Use of turkey meal as partial and total replacement of fish meal in practical diets for sunshine bass (Morone chrysops x Morone saxatilis) grown in tanks

Economical, nutritious diets for hybrid striped bass (HSTB) are required for the continued expansion and sustainability of this industry. Turkey meal (TM) is a by-product of the US turkey industry and is a potentially-valuable local, alternative protein source for use in aquaculture diets because of its excellent nutritional composition and quality. TM may substitute for more expensive fish meal (FM)-based diets; however, there are no published data with regard to using this ingredient in sunshine bass diets. Therefore, a 16-week feeding trial was conducted with juvenile (36 g) sunshine bass (Morone chrysops x Morone saxatilis) to evaluate growth, feed conversion and body composition when fed diets with decreasing levels of FM (300, 200, 100 and 0 g kg(-1)) and increasing levels of turkey meal (0, 97, 175 and 264 g kg(-1)). Four practical diets were formulated to contain 400 g kg(-1) protein and similar energy levels. Twenty fish were stocked into each of the 12, 1200-L circular tanks and were fed twice daily ad libitum. At the conclusion of the feeding trial, there were no significant (P > 0.05) differences in final mean weight, percentage weight gain, specific growth rate and feed conversion ratio among treatments, which averaged 363.7 g, 904.3%, 2.02% day(-1) and 1.73, respectively. Percentage survival of fish fed diet 4 (0 g kg(-1) FM and 264 g kg(-1) TM) was significantly (P > 0.05) lower (survival = 88.3%) than fish fed diet 3 (100 g kg(-1) FM and 175 g kg(-1) TM; survival = 95%), but not different from fish fed diet 1 (survival = 92.5%) and fish fed diet 2 (survival = 93.3%). Fillet weight and amount of abdominal fat were not significantly different among all treatments and averaged 258 and 58 g kg(-1), respectively. Fish fed diet 1 (300 g kg(-1) FM, 0 g kg(-1) TM) and diet 2 (200 g kg(-1) FM and 970 g kg(-1) TM) had a significantly (P < 0.05) lower hepatosomatic index (2.83 and 3.01, respectively) than fish fed diet 4 (3.33), but not different (P > 0.05) compared to fish fed diet 3 (3.14). Lipid in the fillet of fish fed diet 2 (197 g kg(-1)) was significantly (P < 0.05) higher than fish fed all other diets; and the percentage lipid in the fillet of fish fed diet 1 (126 g kg(-1)) was significantly lower than fish fed diets 2 and 4, but not different (P > 0.05) compared to fish fed diet 3. Fillet moisture, protein and ash were similar among fish fed all diets and averaged 748, 798 g kg(-1) and 51.0 g kg(-1) (dry-matter basis), respectively. The amino acid composition of fillets was similar among all treatments with a few slight significant differences. Results from the present study indicate that tank-grown sunshine bass can be fed a diet containing 264 g kg(-1) TM with 0 g kg(-1) FM, compared to diets containing up to 300 g kg(-1) FM, without adverse effects on weight gain, growth rate, feed conversion and body composition. Further research should be conducted using lower-protein diets to determine minimum protein level for tank-grown sunshine bass.