Limiting Amino acids in Lactating Sows

Researchers at the University of Illinois conducted three experiments to evaluate the order of limitations of lysine, threonine and valine in corn-soybean meal diets for lactating sows.  A basal diet containing 0.51% lysine was formulated using corn and soybean as the only source of amino acids.  The basal diet was then diluted with cornstarch, sucrose and soybean oil, and supplemented with amino acids, to obtain various amino acid levels while maintaining the same ratio of corn to soybean meal.  Plasma urea nitrogen was used to evaluate the diet amino acid response.  This procedure allowed for establishing the limiting amino acids in diets of sows showing weight loss during lactation.  The results indicated that lysine is the first-limiting amino acid followed by threonine in a simple corn-soybean meal lactation diet.  (Note-These results have added significance as swine producers consider using higher protein distillers dried grains in swine lactation diets.  Lysine and threonine levels will be even more critical as soybean meal levels are reduced in these rations).

Soltwedel, K.T., R.A. Easter and J.E. Pettigrew.  2006.  Evaluation of the order of limitation of lysine, threonine and valine, as determined by plasma urea nitrogen, in corn-soybean meal diets of lactating sows with high body weight loss.  J. Animal Sci. 84: 1734-1741.