Date of Graduation

12-2025

Document Type

Thesis

Degree Name

Master of Science in Poultry Science (MS)

Degree Level

Graduate

Department

Poultry Science

Advisor/Mentor

Kidd, Michael

Committee Member

Caldwell, David

Second Committee Member

Sun, Xiaolun

Keywords

amino acids; broiler nutrition; Poultry nutrition

Abstract

The majority of research assessing the amino acid responsiveness in broilers has been conducted in experimental designs utilizing pens that contain 12 to 25 birds with high replication. While this trial design is beneficial as a way to perform high replications with multiple treatments in a way that is both economically and spatially feasible, it may not accurately translate to a rearing environment more similar to that of commercial open floor housing. This research was conducted to determine if the effects of lysine driven amino acid density diets that have been found in the traditional floor pen setting correlate to birds reared in a setting closer to that of modern commercial broiler houses. Two separate trials were conducted, the first utilizing Ross 708 male broilers and the second utilizing Cobb 500 male broilers. For both trials, chicks were weighed in groups of 100 before being placed into one of eight large floor pens, with 500 birds per pen. Trial 1 had two treatments, a high and a low amino acid density diet, that were fed from 0 to 42d of age, across 3 feeding phases. Trial 2 also had two treatments, a high- and a low-density diet, that were fed from 0 to 43d of age, across 4 feeding phases. For both experiments, external feed bin load scales were used to measure pen feed consumption and water meters measured intake by pen. Body weights and feed consumption were measures by pen at 0 and 42 d of age for trial 1 and at 0 and 43 d of age for trial 2. These weights were used to calculate mortality-corrected feed conversion ratio (FCR), water conversion ratio, and average body weight (BW). Final bird weights were collected in groups of 5 to allow for a precision sample size calculation to be run on each pen. These calculations were run to aid in reducing workload in future studies performed in big pen facilities. Throughout both trials, there were no differences found in livability, BW, or water conversion ratio between the two treatments. Birds fed the high AA density diet in both trials showed to have significantly decreased (P < 0.05) percentage fat pad yields. The Cobb birds from Trial 2 showed a decrease in percentage fat pad yield, with the birds fed the high-density diet having 16.35% less fat pad yield than those fed the low density diet. Feeding moderate and high amino acid density regimes to increase Ross broiler white meat yields, while decreasing adipose tissue has been well established (Kidd et al., 2004; 2005). While there was not a significant difference in white meat yields picked up within either trial, it should be noted that total white meat yield percentage was numerically increased (P = 0.44 and P = 0.475) in the birds fed the high-density diet in both trials by 0.19 g and 0.38 g respectively. The results of the precision sample size calculations performed appear to be contradictory, with Trial 1 having fewer bird weights required for the low AA density diet, whereas the high-density diet in Trial 2 required fewer bird weights in order to get within the desired range of the true average bird weight.

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