The objective of Smith’s research is to determine the dietary requirement for threonine in growing horses. | Photo: iStock

Kelsey Smith chose to pursue her master’s degree under Kristine Urschel, PhD, an associate professor in the department of animal and food sciences at the University of Kentucky (UK), to gain a solid foundation in basic nutrition. She chose equine nutrition because of the unique difficulty of balancing performance and health, as well as the prevalence of nutrition-related diseases.

The objective of Smith’s research is to determine the dietary requirement for threonine in growing horses. Threonine is an essential amino acid and an important component of many proteins within the body. In the study, she fed horses six diets that all had the same energy and crude protein contents but contained varying levels of threonine. She used the indicator amino acid oxidation method to estimate the rate of synthesis for all proteins within the body. Smith predicts that as horses consume increasing amounts of threonine, protein synthesis will also increase until reaching a plateau at the threonine requirement (meaning that any excess threonine would not make a difference in protein synthesis).

“If we can determine the requirement for individual amino acids, we can reduce crude protein intake and nitrogen excretion,” Smith said. “Excess nitrogen excretion can cause environmental damage, increase the ammonia concentration in barns and possibly cause negative physiological effects that may affect performance in horses