|KOBAYASHI, YUKA - Kentucky State University|
|THOMPSON, KENNETH - Kentucky State University|
|GANNAM, ADNN - Us Fish And Wildlife Service|
|TWIBELL, RONALD - Us Fish And Wildlife Service|
|KOCH, JOAO F. - Universidade Estadual Paulista (UNESP)|
Submitted to: Aquaculture Research
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 9/30/2013
Publication Date: 3/13/2014
Citation: Kobayashi, Y., Webster, C.D., Thompson, K.R., Gannam, A.L., Twibell, R.G., Koch, J.A. 2014. Effects on Growth, Survival, Body Composition, Processing Traits, and Water quality when feeding a diet without vitamin and mineral supplements to Australian red claw crayfish (Cherax quadricarinatus) grown in ponds. Aquaculture Research. DOI: 111/are.12427.
Interpretive Summary: Australian red claw crayfish is a tropical species found in the river systems of northern Queensland and the Northern Territory, Australia, and Papua New Guinea. Globally, red claw has become a popular crustacean species in several countries around the world because of their potential large size and resemblance to high-priced American lobster. Red claw has received attention as an aquaculture species in some states in the U.S. due to their large potential size, ease of culture, and the ability to grow them indoors in recirculating systems. Further, studies have shown that red claw are highly-desired by consumers because of their excellent tail-meat flavor, lobster-like appearance, are larger than shrimp, and have excellent storage quality. However, since red claw are a subtropical species, culture of red claw in temperate climate ponds is constrained by a growing season that last 5-7 months in length. Further, red claw juveniles are not readily-available in the U.S.; therefore, producers must purchase these individuals from hatcheries in other countries (Australia or Mexico) and costs can range from $0.50 to $0.60 (U.S.) per juvenile (with transport costs). Likewise, diet costs can represent up to 80% of the total operating expenses of an aquaculture enterprise. As a result, production of red claw in the U.S. continues to be scattered and small-scale. It is important to keep diet costs as low as possible to help increase producer's profits. Currently, many producers of red claw utilize a modified marine shrimp diet to ensure adequate nutrition and/or use low-quality diets that do not meet all their nutritional requirements, thus compromising growth. Thus, recent efforts to determine specific nutrient requirements and evaluate inexpensive practical diets have been devoted to reduce diet costs and possibly increase profits. To that end, the present study was conducted. Juvenile red claw were stocked into 1/20th-acre research ponds and fed one of three diet treatments. In the first treatment, they were fed a diet containing 42% protein and having added vitamin and mineral mixes, along with hay. In the second treatment, red claw were fed a diet containing 28% protein but without added vitamins and minerals, along with hay. The third treatment had red claw being fed just hay. After 105 days, red claw fed the first two treatments were larger than the red claw fed only hay. There were no differences in final weight, growth rate, nutrient composition, or survival of red claw fed a diet with lower protein (28%) and no vitamins and minerals compared to red claw fed a high-protein diet (42%) with vitamins and minerals. Reducing protein in the diet, and by not adding vitamins and minerals, cost of the diet could be reduced $60-90/ton for farmers which could increase the profitability of the red claw operation. Since there were no differences in the growth of red claw fed the two diets, farmers can use the least-expensive diet and still obtain a high-quality product for market.
Technical Abstract: In order to be profitable, producers must reduce diet costs, which can be as high as 80% of the variable costs of an aquaculture expense. As vitamin and mineral premixes represent a significant cost, eliminating addition of these premixes could reduce diet costs if no adverse effects were observed for growth and production parameters. A 105-day feeding trial was conducted with juvenile Australian red claw crayfish (Cherax quadricarinatus) to evaluate the effects of growth, survival, body composition, processing traits, and water quality when red claw fed a supplemental diet containing 28% crude protein (CP) without vitamin and mineral premixes and supplemented alfalfa hay compared to red claw fed a diet containing 42% CP, vitamin and mineral premixes, and with supplemented alfalfa hay, and red claw only fed alfalfa hay when grown in ponds. Juvenile red claw (mean weight of 15.7 +/- 1.0 g) were randomly stocked into nine 0.02-ha ponds at a rate of 640 per pond (3.2 m2-1), and each treatment was used in three ponds. There were two feedings per day, each consisting of one-half of the total daily ration. At harvest, individual weight, percentage weight gain, specific growth rate, survival, and total yield of red claw fed a control diet was significantly higher (P < 0.05) (83.0 g, 398%, 1.53% day-1, 65.1%, and 1708 kg ha-1, respectively) compared to red claw only fed alfalfa hay (44.9 g, 202%, 1.04% day-1, 30.3%, and 431 kg ha-1, respectively), but not different (P > 0.05) from red claw fed the supplemental diet without vitamin and mineral premixes (76.2 g, 367%, 1.47 % day-1, 57.2%, and 1378 kg ha-1). There were no significant differences (P > 0.05) in feed conversion ratio (FCR) among treatments, which averaged 5.0 (based on prepared diet input). These results indicate that vitamin and mineral supplementation in a diet is not necessary when diet containing 28% CP and alfalfa hay are used in combination for pond grown red claw. These results may help reduce diet costs and thereby increase producers' profits and allow for industry expansion.