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Title:Effects of fiber on the optimum threonine:lysine ratio for 25 to 50 kg growing gilts
Author(s):Mathai, John
Advisor(s):Stein, Hans-Henrik
Contributor(s):Stein, Hans-Henrik
Department / Program:Animal Sciences
Discipline:Animal Sciences
Degree Granting Institution:University of Illinois at Urbana-Champaign
Degree:M.S.
Genre:Thesis
Subject(s):requirement
threonine
pigs
lysine titration
ideal protein
fiber
amino acid digestibility
Abstract:Five experiments were conducted to determine the ideal Thr:Lys ratio for 25 to 50 kg growing gilts and the effects of fiber on said ratio. In Exp. 1, the objectives were to determine the standardized ileal digestible (SID) Lys requirement for gilts from 25 to 50 kg BW. Seventy gilts (initial BW: 24.54 ± 3.28 kg) were used in a growth assay with 2 pigs per pen and 7 pens per treatment. Diets were formulated using corn and soybean meal as the sole sources of AA. Under the assumption that Lys is the first limiting AA in corn-soybean meal diets, soybean meal concentration was increased at the expense of corn to increase SID Lys in the diets. Results indicated that 1.08% SID Lys was needed to maximize ADG and 1.10% SID Lys was needed to maximize G:F. In Exp. 2, the objectives were to determine the standardized ileal digestibility of AA in corn, soybean meal, field peas, fish meal, and soybean hulls. These ingredients were chosen because of their unique AA profiles, which facilitate their use diets that are deficient in only Lys and Thr. Six ileal-cannulated gilts (initial BW: 26.5 ± 0.74 kg) were allotted to a 6 × 6 Latin square design with 6 diets and 6 periods. The results indicated that the standardized ileal digestibility of most indispensable AA was not different among field peas, fish meal, and soybean meal, whereas the standardized ileal digestibility of some indispensable AA was less in soybean hulls than in other ingredients. In Exp. 3, the objectives were to confirm that diets deficient in only Thr and Lys can be formulated. One hundred twenty gilts (initial BW: 24.84 ± 3.39 kg) were allotted to either low fiber or high fiber diets. Within each level of fiber, the 5 different diets were formulated by changing the proportion of synthetic Thr and Lys in the diets. Resulting differences in ADG, ADFI, and G:F between diets indicated that the diets were marginally deficient in Lys and Thr. In Exp. 4, the objectives were to determine the optimal SID Thr:Lys ratio for gilts from 25 to 50 kg BW, and to determine the effects of fiber on that ratio. One hundred ninety-two gilts were used in a growth assay with 2 pigs per pen and 8 pens per treatment. Low-fiber, as well as high-fiber, diets with SID Thr:Lys ratios at 45:100, 54:100, 63:100, 72:100, 81:100, and 90:100 were used. In both types of diets ADG and G:F increased quadratically (P < 0.05), as the concentration of Thr increased in the diets. For pigs fed the low-fiber diets, combined broken-line and quadratic analyses estimated the optimum SID Thr:Lys ratio at 0.66 and 0.63 for ADG and G:F, respectively. For the pigs fed high fiber diets, combined broken-line quadratic analyses estimated the optimum SID Thr:Lys requirement at 0.71 and 0.63 for ADG and G:F, respectively. In Exp. 5, the objective was to confirm the results of Exp. 4 by determining N balance in pigs fed either low-fiber or high-fiber diets that were deficient or adequate in Thr. Thirty-six growing gilts (initial BW: 29.0 ± 0.74 kg) were housed in metabolism cages and there were 9 replicates per diet. Output of N in feces was greater (P < 0.05) from pigs fed high-fiber diets, but output of N in urine was greater (P < 0.05) from pigs fed low-fiber diets. The ATTD of N was greater (P < 0.05) from pigs fed low-fiber diets than in pigs fed high-fiber diets, and retention of N was greater (P < 0.05) in pigs fed low-fiber diets than in pigs fed high-fiber diets. There was greater (P < 0.05) N retention in pigs fed high-Thr diets compared with pigs fed low-fiber diets. There was also an interaction (P < 0.05) between fiber level and Thr for output of N in feces with N output increasing (P < 0.05) as Thr in the high-fiber diet increased, whereas this was not the case for the low-fiber diet. Results indicate that higher fiber diets may require greater concentrations of Thr. In conclusion, results of these experiments indicate that increased fiber levels in diets fed to growing gilts may increase the requirement for Thr and diets with higher fiber levels should include a greater concentration of Thr.
Issue Date:2015-02-04
Type:Thesis
URI:http://hdl.handle.net/2142/78306
Rights Information:Copyright 2015 John Mathai
Date Available in IDEALS:2015-07-22
Date Deposited:May 2015


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