title: The relative effectiveness of 2-hydroxy-4-(methylthio) butanoic acid and DL-methionine in young swine.
abstract: We compared the effectiveness of 2-hydroxy-4-(methylthio) butanoic acid (HMB) and DL-methionine (DLM) as sources of L-methionine activity in methionine-deficient primary cultures of pig liver cells and methionine-deficient early-weaned pigs. Viable hepatocytes were obtained from minced pig liver and maintained in a high density, differentiated, nonproliferation cell culture system. Culture medium was supplemented with HMB, DLM, or L-methionine, and cells were pulse-dosed with L-[14C(U)]leucine for 24 h to determine the level of protein synthesis. Leucine incorporation per milligram of protein indicated a six-to eightfold increase in protein synthesis (P < .01) with methionine levels between 5 and 10 microM, regardless of source of methionine activity. Two 24-pen replicate methionine dose titrations were conducted with 95 early-weaned commercial crossbred pigs. The pelleted corn, dried whey, and porcine plasma basal diet contained 1.5% lysine, .23% methionine, and .48% cystine and was supplemented with 0, .05, or .10% methionine activity as DLM or HMB for 21 d. There was a 134, 104, and 61% increase (P < .01) in cumulative ADG for each successive week on study with a 30 and 19% improvement in feed/gain (P < .01) after 7 and 14 d. Performance responses due to source of methionine activity did not differ and slope ratio potency determinations (gain vs intake of methionine source) of HMB vs DLM indicated a 119, 111, and 95% relative activity for cumulative weekly performance. These results support the hypothesis that HMB and DLM provide equimolar levels of methionine activity in swine.
authors.affiliation: Novus International, Inc., St. Charles, MO 63304, USA.
authors.forename: C D
authors.initials: CD
authors.lastname: Knight
authors.forename: C A
authors.initials: CA
authors.lastname: Atwell
authors.forename: C W
authors.initials: CW
authors.lastname: Wuelling
authors.forename: F J
authors.initials: FJ
authors.lastname: Ivey
authors.forename: J J
authors.initials: JJ
authors.lastname: Dibner
mesh_terms: D000821:Animal Feed; D000818:Animals; D002478:Cells, Cultured; D005527:Food, Fortified; D007930:Leucine / Q000378:metabolism; D008099:Liver / Q000187:drug effects / Q000378:metabolism*; D008715:Methionine / Q000008:administration & dosage / Q000031:analogs & derivatives* / Q000172:deficiency / Q000494:pharmacology*; D008894:Milk Proteins; D014176:Protein Biosynthesis; D013552:Swine; D014886:Weaning; D000067816:Whey Proteins; D003313:Zea mays
chemical_list: D008894:Milk Proteins; D000067816:Whey Proteins; C008391:alpha-hydroxy-gamma-methylmercaptobutyric acid; D008715:Methionine; D007930:Leucine