Article ID | Journal | Published Year | Pages | File Type |
---|---|---|---|---|
2453868 | The Professional Animal Scientist | 2014 | 7 Pages |
Abstract
Management strategies that maintain livestock performance while reducing intake in times of low forage availability, such as drought, are valuable. The hypotheses of this experiment were that a grain-based supplement would decrease forage intake and digestibility, whereas a grain-based supplement plus monensin would decrease forage intake and increase forage digestibility. Crossbred cows (n = 36) grazing native range pasture during the late summer were used in a randomized complete block design for 2 yr (average forage quality for yr 1 = 8.7% CP, 77% NDF, 47% ADF; for yr 2 = 8.0% CP, 76% NDF, 45% ADF). Treatments were control (no supplement; NS), cracked corn (S; 0.91 kg/cow per day, as-fed basis), and S with monensin added at 385 mg/kg of corn (SM). Diet samples were collected from 6 ruminally cannulated cows to calculate digestibility. Cows were dosed with Cr2O3 boluses to determine fecal output, OM intake, and digestible OM intake during 2 sampling periods each year. Forage intake and digestible OM intake as percentages of BW were greater (P < 0.01) for SM than other treatments in yr 1 (1.61, 1.37, and 1.24% for forage intake as a percent of BW and 0.93, 0.69, and 0.59% for digestible OM intake as a percent of BW for the SM, NS, and S treatments, respectively), with no differences (P > 0.05) in yr 2. Starch-based supplement alone reduced OM and NDF digestibility in period 1 of both years compared with NS or SM treatments (P < 0.001). In period 2 of both years, OM digestibility was greatest for the SM treatment (P < 0.001). In period 2 of yr 1, NDF digestibility was greatest in SM (P < 0.001), but similar between SM and NS in yr 2. Under our experimental conditions, monensin fed with a starch-based energy supplement did not decrease forage intake during drought; however, moderate forage quality and type and amount of supplement provided may have affected responses.
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Authors
J.J. Kincheloe, L.G. Wood, D.R. Zobell, K.C. PAS,