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

This 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.