Effects of Reducing the Digestible Lysine and Tryptophan to Lysine Ratio on Growth Performance of Grow-Finish Pigs

Authors

Andres F. Tolosa, Kansas State UniversityFollow
Mike D. Tokach, Kansas State UniversityFollow
Robert D. Goodband, Kansas State UniversityFollow
Jason C. Woodworth, Kansas State UniversityFollow
Joel M. DeRouchey, Kansas State UniversityFollow
Jordan T. Gebhardt, Kansas State UniversityFollow
Craig Steck, New Horizon Farms, Pipestone, MN
Matt L. Wolfe, Provimi North America, Brookville, OH

Keywords

lysine, tryptophan, slow down growth, grow-finish pig

Abstract

A total of 1,080 finishing pigs (327 × 1050, PIC; initially 71.3 ± 1.91 lb) were used in a 119-d growth trial to evaluate the effects of reducing the dietary SID Lys and SID Trp:Lys ratio on growth performance to find strategies to reduce growth rate of pigs during the grow-finish period. Pigs were allotted by initial BW and randomly assigned to 1 of 4 dietary treatments in a completely randomized block design with 27 pigs per pen and 10 pens per treatment. Dietary treatments were corn-soybean meal-based diets with DDGS. Three dietary regimes were formulated to contain either 100, 90, or 80% of the estimated SID Lys requirement for pigs in this facility, and these diets had a SID Trp:Lys ratio of 19%, with the exception of the last dietary phase formulated to 17% SID Trp:Lys. A fourth regime was formulated to 80% SID Lys with a SID Trp:Lys ratio of 16% (80–16% SID Trp:Lys) throughout all phases.

Overall, from d 0 to 119, ADG and final BW decreased (linear, P < 0.001) and F/G tended to worsen (linear, P = 0.087) as SID Lys decreased from 100 to 80% of the requirement. Pigs fed the diet with 80–16% SID Trp:Lys also had decreased ADG and poorer F/G compared with pigs fed 80% of the SID Lys requirement with high a Trp:Lys ratio.

In conclusion, reducing SID Lys decreased growth performance and final BW of pigs during the grow-finish period. A further reduction in Trp:Lys ratio also decreased ADG and tended to worsen feed efficiency. This resulted in a 25 lb difference in final BW between pigs fed Lys and Trp at the requirement (100%) compared with pigs fed the 80% SID Lys and 16% Trp:Lys ratio. This study provides alternatives to producers to reduce growth rate of finishing pigs.

Recommended Citation

Tolosa, Andres F.; Tokach, Mike D.; Goodband, Robert D.; Woodworth, Jason C.; DeRouchey, Joel M.; Gebhardt, Jordan T.; Steck, Craig; and Wolfe, Matt L. (2021) "Effects of Reducing the Digestible Lysine and Tryptophan to Lysine Ratio on Growth Performance of Grow-Finish Pigs," Kansas Agricultural Experiment Station Research Reports: Vol. 7: Iss. 11. https://doi.org/10.4148/2378-5977.8207