title: Estimation of the ideal ratio of true ileal digestible sulfur amino acids:lysine in 8- to 26-kg nursery pigs.
abstract: Four experiments were conducted to determine the ideal ratio of true ileal digestible (TID) sulfur AA to Lys (SAA:LYS) in nursery pigs at two different BW ranges using both DL-Met and 2-hydroxy-4-(methylthio)-butanoic acid (HMTBA) as Met sources. In Exp. 1, 1,549 nursery pigs (Triumph 4 x PIC Camborough 22; initial BW 8.3 +/- 0.08 kg) were allotted to one of nine dietary treatments. The basal diet (Diet 1) was a semicomplex corn-soybean meal-based diet (1.32% TID Lys) with no supplemental HMTBA or DL-Met (47.7% TID SAA:LYS). Diets 2 to 9 consisted of the basal diet supplemented with four equimolar levels of DL-Met or HMTBA (52.7, 57.7, 62.7, and 67.7% TID SAA:LYS). In Exp. 2, 330 nursery pigs (Triumph 4 x PIC Camborough 22; initial BW 11.4 +/- 0.10 kg) were allotted to one of nine dietary treatments. The basal diet (Diet 1) was a corn-soybean meal-based diet (1.15% TID Lys) with no supplemental HMTBA or DL-Met (49% TID SAA:LYS). Diets 2 to 9 consisted of the basal diet supplemented with four equimolar levels of DL-Met or HMTBA (54, 59, 64, and 69% TID SAA:LYS). In Exp. 3, 1,544 nursery pigs (Triumph 4 x PIC Camborough 22; initial BW 12.4 +/- 0.13 kg) were allotted to one of nine dietary treatments as in Exp. 2. In Exp. 4, 343 nursery pigs (Genetiporc; initial BW 12.8 +/- 0.56 kg) were allotted to one of six dietary treatments. The basal diet (Diet 1) was a corn-soybean meal-based diet (1.05% TID Lys) with no supplemental DL-Met (49% TID SAA:LYS). Diets 2 to 5 consisted of the basal diet supplemented with four levels of DL-Met (54, 59, 64, and 69% TID SAA:LYS), and Diet 6 was the basal diet supplemented with one equimolar level of HMTBA to satisfy 59% TID SAA:LYS ratio. In all experiments, increasing the TID SAA:LYS ratio resulted in quadratic improvements in ADG (P < or = 0.09) and G:F (P < or = 0.05). Three different methods were used to estimate the optimal TID SAA:LYS ratio for each experiment. The two-slope broken-line regression model, x-intercept value of the broken-line and quadratic curve, and 95% of upper asymptote across the four experiments indicated that the average optimal TID SAA:LYS ratios were 59.3, 60.1, and 57.7% for ADG and 60.6, 61.7, and 60.1% for G:F, respectively. Thus, the optimal TID SAA:LYS ratio for 8- to 26-kg pigs based on the average value of these three estimates was 59.0% for ADG and 60.8% for G:F.
authors.affiliation: University of Missouri, Columbia, 65211, USA.
authors.forename: A M
authors.initials: AM
authors.lastname: Gaines
authors.forename: G F
authors.initials: GF
authors.lastname: Yi
authors.forename: B W
authors.initials: BW
authors.lastname: Ratliff
authors.forename: P
authors.initials: P
authors.lastname: Srichana
authors.forename: D C
authors.initials: DC
authors.lastname: Kendall
authors.forename: G L
authors.initials: GL
authors.lastname: Allee
authors.forename: C D
authors.initials: CD
authors.lastname: Knight
authors.forename: K R
authors.initials: KR
authors.lastname: Perryman
mesh_terms: D000603:Amino Acids, Sulfur / Q000737:chemistry / Q000378:metabolism*; D000821:Animal Feed / Q000032:analysis*; D000824:Animal Nutritional Physiological Phenomena; D000818:Animals; D001835:Body Weight; D004032:Diet; D004063:Digestion; D007082:Ileum / Q000378:metabolism*; D008239:Lysine / Q000737:chemistry / Q000378:metabolism*; D013552:Swine / Q000378:metabolism*
chemical_list: D000603:Amino Acids, Sulfur; D008239:Lysine