Date of Graduation

12-2018

Document Type

Dissertation

Degree Name

Doctor of Philosophy in Poultry Science (PhD)

Degree Level

Graduate

Department

Poultry Science

Advisor

John Marcy

Committee Member

Craig Bacon

Second Committee Member

Jason K. Apple

Third Committee Member

Casey M. Owens-Hanning

Fourth Committee Member

Navam S. Hettiarachchy

Keywords

Energy, Mineral, Stress, Temperature, Tenderness, Transport

Abstract

Temperature conditions during the transportation to the processing facility of commercial broilers have a direct impact on the meat texture, specifically maximum shear force and shear variation of cooked breast meat. Analysis of a calendar year of flock data (N=346), reveals that the largest impact of transport conditions, specifically temperature, is on the standard deviation of the flocks range of cooked shear values. The optimal transport temperature that yields broiler breast meat with average flock minimum shear and standard deviation values is approximately 60°F. The shear values for flocks at or near 60°F are on average 1 kg less than during temperatures less than 40°F. The location of the test was not subject to an extreme number of high temperature days preventing reporting the impact of high transport temperatures on meat texture. Chemical analysis of the raw Pectoralis Major (PM) muscle revealed no significant correlation between key minerals and the maximum shear force of the cooked PM muscle. There was a weak correlation of 8% between calcium and maximum shear force. The analysis was intended to lead further tests around intentional water chemistry modifications that would have a positive impact on meat texture. Based on the lack of correlation between minerals found in the raw tissue and cooked meat texture no further actions were pursued.

Cortisone accumulations in the flight feathers are a proven indication of the stress history of the bird. Ultra high performance gas liquid chromatography (UHPGLC) detectible levels of cortisone in the flight feathers were found to range from 2 to 8 ppb in a limited number of samples. Norepinephrine levels ranged from 220 ppb to 1872 ppb. The highest levels of norepinephrine were found in the section of the broiler house at the service entry point. This section of the house also had the lowest sample shear and shear variation of the four sections samples. This may indicate a potential relationship between chronic stresses and improved cooked meat texture.

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