Ana Tomás

Growth of mediterranean yellowtail (Seriola dumerilii) fed extruded diets containing different levels of protein and lipid

Young Mediterranean yellowtail were maintained for 10 months in three different weight groups (114, 141 and 192 g initial mean liveweight) and fed four extruded diets containing two protein levels (45 and 50% CP) and two lipid levels (14 and 17%) according to a factorial design. Survival at the end of trial was around 70% and was unaffected by treatment. Final mean liveweights were 1044, 1098, 1336 and 1163 g for groups fed 45/14, 45/17, 50/14 and 50/17 protein/lipid diets, respectively. The effect of lipid level was not significant, but the growth of fish fed diets containing 50% CP was higher than those fed the 45% CP diets. Nutritive parameters such as, feed intake, feed conversion ratio and PER were not affected by diets. Body composition and nutrient retention values were similar for fish fed various diets. Viscerosomatic index was higher for fish fed diets containing 17% lipid and hepatosomatic index was higher for those fed 50% CP or 12% lipid. Dressout percentage was higher for fish fed diets containing 50% CP.

Growth of dentex fingerlings (Dentex dentex) fed diets containing different levels of protein and lipid

Abstract Dentex fingerlings weighing 2.5 g initial live weight were fed 12 extruded diets containing four crude protein levels (40%, 45%, 50% and 55%) and three crude lipid levels (12%, 17% and 22%) according to a factorial design, for 6 weeks. Survival was high (84–92%) and specific growth rate (SGR) values were 3.4%, 3.9%, 4.3% and 4.1% day −1 and food conversion ratio (FCR) were 2.2, 2.1, 1.5 and 1.9 for fish fed the diets containing 40%, 45%, 50% and 55% crude protein, respectively. With respect to lipid levels, SGR values were 4.2%, 4.0% and 3.6% day −1 and FCR were 1.7, 1.8 and 2.3 for 12%, 17% and 22% crude lipid, respectively. The effects of protein and lipid levels were significant; final live weight, SGR, FCR and PER values were best for fish fed 50% crude protein and poorest for those fed 22% lipid diets. The best growth performance was observed in fish fed diets containing 50/12 and 50/17 protein/lipid ratios. The results indicate that optimum growth and nutrient utilisation of dentex fingerlings can be obtained when they are fed a diet containing around 50% crude protein with a lipid level ranging from 12% to 17%, and having a crude protein/gross energy ratio from 22 to 25 g MJ −1 .

Ionic composition and physio-chemical parameters of the European eel (Anguilla anguilla) seminal plasma

Looking for good sperm diluting media, physio-chemical parameters and ionic composition of the eel seminal plasma were studied in relation with sperm motility.

The effect of dietary soybean meal on growth, nutrient utilization efficiency, and digestibility of juvenile common dentex, Dentex dentex (Actinopterygii: Perciformes: Sparidae).

Background. The aim of this work was to study the growth of juvenile dentex fed on cooking-extruded diets, determine the level of substitution of fishmeal by soybean meal may be without affecting the growth in this species and its digestibility. MaterialsandMethods. The availability of defatted soybean meal as a substitute for fish meal was evaluated in juvenile (41 g on average) dentex by feeding diets containing 0%-60% soybean meal, for 97 days. Results. Survival at the end of the experiment was high (80%) except for the fish fed diets with 50% and 60% substitution. Growth, feed gain ratio, and protein efficiency ratio (PER) were slightly reduced at higher soybean meal levels. Fish fed diets containing 0% to 40% of soybean meal grew significantly more and FCR was lower than fish fed other diets. No differences were obtained for protein digestibility coefficients of experimental diets (20%, 30%, 40%, and 50% SBM). Conclusion. The results confirm the best protein level for optimum growth seems to be around 50% and 12% lipid level, and maximum soybean meal substitution of 40%.