Dietary effect of apple cider vinegar and propionic acid on immune related transcriptional responses and growth performance in white shrimp, Litopenaeus vannamei

AbstractThis experiment was conducted to study the effect of various levels of ACV® and Propionic acid (PA) on expression of immune related genes and growth performance in white shrimp (Litopenaeus vannamei). Three hundred and seventy-five shrimps with an average initial weight of 10.2 ± 0.04 g were collected and acclimatized for two weeks. Five experimental diets including control diet, 0.5% PA diet and 1%, 2% and 4% ACV® diets were applied to feed the shrimps. They were fed 4 times a day with 2.5% of body weight. After 60 days of culture, shrimps fed with ACV® and PA diets showed no significant difference in growth performance. Expression of prophenoloxidase (proPo), lysozyme (Lys), penaeidin-3a (Pen-3a) and Crustin (Cru) genes were determined from hepatopancreas, using the real-time PCR after 15, 30 and 60 days. Expression of Lys and proPo genes was significantly up regulated in shrimps fed with ACV® and PA diets compared to the control group after 30 and 60 days of treatment. After 15 days, Pen-3a gene expression was significantly higher in PA group compared to the control group. Also, shrimps fed with 1% and 4% ACV® and PA diets showed significantly increased expression of Pen-3a after 30 days. In contrast, expression of Cru was significantly down regulated in response to ACV® diets, but, Cru expression in treated shrimps with PA diet was greater than the control group after 30 and 60 days. Overall, the results provided evidence that ACV® could be used as a natural immunostimulant for shrimps in order to adjust and enhance expression of the immune related genes

Effect of garlic extract supplementation on growth performance, nonspecific immunity, and antibacterial activity of skin mucus in goldfish, Carassius auratus

In the present study, the effects of dietary supplementation of garlic extract on growth performance, skin mucus immunological parameters and antibacterial activity of Carassius auratus were examined. Fish were stocked in 100 L glass tanks (6 fish per tank) in triplicate and fed diets containing different garlic extracts (0 (control), 5, 10, and 15 ml/kg] for eight weeks. At the end of feeding period, the fish skin mucus was collected for evaluating the components of non-specific immune system (including lysozyme, complement, total immunoglobulin, dissolved protein, and alkaline phosphatase). Additionally, antimicrobial activity of the skin mucus against Aeromonas hydrophila, Yersinia ruckeri, Micrococcus luteus, Streptococcus faecium, and S. iniae was assessed. After the feeding trial, the fish fed diets containing garlic extract showed no significant difference in growth parameters. Significantly higher skin mucus lysozyme, complement, alkaline phosphatase activities, and total immunoglobulin and dissolved protein concentration were observed in the fish fed garlic extract-supplemented diets (P<0.0001). The antimicrobial activity of the skin mucus increased along with the increase in the dietary garlic extract levels (P<0.0001). Moreover, garlic extract exhibited the antimicrobial activity against pathogenic bacterial species. The highest level of dietary garlic extract (15 ml/kg) led to significantly higher inhibition zones against pathogenic bacterial species compared to the other garlic extract levels (P<0.0001). The optimal administration of garlic extract at 15 ml/kg enhance skin mucus immune parameters and antimicrobial activity in goldfish

The effect of delayed first feeding on growth and survival of yellowfin seabream (Acanthopagrus arabicus) larvae

The effect of different initial feeding times (48 h, 72 h, 96 h, and 120 h after hatching) and food deprivation on the point-of-no-return (PNR), survival, and growth of yellowfin seabream Acanthopagrus arabicus larvae were studied under controlled condition. Growth parameters were investigated by evaluating morphometric (head depth, body depth, gut height, musculature height, eye diameter, total length, yolk, and oil globule volume) and gravimetric (dry weight) indices. The larvae commenced to feed exogenously at the mouth opening stage on day 2 after hatching (DAH) and reached PNR between 6 and 7 DAH at 19–20 °C. The time of initial feeding significantly affected the larval growth. From 3 DAH until the end of the trial period at 15 DAH, the growth (all morphometric indices and dry weight) of larvae started which earlier initial feeding start (48 h and 72 h after hatching) were significantly higher than that of 96 h (P < 0.05). Growth parameters were measured until 9 DAH in the larvae commenced feeding at 120 h, since complete mortality was recorded after this sampling point (at 12 DAH). During this period, the larvae showed significantly lower morphometric indices and dry weight compared with larvae in other initial feeding time treatments (48 h, 72 h, and 96 h). Yolk absorption in yellowfin seabream larvae was completed on 4 DAH regardless of the variances in the time of first feeding. Likewise, the oil globule was completely utilized on 5 DAH in all initial feeding trials. No significant differences were noticed in yolk volume and oil globule absorption between different treatments. At the end of the trial at 15 DAH, the survival rate was significantly higher for larvae began first feeding at 48 h (35.67 ± 7.01%) and 72 h (36.48 ± 4.72%) when compared to 96 h first feeding larvae (13.10 ± 2.62%)(P < 0.05). The findings from the current study reveal that the first feeding of yellowfin seabream larvae can be initiated up to 72 h after hatching with no significant differences in growth and survival rate

Black gill disease in Litopenaeus vannamei made by various agents

Melanization of shrimp gills is a general symptom in shrimp black bill diseases (sBG); therefore, the cause is not immediately apparent. This study aimed to determine the primary and secondary agents associated with a black gill outbreak in the Delvar complex in the Bushehr Province of Iran. During July and August of 2020, 450 healthy and affected shrimps were collected based on brown to black gill color from three farms of the Bushehr Province in Iran. Characterization of pathogens was performed by gross signs, wet mounts, microbiological tests, histopathology methods, and sequencing of molecular markers. The mean weight and length of infected shrimps was significantly (P < 0.05) lower than the healthy shrimps. The histological examination of sBG indicated the adhesion of secondary lamellae, accumulation of hemocyte cells at the end of the secondary lamellae, and necrosis of epithelial cells with pyknosis and karyorrhexis. According to our results, Aspergillus sydowii as a primary agent correlates with sBG disease in Litopenaeus vannamei from Iran, and other biotic factors, including bacterial (Vibrio owensii and V. parahaemolyticus) probably are secondary agents associated with sBG disease.</p