Dry matter, protein, and energy digestibility of diets for juvenile Pacific white leg shrimps (Litopenaeus vannamei) reared at different salinity levels

ABSTRACT: This study evaluated the effect of low, medium, and high-water salinity (5, 35, and 50 ppt) on the apparent dry matter, protein, and energy digestibility of two formulated and six commercial diets for juvenile whiteleg shrimp, Litopenaeus vannamei, in a 120-day trial. Digestibility was determined in vivo using chromic oxide as an inert diet marker. Hydrostability in pellets varied from 86.8% to 99.9%; dry matter digestibility varied from 49.1% to 64.1%; protein digestibility showed greater variations at all salinities (56.9%-85.8%); and energy digestibility ranged from 70.1 to 86.4%. Salinity had a significant effect on dry matter, protein, and energy digestibility. Using a principal component analysis (PCA) with a covariance matrix, our findings suggested that the E2 (fishmeal-based formulation) diet and 35 ppt salinity provided optimum hydrostability and digestibility to Pacific white leg shrimp juveniles.

FOOD ACCEPTANCE IN DIFFERENT LARVAL STAGES OF Macrobrachium carcinus

Food acceptance in different larval stages of Macrobrachium carcinus was evaluated by investigating the stage at which the ingestion of inert moist diet food begins and by the incidence of Artemia nauplii and inert moist diet in the digestive tract throughout development. Two experiments were carried out: in the first study, the acceptance of the inert diet was evaluated in 60 larvae of each stage (I to XII) fed ad libitum after two hours of fasting. The inert diet was 100% accepted at zoea stage V. In the second study, newly hatched larva was then kept in larval tanks and fed with Artemia nauplii and inert moist diet simultaneously. Fifteen minutes after feeding, 50 specimens of each larval stage were examined and evaluated for the ingestion of these foods. Larvae at stage I did not feed, while larvae at stage II consumed both live and inert food. From the stage of zoea IX, the exclusive consumption of Artemia nauplii was not verified. These data indicate that feeding M. carcinus in larviculture can be initiated at stage II with inert moist diet and Artemia nauplii, and an exclusive supply of inert moist diet from stage IX can be recommended.

Planktonic Crustacean Culture—Live Planktonic Crustaceans as Live Feed for Finfish and Shrimps in Aquaculture

The cultivation of planktonic crustaceans as live feed is of paramount importance for the aquaculture and aquarium industries. The use of live cladocerans as feed for freshwater fish is limited to the aquarium industry, whereas Artemia and copepods are used to feed edible marine fish larvae with small mouth gape. Live feed production is expensive and time consuming; therefore, it is only used for fish that cannot be fed an inert diet directly, and only until they are ready for weaning to an inert diet. High-quality planktonic crustacean cultures are furthermore used to conduct environmental risk assessments for hazardous chemicals. Cladocerans are widely used for ecotoxicology testing, but Artemia and copepods are emerging as new model species. The present chapter reviews the culturing procedures of these important planktonic crustaceans: Artemia, cladocerans, and copepods. It discusses their use as live feed and as test organisms for environmental risk assessments. The culturing procedures are categorized into three complexity levels: Extensive, semi-extensive, and intensive. In general, the pros for Artemia and cladocerans are that they are easier to culture than copepods. Copepods are often more difficult in term of culture requirements and feeding. Nevertheless, copepods have the advantage of being in either freshwater or saline water, whereas cladocerans are limited to freshwater and Artemia to seawater. Artemia cysts and copepod eggs have a well-defined protocol for storage and distribution to aquaculture end users. Cladocerans, however, have the potential for the ephippia stage, although this is not well developed. For toxicological testing, three species are used: Artemia franciscana, Daphnia magna, and Acartia tonsa, with Artemia and A. tonsa in seawater testing, D. magna in freshwater testing. The chapter concludes with a comparative analysis of these organisms from use and culturing capability and demonstrates that there are strong similarities and challenges across these taxa.

Duration of co-feeding on the Nishikigoi Cyprinus carpio larvae during weaning from live to inert food in an indoor system

ABSTRACT: This study aimed to evaluate the effects of the co-feeding period (C) on the survival and growth of larvae of nishikigoi Cyprinus carpio, during the weaning period from live to inert food. A total of 1680 larvae with initial weight of 1.33 ± 0.12mg and initial length of 6.0 ± 0.33mm were used. The inert diet used was a commercial ration with 55% crude protein and the live food was the newly hatched nauplii of Artemia franciscana. The experiment was conducted following a completely randomized design with six treatments and four replications. Treatments constituted of: a) LF = supply of live food throughout the experimental period; b) C4 = 6 days of live food + 4 days of co-feeding (inert diet and live food) + 16 days of inert diet; c) C8 = 6 days of live food + 8 days of co-feeding + 12 days of inert diet; d) C12 = 6 days of live food + 12 days of co-feeding + 8 days of inert diet; e) IF = supply with inert diet throughout the experimental period; and f) F = fasting. Our results showed that the co-feeding period influences the survival and growth of the larvae. Survival in the treatment with the longest co-feeding period showed an improvement of over 70% when compared to the shortest period. Further, we noted a doubling of the juvenile weight after 26 days of age. There was a quadratic effect for all parameters, with maximum points ranging between 19.4 and 22.6 days of supply of live food. We concluded that the supply of commercial feed as exclusive food is unworkable in nishikigoi larviculture.