An experiment was conducted to investigate the effects of phosphorus (P), citric acid (CA) and formic acid (FA) supplementation on growth and loading of nitrogen (N) and phosphorus (P) in juvenile yellowtail fed fish meal (FM) and alternate plant protein (APP) diets. Six diets designated as F49 (490 g kg )1 FM-based), F49 + P (490 g kg )1 FM with 5 g kg )1 inorganic P), F31 + CA (310 g kg )1 FM containing 200 g kg )1 APP with 5 g kg )1 CA), F31 + FA (310 g kg )1 FM having 200 g kg )1 APP with 4 g kg )1 FA), F23 + CA (230 g kg )1 FM containing 300 g kg )1 APP with 5 g kg )1 CA) and F23 + FA (230 g kg )1 FM having 300 g kg )1 APP with 4 g kg )1 FA) were formulated. Yellowtails were fed one of the diets for 12 weeks under on-site conditions at water temperature 22.0-27.0°C. F49 + P gave the best growth, while F23 + CA the lowest. Specific growth rate and feed conversion ratio of F31 + CA were similar with control group. Addition of CA to APP diets significantly increased retention of P; hence, its excretion was lowered. The results of this study suggest that FM could be replaced up to 70% with the addition of 5 g kg )1 CA to a low P-containing plant protein sources diet without inorganic P supplementation in juvenile yellowtail diets, which in turn would enable a reduction in environmental pollution from aquafeeds.

The present study evaluates the use of rubber seed meal (RSM) and its defatted product on the growth and feeding performance of common carp Cyprinus carpio L. Digestibility test using chromium oxide as a tracer showed that defatted RSM (DRSM) resulted in significantly higher total feed, protein, Ca and P digestibility than those of unprocessed RSM (URSM). Growth test was performed with a control and three experimental diets which were 50% DRSM (50% of protein originated from DRSM), 75% DRSM (75% of protein originated from DRSM) and 50% URSM (50% protein originated from URSM). The use of diet containing URSM to replace 50% protein source resulted in the lowest growth and feeding performance which might correlate to the high cyanide content (1.16%) in the diet. Furthermore, providing the fish with this particular experimental diet also caused decline in fish haematological parameters and increased abnormalities in the fish intestine and kidney. Overall results suggested that the use of defatted RSM to replace 50% of other protein sources resulted in a comparable growth and feeding performance of common carp juvenile without any adverse effect.

The effect of feces collection intervals on the digestibility of feed in rainbow trout was determined in order to substantiate nutrient loss from the feces collected by the Guelph System and TUF column. Feeding experiments were conducted using two different diets, and feces and surrounding water were collected at 3, 6, 9, 12, and 15h after the final feeding.There was no significant difference in the apparent digestibility coefficient (ADC) of crude protein and lipid during collection intervals between data obtained from the Guelph System and TUF column. The ADC of dry matter and energy by the Guelph System exhibited the same trend as protein, but the ADC of dry matter and energy by TUF column at 3h was slightly lower than that at 6h or above.The results obtained have demonstrated that the effect of fecal retrieval intervals on the ADC is very minimal, and hardly and leaching of nutrients occurs from the feces collected with either the Guelph System or TUF column. Thus, it is proved that the Guelph System and TUF column are suitable equipment for collecting feces from salmonid fish to test digestibility.

Whether it is better to use viable or non-viable probionts in aquaculture is still a matter of debate. In this study, the molecular immunomodulation in rainbow trout Oncorhynchus mykiss induced by viable or killed forms of the probiont Lactobacillus rhamnosus JCM 1136 was investigated. Three forms of this probiont:(1) heat-killed (HK), (2) live spray (LI) and (3) freezedried (FD) were incorporated into a basal (control) diet for rainbow trout O. mykiss. The LI and FD diets are referred to as viable diets. A rearing trial, in triplicate, was conducted for 30 days, with the control and probiotic diets as treatments. The cytokine genes such as the tumour necrosis factor (TNF), transforming growth factor (TGF-b), interferon (IFN) and immune gene Immunoglobulin (Ig) found in tissues from the kidney and spleen were assessed for their expression pattern by real-time polymerase chain reaction. The tested immune genes were up-regulated in the treatment groups, sometimes even in many folds like in the case of the Ig gene. The TNF gene was found to be highly (Po0.05) up-regulated (5000-fold) in groups fed both viable forms (LI, FD). With regard to the TGF-b gene, the spleen of the HK and FD groups showed signi¢cant up-regulation of 20-and 30-folds respectively. The IFN gene was upregulated (Po0.05) in all treatments, but more in the viable diet treatments. Kidney and spleen tissues showed similar expression patterns, i.e. all of these genes were up-regulated more with the viable diets that with the control, and in most cases, the viable diets induced a higher expression of the immune genes than the HK diet.

No abstract