Date of Graduation

12-2014

Document Type

Thesis

Degree Name

Master of Science in Poultry Science (MS)

Degree Level

Graduate

Department

Poultry Science

Advisor/Mentor

Watkins, Susan E.

Committee Member

Clark, Fred D.

Second Committee Member

Christensen, Karen D.

Keywords

Corn; Feed Conversion; Grain Sorghum; Nutrition; Poultry Science; Skin Pigmentation

Abstract

Research trials were conducted to evaluate the effects of different levels of dietary grain sorghum on broiler live performance, carcass yield and shank (leg) and breast skin coloring. Iso-caloric diets were formulated where sorghum replaced corn at rates of 0% (control), 20, 40, 60, 80 and 100% for a total of 6 diets. For each of the two trials, 1500 Cobb 500 male broiler chicks were randomly allocated to 60 pens with 25 birds per pen (10 pens/diet) and grown to 46 days for the first research trial and 41 days for the second. There were no differences (P>.05) between treatments for livability and average weight on days 0, 14, 28 and 46/41 (for diets 1 through 6). For Trial 1 (T1), the 0-46 day adjusted feed conversion (FCR) was higher (P<.05) for the 100% grain sorghum diet as compared to 0, 40, 60 and 80% sorghum inclusion diets. For trial 2 (T2), only the 28-41 day adjusted feed conversion was significant with the 80 and 100% diets supporting higher feed conversions as compared to the other diets. No significant differences were seen in yield or abdominal fat in trial 1. For T2, selection weight for processing was heavier for the 0, 20, 60% diets as compared to the 40 and 100% sorghum diets and this trend carried through to the chilled carcass weight. Also in T2, leg quarters were heavier for the 20 and 40% diets as compared to the 60 and 80% diets and abdominal fat was heavier for the 0 and 40% diets as compared to the 80% diets. As dietary levels of sorghum increased, there was a linear decrease (P<0.05) in shank coloring scores as measured with the DSM color fan for both trials, with the 100% corn diets having the most yellow shanks and the 100% grain sorghum diets having the lightest colored shanks. Breast skin color evaluation post processing showed a similar trend (P=.0001) with the birds fed the 0 and 20% grain sorghum diets having the most yellow skins. Coloring steadily decreased as dietary grain sorghum increased with the 80 and 100% sorghum diets having the lightest breast skin coloring in both trials.

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