Substitution of Cottonseed Meal for Marine Animal Protein in Diets for Penaeus vannamei

Solvent-extracted cottonseed meal was used in shrimp Penaeus vannamei diets at levels of 0, 13.3, 26.5, 39.8, 53.0 and 66.3%, substituting on an equal nitrogen basis for 0, 20, 40, 60, 80 and 100% of animal protein mix (53% menhaden fish meal, 34% shrimp waste meal and 13% squid meal). The feeds were formulated to contain 32% crude protein and 3,100 kcal metabolizable energykg. Each diet was fed to juvenile shrimp to satiation four Hmes daily for 8 wk. Shrimp fed the three lowest dietary levels of cottonseed meal (0, 13.3 and 26.5%) had similar weight gain, feed consumption and survival. The performance of shrimp was adversely affected when diets containing more than 26.5% cottonseed meal, or 1,100 ppm free gossypol, were fed. Shrimp fed the diet with 39.8% cottonseed meal or 1,600 ppm free gossypol had depressed weight gain, reduced feed intake and high mortality. The groups receiving the two highest dietary levels of cottonseed meal lost weight by the end of week 4 and all shrimp in these treatments died within 6 to 8 wk. These adverse effects were probably due to the toxicity of free gossypol. Shrimp appeared to accumulate gossypol in the body as evidenced by light yellow-green coloration in shrimp fed diets containing cottonseed meal. Feed is normally the single largest expenditure in semi-intensive and intensive shrimp culture operations, and protein is the most expensive component in feeds for shrimp. This is due to extensive reliance on marine animal protein such as fish meal, shrimp meal and squid meal to meet the high dietary protein requirements for shrimp. These feedstuffs have high nutritional value and palatability but are expensive and not always readily available (Lim and Dominy 1990). Thus, replacement of these high-cost ingredients with less expensive plant proteins would be beneficial in reducing feed costs. Cottonseed meal, which ranks second in the United States (Dorsa et al. 1982) and third in the world (Swick and Tan 1995) in tonnage among the vegetable protein concentrates produced, is available at a much lower cost than animal proteins. At present, cottonseed meal is widely used as a protein supplement for ruminant livestock but its use in nonruminent animal feeds is limited due in part to the presence of gossypol, a toxic component for monogastric animals (Swick and Tan 1995). and the low concentration of lysine. The nutritional value of cottonseed meal has been evaluated for several species of finfish such as chinook and coho salmon (Fowler 1980), tilapia (Jackson et al. 1982; Ofojekwu and Ejike 1984; Robinson et al. 1984; Viola and Zohar 1984; El-Sayed 1990) and channel catfish (Dorsa et al. 1982; Robinson and Rawles 1983; Robinson et al. 1983; Robinson and Daniels 1987; Robinson and Brent 1989; Robinson 1991 ; Robinson and Li 1994; Robinson and Tiersch 1995). Generally, it has been reported that the amount of cottonseed meal that can be included in fish feeds depends on the species and levels of free gossypol, dietary protein and available lysine. Fernandez and Lawrence (1988) reported that different levels of cottonseed meal can be incorporated in the diets of penaeid shrimp depending on the shrimp species and dietary protein levels. Cottonseed meal can also be used as a substitute for fish and shrimp head meals in shrimp diets without reducing growth, but at lower levels than 0 Copyright by the World Aquaculture Society 1996