Veronica R. Alava

The quantitative dietary protein requirements of Penaeus monodon juveniles in a controlled environment

Penaeus monodon juveniles (average weight = 1.32 g) were kept in individual 2 l perforated plastic containers, 10 of which were placed in each of the twenty-four 50 l rectangular wooden-glass aquaria supplied with seawater filtered through a sand-gravel filter (32–34 ppt; 26.5–29.0°C; pH, 7.6–8.2) at 0.8–1.01 l/min. Eight diets were prepared containing 25–60% protein and fed at 10% of the body weight/day for the first 2 weeks and 8% for the succeeding 4 weeks. Shrimps fed the 40% protein diet produced the best growth, feed conversion ratio (FCR), protein efficiency ratio (PER) and survival rate. However, shrimps fed the 30, 35 and 45% protein diets produced comparable results. The protein content of the shrimps was directly related to the level of protein diet up to 50%; whereas fat content seemed to be inversely related up to 50% protein diet.

Carbohydrate requirements of Penaeus monodon (Fabricius) juveniles.

Abstract P. monodon juveniles with an initial mean weight of 0.62 g were fed isonitrogenous (45%) and isolipidic (10%) semi-purified diets containing 10, 20 and 30% trehalose, sucrose and glucose for 56 days. Shrimp fed the diet with 20% trehalose had the highest weight gain. Of the three types of sugar tested, shrimp fed diets containing trehalose and sucrose exhibited better weight gains than those fed glucose diets. A dietary sugar level of 20% resulted in the best weight gain whereas the 30% level gave the lowest weight gain. The survival of shrimp was also affected by the type of carbohydrate fed. Trehalose and sucrose diets promoted higher survival rates than glucose diets. The different types and levels of carbohydrates showed combined effects on the dry matter percentages of crude protein and total lipid. Trehalose and sucrose diets generally promoted increased protein deposition. Trehalose at 30% and sucrose at 20% depressed lipid content.

Effect of salinity, dietary lipid source and level on growth of milkfish (Chanos chanos) fry

Abstract Six semi-purified microparticulate diets containing coconut oil (CO), cod liver oil (CLO), and their 1:1 combination (CO+CLO) at 9% and 18% levels were fed to milkfish fry or late postlarvae in freshwater (0 ‰), brackishwater (16‰), and seawater (34‰) for 30 days. A three-factor factorial design (3×2×3) with three replicates per treatment was followed. Sixty-five milkfish fry (5 mg, 6 mm) were stocked per 15-l rectangular glass aquarium and fed with the experimental diets at 20% of biomass daily. Water temperature was 28±1°C during the culture period. Survival was not affected by water salinity, and lipid source or level. Among the 18 treatments, freshwater-reared milkfish fry fed with 9% CO+CLO had the highest specific growth rate, but this was not significantly different from those of freshwater-reared fish fed with 9–18% CO and 9% CLO diets or brackishwater-reared fish fed with 9% CO diet ( P >0.05). As a main factor, salinity or dietary lipid level, but not lipid source, had significant effects on growth and feed conversion ratio of milkfish fry. Highest growth was observed in fish reared in freshwater and as salinity was increased, growth decreased ( P P P

Artificial diets for milkfish, Chanos chanos (Forsskal), fry reared in seawater

Abstract Milkfish fry obtained from the wild (0.009 g body weight, 10 mm total length) were stocked at 200 individuals in each of 18 fiberglass tanks containing 30 l of filtered aerated seawater. Mean salinity and temperature were 33 ppt and 28.3°C, respectively. The fry were fed with six artificial dry diets containing a mean crude protein of 40.8%. The diets were fed at the rate of 20% of the biomass/day for the first 14 days and 15% of the biomass/day for the last 14 days. Results indicated that there were no significant differences among the treatment means ( P >0.05). Milkfish fry had mean body weights of 0.173–0.202 g, mean total lengths of 29–31 mm, mean feed efficiency values of 0.94–1.16, and mean survival rates of 92–98%. The remarkably similar response of milkfish fry to the six diets demonstrated that the diets contain the essential nutrients necessary for a fast-growing fish. Soybean meal can replace corn gluten meal and meat and bone meal can substitute shrimp head meal for up to 8% of the crude protein.

Effect of dietary fatty acids on growth of milkfish Chanos chanos fry in brackish water

Abstract Five purified microbound diets containing 1% of 18:2 n − 6, 18:3 n − 3, 20:4 n − 6, or n − 3 highly unsaturated fatty acids (HUFA: 60% 20:5 n − 3 + 40% 22:6 n − 3) in addition to 8% 18:1 n − 9, and a control diet containing 9% 18:1 n − 9 were fed to milkfish fry or late postlarvae for 30 days (Trial 1) and 35 days (Trial 2). The salinity was 16–17‰ and temperature was 27 ± 1 °C during the culture periods. A completely randomized design with three replicates per treatment per trial was followed. In each trial, 60 fish (5mg, 6mm) were stocked per 301 oval plastic tank and fed the experimental diets at 20% of biomass per day. Survival of 100% observed for all groups in both trials demonstrated that the milkfish fry reared in brackish water utilized the test diets. Specific growth rates did not differ significantly among treatments ( P 0.05), with values of 9.5–9.9% and 10.0–10.3% in Trials 1 and 2, respectively. Weight, length and feed conversion ratio of milkfish fry fed the various diets also did not differ significantly ( P 0.05). Although not significantly differentiated in Trial 1 ( P 0.05), incidence of eye abnormality was highest in milkfish fry fed the 18:1 n − 9 diet in Trial 2 ( P 0.05).

Nursery Culture of Grouper (Epinephelus fuscoguttatus Forsskal) and Sea Bass (Lates calcarifer Bloch) in Brackish Water Ponds: Co-Feeding of Zooplankton and Formulated Diets Containing L-Tryptophan

This study compared co-feeding zooplankton (ZP, mixed copepods and mysids) and formulated diets (FD) supplemented with L-tryptophan (TRP) on the survival and growth of grouper and sea bass fry nursed in brackish water ponds. Grouper (84 fry m−3) and sea bass (150 fry m−3) were reared for 30 days and 60 days, respectively, in net cages within two separate 743 m2 nursery ponds. Five treatments (with three replicates each) were compared (P < 0.05): FD-1 = ZP + basal FD (no added TRP, but containing 0.29% endogenous TRP); FD-2 = ZP + (FD 0.58% TRP); FD-3 = ZP + (FD 1.22% TRP); FD-4 = ZP + (FD 2.50% TRP); and FD-5 = minced fish (Sardinella sp.) + basal FD (no additional TRP). TRP supplementation in grouper diets produced no significant affect on growth but increased survival at rates of 0.58% and above. TRP supplementation at 2.5% (FD-4) produced significantly better sea bass growth than other diets but had no affect on survival. Zooplankton improved both survival and growth in both grouper and sea bass juveniles compared to the minced fish diet, and may be a practical and lower cost alternative to indoor nursing.