Effects of early weaning strategies on growth, survival and digestive enzyme activities in cobia (Rachycentron canadum L.) larvae

Abstract

The effects of weaning strategies of cobia (Rachycentron canadum L.) larvae to commercial microdiets, either from rotifers or from Artemia, on growth, survival and enzymatic digestive capacity, were investigated. In the first experiment, cobia larvae were weaned from rotifers by co-feeding with a microdiet (Otohime) from 8, 13 or 20 days post-hatching (dph). The larvae in the control treatment were fed rotifers (2-12 dph), Artemia nauplii from 7 dph, and co-fed with the microdiet from 20 dph. In the second experiment, the larvae were weaned from Artemia, which was fed to the larvae from 7 dph, by co-feeding with a microdiet (NRD) from 8, 13 or 18 dph. The larvae in control treatment were fed rotifers, then Artemia to the end of the experiment (28 dph). Weaning of cobia larvae onto a microdiet directly from rotifers significantly reduced growth, survival and digestive capacity of the larvae and did not lead to larval acceptance of the microdiet, compared to those weaned from Artemia in the first experiment. Early weaning of cobia larvae onto NRD microdiet (on 8 or 13 dph) from Artemia in the second experiment also reduced growth, survival rate and gut maturation index, compared to those fed live feed. With available microdiets, weaning of cobia larvae could start from Artemia at around 18 dph in order to obtain comparable growth, survival and gut maturation to larvae fed live feed.

The effect of age, size and digestive tract development on burbot,Lota lota(L.), larvae weaning effectiveness

“…; Nguyen et al . ). Thus, further studies on weaning burbot larvae are needed where feed composition as well as attractiveness of the feed offered should be considered, and thus make a first attempt for developing specific feed.…”

The effect of feeding frequency on growth performance of juvenile cobia, Rachycentron canadum (Linnaeus, 1766)

“…However, in practical farming operations, cobias may be fed more than once per day. During weaning, cobias are fed manually to satiation 5 to 6 times daily (Liao et al., ) or as many as 10 times a day (Nguyen et al., ) as a way to reduce cannibalism. In grow‐out within sea cages, cobia may be fed once a day and 6 days a week (Liao et al., ) or twice a day (Benetti et al., ), while in recirculation aquaculture systems dividing feeding in several daily sessions is preferred as a way to avoid peaks of oxygen demand and ammonia excretion by fish.…”

Sudden weaning of angel fish pterophyllum scalare (Lichtenstein) (Pisces; Cichlidae) larvae from brine shrimp (Artemia sp) nauplii to formulated larval feed

“…Therefore, the least growth performances observed in larvae exclusively fed dry feed (TR4) could be attributed to a less developed digestive system which cannot support fish larvae to fully digest artificial dry feed. Further, Artemia nauplii contain nearly 56% protein and 17% lipid (Garcí a-Ortega et al 1998 ; Nguyen et al 2011) that make it as an excellent feed for first-feeding larvae. Aquaculture organisms are in need of ascorbic acid (vitamin C) during their developmental stages and the requirements vary with the developmental stage.…”