Date of Award


Document Type


Degree Name

Doctor of Philosophy (PhD)


School of Nutrition and Food Sciences

First Advisor

Samuel P. Meyers


The present investigation involved utilization of the chitin-carotenoid complex and the whole meal derived from crayfish (Procambarus clarkii) composite byproduct, in controlled broiler diets to determine the biological value of these substrates as potential sources of growth promoters, red intensifying agents, and protein supplements. Included are basic studies of the unique characteristics of the chitin-protein and chitin-carotenoid complexes. The crawfish chitin-carotenoid substrate did not exhibit any deleterious effects on broiler growth performance in terms of animal weight gain and feed efficiency at levels up to 5% of the total diet. Controlled chitin addition to the diet indicated no apparent relationship with the degree of chitinoclastic activity in the gizzard and intestine of broilers. Similar results were observed between specific chitinase activity and overall broiler growth rates. Astaxanthin pigment in the chitin-carotenoid substrate was demonstrated to impart significant red intensifying effects to broiler skin and shank pigmentation, even at levels as low as 0.52 mg/kg feed. Compared with whole crawfish meal, sieved meal gave a 170% increase in corrected protein, and decreases of 23% in calcium, 24% in ash, and 27% in chitin. The protein quality of whole crawfish meal was comparable to that of soybean meal based on broiler weight gain, feed conversion, and protein efficiency ratio, using a non-protein nitrogen corrected value. The biological availability of the crawfish astaxanthin pigment in the meal was confirmed with practical broiler skin and shank coloration analysis. The protein in the crawfish chitin-protein complex was demonstrated to be associated with chitin by covalent bonding. The ratio of chitin to covalently bound protein was 33.6 to 1, contrasting significantly with data from other crustacean meal studies. Higher astaxanthin stability in the chitin-carotenoid complex was observed compared with earlier studies on pigment stability in crawfish meal, with and without antioxidant treatment. Data suggest this may be attributed to the firmly bound carotenoid/chitin compared with the bonding strength of pigment to calcium and protein in the composite complex. The research confirms the significant physiological availability of astaxanthin from the crawfish chitin-carotenoid complex.