Evaluation of increasing standardized ileal digestible valine: lysine ratio on growth performance and plasma urea nitrogen of 21 to 116 kg pigs

Lay Summary Valine is generally considered the 5th limiting amino acid in corn-soybean meal-based diets for pigs and plays essential roles in protein synthesis, muscle accretion, immune function, and gastrointestinal integrity. The increased use of feed-grade amino acids in diet formulations creates a need for establishing the optimum standardized ileal digestible valine requirement estimate in order to maximize the performance of modern pig genotypes. Therefore, the focus of this research was to determine the standardized ileal digestible valine: lysine ratio requirement estimates throughout the growing and finishing period. Collectively, these results indicate a standardized ileal digestible valine: lysine ratio of 69% appears to maximize gain or feed efficiency in 21 to 67 kg pigs with 99% of performance achieved around 65 to 66% standardized ileal digestible valine: lysine. In 90 to 116 kg pigs a ratio of at least 69% standardized ileal digestible valine: lysine appeared to be sufficient for growth performance.