Date of Graduation


Document Type


Degree Name

Doctor of Philosophy in Poultry Science (PhD)

Degree Level



Poultry Science


Nicholas Anthony

Committee Member

Sami Dridi

Second Committee Member

Casey Owens

Third Committee Member

Charles Rosenkrans


Broiler, Environment, Genetics, Thermal Manipulation


The effect of both genetic and environmental influences on broiler meat quality were evaluated over three experiments. Selection response was assessed for broiler lines selected for high (HBY4) and low (LBY4) four day percentage breast yield which were formed from a random bred control (RAN). A modern random bred population (MRB) created in 2015 was evaluated for differences in 4 day percentage breast yield and the resulting differences in the incidence and severity of the woody breast and white striping myopathies. Additionally, the use of embryonic thermal manipulation to impact cell division and early caloric feed restriction to slow growth was analyzed in a yield type broiler population.

In the first experiment, histological analysis of the LBY4 and HBY4 lines was conducted after five generations of selection at various stages of development. At embryonic day 18 and 4 days post hatch, the HBY4 showed advanced muscle fiber development and formation when compared to the LBY4 line and random bred control. At the processing age of day 56, the only difference between the lines was for muscle fiber diameter in which the HBY4 line had larger muscle fibers with no difference in fiber number.

In the second experiment, the MRB line exhibited sire family differences in 4 day percentage breast yield. At processing age, the sire families with the highest average 4 day breast yield exhibited a higher dressing percentage and a higher percentage breast than the lower families. The sire families with the lowest average breast yield had a higher leg quarter percentage. No differences were reported for woody breast but the upper families had a higher score for white striping.

In the third experiment, a yield type broiler strain was subjected to a period of increased incubator temperature for 3 hours a day on embryonic days 15 through 17. The thermal manipulation treatment showed a slightly delayed hatch when compared to the control (C) with no difference in the hatch of fertile. No differences were observed for body weight however, at processing, the 3 group had a higher percent breast yield and lower severity of woody breast.