Theses and Dissertations
ORCID
https://orcid.org/0009-0008-3094-2142
Advisor
Adhikari, Pratima
Committee Member
Wamsley, Kelley
Committee Member
Zhang, Li
Committee Member
Elliot, Michael
Committee Member
Kriseldi, Ruben
Date of Degree
5-15-2026
Original embargo terms
Embargo 2 years
Document Type
Dissertation - Open Access
Major
Agricultural Science (Poultry Science)
Degree Name
Doctor of Philosophy (Ph.D.)
College
College of Agriculture and Life Sciences
Department
Department of Poultry Science
Abstract
Branched-chain amino acids (BCAAs), including leucine (Leu), isoleucine (Ile), and valine (Val), are critical regulators of protein synthesis, metabolic signaling, and tissue maintenance in poultry. Although individual BCAA requirements have previously been established, limited research has defined their optimal interactive ratios across physiological stages of laying hens. Furthermore, age-related shifts in nutrient partitioning and metabolic efficiency may alter responsiveness to dietary amino acid (AA) supply. The objective of this dissertation was to evaluate the effects of varying dietary BCAA ratios relative to lysine (Lys) on growth performance, egg production, egg quality, skeletal integrity, feather condition, and intestinal AA transporter gene expression of Hy-Line W-36 hens during pullet development, peak production, and late-lay. Chapter I reviews BCAA metabolism, antagonistic interactions, and signaling functions, emphasizing the need for phase-specific ratio optimization in modern laying hens. Chapter II evaluated dietary BCAA ratios during the pullet phase. Balanced BCAA supply supported growth and skeletal development, while imbalanced ratios negatively influenced feed efficiency and bone parameters, highlighting the importance of coordinated AA provision during structural development. Chapter III examined BCAA ratios during peak production. Dietary interactions among Leu:Lys, Ile:Lys, and Val:Lys ratios influenced body weight, feed intake, egg production, and egg mass, as well as egg, bone, and feather quality. Chapter IV assessed BCAA ratios during late-lay, a stage characterized by reduced nutrient utilization efficiency. Although production responses were modest, dietary BCAA balance affected feed intake, bone characteristics, feather condition, and transporter gene expression, suggesting continued physiological sensitivity despite age-related metabolic constraints. Collectively, this research demonstrates that optimal BCAA nutrition is phase-dependent, with interactive effects among Leu, Ile, and Val influencing performance, skeletal integrity, and molecular markers of nutrient transport. The optimal BCAA ratios relative to Lys varied depending on the response criterion, indicating that a single ratio may not support all physiological outcomes. These findings advance precision AA formulation strategies to improve productivity and physiological resilience in modern laying hens.
Recommended Citation
Waters, Charis Annaleigha, "Interaction of branched‑chain amino acids on performance, egg quality, and bone integrity in laying hens across different production phases" (2026). Theses and Dissertations. 7003.
https://scholarsjunction.msstate.edu/td/7003
