Supplemental carbohydrate sources for lactating dairy cows on pasture
2003
Delahoy, J.E. | Muller, L.D. | Bargo, F. | Cassidy, T.W. | Holden, L.A.
Two experiments were conducted to evaluate steamflaked corn and nonforage fibersources as supplemental carbohydrates for lactating dairy cows on pasture. Cows were allotted toa new paddock of an orchardgrass (Dactylis glomerata L.) pasture twice daily in one group inboth trials. In experiment 1, 28 Holstein cows, averaging 216 d in milk, were randomly assignedto either a cracked-corn (CC) or a steam-flaked (SFC) supplement in a split plot design. Thesupplement contained 66.7% of corn and a protein/mineral pellet. In experiment 2, 28 Holsteincows, averaging 182 d in milk, were randomly assigned to either a ground corn (GC) or anonforage fiber (NFF)-based supplemented in a single reversal design. The GC supplementcontained 85% ground corn plus protein, mineral, and vitamins. The NFF supplement contained35% ground corn, 18% beet pulp, 18% soyhulls, 8% wheat middlings plus protein, mineral, andvitamins. In both experiments, cows were fed the grain supplement twice daily after each milkingat 1kg/4 kg milk. In experiment 1, milk production (24.3 kg/d) and composition did not differbetween treatments; however, plasma and milk urea N were lower with the SFC supplement. Inexperiment 2, milk production (27.5 kg/d) was not affected by treatments, which may be relatedto the medium quality of pasture grazed. The GC supplement tended to reduce plasma and milkurea N and increased milk protein percentage (3.23 vs. 3.19%). Pasture dry matter intake,measured using Cr2O3, did not differ between treatments in either experiment 1 (15.1 kg/d) orexperiment 2 (12.2 kg/d). Milk production did not differ when mid-late lactation cows on pasturewere supplemented with SFC or NFF instead of dry corn.
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