title: Availability to lactating dairy cows of methionine added to soy lecithins and mixed with a mechanically extracted soybean meal.
abstract: We evaluated a product containing methionine mixed with soy lecithins and added to a mechanically extracted soybean meal (meSBM-Met). Lactational responses of cows, plasma methionine concentrations, and in vitro degradation of methionine were measured. Twenty-five Holstein cows were used in a replicated 5 × 5 Latin square design and fed a diet designed to be deficient in methionine or the same diet supplemented either with 4.2 or 8.3g/d of supplemental methionine from a ruminally protected source or with 2.7 or 5.3g/d of supplemental methionine from meSBM-Met. All diets were formulated to provide adequate amounts of metabolizable lysine. Concentration of milk true protein was greater when methionine was provided by the ruminally protected methionine than by meSBM-Met, but milk protein yield was not affected by treatment. Milk yields and concentrations and yields of fat, lactose, solids-not-fat, and milk urea nitrogen were not affected by supplemental methionine. Body condition scores increased linearly when methionine from meSBM-Met was supplemented, but responses were quadratic when methionine was provided from a ruminally protected source. Nitrogen retention was not affected by supplemental methionine. Plasma methionine increased linearly when methionine was supplemented from a ruminally protected source, but plasma methionine concentrations did not differ from the control when supplemental methionine from meSBM-Met was provided. In vitro degradation of supplemental methionine from meSBM-Met was complete within 3h. Data suggest that meSBM-Met provides negligible amounts of metabolizable methionine to dairy cows, and this is likely related to extensive ruminal destruction of methionine; however, cow body condition may be improved by ruminally available methionine provided by meSBM-Met.
authors.affiliation: Department of Animal Sciences and Industry, Kansas State University, Manhattan 66506, USA.
authors.forename: D W
authors.initials: DW
authors.lastname: Brake
authors.forename: E C
authors.initials: EC
authors.lastname: Titgemeyer
authors.forename: M J
authors.initials: MJ
authors.lastname: Brouk
authors.forename: C A
authors.initials: CA
authors.lastname: Macgregor
authors.forename: J F
authors.initials: JF
authors.lastname: Smith
authors.forename: B J
authors.initials: BJ
authors.lastname: Bradford
mesh_terms: D000818:Animals; D001682:Biological Availability; D002417:Cattle; D019587:Dietary Supplements; D005260:Female; D007774:Lactation / Q000187:drug effects* / Q000502:physiology; D054709:Lecithins / Q000378:metabolism*; D008715:Methionine / Q000008:administration & dosage / Q000097:blood / Q000493:pharmacokinetics*; D008892:Milk / Q000737:chemistry; D008894:Milk Proteins / Q000032:analysis; D012417:Rumen / Q000378:metabolism; D013025:Glycine max / Q000378:metabolism*
chemical_list: D054709:Lecithins; D008894:Milk Proteins; D008715:Methionine