World Aquaculture 17 (2004) reported that growth of pond-cultured red claw was not different when fed diets containing 22 percent, 32 percent or 42 percent protein with a combination of soybean meal and fishmeal. To test the quality of the protein used in the study, we calculated the essential amino acid index (EAAI) of the four diets by looking at the tail muscle, which has a similar amino acid composition to the whole body. If the protein source is of good quality, then they will have an EAAI value greater than 0.90, while if the protein source is of poor quality it will have an EAAI value lower than 0.70. Calculation of the essential amino acid index on the four Table 1. Ingredient and chemical composition (%) of four practical diets containing two levels of protein with or without fish meal fed to red claw crayfish. Proximate analysis values are means of two replications per diet. Diet number 1 2 3 4 Menhaden FM1 7.3 0.0 11.3 0.0 Soybean meal 0.0 9.5 12.0 35.3 DSG 8.3 18.3 30.0 30.0 Other ingredients 74.4 72.2 47.2 35.2 Chemical analysis Moisture 13.7 13.3 13.3 13.9 Protein3 17.8 18.3 27.8 32.7 Lipid3 9.1 9.2 10.2 10.2 Fiber3 5.3 5.2 5.3 3.7 Ash3 6.9 5.2 7.4 6.6 NFE4 60.9 62.2 49.3 46.8 Available energy5 (kJ) 16.7 16.7 16.7 17.2 1FM= fish meal 2DGS = distiller grains with solubles 3Dry-matter basis. 4NFE= nitrogen-free extract (by difference). 5Available energy was calculated as 16.7, 16.7 and 37.7 kJ/g of protein, carbohydrate and lipid, respectively. Table 2. Means (± S.E.) of specific growth rate (SGR), feed conversion ratio (FCR), percentage survival, and yield of red claw crayfish fed four practical diets containing two levels of protein with our without fish meal. FCR, survival and yield had no significant differences among the diets being fed. Means within a row having different superscripts are significantly different (P < 0.05). Diets 1 2 3 4 SGR (%/day) 1 2.23±0.08c 2.26±0.07bc 2.37±0.03ab 2.43±0.07a FCR2 4.13±0.67 3.48±0.37 3.25±0.27 3.33±0.28 Survival (%) 63.0±8.6 70.1±2.4 66.6±4.6 60.9±2.1 Yield (kg/ha) 645±116 733±65 768±61 748±59 1SGR = (%/day)= 100 x [(ln Wt - lnWi)]/day. 2FCR= total diet fed (kg)/ total wet weight gain (kg) fed Diet 4 was significantly higher (2.43 percent/day) for red claw fed Diets 1 and 2, but not significantly different from that of red claw fed Diet 3 (2.37 percent/day). Feed conversion ratios, survival and total yield did not differ significantly among treatments, averaging 3.55, 65.2 percent, and 724 kg/ha, respectively (Table 2). Processing traits of male red claw showed that males fed Diet 3 had significantly higher claw weight (17.9 g) than males fed Diet 4 (13.7 g), but did not differ significantly from males fed Diet 1 (16.3 g) and Diet 2 (15.6 g). Male red claw fed Diet 3 also had significantly higher weight of tail (with shell) and tail muscle meat (23.6 g and 16.8 g) compared with male red claw fed Diet 1 (19.6 g and 14.1 g) and Diet 2 (20.6 g and 14.6 g), but not different from male red claw fed Diet 4 (21.9 g and 15.5 g). Male red claw fed Diet 3 also had a significantly higher cephalothorax weight (32.2 g) compared with males fed Diet 1 (27.8 g), but did not differ significantly from males fed the other two diets (Figure 2). Female red claw fed Diet 3 had significantly higher claw weight (9.7 g) than females fed the other three diets. In weight of tail (with shell), females fed Diet 1 (17.5 g) were significantly lower than those fed Diets 3 and 4 (19.9 and 19.5 g), but not different from female red claw fed Diet 2 (18.4). Female red claw fed Diets 3 and 4 had significantly higher weight of tail muscle meat (13.2 g and 13.1 g) compared to female red claw fed Diets 1 and 2 (11.7 g and 11.8 g). Female red claw fed Diet 3 had significantly higher cephalothorax weight (26.4 g) than females fed Diets 1 and 2, but did not differ significantly from females fed Diet 4 (Figure 3). Discussion The results of the present study indicate that red claw grown in ponds can be fed a practical diet in which fishmeal is completely replaced with a combination of plant proteins, such as soybean meal and distillers dried grains with solubles with a protein level of 28 percent. However, when red claw were fed diets containing 18 percent crude protein, even with 7.3 percent FM included, growth was reduced. These data are the first to indicate that the quantity and quality of protein is important for growth of red claw grown in ponds. In a previous study, Thompson et al.
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