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The tryptophan requirement of growing and finishing barrows^1,2,3

A. C. Guzik^*, J. L. Shelton^*, L. L. Southern^*,4, B. J. Kerr and T. D. Bidner^*

^* Department of Animal Sciences, Louisiana State University Agricultural Center, Baton Rouge 70803-4210; and and USDA-ARS-SOMMRU, National Swine Research and Information Center, Ames, IA 50011

⁴ Correspondence—e-mail: lsouthern{at}agctr.lsu.edu.

Five experiments were conducted to determine the true ileal digestible Trp (tidTrp) requirement of growing and finishing pigs fed diets (as-fed basis) containing 0.87% (Exp. 3), 0.70% (Exp. 4), 0.61% (Exp. 5), and 0.52% (Exp. 1 and 2) tidLys during the early-grower, late-grower, early-finisher, and late-finisher periods, respectively. Treatments were replicated with three or four replications, with three or four pigs per replicate pen. Treatment differences were considered significant at P = 0.10. Experiment 1 was conducted with 27 pigs (initial and final BW of 78.3 ± 0.5 and 109.8 ± 1.9 kg) to validate whether a corn-feather meal (FM) tidTrp-deficient (0.07%) diet, when supplemented with 0.07% crystalline L-Trp, would result in growth performance and carcass traits similar to a conventional corn-soybean meal (C-SBM) diet. Pigs fed the corn-FM diet without Trp supplementation had decreased growth performance and carcass traits, and increased plasma urea N (PUN) concentration. Supplementing the corn-FM diet with Trp resulted in greater ADG and G:F than pigs fed the positive control C-SBM diet. Pigs fed the corn-FM diet had similar carcass traits as pigs fed the C-SBM diet, but loin muscle area was decreased and fat thickness was increased. In Exp. 2, 60 pigs (initial and final BW of 74.6 ± 0.50 and 104.5 ± 1.64 kg) were used to estimate the tidTrp requirement of finishing pigs. The levels of tidTrp used in Exp. 2 were 0.06, 0.08, 0.10, 0.12, or 0.14% (as-fed basis). Response variables were growth performance, PUN concentrations, and carcass traits and quality. For Exp. 2, the average of the estimates calculated by broken-line regression was 0.104% tidTrp. In Exp. 3, 4, and 5, barrows (n = 60, 60, or 80, respectively) were allotted to five dietary treatments supplemented with crystalline L-Trp at increments of 0.02%. The basal diets contained 0.13, 0.09, and 0.07% tidTrp (as-fed basis) in Exp. 3, 4, and 5, and initial BW of the pigs in these experiments were 30.9 ± 0.7, 51.3 ± 1.1, and 69.4 ± 3.0 kg, respectively. The response variable was PUN, and the basal diet used in Exp. 3 and 4 contained corn, SBM, and Canadian field peas. The tidTrp requirements were estimated to be 0.167% for pigs weighing 30.9 kg, 0.134% for pigs weighing 51.3 kg, and 0.096% for pigs weighing 69.4 kg. Based on our data and a summary of the cited literature, we suggest the following total Trp and tidTrp requirement estimates (as-fed basis): 30-kg pigs, 0.21 and 0.18%; 50-kg pigs, 0.17 and 0.14%; 70-kg pigs, 0.13 and 0.11%; and in 90-kg pigs, 0.13 and 0.11%.

Key Words: Pigs • Requirement • Tryptophan

This article has been cited by other articles:

				D. C. Kendall, A. M. Gaines, B. J. Kerr, and G. L. Allee True ileal digestible tryptophan to lysine ratios in ninety- to one hundred twenty-five-kilogram barrows J Anim Sci, November 1, 2007; 85(11): 3004 - 3012. [Abstract] [Full Text] [PDF]