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/lp/oxford-university-press/efficacy-of-mineral-supplementation-to-growing-cattle-grazing-winter-aXzz3i5dOs
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- Published by Oxford University Press on behalf of the American Society of Animal Science 2019. This work is written by (a) US Government employee(s) and is in the public domain in the US.
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- 2573-2102
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- 10.1093/tas/txz031
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Abstract
Downloaded from https://academic.oup.com/tas/advance-article-abstract/doi/10.1093/tas/txz031/5429549 by Ed 'DeepDyve' Gillespie user on 09 April 2019 Efficacy of mineral supplementation to growing cattle grazing winter-wheat pasture in northwestern Oklahoma 2 3 S. A. Gunter† and G. F. Combs, Jr.* United States Department of Agriculture, Agricultural Research Service, Southern Plains Range Research Station, Woodward, OK 73801 United States Department of Agriculture, Agricultural Research Service, Grand Forks Human Nutrition Center, Grand Forks, ND 58203 Mention of trade names or commercial products in this article is solely for providing specific information and does not imply recommendation or endorsement by the United States Department of Agriculture. The United States Department of Agriculture prohibits discrimination in all its programs and activities based on race, color, national origin, age, disability, and where applicable, sex, marital status, familial status, parental status, religion, sexual orientation, genetic information, political beliefs, reprisal, or because all or part of an individual's income is derived from any public assistance program. Corresponding author: stacey.gunter@ars.usda.gov Current address: Jean Mayer United States Department of Agriculture, Human Nutrition Research Center on Aging, 711 Washington Street, Tufts University, Boston, MA 02111. Published by Oxford University Press on behalf of the American Society of Animal Science 2019. This work is written by (a) US Government employee(s) and is in the public domain in the US. This Open Access article contains public sector information licensed under the Open Government Licence v2.0 (http://www.nationalarchives.gov.uk/doc/open- government-licence/version/2/). Accepted Manuscript Downloaded from https://academic.oup.com/tas/advance-article-abstract/doi/10.1093/tas/txz031/5429549 by Ed 'DeepDyve' Gillespie user on 09 April 2019 ABSTRACT: Two experiments were conducted to evaluate the efficacy of mineral supplementation to cattle grazing winter-wheat pasture. In Exp. 1 (fall), 120 steers and heifers [body weight (BW) = 232 ± 11.4 kg] were assigned randomly to 4 blocks of replicated pastures during the second week of November in 2008 and 2009 and all herds (6 animals/pasture; 4.9 ha/pasture) were allowed to graze for 84 d. In Exp. 2 (spring), 216 steers (BW = 248 ± 7.9 kg) were assigned randomly to 5 blocks of replicated pastures during the second week of February in 2009 and 2010 and all herds (12 or 6 animals/pasture; 4.9 ha/pasture) were allowed to graze for 84 d. Half the pastures in both experiments received a free-choice mineral mixture (Wheat Pasture Pro; Land O’Lakes Purina Feed, LLC; St. Paul, MN; Ca, 16% and P, 4%); mineral feeders were weighed weekly to determine mineral intake. All pastures were planted in early September of each year (67 kg of seed/ha) and fertilized with 50 kg of urea-N/ha. Standing herbage DM was determined midway between weigh dates by clipping wheat forage to the ground along 122-cm of drill-rows at 10 locations/pasture. Data were analyzed by ANOVA, with treatment as the fixed effect and pasture, animal sex (Exp. 1), and block as random effects. In Exp. 1, cattle offered minerals had a 43% faster average daily gain (ADG; P = 0.02, 0.73 kg) than cattle not offered minerals (0.51 kg); hence, supplemented cattle weighed 6% more (P = 0.04; 286 kg) after 84 d than non-supplemented cattle (271 kg). In Exp. 2, cattle offered the mineral supplement had a faster ADG (20% increase; P = 0.04; 1.00 kg) than cattle not offered minerals (0.83 kg). Further, supplemented cattle weighed 4% more (P = 0.03; 326 kg) after 84 d than non-supplemented cattle (312 kg). In both experiments, daily standing herbage dry matter averaged 1,381 kg/animal and never differed (P ≥ 0.47) between treatments. Mineral intakes averaged 135 (Exp. 1) and 124 (Exp. 2) g/d, resulting in a cost of supplement to kilogram of added BW gain of $0.53 and $0.64, respectively (assuming a mineral cost of $0.88/kg). Overall, Accepted Manuscript Downloaded from https://academic.oup.com/tas/advance-article-abstract/doi/10.1093/tas/txz031/5429549 by Ed 'DeepDyve' Gillespie user on 09 April 2019 supplementing an appropriate mineral mixture to cattle grazing winter-wheat pasture increased ADG in a cost-effective manner. Key Words: Minerals, Steers, Supplementation, Wheat pasture Introduction Winter-wheat (Triticum aestivum L) pasture is a unique and economically important resource in the Southern Great Plains because income is derived from both the grain and the cattle body weight (BW) gain from the grazing cattle (Horn et al., 2005). The potential for profit from grazing stocker cattle on wheat pasture is exceptionally good because of the high-quality forage (Stewart et al., 1981; Bohman et al., 1983b; Dove and McMullen, 2009) and the favorable seasonality of prices for feeder cattle prices associated with the annual cycles (Franzmann and Walker, 1972). Cattle grazing winter-wheat pasture have BW gains that normally range from 0.49 to 1.82 kg/d, even when not supplemented (Davenport et al., 1989; Horn et al., 1995; Min et al., 2006; Fieser et al., 2007), depending on the weather and forage allowance (Redmon et al., 1995; Pinchak et al., 1996). Even in light of these facts, the performance of cattle grazing wheat pasture can be improved by providing supplements either in the form of additional energy or minerals (Grigsby et al., 1991; Horn et al., 1995; Fieser et al., 2005; Fieser et al., 2007). Mineral supplementation for cattle grazing wheat pasture can significantly affect net return to the producer by the prevention of metabolic disorders and improved animal performance (Greene, 2000; Horn et al., 2002; Fieser et al., 2007). The analyzed mineral composition of wheat forage indicates that it contains sufficient P and Mg, excessive K, but inadequate Ca to meet metabolic needs (Stewart et al., 1981; Bohman et al., 1983b; Fieser et al., 2007). Wheat forage can contain more than 4% K and as little as 0.22% Ca in the spring, while wheat is rapidly growing (Stewart Accepted Manuscript Downloaded from https://academic.oup.com/tas/advance-article-abstract/doi/10.1093/tas/txz031/5429549 by Ed 'DeepDyve' Gillespie user on 09 April 2019 et al., 1981; Bohman et al., 1983b; Fieser et al., 2007). Calcium is most likely a limiting mineral for cattle grazing wheat pasture (Stewart et al., 1981; Bohman et al., 1983a). Hypocalcemia has been shown to appear in cattle grazing wheat pasture 3 to 4 d before the onset of hypomagnesemia (Bohman et al., 1983a; Grunes et al., 1984). Research from central Oklahoma has indicated improved performance by stocker cattle when provided a complete free-choice mineral supplement high in Ca and low in P (Horn et al., 2002; Fieser et al., 2007). The objective of the 2 following experiments was to test the following hypothesis: cattle grazing wheat pasture in northwest Oklahoma also require a high Ca, low P mineral supplement for maximal performance. Materials and Methods All animal procedures were conducted in accordance with the recommendations of the Consortium (FASS, 2010) and were approved by the Southern Plains Range Research Station Institutional Animal Care and Use Committee. Fall Grazing (Exp. 1). Four 4.9-ha pastures located on the Southern Plains Experimental Range (SPER) of the United States Department of Agriculture, Agricultural Research Service near Ft. Supply, OK were planted (Model 8300, John Deere; Moline, IL; 19.1-cm row spacing) to wheat (67 kg/ha of seed) the first 2 wk of September 2008 (Block 1). Before planting, a conventional-tillage system was used, seedbeds were prepared by offset disking the previous year’s wheat stubble in early June, followed by harrowing with a sweep plow (Stubble Mulch Plow, Richardson Manufacturing Co., Inc.; Cawker City, KS) as needed to control warm-season weeds. Pastures were fertilized before the final harrowing during the last week of August according to soil test recommendations for N (50 kg/ha of N from urea), P, and K from the Oklahoma State University Soil and Water Testing Laboratory (Stillwater, OK). Further, six 4.9- Accepted Manuscript Downloaded from https://academic.oup.com/tas/advance-article-abstract/doi/10.1093/tas/txz031/5429549 by Ed 'DeepDyve' Gillespie user on 09 April 2019 ha pastures located on the SPER were planted to wheat (67 kg/ha of seed) the first 2 wk of September 2009 (Block 2) that had been managed as described in Block 1. In 2009, 6 additional 4.9-ha pastures located on the SPER were planted to wheat (67 kg/ha of seed) the first 2 wk of September (Block 3) that had also been managed as described in Block 1. Last, four 4.9-ha pastures located on the SPER were planted to wheat (67 kg/ha of seed) the first 2 wk of September 2009 (Block 4). This last block of pastures was planted with a no-till drill (Model 750, John Deere; 19.1-cm row spacing) and had weeds controlled during the previous summer by spraying emerging weeds with glyphosate as needed. Pastures in all Blocks consisted of a mixture of Eda Sand, Grandfield Sandy Loam, and Hardeman-Grandmore Complex soils (sandy, mixed, mesic Psammentic Haplustalfs) and are on gently rolling dunes (NRCS Websoils, https://www.nrcs.usda.gov/wps/portal/nrcs/main/soils/survey/). Each year during the second week of November when the plant leaves were at least 20 cm in length [13 November 2008 (Block 1, 4 pasture), and 12 November 2009 (Block 2, 6 pastures) and 17 November 2009 (Blocks 3, 6 pastures; and 4, 4 pastures)], pastures were stocked with 6 animals [24 animals in 2008 (Block 1); 8 heifers and 16 steers; initial BW = 193 ± 12.0 kg and 96 steers in 2009 (Blocks 2, 3, and 4); initial BW = 220 ± 10.6 kg]. Steer, bull, and heifer (Exp. 1 only) calves were annually amalgamated from sales barns near Kaufman, Texas and received at a commercial feedlot for 3 to 6 wk. During receiving, bulls were castrated and horns tipped; all calves were treated for internal and external paracites (Cydectin; Fort Dodge Animal Health), implanted (Ralgro; Schering-Plough Animal Health; Union, NJ), injected with a modified live 4-way vaccine for infectious bovine rhinotracheitis, bovine respiratory parainfluenza-3, bovine respiratory syncytial virus, and bovine virus diarrhea, and injected with a 7-way Clostridial vaccine; calves were re-vaccinated before leaving the feedlot. After receiving, calves were Accepted Manuscript Downloaded from https://academic.oup.com/tas/advance-article-abstract/doi/10.1093/tas/txz031/5429549 by Ed 'DeepDyve' Gillespie user on 09 April 2019 shipped to the SPER (624 km) in mid-October where they were individually weighed, and number branded and then placed on dormant pasture and fed a 41% CP cottonseed meal-based supplement at rates of 0.68 to 0.91 kg/steer per day until the experimental started (4 to 6 wk). Calves were monitored for bovine respiratory disease daily during the dormant-pasture grazing period; no calves were treated for bovine respiratory disease complex. Animals grazed until the first week of February (84 d; ending 5 February 2008, and 4 and 9 February 2009, respectively). Cattle were randomly assigned within blocks to pastures each year. The cattle were stratified by BW (and sex in Block 1); BW was measured 2 d before stocking following a 16-h withdrawal from feed and water to control for variation in gastrointestinal fill (Aiken and Tabler, 2004). Half the pastures within each block were randomly selected and cattle were offered a free- choice mineral supplement (Wheat Pasture Pro; Land O’Lakes Purina Feed, LLC, Saint Paul, MN) in ground-type mineral feeders (Sioux Steel Company; Sioux City, SD). The mineral mixture contained (as-fed) 15 to 17% Ca and 4% P from CaCO and Ca PO , 5.5% Mg from 3 2 4 MgO, 18.5 to 22.0% NaCl, 220,500 IU of vitamin A/kg, and trace minerals (1,250 mg/kg of Mn from MnSO , 650 mg/kg of Cu from basic CuCl, 2,185 mg/kg of Zn from ZnSO , 22 mg/kg Se 4 4 from NaSeO , and 65 mg/kg of I from ethylenediamine dihydroiodide). The other pastures received no salt or supplement of any kind. Mineral feeders were weighed initially and on a weekly basis thereafter to determine mineral intake; DM of the dispensed and weekly orts were determined as described by AOAC (2000) to measure DM disappearance from the feeder. Mineral intake was adjusted back to an as-fed basis (96% DM). Initially and at 28-d intervals until the experiment ended, cattle were weighed following a 16-h withdrawal from feed and water (Aiken and Tabler, 2004). A sample of standing herbage mass was collected 2 wk after weigh-d 0, 28, and 56 at 10 paced transects within each pasture by Accepted Manuscript Downloaded from https://academic.oup.com/tas/advance-article-abstract/doi/10.1093/tas/txz031/5429549 by Ed 'DeepDyve' Gillespie user on 09 April 2019 clipping forage to the ground on 2 sides of a 61-cm rod placed between drill rows (19.1-cm row spacing). Herbage samples were placed in paper sacks, dried in a forced-air oven at 56 C to determine dry matter (DM) content then saved for nutrient analysis. Spring Grazing (Exp. 2). Four 4.9-ha pastures located on the SPER were planted (Model 8300, John Deere; 19.1-cm row spacing) to wheat (67 kg/ha of seed) the first 2 wk of September 2008 (Block 1). Further, six 4.9-ha pastures located on the SPER were planted to wheat (67 kg/ha of seed) the first 2 wk of September 2008 (Block 2) that had been managed as described in Block 1. Four 4.9-ha pastures located on the SPER were planted to wheat (67 kg/ha of seed) the first 2 wk of September 2008 (Block 3). Six 4.9-ha pastures located on the SPER were planted to wheat (67 kg/ha of seed) the first 2 wk of September 2009 (Block 4). Four 4.9-ha pastures located on the SPER were planted to wheat (67 kg/ha of seed) the first 2 wk of September 2009 (Block 5). Weed control and fertilizations protocols for the pastures in Blocks 1, 2, and 4 were identical to the conventional tillage methods described in Exp. 1 and the pastures in Blocks 3 and 5 were planted with a no-till drill as described in Exp. 1. Pastures in all Blocks consisted of a mixture of Eda Sand, Grandfield Sandy Loam, and Hardeman-Grandmore Complex soils (sandy, mixed, mesic Psammentic Haplustalfs) and are on gently rolling dunes, (NRCS Websoils, (https://www.nrcs.usda.gov/wps/portal/nrcs/main/soils/survey/). On 5 February 2009 (Block 1), 12 steer calves (initial BW = 235 ± 6.1 kg, 48 steers) were stocked on each of the 4 pastures (2.5 animal/ha) and subsequently removed on April 30 (84 d of grazing). On 24 February 2009, pastures in Blocks 2 (4 pasture, 24 steers) and 3 (8 pastures, 48 steers) and on 10 February 2010 the pastures in Block 4 (4 pastures, 24 steers) and 5 (12 pastures, 72 steers) were stocked with 6 steers (initial BW = 253 ± 8.0 kg) per pasture and were removed on May 19 and May 5, respectively (84 d of grazing). In the spring of 2009 (Block 1), Accepted Manuscript Downloaded from https://academic.oup.com/tas/advance-article-abstract/doi/10.1093/tas/txz031/5429549 by Ed 'DeepDyve' Gillespie user on 09 April 2019 twice as many steers were stocked on the pastures as on Blocks 2 ,3, 4, and 5 because of an abundant herbage supply on the 4 pastures compared to the remainder. As in Exp. 1, half the pastures were selected randomly, and cattle in selected pastures were offered the free-choice mineral in the ground-type mineral feeders described in Exp. 1; mineral feeders were weighed weekly and adjusted for changes in DM as described in Exp. 1 to determine mineral intake. Also, cattle grazing the non-supplemented pastures received no salt or supplement of any kind. On d 0, 42, and 84, cattle were weighed following a 16-h withdrawal from feed and water to control for variation in gastrointestinal fill (Aiken and Tabler, 2004). A sample of standing herbage mass were collected 3 wk after weigh-d 0 and 42 at 10 paced transects in each pasture by clipping forage to the ground on 2 sides of a 61-cm rod placed between drill rows (19.1-cm row spacing). Herbage samples were placed in paper sacks, dried in a forced-air oven at 56 C to determine DM content then saved for nutrient analysis. Forage Analysis. After drying, herbage samples from Exp. 1 and 2 were weighed and ground in a Wiley mill to pass a 1-mm screen before analysis for total N by combustion (Vario MAX CN; Elementar Ammericas, Inc., Mt. Laurel, NJ). The forage crude protein (CP) was calculated by multiplying N concentration by 6.25, and ash (AOAC, 2000), neutral and acid detergent fiber (NDF and ADF, respectively) were determined (Van Soest et al., 1991) in an Ankom 2000 Fiber Analyzer (Ankom Technology, Macedon, NY), and in vitro OM disappearance (IVOMD) was also determined (White et al., 1981). Aliquots of herbage tissues were prepared for analysis of K, Ca, P, Mg, Zn, Mn, Cu, and Fe by refluxing with nitric acid over a 3-day period at the United States Department of Agriculture, Agricultural Research Service, Grand Forks Human Nutrition Research Center, Grand Forks, ND. Digests were reconstituted with 2% nitric acid and analyzed using inductively coupled, argon plasma emission Accepted Manuscript Downloaded from https://academic.oup.com/tas/advance-article-abstract/doi/10.1093/tas/txz031/5429549 by Ed 'DeepDyve' Gillespie user on 09 April 2019 spectrometry (3100XL; Perkin Elmer Corp., Wellsley, MA) equipped with automated sample injection. Statistical Analyses. In Exp. 1 and 2, BW, ADG, and BW gain/ha were analyzed using the mixed procedure in SAS (SAS Inst., Inc.; Cary, NC). The model included treatment and gender (Exp. 1 only) as fixed effects and pasture, block, and their interactions as random effects (Lentner and Bishop, 1986). Models for BW on d 28, 42, 56, or 84 included initial BW (d 0) as a covariate (P < 0.05). Herbage mass, forage CP and IVOMD, mineral intake (as-fed), minerals/kg of added BW gain, and macro- and micro-elements in herbage were analyzed using the mixed procedure in SAS with treatment as a fixed effect and block as the random effect. Least-squares means were separated using least significant difference procedure in SAS (Lentner and Bishop, 1986). Differences between least-squares means were deemed significant at P ≤ 0.05 and tendencies are mentioned when P ≤ 0.10. Results and Discussion Animal Performance In Exp. 1, initial BW (d 0) did not differ (P = 0.99) between treatments; however, after 28 d of grazing, mineral-supplemented cattle weighed 9 kg more (P ≤ 0.01) than cattle not offered the mineral supplement (Table 1). On d 56 and 84, mineral-supplemented cattle weighed 15 kg more (P ≤ 0.04) than non-supplemented cattle. Average daily gain during the first 28-d periods was 77% greater (P < 0.01) for mineral-supplemented cattle than for the non-supplemented group (Table 1). But during the second and third 28-d periods, ADG did not differ (P ≥ 0.18) between treatments. Even with these lack of treatment differences in the second and third weighing periods, the overall ADG (84 d) was still 43% greater (P = 0.02) for the mineral-supplemented cattle than for the non-supplemented cattle. Body weight gain per hectare tended to increase (P = Accepted Manuscript Downloaded from https://academic.oup.com/tas/advance-article-abstract/doi/10.1093/tas/txz031/5429549 by Ed 'DeepDyve' Gillespie user on 09 April 2019 0.12) 18 kg with mineral supplementation compared with the non-supplemented cattle. Last, standing herbage mass did not differ (P ≥ 0.47) between treatments and mineral intake averaged 135 g/d, which is slightly more than the manufacturer’s suggested intake range of 57 to 114 g/d as noted on the label. In Exp. 2, initial BW (d 0) did not differ (P = 0.91) between treatments (Table 2) and after 42 d of grazing, the mineral-supplemented cattle BW still did not differ (P = 0.39) from the non- supplementation cattle. But, the advantage resulting from mineral-supplementation was 15 kg of BW more (P = 0.01) over the non-supplemented cattle on d 84. Average daily gain during the first 42-d period did not differ (P = 0.48) between treatments, but during the second 42-d period and the entire 84 d, ADG was 25 and 21% greater (P ≤ 0.04), respectively, for mineral- supplemented than non-supplemented cattle (Table 2). Body weight gain per hectare tended to differ (P = 0.08) between treatments (difference 22 kg/ha). Standing herbage mass did not differ (P ≥ 0.73) between treatments, and mineral intake averaged 124 g/d over the 84-d period, which is also slightly more than the manufacturer’s suggested intake range, a trend similar to the one reported for Exp. 1. As a percentage of non-supplemented ADG, the 43 and 21% increase noted in the overall ADG in Exp. 1 and 2, respectively, are greater than or similar to the increases of 11 and 21% increases reported by Horn et al. (2002) and Fieser et al. (2007), respectively, for the free-choice mineral supplementation with cattle grazing winter-wheat pasture reported in central Oklahoma (185 km to the southeast of the SPER). Final BW were 5.5 and 4.6% greater for the mineral- supplemented cattle than non-supplemented cattle in Exp. 1 and 2, respectively, and are comparable to the differences reported by Horn et al. (2002) (4.2% increase) and Fieser et al. (2007) (4.8% increase). Accepted Manuscript Downloaded from https://academic.oup.com/tas/advance-article-abstract/doi/10.1093/tas/txz031/5429549 by Ed 'DeepDyve' Gillespie user on 09 April 2019 Daily mineral intake (Table 1 and 2) was within or slightly higher than the manufacture’s recommended range in both Exp. 1 and 2, and similar to intake rates reported by Horn et al. (2002) and Fieser et al. (2007) for free-choice mineral supplements not containing an ionophore. Further, the mineral intakes noted during fall grazing were less than the amounts reported in the spring (Table 1 and 2). Fieser et al. (2007) reported that mineral intake was greater in the spring than during the winter with stocker steers grazing wheat pasture. Further, Patterson et al. (2013) and Manzano et al. (2012) reported that with cattle grazing perennial cool-season pasture, they consumed more mineral during periods of greater herbage allowance like in the spring. These mineral intake rates and added ADG by the cattle resulted in a ratio of mineral cost to kilogram of added BW of $0.53 and $0.64 for Exp. 1 and 2, respectively (Tables 1 and 2). In contrast, Horn et al. (2002) reported a mineral cost per kilogram of added BW of $1.01. Forage characteristics In Exp. 1, forage CP and IVOMD concentration in the organic matter (OM) did not differ (P ≥ 0.19) between mineral supplementation treatments but decreased from an average of 23.8 to 18.8% and 71.8 to 68.1%, respectively, over the 84-d grazing period (Table 3). Neutral and acid detergent fibers concentrations in the OM did not differ (P ≥ 0.19) between mineral supplementation treatments but did increase over the 84-d grazing period, which corresponds to the decreases noted in IVOMD. In Exp. 2, forage CP concentrations during the first 42-d grazing period was slightly greater (P = 0.05) for pastures grazed by cattle receiving no supplemental mineral than for pastures where cattle received supplemental mineral; however, during the second 42-d grazing period, forage CP concentration did not differ (P = 0.73) between treatments (Table 4). In vitro OM digestion of the OM did not differ (P ≥ 0.37) between mineral supplementation treatments but Accepted Manuscript Downloaded from https://academic.oup.com/tas/advance-article-abstract/doi/10.1093/tas/txz031/5429549 by Ed 'DeepDyve' Gillespie user on 09 April 2019 did decrease over the 84-d grazing period like the trend noted in Exp. 1. Neutral and acid detergent fibers concentrations in the OM did not differ (P ≥ 0.46) between mineral supplementation treatments but did tend to increase over the 84-d grazing period like in Exp. 1. Forage CP concentrations exceeded suggested NASEM (2016) requirements for the growth rate observed in our 2 experiments, suggesting that energy intake was more likely limiting growth rate then protein intake. In addition, IVOMD concentrations did not differ greatly among grazing periods in either experiment. The CP and IVOMD concentrations recorded in our experiment are comparable to concentrations reported for wheat herbage samples at similar times of the year collected in El Reno, OK and Bushland, TX (Stewart et al., 1981), and in Marshall, OK (Fieser et al., 2007). Also, the IVOMD values in our 2 experiments are comparable to digestibilities reports in wheat herbage samples collected at similar maturities in other locations (Dove and McMullen, 2009; McGrath et al., 2015). The ratio of IVOMD:CP in samples from Exp. 1 and 2 ranged from 3.4 to 4.5. A ratio of IVOMD:CP between 4.0 and 4.5 has been suggested to indicate a balance of ruminal available N to ruminal available energy in the diets of cattle (Hogan and Weston, 1970; Gunter et al., 1995). However, with forages in which dietary N is not limiting (ratio < 4.5), a high-starch or digestible fiber supplement would be more beneficial (Nocek and Russell, 1988; Hoover and Stokes, 1991). The ratio of IVOMD:CP was 4.5 or less for all sampling dates in the present study. Hence, a small quantity of a high-energy supplement like corn or soybean hulls would have been the best choice if a greater ADG was desired (Grigsby et al., 1991; Horn et al., 1995; Beck et al., 2008). Forage mineral profiles In Exp. 1, the macro-minerals (Ca, P, Mg, S, and Na) did not differ (P ≥ 0.15) between treatments and no general trend in concentration change was noted as the grazing season Accepted Manuscript Downloaded from https://academic.oup.com/tas/advance-article-abstract/doi/10.1093/tas/txz031/5429549 by Ed 'DeepDyve' Gillespie user on 09 April 2019 advanced (Table 5). Potassium concentration did not differ (P ≥ 0.15) between treatments in the first and second 28-d period, but the K concentration did tend to be greater (P = 0.06) in the non- supplemented pastures compared to the mineral supplemented pastures during the third 28-d period. Further, the K concentration did not differ (P = 0.45) between treatments over the entire 84-d grazing period. The micro-minerals (Cu, Fe, Mn, Mo, Zn, and Se) did not differ (P ≥ 0.15) between non-supplemented pastures and mineral supplemented pastures. In Exp. 2, the macro-minerals (Ca, P, Mg, K, and Na) did not differ (P ≥ 0.11) between treatments and no general trend in concentration change was noted as the grazing season advanced (Table 6). Sulfur concentrations differed (P = 0.05) between the non-supplemented pastures compared to the mineral supplemented pastures during the first 42 d but the S concentration did not differ (P ≥ 0.29) between treatments in the second 42 d. However, S concentrations were greater (P = 0.05) in the non-supplemented pastures than the mineral supplemented pastures over the entire 84-d grazing period. Micro-minerals (Cu, Fe, Zn, and Se) did not differ (P ≥ 0.19) between treatments. Also, Mn concentrations did not differ (P = 0.36) between treatments the first 42-grazing period, but the Mn concentrations were greater (P = 0.02) in the mineral supplemented pasture than the non-supplemented pastures during the second 42 d resulting in Mn concentrations tending to differ (P = 0.08) between treatments over the entire 84- d grazing. Molybdenum concentrations tended to be greater (P = 0.10) in the non-supplemented pastures than the mineral supplemented pastures during the first 42 d but the Mo concentrations did not differ (P ≥ 0.50) between treatments in the second 42 d or over the entire 84-d grazing period. The Ca concentrations in the herbage samples collected during Exp. 1 (fall) and 2 (spring) were less than the NASEM (2016) has stated as necessary for optimal performance. Accepted Manuscript Downloaded from https://academic.oup.com/tas/advance-article-abstract/doi/10.1093/tas/txz031/5429549 by Ed 'DeepDyve' Gillespie user on 09 April 2019 Using the NASEM (2016) Nutrient Requirements of Beef Cattle model to estimate Ca requirements with data from Exp. 1 and 2, it is estimated that the non-supplemented cattle would have needed to consume 3.7 and 4.8 kg/d of herbage DM to produce the 0.51 and 0.83 kg/d of BW gain noted for these experiments, respectively. With the average Ca concentration of 0.27 and 0.35% of DM, these cattle would have consumed 10.0 or 16.8 g/d of Ca with a requirement of 23.6 and 33.6 g/d, respectively (NASEM, 2016). In either experiment for the non- supplemented cattle to meet their Ca requirements with the herbage DM, the herbage Ca concentration would have needed to be more than 0.64% of DM. These negative Ca balances (- 13.6 or -16.3 g/d for Exp. 1 and 2, respectively) have been reported by other researchers for both cattle (Stewart et al., 1981; Fieser et al., 2007) and sheep (Dove and McMullen, 2009; McGrath et al., 2015) with growing animals grazing wheat pasture. The Ca requirements for growing cattle is normally determined by summing the Ca needed for maintenance (15.4 mg Ca/kg BW) which is equal to endogenous fecal loss (Hansard et al., 1954) and growth (7.1 g/kg of protein gain) (Ellenberger et al., 1950; Watson et al., 2018), then correcting for the percentage of digestible Ca (Hansard et al., 1957). In older cattle consuming Ca deficient diets, large stores of Ca are available to them from the skeletal stores to maintain homeostatic level of 9 to 11 mg Ca/dL in blood plasma through hormonal control (Tanaka et al., 1972). But in younger cattle, resorption of stores is more limited and homeostatic control is more challenging during times of insufficient Ca intake. The ability of cattle to resorb Ca is age dependent where younger cattle are more prone to accrete than resorb, where more mature cattle are nearly balanced in their ability to conduct either metabolic activity (NRC, 1988). With the cattle consuming 134 or 124 g of the mineral supplement a day (Exp. 1 and 2, respectively), the mineral provided a 23.6 or 20.1 g/d of supplemental Ca making the Ca intake nearly balanced (2.5 and -0.35 g/d) between the Accepted Manuscript Downloaded from https://academic.oup.com/tas/advance-article-abstract/doi/10.1093/tas/txz031/5429549 by Ed 'DeepDyve' Gillespie user on 09 April 2019 supplied and required (NASEM, 2016). These Ca balance estimates assume that the cattle need to consume 14 and 10% more herbage DM in Exp. 1 and 2, respectively, to meet their additional ME requirement (NASEM, 2016) to gain 0.22 and 0.20 kg more BW daily than the non- supplemented cattle (Table 1). The P concentration in the herbage during Exp. 1 (fall) and 2 (spring) were less that the NASEM (2016) has stated as necessary for optional performance. As with the Ca concentrations, average P concentrations of 0.21 and 0.20% of DM (Exp. 1 and 2, respectively), these cattle would have consumed 7.8 or 10.1 g/d of P with a requirement of 11.6 and 18.7 g/d, respectively (NASEM, 2016) at the respective performance levels. The reason the P requirements differ between treatments is that the P requirements for growing cattle are determined by summing the P needed for maintenance (16 mg P/kg BW) which is equal to endogenous fecal loss (Tillman and Brethour, 1958; Tillman et al., 1959; Challa et al., 1989) and growth (3.9 g/kg of protein gain) (Ellenberger et al., 1950; Watson et al., 2018), then correcting for the P digestibility of the diet (Tillman et al., 1959). So, cattle that have greater levels of performance have an increased P requirement. With the cattle in our research consuming 134 or 124 g of the mineral supplement a day (Exp. 1 and 2, respectively), the mineral provided a 6.5 or 6.0 g/d of supplemental P making the P intake nearly balanced (-2.66 and -0.71 g/d) between the supplied and required P (NASEM, 2016). It seems with a mineral mixture with these lower levels of P, it might be slightly deficient. However, considering the short grazing period that cattle normally spend on wheat pasture and their ability to resorb P from skeletal stores, this P intake is probability adequate. Furthermore, cattle exiting wheat pasture grazing systems are normally placed in the feedlot and fed high- concentrate diets which have been shown to be adequate in P and require no supplemental P (Geisert et al., 2010). Accepted Manuscript Downloaded from https://academic.oup.com/tas/advance-article-abstract/doi/10.1093/tas/txz031/5429549 by Ed 'DeepDyve' Gillespie user on 09 April 2019 The Mg concentration in the herbage during Exp. 1 (0.14% of DM) and 2 (0.14% of DM) were sufficient compared to what NASEM (2016) has stated (0.10% of DM) as necessary for optimal performance. Also, the K concentrations of the herbage during Exp. 1 (1.7% of DM) and 2 (1.8% of DM) were excessive compared to what NASEM (2016) has stated (0.60% of DM) as necessary for optimal performance. In experiments conducted with sheep and cattle consuming either medium concentrate diets (52 to 54%) and varying concentrations of K, Mg absorption was decreased when the K concentrations exceeded dietary requirement because of greater amounts being excreted in feces (Greene et al., 1983a, b; Khorasani and Armstrong, 1990) and resulting in a decrease in the serum Mg concentrations. When the dietary level of Mg in the diet is marginal and K is high, this may result in dangerously low plasma Mg concentrations. Rook and Storry (1962) has indicated that animals with plasma Mg less than 1.0 mg/dL are hypomagnesemic and when they are less than 1.0 mg/dL they are tetany prone (Bohman et al., 1983b; Davenport et al., 1990). Hence, a modest amount of Mg supplementation for cattle grazing pastures with minimal Mg concentration in the herbage and high concentrations of K seems prudent. Average concentrations of S, Fe, Mn, and Se between treatments (Exp. 1, 0.21%, 1118 mg/kg, 185 mg/kg, 0.38 mg/kg; Exp. 2, 0.22%, 599 mg/kg, 115 mg/kg, 0.14 mg/kg, respectively) in the herbage DM were adequate compared to the requirements (0.15% S, 50 mg Fe/kg, 20 mg Mn/kg, and 0.10 mg Se/kg) recommended by the NASEM (2016). In additional research in the region, these 4 minerals were also adequate in herbage samples collected in central Oklahoma (Fieser et al., 2007) and on the Coastal Plains of Arkansas (Gunter et al., 2001). Hence, additional supplementation of these minerals is of lesser priority. Accepted Manuscript Downloaded from https://academic.oup.com/tas/advance-article-abstract/doi/10.1093/tas/txz031/5429549 by Ed 'DeepDyve' Gillespie user on 09 April 2019 The Na requirement in the dietary DM of cattle is 600 to 800 mg/kg (Morris and Gartner, 1971; Morris and Murphy, 1972; NASEM, 2016) and the concentration in the herbage samples was 21.5 mg/kg and 68.7 mg/kg in Exp. 1 and 2, respectively. Sodium deficiency is often a problem in non-supplemented cattle grazing grasslands (Henry, 1995). Because the wheat herbage is supplying less than 10% of the requirement, supplementation is justified. There is some evidence that low Na diets result in a small decrease in Ca absorption in the small intestine (Khorasani and Armstrong, 1990). The decrease in Ca absorption in the afore mentioned research was small and probably biologically insignificant when Ca intake is sufficient, but when Ca intake is low, as with wheat pasture, this reduction could be impactful. Sodium chloride supplementation of grazing cattle on low sodium native rangeland has increased BW gain (Murphy and Plasto, 1972, 1973). The Cu requirements in the dietary DM of cattle is near 10 mg/kg (ARC, 1980; NASEM, 2016; Boudon et al., 2018b) and the concentration in the herbage samples was 4.1 mg/kg and 4.5 mg/kg in Exp. 1 and 2, respectively. Copper deficiency is often a problem in non-supplemented cattle grazing winter-annual pasture (Gunter et al., 2001; Fieser et al., 2007). Further, Mo and S are antagonist (Mo greater than 2 mg/kg DM and S greater than 0.25% of DM) to Cu absorption and decrease the rate of growth in beef cattle (Kegley and Spears, 1994; Ward et al., 1996). Unlike in the research reported by Gunter et al. (2001), in our research Mo and S concentrations were minimal and should not serve as antagonist. Because the wheat herbage is supplied 40 to 80% of the requirement and had minimal interference by antagonists, supplementation with a digestible form of inorganic Cu sources seem justified and would be sufficient. It is commonly believed that the requirement for zinc in the diets of growing beef cattle is 30 mg/kg DM with few factors inhibiting absorption (ARC, 1980; NASEM, 2016), but Boudon Accepted Manuscript Downloaded from https://academic.oup.com/tas/advance-article-abstract/doi/10.1093/tas/txz031/5429549 by Ed 'DeepDyve' Gillespie user on 09 April 2019 et al. (2018b) suggest it may be as high as 50 mg/kg of dietary DM. The concentrations in the herbage samples were 15.1 mg/kg and 17.3 mg/kg in Exp. 1 and 2, respectively. The Zn concentration in Exp. 1 and 2 were inadequate for growing livestock and lower Zn concentrations in cool-season annual herbage occurs often (Corah and Dargatz, 1996; Gunter et al., 2001; Fieser et al., 2007), but there are some exceptions (Hardt et al., 1991). We only know of a single experiment examining the growth response of beef cattle grazing winter-annual pasture and a Zn proteinate increased BW gain by 3.5% compared to a Zn sulfate supplemented group over the first 84-d of the grazing period (Gunter et al., 2001). Even though there are few studies showing increased ADG by cattle grazing wheat pasture when Zn is supplemented, this supplementation would be a recommended practice because this element is intimately involved in animal health (Greene, 2000; Boudon et al., 2018a). Growing cattle grazing wheat pastures will ultimately be transported to a feedlot for finishing where environmental stress is increased, and animal health becomes a significant economic and animal welfare risk. Implications Overall, in our 2 experiments, supplementing a free-choice mineral mixture high in Ca and low in P to cattle grazing wheat pasture in northwest Oklahoma increased ADG. Furthermore, our results suggest that free-choice mineral supplementation is likely to yield a positive return on investment. Mineral analysis of the pasture herbage shows multiple mineral deficiencies and justifies the mineral supplementation both from economic and animal welfare viewpoints. Contrary to other reports for ruminants grazing winter-annual type pastures in other locations, wheat pasture herbage in northwest Oklahoma was deficient in P as well as Ca. Hence, both macro-elements need to be supplied on a supplemental mineral mixture. 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K., K. E. Hales, M. J. Hersom, G. W. Horn, J. J. Wagner, C. R. Krehbiel, M. P. McCurdy, and G. E. Erickson. 2018. Mineral retention of growing and finishing beef cattle across different production systems. Prof. Anim. Sci. 34:250-260. doi: 10.15232/pas.2017-01672 White, L. M., G. P. Hartman, and J. W. Bergman. 1981. In vitro digestibility, crude protein, and phosphorus content of straw of winter wheat, spring wheat, barley, and oat cultivars in eastern montana1. Agron. J. 73:117-121. doi: 10.2134/agronj1981.00021962007300010026x Accepted Manuscript Downloaded from https://academic.oup.com/tas/advance-article-abstract/doi/10.1093/tas/txz031/5429549 by Ed 'DeepDyve' Gillespie user on 09 April 2019 Accepted Manuscript Downloaded from https://academic.oup.com/tas/advance-article-abstract/doi/10.1093/tas/txz031/5429549 by Ed 'DeepDyve' Gillespie user on 09 April 2019 Table 1. Performance of stocker cattle grazing wheat pasture supplemented with free- choice minerals on the Southern Plains Experimental Range near Ft. Supply, OK (Exp. 1) Mineral supplemented Item/period No Yes SE P-value Body weight (BW), kg d 0 205 205 15.8 0.99 d 28 244 253 2.1 < 0.01 d 56 256 271 4.0 < 0.01 d 84 271 286 6.3 0.04 Average daily gain, kg First 28 d 0.49 0.80 0.074 < 0.01 Second 28 d 0.47 0.71 0.131 0.18 Third 28 d 0.50 0.60 0.120 0.52 Overall, 84 d 0.51 0.73 0.068 0.02 BW gain/ha, kg 59 82 6.1 0.08 Herbage mass, kg of dry matter/animal First 28 d 1,393 1,498 225.8 0.74 Second 28 d 1,118 1,219 313.6 0.66 Third 28 d 843 1,011 401.9 0.47 Overall, 84 d 1,082 1,214 210.6 0.49 Mineral intake, g/d as-fed First 28 d -- 91 5.6 -- Second 28 d -- 89 8.3 -- Third 28 d -- 225 22.0 -- Overall, 84 d -- 135 9.1 -- Minerals/kg of added BW gain , $ 0.54 0.11 -- Free-choice mineral (Wheat Pasture Pro Mineral; Land O Lakes Purina Feed, LLC, Saint Paul, MN) supplied in ground-style mineral feeders (Sioux Steel Company; Sioux City, SD). Least squares means were adjusted for BW on d 0 as a covariate (P < 0.05). Purchase price of mineral, $0.875/kg. Accepted Manuscript Downloaded from https://academic.oup.com/tas/advance-article-abstract/doi/10.1093/tas/txz031/5429549 by Ed 'DeepDyve' Gillespie user on 09 April 2019 Table 2. Performance of stocker cattle grazing wheat pasture supplemented with free-choice minerals on the Southern Plains Experimental Range near Ft. Supply, OK (Exp. 2) Mineral supplement Item/period No Yes SE P-value Body weight (BW), kg d 0 245 246 6.9 0.91 d 42 257 261 3.2 0.39 d 84 308 323 4.0 0.01 Average daily gain, kg First 42 d 0.37 0.44 0.074 0.48 Second 42 d 1.16 1.45 0.092 0.04 Overall, 84 d 0.81 0.98 0.048 0.01 BW gain/ha, kg 95 117 13.7 0.08 Herbage mass, kg of dry matter/animal First 42 d 1,603 1,694 576.6 0.73 Second 42 d 1,719 1,841 573.8 0.86 Overall, 84 d 1,624 1,603 230.0 0.95 Mineral intake, g/d as-fed First 42 d -- 103 3.7 -- Second 42 d -- 144 9.0 -- Overall, 84 d -- 124 5.8 -- Minerals/kg of added BW gain $0.64 0.088 -- Free-choice mineral (Wheat Pasture Pro Mineral; Land O Lakes Purina Feed, LLC; Saint Paul, MN) supplied in ground style mineral feeders (Sioux Steel Company; Sioux City, SD). Least squares means were adjusted for calf BW on d 0 as a covariate (P < 0.15). Purchase price of mineral, $0.875/kg. Accepted Manuscript Downloaded from https://academic.oup.com/tas/advance-article-abstract/doi/10.1093/tas/txz031/5429549 by Ed 'DeepDyve' Gillespie user on 09 April 2019 Table 3. Forage quality from wheat pasture grazed by stocker cattle supplemented with free-choice minerals on the Southern Plains Experimental Range near Ft. Supply, OK (Exp. 1) Mineral supplemented Item/period No Yes SE P-value Forage crude protein, % of OM First 28 d 23.2 23.6 1.43 0.65 Second 28 d 18.3 17.4 1.22 0.29 Third 28 d 20.6 18.9 1.69 0.19 Overall, 84 d 20.9 20.1 0.71 0.41 Forage IVOMD , % First 28 d 70.9 71.8 2.03 0.53 Second 28 d 64.9 67.4 1.77 0.35 Third 28 d 68.1 68.2 2.81 0.97 Overall, 84 d 69.3 68.1 1.45 0.59 Forage neutral detergent fiber, % of OM First 28 d 41.4 40.1 1.06 0.19 Second 28 d 41.8 41.1 1.51 0.45 Third 28 d 46.5 48.3 2.14 0.24 Overall, 84 d 43.3 43.2 0.51 0.94 Forage acid detergent fiber, % of OM First 28 d 23.5 24.7 2.55 0.22 Second 28 d 23.7 22.9 2.93 0.26 Third 28 d 26.8 27.9 3.75 0.48 Overall, 84 d 24.8 25.0 2.33 0.68 Free-choice mineral (Wheat Pasture Pro Mineral; Land O Lakes Purina Feed, LLC, Saint Paul, MN) supplied in ground-style mineral feeders (Sioux Steel Company; Sioux City, SD). In vitro OM disappearance. Accepted Manuscript Downloaded from https://academic.oup.com/tas/advance-article-abstract/doi/10.1093/tas/txz031/5429549 by Ed 'DeepDyve' Gillespie user on 09 April 2019 Table 4. Forage quality from wheat pasture grazed by stocker cattle supplemented with free-choice minerals on the Southern Plains Experimental Range near Ft. Supply, OK (Exp. 2) Mineral supplemented Item/period No Yes SE P-value Forage crude protein, % of OM First 42 d 20.5 18.6 1.20 0.05 Second 42 d 18.2 18.5 1.37 0.73 Overall, 84 d 19.4 18.6 1.20 0.34 Forage IVOMD , % First 42 d 71.7 73.1 2.66 0.53 Second 42 d 65.7 66.4 1.51 0.37 Overall, 84 d 68.7 69.8 0.80 0.35 Forage neutral detergent fiber, % of OM First 42 d 41.8 42.5 2.33 0.46 Second 42 d 48.2 48.1 2.83 0.90 Overall, 84 d 45.0 45.3 2.27 0.68 Forage acid detergent fiber, % of OM First 42 d 21.7 21.7 0.89 0.92 Second 42 d 28.4 28.1 0.66 0.51 Overall, 84 d 25.1 24.9 0.58 0.71 Free-choice mineral (Wheat Pasture Pro Mineral; Land O Lakes Purina Feed, LLC, Saint Paul, MN) supplied in ground-style mineral feeders (Sioux Steel Company; Sioux City, SD). In vitro OM disappearance. Accepted Manuscript Downloaded from https://academic.oup.com/tas/advance-article-abstract/doi/10.1093/tas/txz031/5429549 by Ed 'DeepDyve' Gillespie user on 09 April 2019 Table 5. Minerals in herbage from wheat pasture grazed by stocker cattle supplemented with free-choice minerals on the Southern Plains Experimental Range near Ft. Supply, OK (Exp. 1) Mineral supplemented Item/period No Yes SE P-value Ca, % of DM First 28 d 0.26 0.30 0.030 0.53 Second 28 d 0.25 0.29 0.018 0.22 Third 28 d 0.26 0.26 0.025 0.99 Overall, 84 d 0.26 0.28 0.012 0.28 P, % of DM First 28 d 0.23 0.25 0.053 0.82 Second 28 d 0.18 0.18 0.029 0.88 Third 28 d 0.18 0.19 0.016 0.78 Overall, 84 d 0.20 0.21 0.032 0.83 Mg, %of DM First 28 d 0.12 0.16 0.019 0.29 Second 28 d 0.12 0.16 0.021 0.35 Third 28 d 0.13 0.13 0.007 0.55 Overall, 84 d 0.12 0.15 0.015 0.33 K, % of DM First 28 d 2.1 2.3 0.060 0.15 Second 28 d 1.5 1.5 0.019 0.82 Third 28 d 1.5 1.4 0.016 0.06 Overall, 84 d 1.7 1.7 0.027 0.45 S, % of DM First 28 d 0.22 0.22 0.007 0.46 Second 28 d 0.19 0.19 0.005 0.55 Third 28 d 0.21 0.20 0.006 0.36 Overall, 84 d 0.21 0.20 0.002 0.70 Na, mg/kg of DM First 28 d 11.0 28.7 8.06 0.26 Second 28 d 28.0 15.8 4.28 0.18 Third 28 d 20.0 24.9 5.22 0.57 Overall, 84 d 19.7 23.1 3.87 0.59 Cu, mg/kg of DM First 28 d 3.6 4.3 0.56 0.45 Second 28 d 3.1 4.6 0.70 0.29 Third 28 d 3.5 4.6 0.50 0.27 Overall, 84 d 3.4 4.5 0.56 0.30 Fe, mg/kg of DM First 28 d 778 1,132 172.4 0.28 Second 28 d 1,270 1,411 463.8 0.85 Third 28 d 1,020 1,095 300.9 0.88 Overall, 84 d 1,023 1,212 304.8 0.70 Mn, mg/kg of DM First 28 d 197 195 62.9 0.98 Second 28 d 168 190 38.4 0.73 Third 28 d 163 165 34.3 0.57 Overall, 84 d 176 193 45.1 0.81 Accepted Manuscript Downloaded from https://academic.oup.com/tas/advance-article-abstract/doi/10.1093/tas/txz031/5429549 by Ed 'DeepDyve' Gillespie user on 09 April 2019 Mo, mg/kg of DM First 28 d 0.16 0.19 0.062 0.75 Second 28 d 0.20 0.21 0.056 0.91 Third 28 d 0.18 0.14 0.045 0.68 Overall, 84 d 0.18 0.18 0.043 0.95 Zn, mg/kg of DM First 28 d 14.6 15.6 1.12 0.58 Second 28 d 14.6 14.8 0.96 0.88 Third 28 d 15.8 15.2 0.46 0.43 Overall, 84 d 15.0 15.1 0.83 0.87 Se, ng/kg of DM First 28 d 39.8 39.8 14.00 0.99 Second 28 d 36.5 38.5 5.06 0.81 Third 28 d 34.3 37.8 6.21 0.73 Overall, 84 d 36.8 38.7 8.05 0.89 Free-choice mineral (Wheat Pasture Pro Mineral; Land O Lakes Purina Feed, LLC, Saint Paul, MN) supplied in ground-style mineral feeders (Sioux Steel Company; Sioux City, SD). In vitro OM disappearance. Accepted Manuscript Downloaded from https://academic.oup.com/tas/advance-article-abstract/doi/10.1093/tas/txz031/5429549 by Ed 'DeepDyve' Gillespie user on 09 April 2019 Table 6. Minerals in herbage from wheat pasture grazed by stocker cattle supplemented with free-choice minerals on the Southern Plains Experimental Range near Ft. Supply, OK (Exp. 2) Mineral supplemented Item/period No Yes SE P-value Ca, % of DM First 42 d 0.35 0.33 0.039 0.20 Second 42 d 0.34 0.36 0.080 0.57 Overall, 84 d 0.35 0.35 0.058 0.64 P, % of DM First 42 d 0.17 0.16 0.012 0.51 Second 42 d 0.24 0.24 0.011 0.77 Overall, 84 d 0.20 0.20 0.008 0.86 Mg, %of DM First 42 d 0.14 0.14 0.006 0.88 Second 42 d 0.14 0.14 0.015 0.44 Overall, 84 d 0.14 0.14 0.010 0.62 K, % of DM First 42 d 1.7 1.6 0.06 0.11 Second 42 d 2.2 1.9 0.21 0.36 Overall, 84 d 1.9 1.7 0.12 0.23 S, % of DM First 42 d 0.23 0.21 0.011 0.05 Second 42 d 0.23 0.22 0.021 0.29 Overall, 84 d 0.23 0.21 0.016 0.06 Na, mg/kg of DM First 42 d 44.2 111.4 69.89 0.31 Second 42 d 41.0 77.2 49.80 0.29 Overall, 84 d 42.8 94.5 59.50 0.29 Cu, mg/kg of DM First 42 d 4.3 4.0 0.40 0.19 Second 42 d 4.8 4.8 0.41 0.99 Overall, 84 d 4.5 4.4 0.40 0.36 Fe, mg/kg of DM First 42 d 640 594 176.0 0.51 Second 42 d 542 615 253.1 0.55 Overall, 84 d 592 606 193.2 0.83 Mn, mg/kg of DM First 42 d 127 137 19.0 0.36 Second 42 d 87 106 10.0 0.02 Overall, 84 d 107 122 13.4 0.08 Mo, mg/kg of DM First 42 d 0.75 0.68 0.537 0.10 Second 42 d 0.79 0.84 0.634 0.50 Overall, 84 d 0.77 0.76 0.585 0.78 Zn, mg/kg of DM First 42 d 15.9 15.0 2.18 0.25 Second 42 d 19.5 18.9 3.52 0.52 Overall, 84 d 17.7 16.9 2.83 0.29 Accepted Manuscript Downloaded from https://academic.oup.com/tas/advance-article-abstract/doi/10.1093/tas/txz031/5429549 by Ed 'DeepDyve' Gillespie user on 09 April 2019 Se, ng/kg of DM First 42 d 141.0 100.3 70.46 0.21 Second 42 d 182.0 135.0 102.9 0.29 Overall, 84 d 161.5 117.6 86.6 0.25 Free-choice mineral (Wheat Pasture Pro Mineral; Land O Lakes Purina Feed, LLC, Saint Paul, MN) supplied in ground-style mineral feeders (Sioux Steel Company; Sioux City, SD). Accepted Manuscript
Journal
Translational Animal Science – Oxford University Press
Published: Apr 6, 2019