title: Supplemental carbohydrate sources for lactating dairy cows on pasture.
abstract: Two experiments were conducted to evaluate steam-flaked corn and nonforage fiber sources as supplemental carbohydrates for lactating dairy cows on pasture. Cows were allotted to a new paddock of an orchardgrass (Dactylis glomerata L.) pasture twice daily in one group in both trials. In experiment 1, 28 Holstein cows, averaging 216 d in milk, were randomly assigned to either a cracked-corn (CC) or a steam-flaked (SFC) supplement in a split plot design. The supplement contained 66.7% of corn and a protein/mineral pellet. In experiment 2, 28 Holstein cows, averaging 182 d in milk, were randomly assigned to either a ground corn (GC) or a nonforage fiber (NFF)-based supplemented in a single reversal design. The GC supplement contained 85% ground corn plus protein, mineral, and vitamins. The NFF supplement contained 35% ground corn, 18% beet pulp, 18% soyhulls, 8% wheat middlings plus protein, mineral, and vitamins. In both experiments, cows were fed the grain supplement twice daily after each milking at 1 kg/4 kg milk. In experiment 1, milk production (24.3 kg/d) and composition did not differ between treatments; however, plasma and milk urea N were lower with the SFC supplement. In experiment 2, milk production (27.5 kg/d) was not affected by treatments, which may be related to the medium quality of pasture grazed. The GC supplement tended to reduce plasma and milk urea 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) or experiment 2 (12.2 kg/d). Milk production did not differ when mid-late lactation cows on pasture were supplemented with SFC or NFF instead of dry corn.
authors.affiliation: Department of Dairy and Animal Science, The Pennsylvania State University, University Park 16802, USA.
authors.forename: J E
authors.initials: JE
authors.lastname: Delahoy
authors.forename: L D
authors.initials: LD
authors.lastname: Muller
authors.forename: F
authors.initials: F
authors.lastname: Bargo
authors.forename: T W
authors.initials: TW
authors.lastname: Cassidy
authors.forename: L A
authors.initials: LA
authors.lastname: Holden
mesh_terms: D000824:Animal Nutritional Physiological Phenomena; D000818:Animals; D002417:Cattle / Q000502:physiology*; D004040:Dietary Carbohydrates / Q000008:administration & dosage*; D004043:Dietary Fiber / Q000008:administration & dosage; D004044:Dietary Proteins / Q000008:administration & dosage; D019587:Dietary Supplements; D004435:Eating; D005260:Female; D005511:Food Handling; D007774:Lactation; D008892:Milk / Q000737:chemistry; D008903:Minerals / Q000008:administration & dosage; D014508:Urea / Q000032:analysis / Q000097:blood; D014815:Vitamins / Q000008:administration & dosage; D003313:Zea mays
chemical_list: D004040:Dietary Carbohydrates; D004043:Dietary Fiber; D004044:Dietary Proteins; D008903:Minerals; D014815:Vitamins; D014508:Urea