title: Response of lactating dairy cows to steam-flaked sorghum, steam-flaked corn, or steam-rolled corn and protein sources of differing degradability.
abstract: Protein sources with different degradabilities were fed to 48 lactating Holstein cows receiving 37 or 39% of dietary dry matter as steam-flaked sorghum (360 g/L), steam-flaked corn (360 g/L), or steam-rolled corn (490 g/L) in a 3 x 2 factorial arrangement of treatments. Cows were fed an alfalfa-based diet with 7% soybean meal or 5% of an animal-marine protein blend and 37 or 39% grain. Although not significant, cows fed flaked grain yielded a mean of 1.5 kg/d more milk than did those fed rolled grain. Gross feed efficiency was not affected by grain processing or protein source, but diets with the animal-marine protein blend had 9% higher estimated net energy for lactation than did diets with soybean meal. The greater gains in body weight and increased digestibility of the diets with the animal-marine protein blend verify the higher energy concentration of those diets. Yield of milk protein was increased by flaked grain or the animal-marine protein blend, and flaked grain increased percentages of lactose and solids nonfat. Increasing the ratio of rumen-degradable starch to rumen-degradable protein increased milk protein content and yield linearly and increased contents of lactose and solids nonfat. A linear response of dry matter, organic matter, crude protein, and starch digestibilities was observed as the ratio of rumen-degradable starch to rumen-degradable protein increased. These data show improved performance of dairy cows fed a high rumen-undegradable protein source with diets high in rumen-degradable starch from steam-processed grains.
authors.affiliation: Department of Animal Sciences, University of Arizona, Tucson 85721-0038, USA.
authors.forename: J E
authors.initials: JE
authors.lastname: Santos
authors.forename: J T
authors.initials: JT
authors.lastname: Huber
authors.forename: C B
authors.initials: CB
authors.lastname: Theurer
authors.forename: L G
authors.initials: LG
authors.lastname: Nussio
authors.forename: M
authors.initials: M
authors.lastname: Tarazon
authors.forename: F A
authors.initials: FA
authors.lastname: Santos
mesh_terms: D000821:Animal Feed; D000818:Animals; D001806:Blood Urea Nitrogen; D002417:Cattle / Q000502:physiology*; D004044:Dietary Proteins / Q000008:administration & dosage / Q000378:metabolism*; D004063:Digestion; D002523:Edible Grain; D005260:Female; D005511:Food Handling; D006358:Hot Temperature; D006868:Hydrolysis; D007774:Lactation; D000455:Medicago sativa; D010316:Particle Size; D012417:Rumen / Q000378:metabolism; D013025:Glycine max; D013213:Starch / Q000378:metabolism; D003313:Zea mays
chemical_list: D004044:Dietary Proteins; D013213:Starch