Date of Graduation


Document Type


Degree Name

Bachelor of Science in Agricultural, Food and Life Sciences

Degree Level



Poultry Science


Rochell, Samuel

Committee Member/Reader

Ashworth, Amanda

Committee Member/Second Reader

Kidd, Micheal

Committee Member/Third Reader

Erf, Gisela


This study was developed to assess whether microencapsulation of amino acids (AA) improves their absorption to increase broiler growth performance and reduce nitrogen excretion compared to standard feed-grade AA. Five hundred and sixty Ross 708 male broilers were randomly distributed to 70 battery cages and reared for 21 days. Reported data is grouped into periods: 0-7 days, 0-14 days, and 0-21 days. A total of 5 treatment diets were fed: an industry-based control and 4 diets with decreased levels of methionine, lysine, and threonine in either encapsulated or free forms, with or without a botanical feed additive. Encapsulated AA increased (P < 0.05) body weight (BW) and BW gain (BWG) for all periods and increased feed intake (FI) compared to non-encapsulated AA for two of three periods but did not affect feed conversion ratio (FCR). Presence of the botanical additive decreased BW, BWG, and FCR for all periods, and decreased FI for two periods. Nitrogen retention was not different (P > 0.05) among treatments. Encapsulation had no effect (P > 0.05) on intestinal concentration of methionine, lysine, or threonine in the jejunum or ileum. Birds fed encapsulated AA gained more weight in the same amount of time as those fed free-form AA. Although birds fed encapsulated AA treatments consumed more feed, FCR was numerically slightly improved, although this was not significant. These results indicate that encapsulated AA may improve growth performance of young broilers, which could be economically beneficial in a commercial setting. Further research using floor pens instead of cages is required to determine the cause of these effects. Encapsulated AA did not affect nitrogen retention, indicating that the potential environmental and welfare benefits of encapsulated AA are minimal. Subsequent trials with a longer growing cycle and an industry applicable environment are warranted.


poultry, broilers, amino acids, amino acid utilization, encapsulation, nitrogen retention

Available for download on Friday, April 15, 2022