Effects of dietary lipid levels on the growth,fatty acid profile and fecundity in the oriental river prawn,Macrobrachium nipponense

An 8‐week feeding trial was conducted to investigate the effects of dietary lipid levels on growth performance, fatty acid profile and fecundity in the oriental river prawn Macrobrachium nipponense. Five isonitrogenous experimental diets were formulated with graded lipid levels [A (5.02%), B (5.98%), C (6.91%), D (7.91%) and E (8.89%) respectively]. The results indicated that the values of body weight gain, specific growth rate, protein efficiency ratio and protein retention presented a similar trend of increasing first and then decreased with increasing dietary lipid levels. Furthermore, prawns fed diets containing 6.91% lipid showed the best values on these parameters among all the treatments. EPA, DHA and n‐3/n‐6PUFA contents showed associated increasing with the increase in lipid deposition of prawn muscle. The activities of hepatopancreatic amylase, protease and lipase were also significantly (p < .05) improved by dietary 6.91% lipid. Increasing dietary lipid levels could not suppress early maturation with no differences detected in berried females throughout the feeding trial. Significant lower relative fecundity may contribute to describing the dietary moderate lipid level (6.91%) could promote the growth of spawners and decrease spawning quantity. The recommendation dietary lipid requirement, estimated by the broken‐line model based on specific growth rate against dietary lipid levels, was 7.19% of the dry matter for M. nipponense.     

Growth enhancement and protective potential of feed-based outer membrane proteins against vibriosis in <Emphasis Type="Italic">Macrobrachium rosenbergii</Emphasis>

The use of antibiotics to curtail vibriosis, which is a major infectious disease, plaguing shrimp and prawn is rather becoming less effective and the need for a better alternative is expedient. The outer membrane proteins (OMPs) of V. alginolyticus were extracted, mixed with powdered commercial feed and fed to the prawns to evaluate its effect on growth performance and protective potential. Sixty prawns were divided into groups A, B and C of 10 prawns each, with two replicates in six (150 L) glass aquaria. Groups A, B and C were fed with OMPs mixed diet, with OMPs-Freund’s incomplete adjuvant mixed diet and OMPs or adjuvant free diet (control diet) respectively. All the prawns were weighed weekly, and haemolymph was collected to determine the total haemocyte count (THC) and phenoloxidase (PO) activity. At the end of the feeding trial, prawns were intramuscularly challenged with 50 μL of 10⁷ CFU V. alginolyticus. The treated groups were significantly higher in growth performance and THC than the control group, but no significant difference between the groups in terms of PO activity and mortality rate. The study, however, submitted that oral administration of OMPs with or without adjuvant is a good growth promoter and has the potential for protection against vibriosis in giant freshwater prawn (Macrobrachium rosenbergii).     

Effects of biochar on microbial community in bioflocs and gut of Oreochromis niloticus reared in a biofloc system

Aquaculture International - This study investigated the effects of biochar application on the bacterial community structure in bioflocs and intestines of Oreochromis niloticus cultured in a biofloc...