title: Influence of dietary total sulfur amino acids and methionine on growth performance and carcass characteristics of finishing gilts.
abstract: We conducted three experiments to determine the sulfur amino acid (SAA) and methionine requirements of finishing gilts. Gilts (PIC Line 326 x C-15, Exp. 1; Line 326 x C-22, Exp. 2 and 3) were blocked by initial weight in randomized complete block designs. In Exp. 1, 64 gilts (initially 54 kg) were fed diets containing either .56 or .44% apparent digestible lysine with increasing SAA levels (63, 70, and 77% of apparent digestible lysine) in a 2 x 3 factorial. A lysine x SAA interaction (P < .10) was observed for ADG and ADFI. Increasing SAA:lysine ratios from 63 to 70% in diets containing .56% apparent digestible lysine increased ADG and ADFI; however, increasing the SAA:lysine ratio in diets containing .44% apparent digestible lysine decreased ADG and ADFI. Pigs fed .56% apparent digestible lysine had higher (P < .05) ADG and gain:feed ratio (G/F) and lower 10th rib fat depth than pigs fed .44% apparent digestible lysine. Increasing the SAA:lysine ratio had no effect on G/F or carcass characteristics. In Exp. 2, 80 gilts (initially 74 kg) were fed diets containing .225, .25, .275, .30, or .325% apparent digestible SAA (45, 50, 55, 60, or 65% of .50% apparent digestible lysine, respectively). Increasing SAA concentrations decreased ADG and G/F (linear, P < .06). In Exp. 3, 105 gilts (initially 72 kg) were fed diets containing .20% apparent digestible cystine and .10, .125, or .15% apparent digestible methionine (20, 25, or 30% of .50% apparent digestible lysine). Increasing digestible methionine increased ADG, ADFI, plasma methionine concentrations (linear, P < .01), and G/F (quadratic, P < .03). The greatest increases in ADG and G/F were observed when apparent digestible methionine was increased from .10 to .125%. Based on these results, the apparent digestible methionine requirement is no greater than 25% of apparent digestible lysine, in diets containing excess cystine. This equates to an apparent digestible SAA:lysine ratio that is no greater than 50%.
authors.affiliation: Department of Animal Sciences and Industry, Kansas State University, Manhattan 66506-0201, USA.
authors.forename: J A
authors.initials: JA
authors.lastname: Loughmiller
authors.forename: J L
authors.initials: JL
authors.lastname: Nelssen
authors.forename: R D
authors.initials: RD
authors.lastname: Goodband
authors.forename: M D
authors.initials: MD
authors.lastname: Tokach
authors.forename: E C
authors.initials: EC
authors.lastname: Titgemeyer
authors.forename: I H
authors.initials: IH
authors.lastname: Kim
mesh_terms: D000273:Adipose Tissue / Q000254:growth & development; D000603:Amino Acids, Sulfur / Q000008:administration & dosage*; D000704:Analysis of Variance; D000824:Animal Nutritional Physiological Phenomena; D000818:Animals; D001806:Blood Urea Nitrogen; D001823:Body Composition; D004032:Diet / Q000662:veterinary*; D004063:Digestion; D004435:Eating; D005260:Female; D008460:Meat / Q000592:standards*; D008715:Methionine / Q000008:administration & dosage*; D024510:Muscle Development; D018482:Muscle, Skeletal / Q000254:growth & development; D009751:Nutritional Requirements; D011336:Probability; D011897:Random Allocation; D013552:Swine / Q000254:growth & development* / Q000502:physiology; D015430:Weight Gain
chemical_list: D000603:Amino Acids, Sulfur; D008715:Methionine