Channel catfish, Ictalurus punctatus, production is the largest aquaculture industry in North America (Lovell 1992). Arkansas, Alabama, Mississippi and Louisiana are the four largest channel catfish producing states, contributing over 90% of US production (NASS 2004). Commercial production of channel catfish developed in the southern U.S.A. during the late 1950s and early 1960s.
Initially, channel catfish were raised in ponds at low stocking densities and fed low-cost, incomplete diets. As stocking densities increased, development of nutritionally balanced diets became an economic necessity. Commercially produced, complete catfish feeds were based on the nutrient requirements of other animals, such as poultry and salmonids (Wilson and Lovell 1993). In the early 1970s, development of a fish meal shortage emphasized the need to determine the nutrient requirements of channel catfish, which have since been published (Wilson 1991).
The use of plant proteins to replace fish meal in commercial feeds also required greater attention to satisfying dietary amino acid requirements (Wilson et al. 1981). Amino acids can be provided in the form of intact protein in feed ingredients or in purified, crystalline form as dietary supplements.
The increased use of plant proteins in catfish diets in recent years has led to increased use of purified amino acids to avoid deficiencies caused by high levels of plant products. For example, dietary L-lysine can be supplemented in purified form to eliminate the lysine deficiency in soybean meal, (El-Saidy and Gaber 2002). Evidence from fish other than catfish (Cowey and Sargent 1979, Thebault 1985, Lumbard 1997) suggests that amino acids in intact protein are utilized more efficiently than those provided in crystalline form, possibly because crystalline amino acids are absorbed and catabolized more rapidly than amino acids from intact proteins.
CONTENTS
ACKNOWLEDGEMENTS
LIST OF TABLES
LIST OF FIGURES
ABSTRACT
CHAPTER 1: INTRODUCTION
CHAPTER 2: METHODS AND MATERIALS
CHAPTER 3: RESULTS
CHAPTER 4: DISCUSSIONS
LITERATURE CITED
VITA
