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ARS Home » Midwest Area » Ames, Iowa » National Laboratory for Agriculture and The Environment » Agroecosystems Management Research » Research » Publications at this Location » Publication #349150
Research Project: Reducing Production Losses due to Oxidative Stress and Bacterial Pathogens in Swine

Location: Agroecosystems Management Research

Title: Antibiotic inclusion in the diet did not alter the standardized ileal digestible tryptophan to lysine ratio for growing pigs

Author
item YU, HONGYOU - University Of Kentucky
item LINDEMANN, MERLIN - University Of Kentucky
item QUANT, ANTHONY - University Of Kentucky
item JANG, YOUNG - University Of Kentucky
item PAYNE, ROBERT - Evonik Degussa Gmbh
item Kerr, Brian

Submitted to: Journal of Animal Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 10/11/2017
Publication Date: 12/8/2017
Publication URL: http://handle.nal.usda.gov/10113/5927847
Citation: Yu, D.Y., Lindemann, M.D., Quant, A.D., Jang, Y.D., Payne, R.L., Kerr, B.J. 2017. Antibiotic inclusion in the diet did not alter the standardized ileal digestible tryptophan to lysine ratio for growing pigs. Journal of Animal Science. 95(12):5516-5523. https://doi.org/10.2527/jas2017.1982.

Interpretive Summary: Optimum amino acid intake is important to maximize growth, feed efficiency, and carcass lean deposition in growing pigs. Although there has been some research conducted on the tryptophan requirement in growing pigs, the data differs greatly between US and European scientists, with one difference being that past US research often included an antibiotic in the feed while Europe does not. Furthermore, current laws prevent the use of antibiotics for growth promotion in diets fed to growing pigs, such that it needs to be clarified if antibiotics in the feed affect the needs of the pig for dietary tryptophan, which was the objective of the experiments herein. Data from these experiments demonstrate that the optimum tryptophan to lysine ratio for 30 to 50 kg growing pigs is not impacted by the dietary inclusion of antibiotic. Research results described in this report provide nutritionists at universities, feed companies, allied industries, and swine production facilities data on how to define the tryptophan needs of growing pigs to formulate diets necessary to optimize growth performance and subsequently minimize nitrogen losses into the environment.

Technical Abstract: Two 21-d experiments were conducted to determine the optimum standard ileal digestible (SID) Trp:Lys ratio in growing pigs fed diets supplemented with or without an antibiotic. The primary response variables in both experiments were ADG, ADFI, G:F and plasma urea N (PUN) concentrations with the optimum SID Trp:Lys ratio detected using broken-line analysis. Experiment 1 evaluated the optimum SID Trp:Lys ratio in growing pigs fed diets supplemented with an antibiotic. This experiment used 120 crossbred pigs that were blocked by sex and initial BW (24.13 ± 2.72 kg) and allotted to 6 SID Trp:Lys ratios in 4 replicates. Dietary treatments were formulated by the addition of crystalline Trp to create 6 SID Trp:Lys ratios (13.08, 14.06, 15.04, 17.00, 18.95, and 20.91%) with a constant SID Lys level of 0.655%. As SID Trp:Lys ratios increased, ADG, ADFI, and G:F increased and PUN concentrations decreased linearly (P < 0.05) and quadratically (P < 0.05). Linear broken–line analysis yielded an optimum SID Trp:Lys ratio of 17.93% (P < 0.001) and 16.17% (P = 0.009) for ADG and PUN respectively, resulting in a mean optimum SID Trp:Lys ratio of 17.05%. Experiment 2 evaluated the optimum SID Trp:Lys ratio in growing pigs fed diets supplemented with or without an antibiotic. It used a total of 324 crossbred pigs (initial BW: 30.81 ± 3.56 kg) that were allotted to 6 SID Trp:Lys ratios. Dietary treatments were formulated by the addition of crystalline Trp to create 6 SID Trp:Lys ratios (12.52, 14.86, 17.20, 19.54, 21.88, and 24.22%) with a constant SID Lys level of 0.67%. As SID Trp:Lys ratios increased, ADG, ADFI, and G:F increased and PUN concentrations decreased linearly (P < 0.001) and quadratically (P < 0.001) respectively, regardless of antibiotic inclusion. There were no differences by the antibiotic treatment in ADG, ADFI, G:F, or PUN concentrations (P > 0.49) and no interactions between antibiotics and Trp:Lys ratios (P > 0.29). When the data for all pigs were pooled for the various Trp:Lys ratios, the optimum SID Trp:Lys ratios for ADG and PUN based on linear broken-line analysis were 14.58% (P < 0.001) and 14.54% (P < 0.001) respectively, resulting in an optimum SID Trp:Lys ratio of 14.56% as the mean of the determined optima for ADG and PUN responses. These results demonstrate that the optimum SID Trp:Lys ratio for 30 - 50 kg growing pigs is not impacted by the dietary inclusion of antibiotic as long as the diets are formulated on an SID AA basis.