Use of Poultry By-product and Plant Protein Sources in Diets of Redclaw (Cherax quadricarinatus)

A total of 300 juvenile crayfish (13.0±0.03 g) were randomly distributed among 5 dietary groups (n=60, 3 replicates) held within 15×500 L-1 fiberglass tanks connected to a recirculation system (RAS), at 20 crayfish per tank. Each group was fed for 12 weeks one of five experimental diets where the main protein sources were: 1) control, fish-meal-based diet (FM, 48% of the diet); 2) 10% FM + 52.5% poultry by-product meal (PoM); 3) 34.5% soybean meal + 34.5% corn gluten meal (Pmix); 4) 34.5% PoM + 32.soybean/corn gluten meal mix (PoM/Pmix); and 5) 10% FM + 27.5% soybean + 27.5% corn gluten meal (FM/Pmix). The results demonstrated that there were no significant differences among diets in terms of growth and feed utilization efficiency. Muscle amino acid profile of redclaw crayfish fed the FM diet had the highest level of total essential amino acids, followed by FM/PMix, Pmix, PoM/Pmix, and PoM diets. Particularly, in all experimental groups, the highest essential amino acids (EAA) were lysine, arginine, and leucine. Based on these findings, we conclude that redclaw can perform well with FM-free vegetable diets and PoM-based diets although more research is needed into the total composition of EAA and FA in muscle

Partial Replacement of Fishmeal with Hazelnut Meal in Diets for Juvenile Gilthead Sea bream (Sparus aurata)

Hazelnut meal was evaluated as an alternative protein source to fishmeal in diets of gilthead sea bream with an initial weight of 35.08±0.29 g. Incorporation levels of hazelnut meal were 0% (con- trol), 10%, 20%, 30%, and 40%. Each diet was tested in triplicate for ten weeks. There were no significant differences between the experimental diets and the control in final body weight, weight gain, specific growth rate, or feed and protein efficiency ratios. In addition, the level of hazelnut meal did not significantly affect the whole body composition of the sea bream. In con- clusion, up to 40% hazelnut meal could be included in diets for gilthead sea bream juveniles with- out adverse effects on growth rate or body composition

Effects of Replacement of Fishmeal with Hazelnut Meal on Growth Performance, Body Composition, and Nutrient Digestibility Coefficients in Rainbow Trout, Oncorhynchus mykiss

Hazelnut meal was evaluated as an alternative protein source to fishmeal in diets for rainbow trout, Oncorhynchus mykiss (initial wt 57.5±0.1 g). Hazelnut meal was incorporated in the diet at levels of 0% (control), 7.5%, 15%, 22.5%, and 30%. Diets were tested in triplicate for ten weeks. Higher levels of hazelnut meal produced better growth performance, that was sig- nificantly higher in fish fed 30% hazelnut meal than in the control (p<0.05). Feed utilization and protein efficiency ratios followed a similar trend while the level of hazelnut meal did not significantly affect whole body composi- tion. Apparent digestibility of dry matter and energy of fish fed hazelnut meal at all levels was significantly lower than in fish fed the control (p<0.05). Crude and digestible protein, as well as energy retention, were significant- ly correlated with hazelnut meal level. Nevertheless, energy retention declined in fish fed 30% hazelnut meal. Based on growth performance and nutrient retention, the optimal level of hazelnut meal in diets for rainbow trout may be around 30%

Effects of natural and synthetic pigments in diets on flesh coloration and growth of rainbow trout (Oncorhynchus mykiss W.)

The desired pink to red color of rainbow trout flesh (Oncorhynchus mykiss W.) can be obtained by adding carotenoids to the fish diet. This study was conducted to determine the effects on growth and color retention of natural pigments (30 ppm red pepper meal, 60 ppm red pepper meal, 30 ppm shrimp by-products meal, 60 ppm shrimp by-products meal), synthetic carotenoids (30 ppm astaxanthin, 60 ppm astaxanthin), and a control group (no added pigment). Duplicates of each of the seven treatments were reared for three months. The best specific growth rates were obtained with 30 ppm astaxanthin (0.83%) and 60 ppm red pepper meal (0.84%); the low- est was in the control (0.54%). The lowest food conversion ratio was obtained with 30 ppm astax- anthin (1.38) and highest in the control (2.23; p<0.05). Visual coloration values ranged from 14.46±0.23 in the 30 ppm astaxanthin group to 11.55±0.25 in the control. Retention coefficients ranged from 6.63 in the 30 ppm astaxanthin group to 1.79 in the 60 ppm shrimp by-products meal (p<0.05). Tristimulus chromometer a values ranged from 0.87±0.47 in the control to 6.96±0.47 in the 60 ppm astaxanthin treatment, b values from 10.94±0.27 in the control to 12.90±0.27 in the 60 ppm red pepper meal treatment, and L values from 46.81±0.50 in the 60 ppm astaxanthin group to 54.57±0.26 in the control (p<0.05)