86-d trial were lesser in NON vs. RAC (P < 0.03). Overall, SUPZN appears to improve N retention, suggesting that increasing dietary Zn may be important for cattle growth beyond that induced by ractopamine hydrochloride.

To compare trace mineral (TM) repletion in feedlot steers after depletion by S and Mo, 72 Red Angus steers blocked by BW (253 ± 14 kg) were assigned (6 steers per pen, fed via GrowSafe bunks) to corn silage depletion diets (depletion, DEP) supplemented with NRC (1996) recommended concentrations of Cu, Mn, Se, and Zn (CON) or supplemented with 0.3% S (CaSO4), 2 mg of Mo/kg dry matter (DM), and no added Cu, Mn, Zn, or Se (antagonist, ANT). Three 62 d TM repletion strategies (repletion, REP) were applied within DEP diets on day 89: 1) Multimin90 injection (contains Cu, Mn, Se, Zn) and 100% of recommended Cu, Mn, Zn, and Se from inorganic sources (ITM), 2) saline injection and 150% of recommended TM from inorganic sources (ING), or 3) saline injection and 150% of recommended TM provided as 25% organic and 75% inorganic sources (BLEND). Subcutaneous injections were given at 1 mL/68 kg BW. Inorganic sources were Cu, Mn, and Zn SO4, and sodium selenite, and organic sources were Availa Cu, Mn and Zn, and SelPlex Se. Repletion period liver and blood were collected on day -10, 14, 28, and 42 and data were analyzed as a 2 × 3 factorial (n = 12 steers per treatment) using Proc Glimmix of SAS with plasma and liver analytes analyzed as repeated measures. Liver Cu, Se, and Mn were decreased (P < 0.01) by ANT during DEP. There were no DEP × REP × day interactions in liver TM (P ≥ 0.18). A DEP × day effect was noted for liver Cu (P < 0.01) and Mn (P = 0.07), where ANT Cu increased linearly from day 0 to day 42, CON Cu was slightly increased on day 14 and day 28, and ANT Mn was lesser than CON Mn on all days except day 42. There were REP × day effects on liver Cu (P < 0.01) and Se (P < 0.01) where status was improved by ITM by day 14, increased in BLEND by day 28, and not different by day 42. Liver Se concentrations were lesser (P < 0.01) in ANT vs. CON throughout repletion. Liver Zn was greater (P < 0.01) on day 0 than day 14, 28, and 42, and concentrations were greater on day 42 than day 28. Glutathione peroxidase activity tended to be lesser (P = 0.07) on day 14 relative to other days. Manganese superoxide dismutase activity was lesser (P < 0.01) on day 14 and 28 compared to day 0 and 42, and tended to be lesser (P = 0.06) in ANT than CON during repletion. Final body weight (BW) and average daily gain (ADG) were not affected by treatment (P ≥ 0.60), and ANT decreased dry matter intake (DMI) (P = 0.04) and improved G:F (P < 0.01) during repletion. All repletion strategies were effective at increasing TM status of steers, and ITM had the most rapid recovery of Cu and Se status, followed by BLEND, and ING.

To determine the effects of trace mineral (TM) supplementation and hormone implant strategy on growth and carcass characteristics of cattle, 72 Angus-cross steers (388 ± 17 kg) were blocked by body weight (six steers per pen) to a 2 × 3 factorial. Factors included growth-stimulating implant (GS): day 0 with Component TE-IS, reimplanted day 56 with Component TE-200 (IMP) or no implant (NoIMP), and TM supplementation (TM): no supplemental TM (CON), TM supplemented at national (NASEM, 2016). Nutrient requirements of beef cattle. 8th ed. Washington, DC: The National Academics Press) recommendations of 10 Cu, 30 Zn, 20 Mn, 0.10 Se, 0.15 Co, and 0.50 I (mg/kg; REC), or TM supplemented at feedlot consultant recommendations of 20 Cu, 100 Zn, 50 Mn, 0.30 Se, 0.20 Co, and 0.50 I (mg/kg; IND). Steers received a finishing diet for 124 d in GrowSafe bunks and were harvested on day 125. Data were analyzed in SAS as a 2 × 3 factorial with steer as the experimental unit (n = 12 per combination). Day -7 liver trace mineral concentrations were used as a covariate in analysis. There were no GS × TM effects for liver Zn, Mn, Se, or Co (P ≥ 0.11) on day 70 or 125. Implanted steers had lesser liver Cu and Mn on day 70 (P ≤ 0.05) and day 125 compared with NoIMP. There was a GS × TM interaction for liver Cu on day 125 (P = 0.05) where IMP/REC, IMP/IND, and NoIMP/REC had greater liver Cu than NoIMP/CON, which had greater liver Cu than IMP/CON. There was a TM effect for liver Cu on day 70 (P < 0.01) with IND having greater liver Cu than REC and CON. There was a TM effect (P ≤ 0.01) for liver Mn and Se on day 70 where IND had greater Mn and Se than CON, with REC being intermediate. There was a TM effect (P < 0.01) on liver Mn on day 125 where IND had greater liver Mn than CON and greater (P < 0.01) liver Se than CON and REC on day 125, whereas day 125 liver Se was greater in REC vs. CON. Implanted steers had greater (P < 0.01) dry matter intake (DMI), final body weight (BW), overall average daily gain (ADG), G:F, and hot carcass weight (HCW) than NoIMP. Overall DMI was affected by TM (P < 0.01) with REC and IND being greater than CON. There was a TM effect for carcass-adjusted final BW, ADG, and DMI (P ≥ 0.03) and a tendency for TM to affect adjusted G:F (P = 0.07). There was a TM effect (P = 0.03) for HCW where IND was greater than CON and REC. There was a GS × TM (P = 0.02) for ribeye area (REA); within IMP, CON were greater than IND, whereas REC were intermediate while NoIMP had smaller REA, regardless of TM supplementation. Additional research is needed to better determine trace mineral requirements of finishing beef steers for optimal performance.

Trace minerals are pivotal in enhancing cattle growth and ensuring profitability in beef production. Historically, supplementation strategies have aimed at preventing deficiencies, significantly improving growth and reproductive performance. However, as cattle breeding has evolved to achieve remarkable growth rates, the challenges related to health and stress during the feeding period have intensified. This presentation explores refined trace mineral recommendations, focusing on zinc’s “stress requirement” for cattle undergoing transit and health challenges, and its impact on performance. The segmented nature of the beef industry, necessitating multiple transports, induces physiological stress and oxidative stress, highlighting the need for tailored mineral supplementation. Further, when recognizing feedlot cattle as the high-performing athletes they are, the potential benefits of adjusted trace mineral concentrations become apparent. Preliminary findings suggest that optimal zinc concentrations may exceed current National Academies of Sciences, Engineering, and Medicine (NASEM) 2016 recommendations, whereas for other minerals like copper and manganese, the existing guidelines remain appropriate. This presentation will explore the differential effects of increasing dietary zinc and copper in conjunction with various growth-promoting technologies. Preliminary data indicates that increasing zinc concentrations can linearly enhance average daily gain (ADG) and hot carcass weight (HCW), especially when using potent anabolic implants, while the response to increased copper concentrations exhibits a more quadratic relationship with performance. Building upon the foundational work of pioneering researchers in the field of mineral nutrition, this presentation advocates for the continuous refinement and optimization of trace mineral supplementation strategies. By integrating cutting-edge technologies and fostering collaborative research efforts, we aim to further enhance the sustainability of the beef industry. A deeper understanding of trace mineral requirements in the face of modern production challenges will pave the way for more precise and effective nutritional strategies. [ABSTRACT FROM AUTHOR]

minerals, such as selenium, copper, zinc, and manganese, are important in the immune response. These trace minerals are included in an injectable trace mineral product, Multimin90, which has previously been utilized to boost the immune response during vaccination. However, little is known about its effects on morbid animals. Angus-crossbred steers [n = 32; body weight (BW) = 284 ± 8.5 kg] were used to determine the effects of Multimin90 (ITM; 1 mL/45 kg BW) before or during treatment for bacterial respiratory infection. Steers were fed a common ryelage-based growing diet without supplementation of Zn, Cu, Mn and Se for 4 to 6 wk prior to and during the challenge study. The study was completed in two groups (n = 14 to 18) for sampling logistics. Steers were stratified by BW into three treatments: CON (control, saline injection; n = 9), ITMPRE (ITM 6 d before infection; n = 12) and ITMPOST (ITM 2 d post infection; n = 11). Steers were shipped for 6 h and received at ISU Animal Resource Station (Ames, IA) 7 d before being intratracheally infected with M. haemolytica strain D153 at 9.48 × 108 colony forming units on d 0 followed by tulathromycin treatment 2 d post infection (dpi). Liver biopsies were collected -10, 2 and 10 dpi. Blood and bronchoalveolar lavage (BAL) samples were collected on 0, 2 and 5 dpi. Statistics were analyzed using a two-way ANOVA (mixed-effects model) with Tukey’s multiple comparisons test in Prism v9.2.0 (GraphPad Software, Inc). Liver and plasma were analyzed for trace mineral concentration, all steers had adequate trace mineral status prior to and throughout disease challenge. Steers were monitored for signs of clinical illness after inoculation by a trained observer blinded to treatment using a modified Wisconsin clinical scoring system, including cough, nasal discharge and ear score. Compared with CON, steers in ITMPRE and ITMPOST had lesser clinical scores (P < 0.05); treatment did not affect rectal temperatures, which peaked 2 or 3 dpi (Time P = 0.02). There was no difference between treatment in the detection of M. haemolytica in BAL or nasopharyngeal swab samples (P ≥ 0.14). In BAL cells, there were increased frequencies of gamma delta T cells and natural killer cells 5 dpi in ITM treated steers compared with CON (P ≤ 0.04). Treatment did not affect the frequencies of alveolar macrophages, neutrophils, B cells, CD4+ and CD8+ T cell populations in BAL cells (P ≥ 0.15). Overall, ITM administration in TM adequate steers at arrival or during respiratory disease treatment positively affects lung cell recruitment and clinical scores with no negative impacts on disease outcome compared with controls. Further work in TM deficient animals or with more aggressive disease challenge is warranted. [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]

Zinc is beneficial in growth and immune system function in cattle. Angus-cross steers (n = 72; initial BW = 261 ± 14 kg) were used in this 58-day study to determine the effects of supplemental Zn on growth, trace mineral status, and circulating immune cell populations. On d 0, steers received a Component E-S with Tylan implant (Elanco Animal Health, Greenfield, IN) and were stratified by BW into twelve GrowSafeequipped pens. Dietary treatments included: control (CON; no supplemental Zn), Zn100 (100 mg supplemental Zn/kg DM), and Zn150 (150 mg supplemental Zn/kg DM). Supplemental Zn was provided as Zn sulfate, and other trace minerals were supplemented at NASEM (2016) recommendations. Individual BW was recorded on days -1, 0, 12, 13, 27, 28, 56, and 57. Blood was collected from 9 steers per treatment on d 13 for immune cell population and function assays. Liver biopsies were conducted on 18 steers per treatment on d 14. On d 16, implant abscesses (ABSC) were evaluated, and all steers were treated with meloxicam (285 mg). Data were analyzed using the Mixed procedure of SAS (Cary, NC) with fixed effects of treatment and ABSC prevalence using steer as the experimental unit. Abscess prevalence among treatments was analyzed using Proc Glimmix. Sixty percent of steers had ABSC; ABSC prevalence was similar by treatment (P = 0.67). Steers without ABSC had greater (P = 0.04) ADG d 0 to 13 and tended to have greater (P = 0.09) ADG d 0 to 57. There was also a tendency (Trt × ABSC; P ≤ 0.09) for steers without ABSC to have greater ADG and G:F from d 14 to 27 in CON and Zn100 while within Zn150 steers without ABSC tended to have lesser ADG and G:F than ABSC steers. No other treatment by ABSC or treatment effects (P ≥ 0.14) for growth performance were observed. There were no treatment by ABSC effects for immune cell populations on d 13 (P ≥ 0.26). In Zn150 steers, activated natural killer and gamma delta T cells were increased (P ≤ 0.03) on d 13. Similarly, CD21+ MHC IIhi B cells tended to be increased in Zn150 steers (P = 0.08). Steers with ABSC had increased relative frequency of CD5+ and CD21+ B cells (P ≤ 0.05) and tended to have increased natural killer and CD21+ MHC IIhi B cells (P ≤ 0.09). In addition, steers without ABSC had greater liver Mn on d 14 than ABSC steers (P = 0.05). There were no other effects on liver trace mineral concentrations (P ≥ 0.17). These observations suggest Zn supplementation has greater impact on the cellular immune system, while ABSC have a greater effect on B cells and the adaptive immune system. [ABSTRACT FROM AUTHOR]

Angus-cross steers (n = 144; 362 kg ± 20.4) were used to determine the interaction of Zn and steroidal implants on growth and trace mineral (TM) status. Steers (n = 6/pen) were stratified by BW in a 3 × 2 factorial arrangement. Dietary treatments were fed for 60 days pre-implant, with a roughage-based diet from d -60 to -38, transition to a high concentrate diet, and 23 d on finishing diet before implant. Dietary treatments (8 pens per treatment; Zn as ZnSO4) included: 1) no supplemental Zn (analyzed 54 mg Zn/kg DM; Zn0); 2) 30 mg supplemental Zn/kg DM (Zn30); 3) 100 mg supplemental Zn/kg DM (Zn100). Within Zn treatment, steers received a steroidal implant treatment on d 0: 1) no implant; NO; or 2) high potency combination implant (TE-200, Elanco, Greenfield, IN; 200 mg TBA, 20 mg E2; TE200). Body weights were taken on d -1, 0, 28, 56, and 89, 90. Liver and blood were collected on d 0, 20, 40, and 84 for TM. GrowSafe bunks recorded individual feed intake (steer as experimental unit; n = 24 per treatment). Proc Mixed of SAS evaluated linear and quadratic effects of Zn within implant treatments and the effect of supplemental Zn within TE200. Performance and carcass characteristics used d -60 BW as a covariate. Plasma and liver TM data were analyzed as repeated measures. After 60 d plasma Zn was similar amongst Zn treatments (1.36 mg/L; P = 0.15). TE200 tended to decrease plasma Zn 8.4% from d 0 to 20 whereas NO cattle decreased 3.6% (implant × day; P = 0.08). Supplementation of Zn increased overall liver Zn concentration (P = 0.05). TE200 decreased liver Mn 13.8% from d 0 to 20 while NO decreased 1.2% (implant × day; P = 0.01). During the first 28 d post-implant, no linear or quadratic effects of Zn were noted within NO or TE200 for BW, ADG, G:F, or DMI (P = 0.12). However, within TE200, Zn supplementation improved d 0-28 ADG and G:F (P = 0.04). From d 56-90 steer performance was lackluster; however, within TE200, increasing concentration of supplemental Zn tended to linearly increase G:F (P = 0.07). Within TE200, marbling tended to be quadratically affected (P = 0.06) where Zn30 was lesser than Zn100 with Zn0 intermediate. No additional linear, quadratic, or Zn within TE200 carcass responses (P = 0.11) were noted. From d 0 to 28 Zn supplementation improved ADG and G:F of implanted steers; beyond this, few growth performance differences were noted due to Zn. However, liver and plasma TM results are consistent with our prior work, suggesting steroidal implants increase demand for Zn and Mn following implant administration to support improved growth and efficiency. [ABSTRACT FROM AUTHOR]

Weaned Angus-crossbred steers (n = 72; 626 ± 54 lbs) were enrolled in a 42-d receiving study evaluating trace mineral (TM) source and concentration on growth performance, immune, and TM status. Steers were housed in pens of 6, equipped with GrowSafe bunks to determine individual feed disappearance. Dietary treatments (n = 24 steers/treatment) included: 1) TM from an organic source (Availa4; Zinpro Corp., Eden Prairie, MN) at 7 g·steer-1·d-1; for 42 d (ORG); 2) ORG for entire 42-d plus AvailaZn to provide 1,000 mg Zn·steer-1·d-1 for first 14 d (ORG+Z); 3) inorganic TM sources to match TM concentration in ORG (ING) for 42-d. Cattle were weighed on d -1, 0, 14, 41, and 42. Data were analyzed using Proc Mixed with fixed effect of treatment and steer as experimental unit. Initial BW was covariate for growth performance. Final BW and overall ADG did not differ (P = 0.19). However, overall DMI tended to differ (P = 0.06) and G:F was greater (P = 0.04) in ORG+Z than ING, with ORG intermediate. Plasma Zn increased from d 0 to d 14, while d 14 and d 42 did not differ (Day; P = 0.02) and was unaffected by treatment (p value). Based on repeated measures, plasma Cu concentration was greater (P = 0.06) in ING than ORG+Z, while ORG was intermediate and plasma Cu concentrations decreased over time (Day; P = 0.01). Frequency of total circulating NK and CD8 T cells measured on d 0, 14, 42 did not differ (P = 0.07). Markers of activation (CD16, CD44 and CD8) on NK cells measured on d 14 differed by treatment (P = 0.05). In this study, organic TM supplementation improved feed efficiency in received weaned beef steers and TM supplementation influenced markers of immune function. [ABSTRACT FROM AUTHOR]

Simple Summary: Though anabolic implants are commonly utilized in U.S. cattle production, comparisons between hormone type and content of different implants and the effects on growth and trace mineral stores is limited. The objective of this study was to evaluate the effects of anabolic implants varying in hormone type and concentration on growth, carcass characteristics, and trace mineral concentrations in Angus steers. Cattle administered an estradiol only implant did not experience differences in growth compared to non-implanted controls. However, cattle implanted with a trenbolone acetate only implant or a combined (estradiol and trenbolone acetate) implant experienced improvements in growth and changes in plasma and liver trace mineral concentrations. Greatest differences in growth and trace mineral concentrations were observed in steers administered the combination implant compared to non-implanted controls. These data suggest hormone type and concentration influence implant-induced growth and changes in plasma and liver trace mineral concentrations. 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. [ABSTRACT FROM AUTHOR]

One hundred twenty-eight Angus-cross steers (492 ± 29 kg) were utilized in a 2 × 4 factorial to determine the effects of dietary Zn within implant strategy on performance, carcass characteristics, and Zn status. Factors included Zn supplemented at 0, 30, 100, or 150 mg/kg dry matter ([DM]; Zn0, Zn30, Zn100, Zn150, respectively) from ZnSO4 and implant administered on d 0 as no implant (NoIMP) or Component TE-200 (TE-200; Elanco, Greenfield, IN). Cattle were stratified by bodyweight (BW) to GrowSafe equipped pens of 5 or 6 steers and assigned to pen-wide treatments (experimental unit of steer; n = 16/treatment). Steers were weighed on d -1, 0, 18, and 59 with blood collected on -1, 18, and 40. Via Proc Mixed of SAS, linear and quadratic effects of Zn within implant treatments and assessment of NoIMP vs. TE-200 were tested for performance, carcass characteristics, and plasma data, with initial value covariates. Plasma Zn concentrations on d 18 and 40 linearly increased within NoIMP and TE-200 (P ≤ 0.03) and were lesser for TE-200 than NoIMP on d 18 (P = 0.001). Zinc linearly increased (P ≤ 0.002) d 18 BW and d 0-18 average daily gain (ADG). Within TE-200, Zn increased dressing percentage (P = 0.01) and tended to increase hot carcass weight (P = 0.09) linearly. Carcass-adjusted final BW and overall ADG tended to increase (P = 0.10) linearly within TE-200, with no Zn effects within NoIMP (P ≥ 0.18). Implanting increased carcass-adjusted final BW 13 kg over NoIMP (P < 0.0001). Overall feed efficiency quadratically increased within NoIMP (P = 0.01) peaking at Zn100 with no observed Zn effects within NoIMP or TE-200 for overall DM intake (P ≥ 0.15). These data suggest implant-induced growth in steers may require dietary Zn above current national recommendations. [ABSTRACT FROM AUTHOR]

The purpose of this presentation is to summarize state of the art data related to our understanding of feedlot cattle mineral requirements. To date, mineral requirements of cattle have been estimated based on historical research, some conducted as early as the 1930s and 40s. In comparison to earlier editions of the beef cattle nutritional requirements, relatively few alterations in mineral feeding recommendations were noted in NASEM (2016). However, consultants working in the industry commonly report feeding minerals far in excess of the NASEM (2016) recommendations. In addition, an abundance of mineral supplementation strategies has contributed to misunderstandings associated with cattle mineral requirements. Trace minerals, in particular, are available in a variety of chemical forms that affect site of solubility, potential bioavailability and may allow supplementation via various routes (dietary, injection, bolus, oral drench). Published and unpublished data comparing national vs. industry recommendations of trace minerals on beef cattle performance and data pertaining to source comparisons in fed cattle will be presented. [ABSTRACT FROM AUTHOR]

The objective of this study was to evaluate the plasma metabolome of steers fed a Cu deficient or Cu adequate diet in response to a feed restriction (FR) challenge. Twenty-four Angus-cross steers (463 ± 29 kg) fed a common diet (4.5 mg Cu/kg DM) were utilized in a 2×2 factorial consisting of supplemental Cu concentration: 0 (CON) or 10 (SUPP) mg Cu/kg DM as CuSO4 and 5-d FR treatment: ad-libitum feed intake (AdLib) or restricted intake (RES-INT 50% of average pen DMI for 10 d prior). Steers were enrolled in a prior trial resulting in distinct liver Cu statuses of 6.7 ± 3.34 and 72.3 ± 26.6 mg Cu/kg DM for CON and SUPP, respectively. Steers were housed in pens (6 steers/pen) with GrowSafe bunks; steer was experimental unit. Steers were weighed at start and end of FR and plasma was collected at end of FR for non-targeted metabolomic analysis by GC/MS. Analyzed via Proc Mixed of SAS as a 2×2 factorial, DMI and ADG during FR were lesser in RES-INT than Adlib (P < 0.001), per design. Metabolites were analyzed in Metaboanalyst 4.0 by volcano plots, ANOVA, and significant analysis for microarrays with the fixed effects of Cu supplementation, feeding strategy, and the interaction. There were no interactions between Cu supplementation and feeding strategy (P > 0.99). Phenylalanine concentrations were greater (P < 0.001) while ornithine and glucose concentrations were lesser (P < 0.05) in SUPP vs. CON. Lactic acid concentrations were greater (P < 0.001), while heptadecanoic acid concentrations were lesser (P = 0.002) in Adlib vs. RES-INT. These data suggest that supplemental Cu concentration and feed restriction may alter the bovine plasma metabolome. Copper is required for phenylalanine metabolism, but further research is needed to fully evaluate the impacts of trace mineral status and feed intake on the bovine plasma metabolome. [ABSTRACT FROM AUTHOR]

• Repeated ACTH injections decreased plasma Zn concentrations in lambs receiving supplemental Zn, to concentrations considered to be marginally deficient. • Fiber digestion was negatively affected by supplemental Zn from ZnSO4. • Fecal Zn tended to increase due to ACTH in lambs fed supplemental Zn. • Trace mineral apparent absorption, and nutrient digestibility were not affected by ACTH injection administration. The objective was to evaluate the effects of Zn supplementation and adrenocorticotropic hormone (ACTH) injections on nutrient digestibility, trace mineral metabolism and status. It was hypothesized that ACTH would decrease nutrient digestibility and Zn retention, but Zn supplementation would improve Zn retention, regardless of ACTH administration. Twenty-two Polypay cross weathers previously enrolled in a trial, consumed a moderately Zn deplete diet (22 mg Zn/kg DM) for 52 d, followed by being housed in metabolism crates for 15 d while receiving one of two diets: CON (Zn deplete diet) or ZINC (CON plus 40 mg Zn/d from ZnSO 4). Lambs rested for one day outside of crates then returned to crates for this 5 d study. Lambs continued to receive dietary Zn treatments and were randomly assigned to receive injectable treatments, once daily on d 1–4 at feeding: SALINE (2 mL saline I.M.), STRESS (80 I.U. ACTH I.M.); lamb was experimental unit (n = 5–6/treatment) in a 2 × 2 factorial design. Total fecal and urine collection was conducted on d 3–5, and blood samples were collected on d 0, 1, and 4, 3 h post feeding. Day 4 plasma Zn concentrations, covariate adjusted with d 0 concentrations, displayed a diet × injection tendency (P = 0.06) where ACTH given to ZINC lambs depressed plasma Zn to values similar to CON lambs. Day 1 and 4 cortisol concentrations determined 3 h after injection administration were increased in STRESS vs. SALINE (P < 0.01). Day 4 plasma Cu concentrations, covariate adjusted with d 0 concentrations were lesser in STRESS vs. SALINE (P = 0.04). Day 4 plasma Fe concentrations were unaffected by diet or injection treatment (P ≥ 0.18). Apparent absorption of Zn was increased (P < 0.01) in CON vs. ZINC, but were similar in STRESS vs. SALINE (P = 0.13). Zinc retention, and apparent absorption of Mn and Cu was similar across treatments (P ≥ 0.19). Organic matter (OM) digestibility tended to be decreased in ZINC vs. SALINE (P = 0.07); neutral detergent fiber (NDF) and acid detergent fiber (ADF) digestibility were decreased (P ≤ 0.04) in ZINC vs. SALINE. Injection treatment had no effect on macronutrient digestibility (P ≥ 0.37). The CON lambs were marginally Zn deficient based on plasma Zn concentrations and rate of apparent absorption, while fiber digestion was impaired by Zn supplementation. Plasma cortisol concentrations indicate lambs receiving ACTH experienced physiological stress, however this had limited effects on macro or micronutrient metabolism. [ABSTRACT FROM AUTHOR]