Honors Theses and Capstones

Date of Award

Spring 2023

Project Type

Senior Honors Thesis

College or School



Agriculture, Nutrition, & Food Systems

Program or Major

Animal Science

Degree Name

Bachelor of Science

First Advisor

Nancy Whitehouse


The milk production of lactating dairy cows is dependent on factors such as housing conditions, lineage, climate, and health, but the quality of their diets is generally the most influential. Maintaining a proper balance of nutrients is necessary to achieve the greatest milk production at the lowest cost. Maximum feed efficiency is not only critical for increasing the economic profits of an individual farm, but also for increasing food supply without increasing environmental demand. Supplementing cows’ diets with lysine (Lys), an essential amino acid (AA), can aid in maximizing protein synthesis. Providing this nutrient in a rumen-protected (RP) coating can increase its bioavailability by delaying its degradation in the rumen. Using a reliable method to assess the bioavailability of an AA is important for ensuring accurate results that can be utilized to yield further improvements in the development of these supplements.

The objective of this experiment was to determine the bioavailability of RP-Lys supplements using plasma Lys concentrations for analysis via the area under the curve (AUC) method and the plasma dose response (PDR) method. Lactating Holsteins, fitted with rumen cannulas, were used in two experiments, through which they received varying forms of Lys. Blood samples were collected, and plasma concentration was measured for each cow. Feed intake, milk yield, and milk components were observed. Data was analyzed to determine average milk yield and dry matter intake, and AUC and PDR statistical analyses were performed to measure the bioavailability of each treatment. While no statistical significance was seen among the Lys prototypes, Prototype II exhibited a higher bioavailability via the AUC method, while Prototype IL exhibited a higher bioavailability via the PDR method. Ultimately, the PDR method appears to be a more effective strategy for determining the bioavailability of Lys.

Included in

Dairy Science Commons