Submitted to: American Society of Animal Science Annual Meeting
Publication Type: Abstract Only
Publication Acceptance Date: March 1, 2010
Publication Date: July 11, 2010
Citation: Gunter, S.A., Combs, G.F. 2010. Effect of mineral supplementation on the performance by stocker cattle grazing winter-wheat pasture [abstract]. Journal of Animal Science. 88(E-Suppl.2):194-195. Technical Abstract: To evaluate the efficacy of a complete mineral mixture on the performance of stocker cattle grazing wheat pasture, 2 experiments were conducted. In Exp 1, 72 steer and heifer calves (BW = 228±11.4 kg) were randomly assigned to 12, 4.9-ha pastures on November 12 at 1.2 animals/ha (4 pastures), and February 5 at 2.5 animals/ha (8 pastures) for 84-d grazing periods. In Exp 2, 38 steers (BW = 248±4.8 kg) were randomly assigned to 12, 2.5-ha wheat pastures on February 24 for 84 d at 1.3 steers/ha. The pastures in Exp 2 were planted with either conventional tillage or a no-till drill. In both experiments, animals on half the pastures received a free-choice mineral mixture (Wheat Pasture Pro; Land O Lakes Purina Feed, LLC; St. Paul, MN; Ca, 12% and P, 4%) provided in ground-type mineral feeders (Exp 1: completely random design; Exp 2: 2x2 factorial); feeders were weighed weekly to determine mineral intake. All pastures were drilled during the first 2 wk of September 2008 with 67 kg of seed/ha, and were fertilized with 50 kg of urea-N/ha. Standing herbage DM was determined in each pasture every weigh date by clipping wheat to the ground along 122 cm of drill row at 10 paced transects. Data were analyzed by AOV with treatment as the fixed effect and pasture as the random effect. In Exp 1, cattle offered the mineral mixture had a 45% faster ADG (P<0.01; 0.75 kg) than cattle not offered minerals (0.52 kg) over the 84-d; hence, the supplemented cattle weighed 8% more (P<0.01; 308 kg) after grazing than non-supplemented cattle (289 kg). In Exp 2, supplementation did not interact (P>0.44) with tillage for any dependent variable. Also, steers offered the mineral had a 30% faster ADG (P=0.03; 1.12 kg) than steers not offered minerals (0.86 kg) and the supplemented cattle weighed 6% more (P=0.03; 341 kg) after grazing than non-supplemented cattle (320 kg). In both experiments, daily standing herbage DM averaged 1,536 kg/animal and never differed (P>0.13) between treatments. Mineral intakes averaged 73 (Exp 1) and 168 (Exp 2) g/d, resulting in cost (US $) of supplement to kilogram of added BW gain conversions of 0.26 and 0.57 assuming a mineral cost of $0.88/kg. Overall, there was an improvement in animal growth rate and the supplement to added BW gain conversion rates seemed profitable.