The effect of standardized ileal digestible isoleucine:lysine in diets containing 20% dried distillers grains with solubles on finishing pig performance and carcass characteristics.

The use of corn by-products, such as dried distillers grains with solubles (DDGS), from the ethanol industry in swine rations is a common practice when economical. However, the inclusion of these by-products can potentially impact the nutrient requirements of pigs. It is important to understand how one should adjust diets to meet these changes in nutrient requirements and to minimize the reduction in growth performance. Previous research has indicated that the excess of a specific amino acid, leucine, can negatively impact the performance of pigs through the increased breakdown of other amino acids, more specifically valine and isoleucine. This increased breakdown of valine and isoleucine can result in inadequate amounts being available for protein deposition and, therefore, reduce growth performance. In the present study, late finishing pigs fed a diet containing 20% DDGS required a ratio of 70% between the amino acids isoleucine and lysine, on a digestible basis, to perform similarly to pigs receiving a standard corn soybean meal diet. Further research is necessary to more accurately define the optimal dietary isoleucine level for finishing pigs when fed 20% DDGS.