title: Effect of source and amount of protein on milk production in dairy cows.
abstract: Forty multiparous Alpine does (mean BW of 61.5 kg) were utilized in a 13-wk trial to investigate the effects of a TMR differing in CP amount (13 or 17%) and source (solvent-extracted soybean meal or heat-treated soybean meal with or without urea) on lactational performance. Protein supplements contributed 30% of the N in 13% CP diets and 50% of the N in 17% CP diets. All diets were isoenergetic (2.5 Mcal of metabolizable energy/kg of DM) and were fed for ad libitum intake for the entire trial. Mean DMI (2.88 kg/d), milk production (2.65 kg/d), milk fat (4.05%), milk protein (2.68%), milk lactose (4.54%), and milk SNF (7.81%) did not differ among dietary treatments. Plasma urea N was greater (23.2 vs. 10.9 mg/dl) in does receiving the 17% CP diets; however, blood hematocrit (27.4%), beta-hydroxybutyrate (843 microM), plasma glucose (68.8 mg/dl), NEFA (600 mu eq/dl), and plasma total protein (74.% g/L) were not significantly affected by treatment. The apparent absence of a dietary effect on lactational performance may be due to the high DMI of the does (4.7% when expressed as DMI per kilogram of BW) and high CP intake providing a surfeit of protein relative to requirements.
authors.affiliation: E. (Kika) de la Garza Institute for Goat Research, Langston University, OK 73050.
authors.forename: T
authors.initials: T
authors.lastname: Sahlu
authors.forename: J M
authors.initials: JM
authors.lastname: Fernandez
authors.forename: Z H
authors.initials: ZH
authors.lastname: Jia
authors.forename: A O
authors.initials: AO
authors.lastname: Akinsoyinu
authors.forename: S P
authors.initials: SP
authors.lastname: Hart
authors.forename: T H
authors.initials: TH
authors.lastname: Teh
mesh_terms: D020155:3-Hydroxybutyric Acid; D000818:Animals; D001835:Body Weight; D004044:Dietary Proteins / Q000008:administration & dosage*; D004435:Eating; D002149:Energy Intake; D005232:Fatty Acids, Volatile / Q000378:metabolism; D005260:Female; D006041:Goats / Q000502:physiology*; D006400:Hematocrit; D006863:Hydrogen-Ion Concentration; D006885:Hydroxybutyrates / Q000097:blood; D007774:Lactation; D008892:Milk / Q000737:chemistry; D014674:Plant Proteins, Dietary; D012417:Rumen / Q000378:metabolism; D030262:Soybean Proteins; D014508:Urea / Q000097:blood
chemical_list: D004044:Dietary Proteins; D005232:Fatty Acids, Volatile; D006885:Hydroxybutyrates; D014674:Plant Proteins, Dietary; D030262:Soybean Proteins; D014508:Urea; D020155:3-Hydroxybutyric Acid