The goal of balancing diets for amino acids is to avoid an excessive supply of nitrogen, thus reducing nitrogen excretion. This should lead to greater income over feed costs and lower environmental impacts. Variable responses have been observed when feeding rumen-protected amino acids, particularly lysine. Dr. Lee suggests research should focus on identifying factors that cause the variable responses, hopefully leading to more consistency. Some potential factors include flexible amino acid utilization by tissues, different requirements of amino acids between lactation stages, and varying prediction rates between models. To achieve a more consistent response, we must better understand both the roles of lysine in the mammary gland and the amino acid requirements of fresh cows, as well as determine an accurate bioavailability of rumen-protected lysine.
