Masters Theses

Date of Award

8-2008

Degree Type

Thesis

Degree Name

Master of Science

Major

Animal Science

Major Professor

Kelly R. Robbins

Committee Members

Michael O. Smith, Judith M. Grizzle

Abstract

Consumer demand for chicken breast meat has led poultry breeders to emphasize selection for high breast muscle yield, resulting in contemporary broilers that grow rapidly with heavy muscling. Genetic selection for fast growth and high yield has increased the incidence of PSE-like meat that occurs when low muscle glycogen levels decrease quickly resulting in lactic acid build-up, rapid pH decline, and early rigor mortis onset. Preliminary research in our laboratory suggests that dietary inclusion of creatine in broiler diets may reduce the incidence of Pale, Soft, and Exudative (PSE) like meat. We hypothesized that creatine supplementation in broiler diets increases muscle creatine concentration, which may slow glycogen breakdown, decrease the rate of pH decline, and delay the onset of rigor mortis. To test this hypothesis we fed fast-growth mixed sex broilers creatine-supplemented and non-supplemented (control) corn-soybean diets. Three nutritionally complete diets were formulated for each phase of boiler growth: starter, grower, and finisher. The control diet contained 0% creatine; the other two experimental diets each contained 0.05% creatine provided as either the monohydrate (CMH) or monohydrochloride (CMHC) form. Five birds from each pen were used to determine total body composition; the remaining ten birds in each pen provided samples from the breast muscle that were used to determine pH (<30 min, and 4, 7, and 24 hours), expressible moisture, drip loss, and CIE color values for L*, a*, and b*. Breast muscle from birds fed creatine-supplemented diets underwent a more rapid rate of pH decline than birds fed the control diet (P<.05). The degree of lightness (L*) and degree of redness (a*) was higher in the muscle from birds fed creatine-supplemented diets compared to birds fed the control diet, but only the L* value from birds fed the CMH supplemented diet and a* value from birds fed the CMHC diet were found to be significantly higher than values from muscle of control birds (P<.05). The addition of creatine monohydrate in the diet resulted in markedly higher drip loss percentage compared to the birds fed a control diet (P<.05). Overall, supplementing creatine in the broiler diet adversely affected meat quality characteristics.

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