title: Individual response of growing pigs to sulphur amino acid intake.
abstract: Two N balance experiments were conducted to study the individual response of growing pigs to limiting amino acid (AA) intake. Series of fifteen diets with increasing concentration of sulphur amino acids (SAA, Expt 1) or methionine in the presence of excess cystine (Expt 2) were fed sequentially to nine pigs during a 15-day experimental period. The concentration of the AA under test ranged from 50% to 140% of the requirement while other essential AA were given in a 25% excess relative to the limiting AA. N retention was related to the limiting AA intake using rectilinear and curvilinear models. In Expt 1, the quadratic-plateau model fitted the individual data significantly better (p = 0.01) than the linear-plateau model. No difference was found between the two models in Expt. 2, presumably due to the sparing effect of excess cystine on methionine utilization. Exponential, saturation kinetics or four-parameter logistic models fitted to data for all pigs showed that their goodness of fit was similar to those of quadratic-plateau or linear-plateau models. Significant differences (p < 0.05) were found between individual plateau values for N retention within each experiment while the slopes of the regression lines did not significantly differ either in Expt 1 (p = 0.07) or Expt 2 (p = 0.45). There was a positive correlation between the slope and plateau values of the linear-plateau model in Expt 1 (r = 0.74, p = 0.02) but no significant correlation was found in Expt 2 (r = -0.48, p = 0.13). Marginal efficiencies of SAA and methionine utilization derived from the linear-plateau model were 0.43 and 0.65 respectively. Based on linear-plateau and quadratic-plateau models, daily requirements of SAA and methionine for a 50 kg pig were estimated to be 13.0 and 5.9 g and 14.3 and 6.1 g respectively.
authors.affiliation: Department of Nutrition, Research Institute of Animal Production, Slovak Agricultural Research Centre, Nitra, Slovakia. jheger@tiscali.cz
authors.forename: J
authors.initials: J
authors.lastname: Heger
authors.forename: L
authors.initials: L
authors.lastname: Krízová
authors.forename: M
authors.initials: M
authors.lastname: Sustala
authors.forename: S
authors.initials: S
authors.lastname: Nitrayová
authors.forename: P
authors.initials: P
authors.lastname: Patrás
authors.forename: D
authors.initials: D
authors.lastname: Hampel
mesh_terms: D000603:Amino Acids, Sulfur / Q000008:administration & dosage* / Q000378:metabolism; D000821:Animal Feed; D000824:Animal Nutritional Physiological Phenomena; D000818:Animals; D018592:Cross-Over Studies; D003553:Cystine / Q000008:administration & dosage / Q000378:metabolism; D004044:Dietary Proteins / Q000008:administration & dosage / Q000378:metabolism; D004305:Dose-Response Relationship, Drug; D005260:Female; D005772:Gastrointestinal Transit / Q000187:drug effects / Q000502:physiology; D016014:Linear Models; D016015:Logistic Models; D008715:Methionine / Q000008:administration & dosage* / Q000378:metabolism; D009751:Nutritional Requirements; D009753:Nutritive Value; D011897:Random Allocation; D013552:Swine / Q000254:growth & development* / Q000378:metabolism*; D015430:Weight Gain
chemical_list: D000603:Amino Acids, Sulfur; D004044:Dietary Proteins; D003553:Cystine; D008715:Methionine