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Effects of supplemental zinc, copper, and manganese concentration and source on performance and carcass characteristics of feedlot steers1
The Professional Animal Scientist 33:63–72 https://doi.org/10.15232/pas.2016-01531 ©2017 American Registry of Professional Animal Scientists. All rights reserved.
Effects of supplemental zinc, copper, and manganese concentration and source on performance and carcass characteristics of feedlot steers1 E. Caldera,* PAS, J. J. Wagner,* PAS, K. Sellins,* S. B. Laudert,† J. W. Spears,‡ PAS, S. L. Archibeque,* and T. E. Engle,*2 PAS *Department of Animal Sciences, Colorado State University, Fort Collins 80523; †Micronutrients, Indianapolis, IN 46231; and ‡Department of Animal Science, North Carolina State University, Raleigh 27695
ABSTRACT Feedlot diets are typically fortified with trace minerals because the basal diet contains inadequate concentrations of certain essential trace minerals or the basal diet may contain elevated concentrations of known trace mineral antagonists. Providing mineral sources that are more available to the animal may allow for lower supplemental inclusion rates to the diet. A total of 400 crossbred steers (initial BW 336 ± 9.6 kg) were used to investigate the effects of supplemental Zn, Cu, and Mn concentration and source on performance and carcass characteristics of feedlot steers fed a steam-flaked corn–based finishing diet for 145 or 159 d. The experimental design was a randomized complete block design. Steers were blocked by weight and randomly assigned within block to 1 of 5 treatments (8 pens per treatment; 10 steers per pen). Treatments consisted of (1) sulfate (90 mg of Zn/kg of DM from ZnSO4, 17.5 mg of Cu/kg of DM from CuSO4, 48 mg of Mn/kg of DM from MnSO4); (2) hydroxy trace minerals (HTM1; 30 mg of Zn/kg of DM from Zn hydroxychloride, 10 mg of Cu/kg of DM from basic CuCl, 20 mg of Mn/kg of DM from Mn hydroxychloride); (3) HTM-2 (45 mg of Zn/kg of DM from Zn hydroxychloride, 12.5 mg of Cu/kg of DM from basic CuCl, 29.5 mg of Mn/kg of DM from Mn hydroxychloride); (4) HTM-3 (60 mg of Zn/kg of DM from Zn hydroxychloride, 15 mg of Cu/kg of DM from basic CuCl, 39 mg of Mn/kg of DM from Mn hydroxychloride); and (5) HTM-4 (90 mg of Zn/kg of DM from Zn hydroxychloride, 17.5 mg of Cu/kg of DM from basic CuCl, 48 mg of Mn/kg of DM from Mn hydroxychloride). Steers were individually weighed on d −1, 0, 55, and 112 and pen weighed on 2 consecutive days at the termination Use of trade names in this publication does not imply endorsement by Colorado State University or criticism of similar products not mentioned. Mention of a proprietary product does not constitute a guarantee or warranty of the products by Colorado State University or the authors and does not imply its approval to the exclusion of other products that may also be suitable. 2 Corresponding author: [email protected] 1
of the experiment. On d 112, 3 steers per pen were bled via jugular venipuncture. Equal numbers of pen replicates per treatment were transported to a commercial abattoir (d 145 and 159) and slaughtered, and individual carcass data and liver samples, from the same animals bled on d 112, were collected. Pen initial BW was used as a covariate in the statistical analysis, and significance was determined at P ≤ 0.05. No differences were observed for final BW (P ≥ 0.42). Overall ADG, DMI, and feed efficiency were similar across treatments. Hot carcass weight, DP, YG, longissimus muscle area, adjusted fat thickness, KPH, and marbling score were similar across treatments. Concentrations of Zn, Cu, and Mn in liver and blood samples were similar across treatments. These data indicate that under the conditions of this experiment, supplemental Zn, Cu, and Mn concentration and source had no effect on performance, mineral status, and carcass characteristics in feedlot steers. Key words: feedlot, cattle, trace mineral, zinc, copper, manganese
INTRODUCTION Consulting nutritionists typically fortify feedlot diets with trace minerals. Fortification is typically done for 2 reasons: (1) feed ingredients used in feedlot diets tend to be inadequate in concentrations of certain essential trace minerals or (2) the basal diets may contain elevated concentrations of known mineral antagonists (Suttle, 2010). In a 2007 survey of consulting feedlot nutritionists, Vasconcelos and Galyean (2007) reported that, on average, consulting nutritionists formulate feedlot diets to contain 3 times the NRC (2000) recommendation for certain trace minerals and that some consulting nutritionists reported using a combination of inorganic and organic trace mineral sources in feedlot diets. Hydroxychloride trace minerals (HTM) are manufactured by reacting high purity forms (elemental metal or metal oxides) of a desired trace metal with water (as the source of hydroxyl groups) and hydrochloric acid (as the
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source of chloride). During the manufacturing process, hydroxychloride crystals are formed that contain the trace metal covalently bound to hydroxyl groups and chloride. Spears et al. (2004) reported that Cu from Cu hydroxychloride was relatively insoluble (0.6%) in water (pH 7.0) and highly soluble (81.4%) at a low pH (2.2), whereas Cu from CuSO4 was almost completely soluble in water (94.5%) and at a low pH (97.6%). Furthermore, compared with CuSO4, relative bioavailability of Cu from Cu hydroxychloride was greater than CuSO4 based on plasma Cu, ceruloplasmin activity, and liver Cu concentrations in steers fed a diet containing known Cu antagonists (5.0 mg of Mo/kg of diet DM and 0.15% S). Zinc from Zn hydroxychloride has also been reported to be less soluble in the rumen of feedlot cattle compared with Zn from ZnSO4 (Shaeffer, 2006). However, cattle receiving Zn hydroxychloride had greater apparent Zn absorption and retention than cattle supplemented with ZnSO4. Therefore, the objectives of the present study were to (1) compare performance and mineral status of finishing steers fed sulfate and hydroxychloride forms of Zn, Cu, and Mn at concentrations typical of those used by feedlot nutritionists, and (2) determine whether HTM can be supplemented at concentrations lower than those typically used, without negatively affecting performance.
MATERIALS AND METHODS Prior to the initiation of this experiment all animal care, handling, and procedures described herein were approved by the Colorado State University Animal Care and Use Committee (Approval # A13–4041). A total of 505 crossbred steers (initial BW 335 ± 9.6 kg) were transported to the Colorado State University Agriculture, Research, Development, and Education Center, Fort Collins, Colorado. Upon arrival steers were individually weighed, identified with an unique ear tag, vaccinated with Presponse (Pasteurella multocida bacterial extract– Mannheimia haemolytica toxoid, Boehringer Ingelheim Vetmedica Inc., St. Joseph, MO) and Pyramid 2 plus Type II BVD [bovine rhinotracheitis and bovine virus diarrhea (Types I and II), Boehringer Ingelheim Vetmedica Inc.] respiratory vaccines, injected with Promectin (ivermectin, Vedco Inc., Saint Joseph, MO) and drenched with Synanthic (oxfendazole, Boehringer Ingelheim Vetmedica Inc.) for parasite control, and implanted with Revalor–XS (120 mg trenbolone acetate and 24 mg estradiol, Merck Animal Health, De Soto, KS). During processing, breed type was assigned to all cattle based on hair color and phenotype (red, black, black-white face, white, Bos indicus, dairy, and so on). Following initial weighing, steers had ad libitum access to long-stem grass hay and water overnight and were housed in 10 head pens. Steers were then ranked by BW, and individuals that were beyond ±2 SD from the mean BW were eliminated from further consideration for the experiment. Steers exhibiting excessive Bos indicus, Longhorn, or dairy pheno-
types or found to be bulls, heifers, or displaying symptoms of health problems were eliminated from consideration. The remaining steers were assigned a random number from 1 to 1,000 using the random number function in Excel 2007 (Microsoft Corporation, Redmond, WA). Steers with the lowest random numbers were eliminated from the experiment, reducing the number of remaining steers to 400. The 400 eligible steers were ranked by weight and divided into 8 weight block replicates, each one consisting of 50 steers. Within each weight block replicate, steers were ranked by weight within phenotype and randomly assigned to 1 of 5 pens. By following this randomization schedule, 8 weight block replicates, each containing 5 pens with 10 steers per pen with similar phenotypic distribution (7 black or 7 black-white face and 3 red steers per pen), were assembled for each of the 5 treatments in the experiment. The following day steers were weighed before being fed, and visual ear tags identifying each animal were applied. Steers were then sorted into their respective treatment pens, and the experiment was initiated. Initial BW used for the experiment was the average of the 2 weights obtained on d −1 and 0. Pens were checked daily to ensure that cattle were in the appropriate pens, that all cattle had ad libitum access to feed and water, and that all gates were secure. Furthermore, all cattle were monitored for health and locomotion problems daily. Steers exhibiting significant symptoms of respiratory disease were removed from the pen, and rectal body temperatures were recorded. Steers with body temperatures greater than 39.4°C were considered morbid. All morbid steers were treated according to the appropriate treatment schedule and immediately returned to their original pen and allowed a chance to recover. If problems persisted concerning the health status of a specific steer, the steer was removed from the experiment. If a steer was removed from the experiment, the steer was weighed, the feed in the feed bunk was weighed and placed back into the feed bunk, a feed sample was obtained for DM determination, and the feed delivery was adjusted accordingly for that pen the next day. Two steers were treated for respiratory disease and recovered within 3 d after being treated. There were no mortalities during the experiment.
Diets All steers were fed a steam-flaked corn–based finishing diet. Steers were adjusted to the finishing diet using a series of step-up diets (starter, step 1, step 2, and finisher; Table 1). Diet changes during the step-up program were simultaneous (every 5 to 7 d) for all treatments, and cattle reached the finishing diet by d 24 of the experiment. Finishing diet TMR were formulated to meet or exceed NRC (2000) requirements for growing and finishing beef cattle. Nutrient target values were 13.5% CP with 3.5% CP equivalent from NPN, 3.5% added fat, 0.7% calcium, 0.36% phosphorus, 0.7% potassium, 0.25% magnesium, 0.10 mg of Co/kg of DM; 0.3 mg of Se/kg of DM, 33
65
Zinc, copper, and manganese in feedlot cattle diets
g/t of monensin (Rumensin 90, Elanco Animal Health, Greenfield, IN), and 11 g/t of tylosin phosphate (Tylan 100, Elanco Animal Health) on a DM basis. Vitamins A and E were included in the diets at 2,200 and 40 IU/kg of DM, respectively, and were administered in the liquid supplement and macro- and microminerals were added as inorganic sources to meet the targeted values of the TMR. Zilpaterol hydrochloride was fed for 21 of the final 26 d of the finishing period. Diets were delivered once daily in the morning (0800 h) in amounts to allow cattle ad libitum access to feed for a 24-h period. Orts were determined for each pen on the days cattle were weighed. Subsamples of orts for each pen were analyzed for DM and used to calculate the DM weight of the orts for a given period. This value was then subtracted from the total DM delivered to a given pen of cattle to calculate DMI for a given period.
Trace minerals appropriate for each treatment were formulated and pelleted separately. All other required macro- and microminerals were added to all treatment pellets from the same mineral sources in amounts that met our targeted macro- and micromineral values for the TMR as described above. Dietary treatments consisted of (1) sulfate (90 mg of Zn/kg of DM from ZnSO4, 17.5 mg of Cu/kg of DM from CuSO4, 48 mg of Mn/kg of DM from MnSO4); (2) HTM-1 (30 mg of Zn/kg of DM from Zn hydroxychloride, 10 mg of Cu/kg of DM from basic CuCl, 20.0 mg of Mn/kg of DM from Mn hydroxychloride); (3) HTM-2 (45 mg of Zn/kg of DM from Zn hydroxychloride, 12.5 mg of Cu/kg of DM from basic CuCl, 29.5 mg of Mn/ kg of DM from Mn hydroxychloride); (4) HTM-3 (60 mg of Zn/kg of DM from Zn hydroxychloride, 15 mg of Cu/kg of DM from basic CuCl, 39 mg of Mn/kg of DM from Mn
Table 1. Dry matter ingredient composition of basal diet without supplemental copper, zinc, or manganese Item
Starter
Step 1
Step 2
Finisher
Ingredient, % Corn silage Steam-flaked corn Alfalfa hay Liquid supplement1 Pellet supplement Analyzed nutrient composition DM, % as fed CP, % NPN,2 % ADF, % NDF, % Ether extract, % NEg,3 Mcal/kg NEm,4 Mcal/kg Calcium, % Magnesium, % Phosphorus, % Potassium, % Sulfur, % Cobalt, mg/kg Copper, mg/kg Iron, mg/kg Manganese, mg/kg Molybdenum, mg/kg Selenium, mg/kg Zinc, mg/kg
16.38 35.0 43.93 — 4.69 59.79 13.85 0.10 19.25 28.58 3.56 1.07 1.68 0.72 0.21 0.32 1.44 0.19 0.27 3.14 318.47 13.26 1.51 0.44 13.76
13.38 51.50 28.19 2.17 4.76 63.86 14.28 1.92 14.25 22.80 3.50 1.19 1.82 0.78 0.19 0.32 1.12 0.16 0.22 2.90 227.68 11.78 1.20 0.40 14.97
13.38 66.17 12.44 3.25 4.76 63.10 13.78 2.88 6.78 18.19 3.50 1.28 1.89 0.73 0.16 0.32 0.82 0.14 0.17 2.65 138.55 11.04 0.88 0.35 16.05
13.37 78.81 — 4.32 3.50 63.0 13.45 3.45 6.15 14.66 4.12 1.42 2.06 0.65 0.14 0.32 0.68 0.15 0.12 2.48 67.45 10.55 0.63 0.29 17.07
Contained on a DM basis: 55,785.7 IU of vitamin A/kg, 223.1 IU of vitamin E/kg, 837.6 g of monensin/t (Rumensin 90, Elanco Animal Health, Greenfield, IN), and 251.4 g of tylosin/t (Tylan 100, Elanco Animal Health). 2 CP equivalent. 3 NEg = {[1.42 × (TDN × 0.0361)] − [0.174 × (TDN × 0.0361) × (TDN × 0.0361)] + [0.0122 × (TDN × 0.0361) × (TDN × 0.0361) × (TDN × 0.0361) − 1.65]} ÷ 2.205. 4 NEm = {[1.37 × (TDN × 0.0361)] − [0.0138 × (TDN × 0.0361) × (TDN × 0.0361)] + [0.0105 × (TDN × 0.0361) × (TDN × 0.0361) − 1.12]} ÷ 2.205. 1
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hydroxychloride); and (5) HTM-4 (90 mg of Zn/kg of DM from Zn hydroxychloride, 17.5 mg of Cu/kg of DM from basic CuCl, 48 mg of Mn/kg of DM from Mn hydroxychloride). With this treatment structure, (1) iso-amounts of Cu, Zn, and Mn from sulfate and HTM were compared (sulfate vs. HTM-4); (2) NRC versus industry concentrations of Cu, Zn, and Mn (HTM-1 vs. HTM-4) were compared; and (3) a dose response of HTM (HTM-1, HTM-2, HTM-3, and HTM-4) was evaluated. Supplemental trace mineral concentrations supplied in the sulfate and HTM-4 treatments were similar to the average supplemental trace mineral concentrations that were recommended by consulting nutritionists surveyed by Vasconcelos and Galyean (2007). The analyzed Zn, Cu, and Mn concentrations for the TMR for each finishing diet treatment were as follows: sulfate: 112.1 mg of Zn/kg of DM, 19.8 mg of Cu/kg of DM, and 65.7 mg of Mn/kg of DM; HTM-1: 42.6 mg of Zn/kg of DM, 11.2 mg of Cu/kg of DM, and 29.7 mg of Mn/kg of DM; HTM-2: 60.5 mg of Zn/kg of DM, 12.1 mg of Cu/kg of DM, and 41.2 mg of Mn/kg of DM; HTM-3: 78.5 mg of Zn/kg of DM, 17.1 mg of Cu/kg of DM, and 52.4 mg of Mn/kg of DM; and HTM-4: 114.2 mg of Zn/kg of DM, 20.1 mg of Cu/kg of DM, and 63.1 mg of Mn/kg of DM. General water quality samples were obtained twice throughout the experiment. Water samples were obtained at the main water supply line to the feedlot and sent to an established laboratory (SDK Labs, Hutchinson, KS) for routine water quality analysis (pH = 7.37 ± 0.19; total hardness, mg/L = 750.3 ± 63.1; sulfate, mg/L = 482.7 ± 35.8; sodium, mg/L = 70.3 ± 10.1; chloride, mg/L = 30.0 ± 4.1; total dissolved solids, mg/L = 1,094.3 ± 73.1; electrical conductivity, μS/cm = 1,543.3 ± 103.3).
Weighing, Sampling, and Carcass Data Collection Steers were individually weighed on d −1, 0, 55, and 112, and pen weights were obtained on 2 consecutive days at the termination of the experiment. Jugular blood samples were collected on d 112 from 3 animals per pen and analyzed for plasma Zn, Cu, and Mn concentrations. Equal numbers of pen replicates per treatment were transported to a commercial abattoir (d 145 and 159) and slaughtered, and individual carcass data and liver samples were collected. Hot carcass weight was determined at the time of slaughter. Carcasses were allowed to chill for approximately 36 h before carcass data were obtained. Carcass data were collected by Center for Meat Safety and Quality personnel at Colorado State University. Carcass data collected included DP, longissimus muscle area, s.c. adipose tissue thickness, adjusted s.c. adipose tissue thickness (USDA, 1989), KPH, marbling score, QG, and YG (calculated). Liver samples were collected (approximately 200 g of wet weight) on the day of slaughter from the left lobe of each liver after being inspected by USDA personnel. Following collection, liver samples were placed in Whirl-Pak bags containing the slaughter order number,
placed on ice, and transported to the laboratory. Samples were then stored at –20°C until they were analyzed. At the time of liver analysis, only liver samples from cattle that were bled on d 112 were analyzed for Zn, Cu, and Mn concentrations.
Analytical Procedures Liver tissue samples and 1.0 mL of plasma were dried at 60°C for 24 h in a preweighed crucible. Samples were weighed after drying and dry ashed at 600°C for 12 h. Liver tissues and plasma samples were analyzed for mineral concentrations via inductively coupled plasma-atomic emission spectroscopy methods as described by Ahola et al. (2004) for Zn, Cu, and Mn concentrations. Samples were diluted in distilled H2O to fit within a linear range of a standard curve generated by linear regression of known trace mineral concentrations. Multielemental analysis was then carried out by simultaneous/sequential inductively coupled plasma-atomic emission spectroscopy analysis with cross flow nebulization.
Statistics Feedlot performance, plasma and liver trace mineral concentrations, and continuous carcass data were analyzed on a pen mean basis as a randomized block design using PROC MIXED of SAS (SAS Institute Inc., Cary, NC). Treatment was included in the model as a fixed classification effect, and weight block pen replicate was included in the model as a random effect. The linear and quadratic effects of treatment dose were determined by using orthogonal polynomial coefficients derived using PROC IML of SAS that were applied to treatments HTM-1 through HTM-4 as quantitative factors that were unequally spaced. These procedures were completed to derive the Type I sum of squares for the increasing doses. Quality grade, YG, HCW category, carcass maturity, and liver abscess data were evaluated as categorical data using PROC GLIMMIX of SAS assuming a binomial distribution. The Link = Logit option of the model statement and ILINK option of the LSMEANS statement were used to calculate the likelihood ± SEM that an individual within each pen qualified for a specific category (≥low choice, select, or ≤standard). Significance was determined at P ≤ 0.05. Pen initial BW was used as a covariate in the analysis of all response variables.
RESULTS AND DISCUSSION The effect of trace mineral concentration and source on animal performance is presented in Table 2. Initial and final BW, DMI, ADG, and feed efficiency were similar across treatments. Previously published literature investigating the effect of supplementing Cu, Zn, and Mn in combination with one another at different doses is limited. Ahola et al. (2005) reported that finishing cattle fed a control diet with no supplemental Cu, Zn, and Mn had
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Zinc, copper, and manganese in feedlot cattle diets
Table 2. Effect of supplemental copper, zinc, and manganese concentration and source on performance and feed efficiency of feedlot cattle1 Treatment (TRT)2 Item
Sulfate
HTM-1
HTM-2
HTM-3
Contrast (P <) HTM-4
Sulfate HTM-1 TRT vs. HTM-4 vs. HTM-4 Linear3 Quadratic3
SEM
BW, kg Initial 337.5 336.8 335.3 335.1 334.9 Final 654.6 647.0 647.3 655.6 651.4 DMI, kg/d d 0–final 11.3 11.5 11.6 11.6 11.5 ADG, kg/d 2.03 1.98 1.99 2.04 1.99 d 0–final G:F 0.179 0.173 0.172 0.177 0.174 d 0–final
9.57 4.83 0.13 0.029 0.003
0.32 0.42 0.31 0.54 0.40
0.09 0.57 0.45 0.37 0.22
0.58 0.19 0.47 0.27 0.16
0.27 0.25 0.94 0.61 0.58
0.59 0.62 0.16 0.37 0.94
Pen initial BW was used as a covariate in the analysis of all response variables. Experimental treatments: sulfate (90 mg of Zn/kg of DM from ZnSO4, 17.5 mg of Cu/kg of DM from CuSO4, 48 mg of Mn/ kg of DM from MnSO4); hydroxychloride trace minerals (HTM-1; 30 mg of Zn/kg of DM from Zn hydroxychloride, 10 mg of Cu/kg of DM from basic CuCl, 20 mg of Mn/kg of DM from Mn hydroxychloride); HTM-2 (45 mg of Zn/kg of DM from Zn hydroxychloride, 12.5 mg of Cu/kg of DM from basic CuCl, 29.5 mg of Mn/kg of DM from Mn hydroxychloride); HTM-3 (60 mg of Zn/kg of DM from Zn hydroxychloride, 15 mg of Cu/kg of DM from basic CuCl, 39 mg of Mn/kg of DM from Mn hydroxychloride); and HTM-4 (90 mg of Zn/kg of DM from Zn hydroxychloride, 17.5 mg of Cu/kg of DM from basic CuCl, 48 mg of Mn/kg of DM from Mn hydroxychloride). 3 Linear and quadratic responses were determined using treatments: HTM-1, HTM-2, HTM-3, and HTM-4. 1 2
similar ADG but tended (P = 0.10) to have lesser DMI than cattle supplemented with Cu, Zn, and Mn at concentrations of 10, 30, and 20 mg/kg of DM, respectively. The control diet used by Ahola et al. (2005) analyzed 6.4 mg of Cu, 15 mg of Zn, and 15.7 mg of Mn/kg of DM. Increasing the concentration of supplemental Cu, Zn, Mn, and Co from 1.0 to 1.5 times NRC (2000) recommendations from organic sources or from 1.5 to 3.0 times NRC (2000) recommendations from sulfate sources did not affect performance of finishing steers (Rhoads et al., 2003). Berrett et al. (2015) reported that yearling feedlot steers receiving no supplemental Cu, Zn, and Mn had similar performance to steers receiving NRC (2000) or greater than NRC (2000) concentrations of Cu, Zn, and Mn in both organic and inorganic forms. Several experiments comparing different doses of a single trace mineral on feedlot cattle performance have been conducted. Results from experiments evaluating Cu supplementation have been variable. Copper supplementation to feedlot cattle consuming a high concentrate diet has been reported to have a positive (Ward and Spears, 1997; Engle et al., 2000a), negative (Engle and Spears, 2000b), or no effect (Engle and Spears, 2000a; 2001) on performance compared with nonsupplemented controls. Supplementation of a control diet containing 8.1 mg of Mn/kg of DM with 10, 20, or 30 mg of MnSO4/kg of DM did not affect performance of finishing steers (Legleiter et al., 2005).
Variable feedlot cattle performance responses to Zn supplementation have also been reported. Increasing supplemental Zn from 30 to 70 mg/kg of DM slightly increased (P = 0.10) DMI but did not affect ADG or G:F (Galyean et al., 1995). Malcolm-Callis et al. (2000) reported no differences in ADG or G:F during a 112-d finishing period with added Zn (as ZnSO4) concentrations at 20, 100, or 200 mg/kg of dietary DM. However, DMI decreased (linear, P = 0.10) slightly as Zn concentration increased. Spears and Kegley (2002) reported that Zn supplementation (25 mg of Zn/kg of DM) did not affect performance of finishing steers relative to those fed the control diet (analyzed 26 mg of Zn/kg of DM). Supplementing 75 mg of Zn/kg of DM to a control diet that analyzed 50 mg of Zn/kg of DM, tended to improve ADG (P = 0.11) and G:F (P = 0.06) in finishing heifers (Nunnery et al., 2007). Reaching an objective conclusion about the effect of Cu, Zn, and Mn supplementation on finishing cattle performance is difficult. Numerous factors can influence an animal’s response to trace mineral supplementation, such as initial trace mineral status of the animal, disease status, mineral antagonists, stress, breed, mineral bioavailability, environmental factors, as well as basal dietary mineral concentrations. The influence of trace mineral concentration and source on carcass characteristics is presented in Tables 3 and 4. There was a quadratic (P < 0.04) response for YG across the HTM treatments. As dose of Cu, Zn, and Mn in-
416.6 63.7 2.85 96.9 1.31 2.02 391.2
HCW, kg DP YG Longissimus muscle area, cm2 Adjusted fat thickness,4 cm KPH, % Marbling score5
412.3 63.7 2.87 95.9 1.19 2.04 389.9
HTM-1 413.0 63.9 2.69 98.3 1.16 2.03 386.9
HTM-2 413.9 63.2 2.66 97.5 1.20 2.05 394.1
HTM-3 418.9 64.4 2.90 96.6 1.22 2.01 392.5
HTM-4 3.07 0.57 0.09 1.39 0.07 0.02 9.93
SEM 0.45 0.55 0.19 0.78 0.52 0.82 0.97
TRT 0.57 0.32 0.63 0.86 0.33 0.75 0.90
Sulfate vs. HTM-4
0.26 0.97 0.84 0.68 0.18 0.67 0.85
HTM-1 vs. HTM-4
Contrast (P <)
0.14 0.62 0.88 0.89 0.65 0.71 0.68
Linear3
0.54 0.31 0.04 0.27 0.68 0.62 0.94
Quadratic3
2
1
Pen initial BW was used as a covariate in the analysis of all response variables. Experimental treatments: sulfate (90 mg of Zn/kg of DM from ZnSO4, 17.5 mg of Cu/kg of DM from CuSO4, 48 mg of Mn/kg of DM from MnSO4); hydroxychloride trace minerals (HTM-1; 30 mg of Zn/kg of DM from Zn hydroxychloride, 10 mg of Cu/kg of DM from basic CuCl, 20 mg of Mn/kg of DM from Mn hydroxychloride); HTM-2 (45 mg of Zn/kg of DM from Zn hydroxychloride, 12.5 mg of Cu/kg of DM from basic CuCl, 29.5 mg of Mn/kg of DM from Mn hydroxychloride); HTM-3 (60 mg of Zn/kg of DM from Zn hydroxychloride, 15 mg of Cu/kg of DM from basic CuCl, 39 mg of Mn/kg of DM from Mn hydroxychloride); and HTM-4 (90 mg of Zn/kg of DM from Zn hydroxychloride, 17.5 mg of Cu/kg of DM from basic CuCl, 48 mg of Mn/kg of DM from Mn hydroxychloride). 3 Linear and quadratic responses were determined using treatments: HTM-1, HTM-2, HTM-3, and HTM-4. 4 USDA, 1989. 5 Marbling score: 300 = Slight0, 400 = Small0, 500 = Modest0.
Sulfate
Item
Treatment (TRT)2
Table 3. Effect of supplemental copper, zinc, and manganese concentration and source on carcass characteristics of feedlot cattle1
68 Caldera et al.
77 37.5 ± 8.6 56.0 ± 9.1 6.5 96.1 3.9
Sulfate 80 36.5 ± 8.6 60.8 ± 8.8 2.7 97.3 2.7
HTM-1 79 34.0 ± 8.3 61.3 ± 8.7 4.7 100 0
HTM-2 80 37.3 ± 8.6 55.5 ± 9.0 7.2 97.5 2.5
HTM-3 79 33.9 ± 8.2 64.6 ± 8.4 1.5 93.0 7.0
HTM-4
NA NA
0.98 0.79 NA5
TRT
NA NA
0.66 0.32 NA
Sulfate vs. HTM-4
NA NA
0.94 0.56 NA
HTM-1 vs. HTM-4
Contrast (P <)
NA NA
0.89 0.84 NA
Linear2
NA NA
0.95 0.56 NA
Quadratic2
1
Experimental treatments: sulfate (90 mg of Zn/kg of DM from ZnSO4, 17.5 mg of Cu/kg of DM from CuSO4, 48 mg of Mn/kg of DM from MnSO4); hydroxychloride trace minerals (HTM-1; 30 mg of Zn/kg of DM from Zn hydroxychloride, 10 mg of Cu/kg of DM from basic CuCl, 20 mg of Mn/kg of DM from Mn hydroxychloride); HTM-2 (45 mg of Zn/kg of DM from Zn hydroxychloride, 12.5 mg of Cu/kg of DM from basic CuCl, 29.5 mg of Mn/kg of DM from Mn hydroxychloride); HTM-3 (60 mg of Zn/kg of DM from Zn hydroxychloride, 15 mg of Cu/kg of DM from basic CuCl, 39 mg of Mn/kg of DM from Mn hydroxychloride); and HTM-4 (90 mg of Zn/kg of DM from Zn hydroxychloride, 17.5 mg of Cu/kg of DM from basic CuCl, 48 mg of Mn/kg of DM from Mn hydroxychloride). 2 Linear and quadratic responses were determined using treatments: HTM-1, HTM-2, HTM-3, and HTM-4. 3 ±SD. 4 Results are expressed as the percentage likelihood that an individual carcass within each pen qualifies for a specific QG unless stated otherwise. 5 NA = not applicable. 6 Percentage of individual livers showing one or more liver abscesses.
n QG, % ≥Low Choice3 Select3,4 ≤Standard4 Liver scores, % Normal Abscesses6
Item
Treatment (TRT)1
Table 4. Effect of supplemental copper, zinc, and manganese concentration and source on categorical carcass characteristics and liver abscesses of feedlot cattle
Zinc, copper, and manganese in feedlot cattle diets
69
1.07 0.98 7.14
105.0 273.5 10.4
Sulfate
1.11 1.02 8.25
100.9 251.2 9.9
HTM-1
1.02 1.01 7.80
97.9 261.0 10.2
HTM-2
1.00 0.96 7.50
95.0 274.2 10.2
HTM-3
1.06 1.04 7.94
108.2 269.2 9.9
HTM-4
0.11 0.07 0.98
3.70 14.6 0.30
SEM
0.35 0.83 0.47
0.02 0.78 0.74
TRT
0.20 0.37 0.98
0.44 0.84 0.28
Sulfate vs. HTM-4
0.29 0.97 0.15
0.28 0.24 0.34
HTM-1 vs. HTM-4
Contrast (P <)
0.76 0.48 0.16
0.17 0.38 0.95
Linear2
0.07 0.64 0.48
0.03 0.64 0.33
Quadratic2
1
Experimental treatments: sulfate (90 mg of Zn/kg of DM from ZnSO4, 17.5 mg of Cu/kg of DM from CuSO4, 48 mg of Mn/kg of DM from MnSO4); hydroxychloride trace minerals (HTM-1; 30 mg of Zn/kg of DM from Zn hydroxychloride, 10 mg of Cu/kg of DM from basic CuCl, 20 mg of Mn/kg of DM from Mn hydroxychloride); HTM-2 (45 mg of Zn/kg of DM from Zn hydroxychloride, 12.5 mg of Cu/kg of DM from basic CuCl, 29.5 mg of Mn/kg of DM from Mn hydroxychloride); HTM-3 (60 mg of Zn/kg of DM from Zn hydroxychloride, 15 mg of Cu/kg of DM from basic CuCl, 39 mg of Mn/kg of DM from Mn hydroxychloride); and HTM-4 (90 mg of Zn/kg of DM from Zn hydroxychloride, 17.5 mg of Cu/kg of DM from basic CuCl, 48 mg of Mn/kg of DM from Mn hydroxychloride). 2 Linear and quadratic responses were determined using treatments: HTM-1, HTM-2, HTM-3, and HTM-4. 3 Liver samples were collected (approximately 200 g of wet weight) on the day of slaughter from the left lobe of each liver after being inspected by USDA personnel. 4 Three animals from each pen were bled via jugular venipuncture on d 112.
Liver3 Zn, mg/kg of DM Cu, mg/kg of DM Mn, mg/kg of DM Plasma, d 1124 Zn, mg/L Cu, mg/L Mn, μg/L
Item
Treatment (TRT)1
Table 5. Effect of supplemental copper, zinc, and manganese concentration and source on mineral status of feedlot cattle
70 Caldera et al.
Zinc, copper, and manganese in feedlot cattle diets
creased, YG decreased for HTM-2 and HTM-3 treatments and increased for HTM-4 treatment (Table 3). Hot carcass weight, DP, longissimus muscle area, s.c. adipose tissue depth, and marbling score were similar across treatments. Quality grades and liver abscess scores were not affected by treatment (Table 4). These finding are similar to those reported by Rhoads et al. (2003), Ahola et al. (2005), and Berrett et al. (2015), where Zn, Cu, and Mn concentration and source had minimal effect on carcass characteristics of feedlot steers. Malcolm-Callis et al. (2000) reported a quadratic response of added Zn (as ZnSO4) on fat thickness and YG (P < 0.01). Zinc supplementation to a control diet, containing 26 mg of Zn/kg of DM, increased quality and YG of finishing steers (Spears and Kegley, 2002). In other studies (Galyean et al., 1995; Nunnery et al., 2007), increasing dietary Zn did not affect carcass characteristics of finishing cattle. Copper supplementation to finishing diets low in Cu (4.9 mg of Cu/kg of DM) has reduced backfat (Engle and Spears, 2000a; Engle et al., 2000a,b), and varying dietary Mn from 8 to 240 mg/kg of DM did not affect carcass characteristics of finishing steers (Legleiter et al., 2005). Although not all previously cited experiments measured mineral status in cattle, no clinical signs of mineral deficiencies were reported. Furthermore, those experiments where mineral status was reported indicated that plasma or liver Cu, Mn, and Zn concentrations were adequate for beef cattle. Liver and plasma Cu, Zn, and Mn concentrations are presented in Table 5. Concentrations of Cu, Zn, and Mn in liver and plasma samples were within the normal range expected in cattle receiving an adequate supply of these trace minerals (Suttle, 2010). Copper and Mn concentrations in liver samples collected at slaughter were similar across treatments. A quadratic (P < 0.03) response was noted in liver Zn concentration with increasing Zn doses, and the greatest Zn liver concentration was observed in the HTM-4 treatment at 108.2 mg of Zn/kg of DM (Table 5). Wright and Spears (2004) reported that supplementing 25 mg of Zn/kg of DM to a control diet (analyzed 28 mg of Zn/kg of DM) increased liver Zn concentrations in Holstein calves. Concentrations of Zn, Cu, and Mn in plasma samples collected on d 112 were similar across treatments (Table 5). In previous studies, the addition of 25 to 75 mg of Zn/kg of DM to control diets, containing 26 to 50 mg of Zn/kg of DM, had little or no effect on plasma or serum Zn concentrations (Spears and Kegley, 2002; Wright and Spears, 2004; Nunnery et al., 2007). The addition of 10 mg of Cu/kg of DM to a finishing diet containing 4.9 mg of Cu/kg of DM increased plasma and liver Cu concentrations (Engle and Spears, 2000a). However, increasing supplemental Cu in this study from 10 to 20 mg/kg of DM did not result in further increases in plasma Cu. It is well documented that plasma Cu does not generally decline to deficient concentrations until liver Cu stores are depleted (Claypool et al., 1975). In the present study, liver Cu concentrations were well above those considered even marginally deficient and the lowest concentration of Cu
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supplemented was 10 mg/kg of DM. Supplementing from 10 to 240 mg of Mn/kg of DM did not increase plasma Mn above values observed in finishing steers fed a control diet (analyzed 8.1 mg of Mn/kg of DM; Legleiter et al., 2005). It should be noted that mineral antagonists such as Mo, S, and Fe were not at concentrations know to be antagonistic to Cu or Zn absorption or metabolism (NRC, 2000). Furthermore, mean water quality measurements for all treatments were suitable for livestock consumption based on previous publications (NRC, 2001; NRC, 2005; Wright, 2007; National Academies of Sciences, Engineering, and Medicine, 2016).
IMPLICATIONS Under the conditions of this experiment, supplemental Zn, Cu, and Mn concentration and source had no effect on performance and carcass characteristics and minimal effects on liver and plasma Cu, Zn, and Mn concentrations. The lack of a dose response within the HTM treatments (HTM-1, HTM-2, HTM-3, and HTM-4) as well as the lack of a response when HTM-1 was compared with HTM-4 on performance response variables suggests that Cu, Zn, and Mn can be supplemented at lower concentrations than those reported by consulting feedlot nutritionists (Vasconcelos and Galyean, 2007) without adversely affecting cattle performance or carcass characteristics.
ACKNOWLEDGMENTS This research was supported in part by the Colorado State University Agricultural Experiment Station and by Micronutrients (Indianapolis, IN).
LITERATURE CITED Ahola, J. K., D. S. Baker, P. D. Burns, R. G. Mortimer, R. M. Enns, J. C. Whittier, T. W. Geary, and T. E. Engle. 2004. Effect of copper, zinc, and manganese supplementation and source on reproduction, mineral status, and performance in grazing beef cattle over a two-year period. J. Anim. Sci. 82:2375–2383. Ahola, J. K., L. R. Sharpe, K. L. Dorton, P. D. Burns, T. L. Stanton, and T. E. Engle. 2005. Effects of lifetime copper, zinc, and manganese supplementation and source on performance, mineral status, immunity, and carcass characteristics of feedlot cattle. Prof. Anim. Sci. 21:305–317. Berrett, C. J., J. J. Wagner, K. L. Neuhold, E. Caldera, K. S. Sellins, and T. E. Engle. 2015. Comparison of National Research Council standards and industry dietary trace mineral supplementation strategies for yearling feedlot steers. Prof. Anim. Sci. 31:237–247. Claypool, D. W., F. M. Adams, H. W. Pendell, N. A. Hartmann, and J. F. Bone. 1975. Relationship between the level of copper in the blood plasma and liver in cattle. J. Anim. Sci. 41:911–914. Engle, T. E., and J. W. Spears. 2000a. Dietary copper effects on lipid metabolism, performance, and ruminal fermentation in finishing steers. J. Anim. Sci. 78:2452–2458. Engle, T. E., and J. W. Spears. 2000b. Effects of dietary copper concentration and source on performance and copper status of growing and finishing steers. J. Anim. Sci. 78:2446–2451.
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Engle, T. E., and J. W. Spears. 2001. Performance, carcass characteristics, and lipid metabolism in growing and finishing Simmental steers fed varying concentrations of copper. J. Anim. Sci. 79:2920–2925. Engle, T. E., J. W. Spears, T. A. Armstrong, C. L. Wright, and J. Odle. 2000a. Effects of dietary copper source and concentration on carcass characteristics and lipid and cholesterol metabolism in growing and finishing steers. J. Anim. Sci. 78:1053–1059. Engle, T. E., J. W. Spears, L. Xi, and F. W. Edens. 2000b. Dietary copper effects on lipid metabolism and circulating catecholamine concentrations in finishing steers. J. Anim. Sci. 78:2737–2744. Galyean, M. L., K. J. Malcolm-Callis, S. A. Gunter, and R. A. Berrie. 1995. Effect of zinc source and level and added copper lysine in the receiving diet on performance of growing and finishing steers. Prof. Anim. Sci. 11:139–148. Legleiter, L. R., J. W. Spears, and K. L. Lloyd. 2005. Influence of dietary manganese on performance, lipid metabolism, and carcass composition of growing and finishing steers. J. Anim. Sci. 83:2434–2439. Malcolm-Callis, K., G. Duff, S. Gunter, E. Kegley, and D. Vermeire. 2000. Effects of supplemental zinc concentration and source on performance, carcass characteristics, and serum values in finishing beef steers. J. Anim. Sci. 78:2801–2808.
supplementary zinc on performance and humoral immunity in beef heifers. J. Anim. Sci. 85:2304–2313. Rhoads, A. R., T. L. Stanton, T. E. Engle, and C. V. Kimberling. 2003. Effects of concentration and source of trace minerals on performance, immunity, mineral and lipid metabolism, and carcass characteristics of beef steers. Prof. Anim. Sci. 19:150–158. Shaeffer, G. L. 2006. Evaluation of basic zinc chloride as a zinc source for cattle. MS Thesis. North Carolina State Univ., Raleigh, NC. http://www.lib.ncsu.edu/resolver/1840.16/1835. Spears, J. W., and E. B. Kegley. 2002. Effect of zinc source (zinc oxide vs zinc proteinate) and level on performance, carcass characteristics, and immune response of growing and finishing steers. J. Anim. Sci. 80:2747–2752. Spears, J. W., E. B. Kegley, and L. A. Mullis. 2004. Bioavailability of copper from tribasic copper chloride and copper sulfate in growing cattle. Anim. Feed Sci. Technol. 116:1–13. Suttle, N. F. 2010. Mineral Nutrition of Livestock. 4th ed. CABI Publ., Wallingford, Oxfordshire, UK. USDA. 1989. Official United States Standards for Grades of Carcass Beef. Agric. Market. Serv.-USDA, Washington DC.
National Academies of Sciences, Engineering, and Medicine. 2016. Nutrient Requirements of Beef Cattle, 8th rev. ed. Natl. Acad. Press, Washington, DC. https://doi.org/10.17226/19014.
Vasconcelos, J. T., and M. L. Galyean. 2007. Nutritional recommendations of feedlot consulting nutritionists: The 2007 Texas Tech University survey. J. Anim. Sci. 85:2772–2781.
NRC. 2000. Nutrient Requirements of Beef Cattle. 7th rev. ed. Natl. Acad. Press, Washington, DC.
Ward, J. D., and J. W. Spears. 1997. Long-term effects of consumption of low-copper diets with or without supplemental molybdenum on copper status, performance, and carcass characteristics of cattle. J. Anim. Sci. 75:3057–3065.
NRC. 2001. Nutrient Requirements of Dairy Cattle. Natl. Acad. Press, Washington, DC. NRC. 2005. Mineral Tolerance of Domestic Animals. Natl. Acad. Press, Washington, DC. Nunnery, G. A., J. T. Vasconcelos, C. H. Parsons, G. B. Salyer, P. J. Defoor, F. R. Valdez, and M. L. Galyean. 2007. Effects of source of
Wright, C. L. 2007. Management of water quality for beef cattle. Vet. Clin. North Am. Food Anim. Pract. 23:91–103. Wright, C. L., and J. W. Spears. 2004. Effect of zinc source and dietary level on zinc metabolism in Holstein calves. J. Dairy Sci. 87:1085–1091.
Effects of supplemental zinc, copper, and manganese concentration and source on performance and carcass characteristics of feedlot steers1 E. Caldera,* PAS, J. J. Wagner,* PAS, K. Sellins,* S. B. Laudert,† J. W. Spears,‡ PAS, S. L. Archibeque,* and T. E. Engle,*2 PAS *Department of Animal Sciences, Colorado State University, Fort Collins 80523; †Micronutrients, Indianapolis, IN 46231; and ‡Department of Animal Science, North Carolina State University, Raleigh 27695
ABSTRACT Feedlot diets are typically fortified with trace minerals because the basal diet contains inadequate concentrations of certain essential trace minerals or the basal diet may contain elevated concentrations of known trace mineral antagonists. Providing mineral sources that are more available to the animal may allow for lower supplemental inclusion rates to the diet. A total of 400 crossbred steers (initial BW 336 ± 9.6 kg) were used to investigate the effects of supplemental Zn, Cu, and Mn concentration and source on performance and carcass characteristics of feedlot steers fed a steam-flaked corn–based finishing diet for 145 or 159 d. The experimental design was a randomized complete block design. Steers were blocked by weight and randomly assigned within block to 1 of 5 treatments (8 pens per treatment; 10 steers per pen). Treatments consisted of (1) sulfate (90 mg of Zn/kg of DM from ZnSO4, 17.5 mg of Cu/kg of DM from CuSO4, 48 mg of Mn/kg of DM from MnSO4); (2) hydroxy trace minerals (HTM1; 30 mg of Zn/kg of DM from Zn hydroxychloride, 10 mg of Cu/kg of DM from basic CuCl, 20 mg of Mn/kg of DM from Mn hydroxychloride); (3) HTM-2 (45 mg of Zn/kg of DM from Zn hydroxychloride, 12.5 mg of Cu/kg of DM from basic CuCl, 29.5 mg of Mn/kg of DM from Mn hydroxychloride); (4) HTM-3 (60 mg of Zn/kg of DM from Zn hydroxychloride, 15 mg of Cu/kg of DM from basic CuCl, 39 mg of Mn/kg of DM from Mn hydroxychloride); and (5) HTM-4 (90 mg of Zn/kg of DM from Zn hydroxychloride, 17.5 mg of Cu/kg of DM from basic CuCl, 48 mg of Mn/kg of DM from Mn hydroxychloride). Steers were individually weighed on d −1, 0, 55, and 112 and pen weighed on 2 consecutive days at the termination Use of trade names in this publication does not imply endorsement by Colorado State University or criticism of similar products not mentioned. Mention of a proprietary product does not constitute a guarantee or warranty of the products by Colorado State University or the authors and does not imply its approval to the exclusion of other products that may also be suitable. 2 Corresponding author: [email protected] 1
of the experiment. On d 112, 3 steers per pen were bled via jugular venipuncture. Equal numbers of pen replicates per treatment were transported to a commercial abattoir (d 145 and 159) and slaughtered, and individual carcass data and liver samples, from the same animals bled on d 112, were collected. Pen initial BW was used as a covariate in the statistical analysis, and significance was determined at P ≤ 0.05. No differences were observed for final BW (P ≥ 0.42). Overall ADG, DMI, and feed efficiency were similar across treatments. Hot carcass weight, DP, YG, longissimus muscle area, adjusted fat thickness, KPH, and marbling score were similar across treatments. Concentrations of Zn, Cu, and Mn in liver and blood samples were similar across treatments. These data indicate that under the conditions of this experiment, supplemental Zn, Cu, and Mn concentration and source had no effect on performance, mineral status, and carcass characteristics in feedlot steers. Key words: feedlot, cattle, trace mineral, zinc, copper, manganese
INTRODUCTION Consulting nutritionists typically fortify feedlot diets with trace minerals. Fortification is typically done for 2 reasons: (1) feed ingredients used in feedlot diets tend to be inadequate in concentrations of certain essential trace minerals or (2) the basal diets may contain elevated concentrations of known mineral antagonists (Suttle, 2010). In a 2007 survey of consulting feedlot nutritionists, Vasconcelos and Galyean (2007) reported that, on average, consulting nutritionists formulate feedlot diets to contain 3 times the NRC (2000) recommendation for certain trace minerals and that some consulting nutritionists reported using a combination of inorganic and organic trace mineral sources in feedlot diets. Hydroxychloride trace minerals (HTM) are manufactured by reacting high purity forms (elemental metal or metal oxides) of a desired trace metal with water (as the source of hydroxyl groups) and hydrochloric acid (as the
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source of chloride). During the manufacturing process, hydroxychloride crystals are formed that contain the trace metal covalently bound to hydroxyl groups and chloride. Spears et al. (2004) reported that Cu from Cu hydroxychloride was relatively insoluble (0.6%) in water (pH 7.0) and highly soluble (81.4%) at a low pH (2.2), whereas Cu from CuSO4 was almost completely soluble in water (94.5%) and at a low pH (97.6%). Furthermore, compared with CuSO4, relative bioavailability of Cu from Cu hydroxychloride was greater than CuSO4 based on plasma Cu, ceruloplasmin activity, and liver Cu concentrations in steers fed a diet containing known Cu antagonists (5.0 mg of Mo/kg of diet DM and 0.15% S). Zinc from Zn hydroxychloride has also been reported to be less soluble in the rumen of feedlot cattle compared with Zn from ZnSO4 (Shaeffer, 2006). However, cattle receiving Zn hydroxychloride had greater apparent Zn absorption and retention than cattle supplemented with ZnSO4. Therefore, the objectives of the present study were to (1) compare performance and mineral status of finishing steers fed sulfate and hydroxychloride forms of Zn, Cu, and Mn at concentrations typical of those used by feedlot nutritionists, and (2) determine whether HTM can be supplemented at concentrations lower than those typically used, without negatively affecting performance.
MATERIALS AND METHODS Prior to the initiation of this experiment all animal care, handling, and procedures described herein were approved by the Colorado State University Animal Care and Use Committee (Approval # A13–4041). A total of 505 crossbred steers (initial BW 335 ± 9.6 kg) were transported to the Colorado State University Agriculture, Research, Development, and Education Center, Fort Collins, Colorado. Upon arrival steers were individually weighed, identified with an unique ear tag, vaccinated with Presponse (Pasteurella multocida bacterial extract– Mannheimia haemolytica toxoid, Boehringer Ingelheim Vetmedica Inc., St. Joseph, MO) and Pyramid 2 plus Type II BVD [bovine rhinotracheitis and bovine virus diarrhea (Types I and II), Boehringer Ingelheim Vetmedica Inc.] respiratory vaccines, injected with Promectin (ivermectin, Vedco Inc., Saint Joseph, MO) and drenched with Synanthic (oxfendazole, Boehringer Ingelheim Vetmedica Inc.) for parasite control, and implanted with Revalor–XS (120 mg trenbolone acetate and 24 mg estradiol, Merck Animal Health, De Soto, KS). During processing, breed type was assigned to all cattle based on hair color and phenotype (red, black, black-white face, white, Bos indicus, dairy, and so on). Following initial weighing, steers had ad libitum access to long-stem grass hay and water overnight and were housed in 10 head pens. Steers were then ranked by BW, and individuals that were beyond ±2 SD from the mean BW were eliminated from further consideration for the experiment. Steers exhibiting excessive Bos indicus, Longhorn, or dairy pheno-
types or found to be bulls, heifers, or displaying symptoms of health problems were eliminated from consideration. The remaining steers were assigned a random number from 1 to 1,000 using the random number function in Excel 2007 (Microsoft Corporation, Redmond, WA). Steers with the lowest random numbers were eliminated from the experiment, reducing the number of remaining steers to 400. The 400 eligible steers were ranked by weight and divided into 8 weight block replicates, each one consisting of 50 steers. Within each weight block replicate, steers were ranked by weight within phenotype and randomly assigned to 1 of 5 pens. By following this randomization schedule, 8 weight block replicates, each containing 5 pens with 10 steers per pen with similar phenotypic distribution (7 black or 7 black-white face and 3 red steers per pen), were assembled for each of the 5 treatments in the experiment. The following day steers were weighed before being fed, and visual ear tags identifying each animal were applied. Steers were then sorted into their respective treatment pens, and the experiment was initiated. Initial BW used for the experiment was the average of the 2 weights obtained on d −1 and 0. Pens were checked daily to ensure that cattle were in the appropriate pens, that all cattle had ad libitum access to feed and water, and that all gates were secure. Furthermore, all cattle were monitored for health and locomotion problems daily. Steers exhibiting significant symptoms of respiratory disease were removed from the pen, and rectal body temperatures were recorded. Steers with body temperatures greater than 39.4°C were considered morbid. All morbid steers were treated according to the appropriate treatment schedule and immediately returned to their original pen and allowed a chance to recover. If problems persisted concerning the health status of a specific steer, the steer was removed from the experiment. If a steer was removed from the experiment, the steer was weighed, the feed in the feed bunk was weighed and placed back into the feed bunk, a feed sample was obtained for DM determination, and the feed delivery was adjusted accordingly for that pen the next day. Two steers were treated for respiratory disease and recovered within 3 d after being treated. There were no mortalities during the experiment.
Diets All steers were fed a steam-flaked corn–based finishing diet. Steers were adjusted to the finishing diet using a series of step-up diets (starter, step 1, step 2, and finisher; Table 1). Diet changes during the step-up program were simultaneous (every 5 to 7 d) for all treatments, and cattle reached the finishing diet by d 24 of the experiment. Finishing diet TMR were formulated to meet or exceed NRC (2000) requirements for growing and finishing beef cattle. Nutrient target values were 13.5% CP with 3.5% CP equivalent from NPN, 3.5% added fat, 0.7% calcium, 0.36% phosphorus, 0.7% potassium, 0.25% magnesium, 0.10 mg of Co/kg of DM; 0.3 mg of Se/kg of DM, 33
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Zinc, copper, and manganese in feedlot cattle diets
g/t of monensin (Rumensin 90, Elanco Animal Health, Greenfield, IN), and 11 g/t of tylosin phosphate (Tylan 100, Elanco Animal Health) on a DM basis. Vitamins A and E were included in the diets at 2,200 and 40 IU/kg of DM, respectively, and were administered in the liquid supplement and macro- and microminerals were added as inorganic sources to meet the targeted values of the TMR. Zilpaterol hydrochloride was fed for 21 of the final 26 d of the finishing period. Diets were delivered once daily in the morning (0800 h) in amounts to allow cattle ad libitum access to feed for a 24-h period. Orts were determined for each pen on the days cattle were weighed. Subsamples of orts for each pen were analyzed for DM and used to calculate the DM weight of the orts for a given period. This value was then subtracted from the total DM delivered to a given pen of cattle to calculate DMI for a given period.
Trace minerals appropriate for each treatment were formulated and pelleted separately. All other required macro- and microminerals were added to all treatment pellets from the same mineral sources in amounts that met our targeted macro- and micromineral values for the TMR as described above. Dietary treatments consisted of (1) sulfate (90 mg of Zn/kg of DM from ZnSO4, 17.5 mg of Cu/kg of DM from CuSO4, 48 mg of Mn/kg of DM from MnSO4); (2) HTM-1 (30 mg of Zn/kg of DM from Zn hydroxychloride, 10 mg of Cu/kg of DM from basic CuCl, 20.0 mg of Mn/kg of DM from Mn hydroxychloride); (3) HTM-2 (45 mg of Zn/kg of DM from Zn hydroxychloride, 12.5 mg of Cu/kg of DM from basic CuCl, 29.5 mg of Mn/ kg of DM from Mn hydroxychloride); (4) HTM-3 (60 mg of Zn/kg of DM from Zn hydroxychloride, 15 mg of Cu/kg of DM from basic CuCl, 39 mg of Mn/kg of DM from Mn
Table 1. Dry matter ingredient composition of basal diet without supplemental copper, zinc, or manganese Item
Starter
Step 1
Step 2
Finisher
Ingredient, % Corn silage Steam-flaked corn Alfalfa hay Liquid supplement1 Pellet supplement Analyzed nutrient composition DM, % as fed CP, % NPN,2 % ADF, % NDF, % Ether extract, % NEg,3 Mcal/kg NEm,4 Mcal/kg Calcium, % Magnesium, % Phosphorus, % Potassium, % Sulfur, % Cobalt, mg/kg Copper, mg/kg Iron, mg/kg Manganese, mg/kg Molybdenum, mg/kg Selenium, mg/kg Zinc, mg/kg
16.38 35.0 43.93 — 4.69 59.79 13.85 0.10 19.25 28.58 3.56 1.07 1.68 0.72 0.21 0.32 1.44 0.19 0.27 3.14 318.47 13.26 1.51 0.44 13.76
13.38 51.50 28.19 2.17 4.76 63.86 14.28 1.92 14.25 22.80 3.50 1.19 1.82 0.78 0.19 0.32 1.12 0.16 0.22 2.90 227.68 11.78 1.20 0.40 14.97
13.38 66.17 12.44 3.25 4.76 63.10 13.78 2.88 6.78 18.19 3.50 1.28 1.89 0.73 0.16 0.32 0.82 0.14 0.17 2.65 138.55 11.04 0.88 0.35 16.05
13.37 78.81 — 4.32 3.50 63.0 13.45 3.45 6.15 14.66 4.12 1.42 2.06 0.65 0.14 0.32 0.68 0.15 0.12 2.48 67.45 10.55 0.63 0.29 17.07
Contained on a DM basis: 55,785.7 IU of vitamin A/kg, 223.1 IU of vitamin E/kg, 837.6 g of monensin/t (Rumensin 90, Elanco Animal Health, Greenfield, IN), and 251.4 g of tylosin/t (Tylan 100, Elanco Animal Health). 2 CP equivalent. 3 NEg = {[1.42 × (TDN × 0.0361)] − [0.174 × (TDN × 0.0361) × (TDN × 0.0361)] + [0.0122 × (TDN × 0.0361) × (TDN × 0.0361) × (TDN × 0.0361) − 1.65]} ÷ 2.205. 4 NEm = {[1.37 × (TDN × 0.0361)] − [0.0138 × (TDN × 0.0361) × (TDN × 0.0361)] + [0.0105 × (TDN × 0.0361) × (TDN × 0.0361) − 1.12]} ÷ 2.205. 1
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hydroxychloride); and (5) HTM-4 (90 mg of Zn/kg of DM from Zn hydroxychloride, 17.5 mg of Cu/kg of DM from basic CuCl, 48 mg of Mn/kg of DM from Mn hydroxychloride). With this treatment structure, (1) iso-amounts of Cu, Zn, and Mn from sulfate and HTM were compared (sulfate vs. HTM-4); (2) NRC versus industry concentrations of Cu, Zn, and Mn (HTM-1 vs. HTM-4) were compared; and (3) a dose response of HTM (HTM-1, HTM-2, HTM-3, and HTM-4) was evaluated. Supplemental trace mineral concentrations supplied in the sulfate and HTM-4 treatments were similar to the average supplemental trace mineral concentrations that were recommended by consulting nutritionists surveyed by Vasconcelos and Galyean (2007). The analyzed Zn, Cu, and Mn concentrations for the TMR for each finishing diet treatment were as follows: sulfate: 112.1 mg of Zn/kg of DM, 19.8 mg of Cu/kg of DM, and 65.7 mg of Mn/kg of DM; HTM-1: 42.6 mg of Zn/kg of DM, 11.2 mg of Cu/kg of DM, and 29.7 mg of Mn/kg of DM; HTM-2: 60.5 mg of Zn/kg of DM, 12.1 mg of Cu/kg of DM, and 41.2 mg of Mn/kg of DM; HTM-3: 78.5 mg of Zn/kg of DM, 17.1 mg of Cu/kg of DM, and 52.4 mg of Mn/kg of DM; and HTM-4: 114.2 mg of Zn/kg of DM, 20.1 mg of Cu/kg of DM, and 63.1 mg of Mn/kg of DM. General water quality samples were obtained twice throughout the experiment. Water samples were obtained at the main water supply line to the feedlot and sent to an established laboratory (SDK Labs, Hutchinson, KS) for routine water quality analysis (pH = 7.37 ± 0.19; total hardness, mg/L = 750.3 ± 63.1; sulfate, mg/L = 482.7 ± 35.8; sodium, mg/L = 70.3 ± 10.1; chloride, mg/L = 30.0 ± 4.1; total dissolved solids, mg/L = 1,094.3 ± 73.1; electrical conductivity, μS/cm = 1,543.3 ± 103.3).
Weighing, Sampling, and Carcass Data Collection Steers were individually weighed on d −1, 0, 55, and 112, and pen weights were obtained on 2 consecutive days at the termination of the experiment. Jugular blood samples were collected on d 112 from 3 animals per pen and analyzed for plasma Zn, Cu, and Mn concentrations. Equal numbers of pen replicates per treatment were transported to a commercial abattoir (d 145 and 159) and slaughtered, and individual carcass data and liver samples were collected. Hot carcass weight was determined at the time of slaughter. Carcasses were allowed to chill for approximately 36 h before carcass data were obtained. Carcass data were collected by Center for Meat Safety and Quality personnel at Colorado State University. Carcass data collected included DP, longissimus muscle area, s.c. adipose tissue thickness, adjusted s.c. adipose tissue thickness (USDA, 1989), KPH, marbling score, QG, and YG (calculated). Liver samples were collected (approximately 200 g of wet weight) on the day of slaughter from the left lobe of each liver after being inspected by USDA personnel. Following collection, liver samples were placed in Whirl-Pak bags containing the slaughter order number,
placed on ice, and transported to the laboratory. Samples were then stored at –20°C until they were analyzed. At the time of liver analysis, only liver samples from cattle that were bled on d 112 were analyzed for Zn, Cu, and Mn concentrations.
Analytical Procedures Liver tissue samples and 1.0 mL of plasma were dried at 60°C for 24 h in a preweighed crucible. Samples were weighed after drying and dry ashed at 600°C for 12 h. Liver tissues and plasma samples were analyzed for mineral concentrations via inductively coupled plasma-atomic emission spectroscopy methods as described by Ahola et al. (2004) for Zn, Cu, and Mn concentrations. Samples were diluted in distilled H2O to fit within a linear range of a standard curve generated by linear regression of known trace mineral concentrations. Multielemental analysis was then carried out by simultaneous/sequential inductively coupled plasma-atomic emission spectroscopy analysis with cross flow nebulization.
Statistics Feedlot performance, plasma and liver trace mineral concentrations, and continuous carcass data were analyzed on a pen mean basis as a randomized block design using PROC MIXED of SAS (SAS Institute Inc., Cary, NC). Treatment was included in the model as a fixed classification effect, and weight block pen replicate was included in the model as a random effect. The linear and quadratic effects of treatment dose were determined by using orthogonal polynomial coefficients derived using PROC IML of SAS that were applied to treatments HTM-1 through HTM-4 as quantitative factors that were unequally spaced. These procedures were completed to derive the Type I sum of squares for the increasing doses. Quality grade, YG, HCW category, carcass maturity, and liver abscess data were evaluated as categorical data using PROC GLIMMIX of SAS assuming a binomial distribution. The Link = Logit option of the model statement and ILINK option of the LSMEANS statement were used to calculate the likelihood ± SEM that an individual within each pen qualified for a specific category (≥low choice, select, or ≤standard). Significance was determined at P ≤ 0.05. Pen initial BW was used as a covariate in the analysis of all response variables.
RESULTS AND DISCUSSION The effect of trace mineral concentration and source on animal performance is presented in Table 2. Initial and final BW, DMI, ADG, and feed efficiency were similar across treatments. Previously published literature investigating the effect of supplementing Cu, Zn, and Mn in combination with one another at different doses is limited. Ahola et al. (2005) reported that finishing cattle fed a control diet with no supplemental Cu, Zn, and Mn had
67
Zinc, copper, and manganese in feedlot cattle diets
Table 2. Effect of supplemental copper, zinc, and manganese concentration and source on performance and feed efficiency of feedlot cattle1 Treatment (TRT)2 Item
Sulfate
HTM-1
HTM-2
HTM-3
Contrast (P <) HTM-4
Sulfate HTM-1 TRT vs. HTM-4 vs. HTM-4 Linear3 Quadratic3
SEM
BW, kg Initial 337.5 336.8 335.3 335.1 334.9 Final 654.6 647.0 647.3 655.6 651.4 DMI, kg/d d 0–final 11.3 11.5 11.6 11.6 11.5 ADG, kg/d 2.03 1.98 1.99 2.04 1.99 d 0–final G:F 0.179 0.173 0.172 0.177 0.174 d 0–final
9.57 4.83 0.13 0.029 0.003
0.32 0.42 0.31 0.54 0.40
0.09 0.57 0.45 0.37 0.22
0.58 0.19 0.47 0.27 0.16
0.27 0.25 0.94 0.61 0.58
0.59 0.62 0.16 0.37 0.94
Pen initial BW was used as a covariate in the analysis of all response variables. Experimental treatments: sulfate (90 mg of Zn/kg of DM from ZnSO4, 17.5 mg of Cu/kg of DM from CuSO4, 48 mg of Mn/ kg of DM from MnSO4); hydroxychloride trace minerals (HTM-1; 30 mg of Zn/kg of DM from Zn hydroxychloride, 10 mg of Cu/kg of DM from basic CuCl, 20 mg of Mn/kg of DM from Mn hydroxychloride); HTM-2 (45 mg of Zn/kg of DM from Zn hydroxychloride, 12.5 mg of Cu/kg of DM from basic CuCl, 29.5 mg of Mn/kg of DM from Mn hydroxychloride); HTM-3 (60 mg of Zn/kg of DM from Zn hydroxychloride, 15 mg of Cu/kg of DM from basic CuCl, 39 mg of Mn/kg of DM from Mn hydroxychloride); and HTM-4 (90 mg of Zn/kg of DM from Zn hydroxychloride, 17.5 mg of Cu/kg of DM from basic CuCl, 48 mg of Mn/kg of DM from Mn hydroxychloride). 3 Linear and quadratic responses were determined using treatments: HTM-1, HTM-2, HTM-3, and HTM-4. 1 2
similar ADG but tended (P = 0.10) to have lesser DMI than cattle supplemented with Cu, Zn, and Mn at concentrations of 10, 30, and 20 mg/kg of DM, respectively. The control diet used by Ahola et al. (2005) analyzed 6.4 mg of Cu, 15 mg of Zn, and 15.7 mg of Mn/kg of DM. Increasing the concentration of supplemental Cu, Zn, Mn, and Co from 1.0 to 1.5 times NRC (2000) recommendations from organic sources or from 1.5 to 3.0 times NRC (2000) recommendations from sulfate sources did not affect performance of finishing steers (Rhoads et al., 2003). Berrett et al. (2015) reported that yearling feedlot steers receiving no supplemental Cu, Zn, and Mn had similar performance to steers receiving NRC (2000) or greater than NRC (2000) concentrations of Cu, Zn, and Mn in both organic and inorganic forms. Several experiments comparing different doses of a single trace mineral on feedlot cattle performance have been conducted. Results from experiments evaluating Cu supplementation have been variable. Copper supplementation to feedlot cattle consuming a high concentrate diet has been reported to have a positive (Ward and Spears, 1997; Engle et al., 2000a), negative (Engle and Spears, 2000b), or no effect (Engle and Spears, 2000a; 2001) on performance compared with nonsupplemented controls. Supplementation of a control diet containing 8.1 mg of Mn/kg of DM with 10, 20, or 30 mg of MnSO4/kg of DM did not affect performance of finishing steers (Legleiter et al., 2005).
Variable feedlot cattle performance responses to Zn supplementation have also been reported. Increasing supplemental Zn from 30 to 70 mg/kg of DM slightly increased (P = 0.10) DMI but did not affect ADG or G:F (Galyean et al., 1995). Malcolm-Callis et al. (2000) reported no differences in ADG or G:F during a 112-d finishing period with added Zn (as ZnSO4) concentrations at 20, 100, or 200 mg/kg of dietary DM. However, DMI decreased (linear, P = 0.10) slightly as Zn concentration increased. Spears and Kegley (2002) reported that Zn supplementation (25 mg of Zn/kg of DM) did not affect performance of finishing steers relative to those fed the control diet (analyzed 26 mg of Zn/kg of DM). Supplementing 75 mg of Zn/kg of DM to a control diet that analyzed 50 mg of Zn/kg of DM, tended to improve ADG (P = 0.11) and G:F (P = 0.06) in finishing heifers (Nunnery et al., 2007). Reaching an objective conclusion about the effect of Cu, Zn, and Mn supplementation on finishing cattle performance is difficult. Numerous factors can influence an animal’s response to trace mineral supplementation, such as initial trace mineral status of the animal, disease status, mineral antagonists, stress, breed, mineral bioavailability, environmental factors, as well as basal dietary mineral concentrations. The influence of trace mineral concentration and source on carcass characteristics is presented in Tables 3 and 4. There was a quadratic (P < 0.04) response for YG across the HTM treatments. As dose of Cu, Zn, and Mn in-
416.6 63.7 2.85 96.9 1.31 2.02 391.2
HCW, kg DP YG Longissimus muscle area, cm2 Adjusted fat thickness,4 cm KPH, % Marbling score5
412.3 63.7 2.87 95.9 1.19 2.04 389.9
HTM-1 413.0 63.9 2.69 98.3 1.16 2.03 386.9
HTM-2 413.9 63.2 2.66 97.5 1.20 2.05 394.1
HTM-3 418.9 64.4 2.90 96.6 1.22 2.01 392.5
HTM-4 3.07 0.57 0.09 1.39 0.07 0.02 9.93
SEM 0.45 0.55 0.19 0.78 0.52 0.82 0.97
TRT 0.57 0.32 0.63 0.86 0.33 0.75 0.90
Sulfate vs. HTM-4
0.26 0.97 0.84 0.68 0.18 0.67 0.85
HTM-1 vs. HTM-4
Contrast (P <)
0.14 0.62 0.88 0.89 0.65 0.71 0.68
Linear3
0.54 0.31 0.04 0.27 0.68 0.62 0.94
Quadratic3
2
1
Pen initial BW was used as a covariate in the analysis of all response variables. Experimental treatments: sulfate (90 mg of Zn/kg of DM from ZnSO4, 17.5 mg of Cu/kg of DM from CuSO4, 48 mg of Mn/kg of DM from MnSO4); hydroxychloride trace minerals (HTM-1; 30 mg of Zn/kg of DM from Zn hydroxychloride, 10 mg of Cu/kg of DM from basic CuCl, 20 mg of Mn/kg of DM from Mn hydroxychloride); HTM-2 (45 mg of Zn/kg of DM from Zn hydroxychloride, 12.5 mg of Cu/kg of DM from basic CuCl, 29.5 mg of Mn/kg of DM from Mn hydroxychloride); HTM-3 (60 mg of Zn/kg of DM from Zn hydroxychloride, 15 mg of Cu/kg of DM from basic CuCl, 39 mg of Mn/kg of DM from Mn hydroxychloride); and HTM-4 (90 mg of Zn/kg of DM from Zn hydroxychloride, 17.5 mg of Cu/kg of DM from basic CuCl, 48 mg of Mn/kg of DM from Mn hydroxychloride). 3 Linear and quadratic responses were determined using treatments: HTM-1, HTM-2, HTM-3, and HTM-4. 4 USDA, 1989. 5 Marbling score: 300 = Slight0, 400 = Small0, 500 = Modest0.
Sulfate
Item
Treatment (TRT)2
Table 3. Effect of supplemental copper, zinc, and manganese concentration and source on carcass characteristics of feedlot cattle1
68 Caldera et al.
77 37.5 ± 8.6 56.0 ± 9.1 6.5 96.1 3.9
Sulfate 80 36.5 ± 8.6 60.8 ± 8.8 2.7 97.3 2.7
HTM-1 79 34.0 ± 8.3 61.3 ± 8.7 4.7 100 0
HTM-2 80 37.3 ± 8.6 55.5 ± 9.0 7.2 97.5 2.5
HTM-3 79 33.9 ± 8.2 64.6 ± 8.4 1.5 93.0 7.0
HTM-4
NA NA
0.98 0.79 NA5
TRT
NA NA
0.66 0.32 NA
Sulfate vs. HTM-4
NA NA
0.94 0.56 NA
HTM-1 vs. HTM-4
Contrast (P <)
NA NA
0.89 0.84 NA
Linear2
NA NA
0.95 0.56 NA
Quadratic2
1
Experimental treatments: sulfate (90 mg of Zn/kg of DM from ZnSO4, 17.5 mg of Cu/kg of DM from CuSO4, 48 mg of Mn/kg of DM from MnSO4); hydroxychloride trace minerals (HTM-1; 30 mg of Zn/kg of DM from Zn hydroxychloride, 10 mg of Cu/kg of DM from basic CuCl, 20 mg of Mn/kg of DM from Mn hydroxychloride); HTM-2 (45 mg of Zn/kg of DM from Zn hydroxychloride, 12.5 mg of Cu/kg of DM from basic CuCl, 29.5 mg of Mn/kg of DM from Mn hydroxychloride); HTM-3 (60 mg of Zn/kg of DM from Zn hydroxychloride, 15 mg of Cu/kg of DM from basic CuCl, 39 mg of Mn/kg of DM from Mn hydroxychloride); and HTM-4 (90 mg of Zn/kg of DM from Zn hydroxychloride, 17.5 mg of Cu/kg of DM from basic CuCl, 48 mg of Mn/kg of DM from Mn hydroxychloride). 2 Linear and quadratic responses were determined using treatments: HTM-1, HTM-2, HTM-3, and HTM-4. 3 ±SD. 4 Results are expressed as the percentage likelihood that an individual carcass within each pen qualifies for a specific QG unless stated otherwise. 5 NA = not applicable. 6 Percentage of individual livers showing one or more liver abscesses.
n QG, % ≥Low Choice3 Select3,4 ≤Standard4 Liver scores, % Normal Abscesses6
Item
Treatment (TRT)1
Table 4. Effect of supplemental copper, zinc, and manganese concentration and source on categorical carcass characteristics and liver abscesses of feedlot cattle
Zinc, copper, and manganese in feedlot cattle diets
69
1.07 0.98 7.14
105.0 273.5 10.4
Sulfate
1.11 1.02 8.25
100.9 251.2 9.9
HTM-1
1.02 1.01 7.80
97.9 261.0 10.2
HTM-2
1.00 0.96 7.50
95.0 274.2 10.2
HTM-3
1.06 1.04 7.94
108.2 269.2 9.9
HTM-4
0.11 0.07 0.98
3.70 14.6 0.30
SEM
0.35 0.83 0.47
0.02 0.78 0.74
TRT
0.20 0.37 0.98
0.44 0.84 0.28
Sulfate vs. HTM-4
0.29 0.97 0.15
0.28 0.24 0.34
HTM-1 vs. HTM-4
Contrast (P <)
0.76 0.48 0.16
0.17 0.38 0.95
Linear2
0.07 0.64 0.48
0.03 0.64 0.33
Quadratic2
1
Experimental treatments: sulfate (90 mg of Zn/kg of DM from ZnSO4, 17.5 mg of Cu/kg of DM from CuSO4, 48 mg of Mn/kg of DM from MnSO4); hydroxychloride trace minerals (HTM-1; 30 mg of Zn/kg of DM from Zn hydroxychloride, 10 mg of Cu/kg of DM from basic CuCl, 20 mg of Mn/kg of DM from Mn hydroxychloride); HTM-2 (45 mg of Zn/kg of DM from Zn hydroxychloride, 12.5 mg of Cu/kg of DM from basic CuCl, 29.5 mg of Mn/kg of DM from Mn hydroxychloride); HTM-3 (60 mg of Zn/kg of DM from Zn hydroxychloride, 15 mg of Cu/kg of DM from basic CuCl, 39 mg of Mn/kg of DM from Mn hydroxychloride); and HTM-4 (90 mg of Zn/kg of DM from Zn hydroxychloride, 17.5 mg of Cu/kg of DM from basic CuCl, 48 mg of Mn/kg of DM from Mn hydroxychloride). 2 Linear and quadratic responses were determined using treatments: HTM-1, HTM-2, HTM-3, and HTM-4. 3 Liver samples were collected (approximately 200 g of wet weight) on the day of slaughter from the left lobe of each liver after being inspected by USDA personnel. 4 Three animals from each pen were bled via jugular venipuncture on d 112.
Liver3 Zn, mg/kg of DM Cu, mg/kg of DM Mn, mg/kg of DM Plasma, d 1124 Zn, mg/L Cu, mg/L Mn, μg/L
Item
Treatment (TRT)1
Table 5. Effect of supplemental copper, zinc, and manganese concentration and source on mineral status of feedlot cattle
70 Caldera et al.
Zinc, copper, and manganese in feedlot cattle diets
creased, YG decreased for HTM-2 and HTM-3 treatments and increased for HTM-4 treatment (Table 3). Hot carcass weight, DP, longissimus muscle area, s.c. adipose tissue depth, and marbling score were similar across treatments. Quality grades and liver abscess scores were not affected by treatment (Table 4). These finding are similar to those reported by Rhoads et al. (2003), Ahola et al. (2005), and Berrett et al. (2015), where Zn, Cu, and Mn concentration and source had minimal effect on carcass characteristics of feedlot steers. Malcolm-Callis et al. (2000) reported a quadratic response of added Zn (as ZnSO4) on fat thickness and YG (P < 0.01). Zinc supplementation to a control diet, containing 26 mg of Zn/kg of DM, increased quality and YG of finishing steers (Spears and Kegley, 2002). In other studies (Galyean et al., 1995; Nunnery et al., 2007), increasing dietary Zn did not affect carcass characteristics of finishing cattle. Copper supplementation to finishing diets low in Cu (4.9 mg of Cu/kg of DM) has reduced backfat (Engle and Spears, 2000a; Engle et al., 2000a,b), and varying dietary Mn from 8 to 240 mg/kg of DM did not affect carcass characteristics of finishing steers (Legleiter et al., 2005). Although not all previously cited experiments measured mineral status in cattle, no clinical signs of mineral deficiencies were reported. Furthermore, those experiments where mineral status was reported indicated that plasma or liver Cu, Mn, and Zn concentrations were adequate for beef cattle. Liver and plasma Cu, Zn, and Mn concentrations are presented in Table 5. Concentrations of Cu, Zn, and Mn in liver and plasma samples were within the normal range expected in cattle receiving an adequate supply of these trace minerals (Suttle, 2010). Copper and Mn concentrations in liver samples collected at slaughter were similar across treatments. A quadratic (P < 0.03) response was noted in liver Zn concentration with increasing Zn doses, and the greatest Zn liver concentration was observed in the HTM-4 treatment at 108.2 mg of Zn/kg of DM (Table 5). Wright and Spears (2004) reported that supplementing 25 mg of Zn/kg of DM to a control diet (analyzed 28 mg of Zn/kg of DM) increased liver Zn concentrations in Holstein calves. Concentrations of Zn, Cu, and Mn in plasma samples collected on d 112 were similar across treatments (Table 5). In previous studies, the addition of 25 to 75 mg of Zn/kg of DM to control diets, containing 26 to 50 mg of Zn/kg of DM, had little or no effect on plasma or serum Zn concentrations (Spears and Kegley, 2002; Wright and Spears, 2004; Nunnery et al., 2007). The addition of 10 mg of Cu/kg of DM to a finishing diet containing 4.9 mg of Cu/kg of DM increased plasma and liver Cu concentrations (Engle and Spears, 2000a). However, increasing supplemental Cu in this study from 10 to 20 mg/kg of DM did not result in further increases in plasma Cu. It is well documented that plasma Cu does not generally decline to deficient concentrations until liver Cu stores are depleted (Claypool et al., 1975). In the present study, liver Cu concentrations were well above those considered even marginally deficient and the lowest concentration of Cu
71
supplemented was 10 mg/kg of DM. Supplementing from 10 to 240 mg of Mn/kg of DM did not increase plasma Mn above values observed in finishing steers fed a control diet (analyzed 8.1 mg of Mn/kg of DM; Legleiter et al., 2005). It should be noted that mineral antagonists such as Mo, S, and Fe were not at concentrations know to be antagonistic to Cu or Zn absorption or metabolism (NRC, 2000). Furthermore, mean water quality measurements for all treatments were suitable for livestock consumption based on previous publications (NRC, 2001; NRC, 2005; Wright, 2007; National Academies of Sciences, Engineering, and Medicine, 2016).
IMPLICATIONS Under the conditions of this experiment, supplemental Zn, Cu, and Mn concentration and source had no effect on performance and carcass characteristics and minimal effects on liver and plasma Cu, Zn, and Mn concentrations. The lack of a dose response within the HTM treatments (HTM-1, HTM-2, HTM-3, and HTM-4) as well as the lack of a response when HTM-1 was compared with HTM-4 on performance response variables suggests that Cu, Zn, and Mn can be supplemented at lower concentrations than those reported by consulting feedlot nutritionists (Vasconcelos and Galyean, 2007) without adversely affecting cattle performance or carcass characteristics.
ACKNOWLEDGMENTS This research was supported in part by the Colorado State University Agricultural Experiment Station and by Micronutrients (Indianapolis, IN).
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