Effects of different weaning strategies on survival and growth in Chinese longsnout catfish (Leiocassis longirostris Gunther) larvae

The effects of different weaning strategies during the larval rearing of Chinese longsnout catfish were determined in two trials. In the first trial, the effect of abrupt-weaning from live prey (Artemia nauplii) to micro-diet at 5, 6, 7, 8, 10 dph, respectively was investigated. The second trial examined the effect of weaning with co-feeding at different ages (6, 8 and 10 dph). The survival, growth, digestive enzymes, coefficient of variation of final body weight (CVFBW) and body length (CVBL), digestive enzyme activities, fish body lysozyme and fish body glucose were significantly influenced by abrupt-introducing of microdiet (P<0.05). When weaning with live prey, only the fish body lysozyme significantly increased in the group introduced to microdiet on 8 and 10 dph (P<0.05). The study showed that abrupt-weaning of Chinese longsnout catfish should be obtained after 10 dph. Co-feeding could reduce the stress to larvae and therefore the weaning could start at 6 dph with co-feeding. (C) 2012 Elsevier B.V. All rights reserved.The effects of different weaning strategies during the larval rearing of Chinese longsnout catfish were determined in two trials. In the first trial, the effect of abrupt-weaning from live prey (Artemia nauplii) to micro-diet at 5, 6, 7, 8, 10 dph, respectively was investigated. The second trial examined the effect of weaning with co-feeding at different ages (6, 8 and 10 dph)

Effects of dietary oxidized fish oil on growth performance and skin colour of Chinese longsnout catfish (Leiocassis longirostris Gunther)

A 61-day experiment was carried out to investigate the effect of dietary oxidized fish oil on growth performance and skin colour of Chinese longsnout catfish (Leiocassis longirostris Gunther). Seven diets (Diet 1-7) containing different levels of oxidized fish oil (0, 10, 20, 30, 40, 50 and 60 g kg(-1) dry diet) were evaluated at same dietary lipid level (60 g kg(-1) diet). Fish skin colour (CIE L*a*b*) and melanin content was measured at three zones of fish body: back (Zone I), belly (Zone II) and tail (Zone III). The results showed that there were no significant differences in growth or feed utilization. Apparent digestibility coefficient of energy (ADCe) decreased while those of dry matter (ADCd), protein (ADCp) or lipid (ADCl) were not affected. Lightness (L*) of Zone I or II were not influenced while L* of Zone III decreased. Oxidized oil increased melanin content of Zone III. No apparent effects on the thiobarbituric acid reactive substances (TBARS) values of blood serum, liver and muscle were observed. In conclusion, dietary oil oxidation did not affect fish growth performance. Fish tail skin lightness was lower in the fish fed with high dietary oxidized fish oil and was positively correlated to melanin content