Dietary taurine enhances growth and digestive enzyme activities in larval cobia

Abstract

The establishment of a commercial cobia aquaculture is hampered by high mortality rates (>90%) during the larval rearing. Dietary taurine supplementation has been reported to greatly improve survival rates; however, nutritional role of taurine remains poorly understood in fish. The purpose of this trial was to study the effect of taurine supplementation on growth, amylase, lipase, trypsin, and pepsin-like activities during larval cobia development and weaning. Taurine was delivered using bioencapsulation techniques wherein rotifer and Artemia nauplii were co-enriched with 4gtaurineL−1d−1. At first feeding (3 dph), amylase and trypsin activities were detectable while lipase and pepsin-like activities were not. On a per-larvae basis and regardless of taurine supplementation, enzymatic onset commenced around 16 dph, except for pepsin. However, taurine-supplemented larvae had higher specific trypsin and amylase activities prior to 16 dph. Lipase specific activity was significantly increased only at 11 and 22 dph. Pepsin-like activity remained undetectable until 22 dph, at which point the specific activity was higher (P<0.05) in taurine-supplemented larvae. Overall, specific enzyme activities of control larvae were low during the first half of the larval period (3–16 dph) but increased during the second half (17–27 dph). Specific activities of taurine-supplemented larvae showed the opposite trend. Together with previous work, the present data strongly indicate that taurine is an essential nutrient for cobia larvae. Taurine supplementation does not affect the onset of total enzyme activities, but does increase specific amylase and trypsin activities in early larval stages. These heightened enzymatic activities may lead to enhanced nutrient availability, thus providing some explanation to the improved development, growth, and survival rates observed in taurine-supplemented larvae.