Theses and Dissertations

Rosana Hirai

Issuing Body

Mississippi State University

Advisor

Wamsley, Kelley G. S.

Committee Member

McDaniel, Christopher D.

Committee Member

Zhai, Wei

Committee Member

Mejia, Leonel

Committee Member

Kiess, Aaron S.

Other Advisors or Committee Members

Hopper, George M.

Date of Degree

8-9-2019

Original embargo terms

Visible to MSU only for 2 years

Document Type

Dissertation - Open Access

Major

Agricultural Science

Degree Name

Doctor of Philosophy

College

College of Agriculture and Life Sciences

Department

Department of Poultry Science

Abstract

To maximize the economics of a new commercial broiler cross, research on its nutritional specifications is necessary. Study 1 investigated the effects of feeding four amino acid densities (AAD) on performance and yield of Cobb MV × Cobb 500 broilers at d 33 and 36. Data demonstrated a stepwise decrease in feed conversion ratio (FCR) as AAD level increased. Improvements in performance, processing, and economic return were observed when feeding higher AAD levels. Study 2 estimated the digestible lysine (dLys) requirements of Cobb MV × Cobb 500 broilers from d 0-14 and evaluated the impact of varying starter dLys levels on their performance, processing, and economic return during a 42 d grow-out. Data suggested that d 0-14 dLys requirements varied based on broiler response and statistical model. Improvements in overall performance was observed when feeding ≥1.12% dLys during the starter phase. The greatest economic return was associated with feeding starter dLys of 1.20%. Due to the potential interaction between AA and apparent metabolizable energy (AME), Study 3 examined the response of Cobb MV × Cobb 500 to varying dLys and AME levels from d 0-14 on d 0-42 performance and processing. A dLys × AME interaction was observed for d 0-28 FCR and for dLys and AME for early performance parameters. However, this significance was lost by the end of the study. Due to the variation in broiler response to feeding strategies at different ages, Study 4 evaluated the impact of varying dLys and AME levels from d 14-28 on performance and processing of 42-day old Cobb MV × Cobb 500 broilers. Data demonstrated significant dLys × AME interactions for d 14-28 and 14-35 FCR, as well as significances for main effect of dLys and AME for performance and processing (d 42). Feeding grower diets formulated to 1.18% dLys + 3028 kcal/kg AME was the most profitable diet. Overall, this research demonstrates that higher AAD improved broiler performance, especially ≥1.12% starter dLys. Varying dLys and AME during the starter phase did not affect performance at d 42; however, it did when this regimen was exercised during the grower phase.

URI

https://hdl.handle.net/11668/14571

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