Vitamin A (VA ) is an essential fat-soluble micronutrient that plays a crucial role in various physiological processes such as growth, immunity and gene regulation. However, the dietary VA requirements of pacific white shrimp are still unknown. This study was conducted to determine the dietary requirement of VA and its effect on the growth performance, feed utilization, digestive enzyme activities and gene expression related to antioxidant capacity and non-specific immunity of post-larval pacific white shrimp.
Six diets were prepared by supplementing 0, 2, 6, 8, 10 and 20 mg VA/kg diet (designated as VA0, VA2, VA6, VA8, VA10 and VA20, respectively). A total of 3600 shrimp (initial body weight: 0.95 mg) were randomly distributed in triplicate among 18 tanks (110 L). The shrimp were fed one of the experimental diets four times a day for 30 days.
At the end of the feeding trial, final body weight (FBW) and weight gain (WG) in VA6 and VA8 groups were significantly higher than those in VA0 group. Protein efficiency ratio (PER) in VA8 group was significantly higher than that in VA0 group. Feed conversion ratio (FCR) in VA2, VA6, VA8 and VA10 groups were significantly lower than that in VA0 group. Survival of the shrimp was not significantly different among all the groups. During ammonia stress test, all the VA supplemented groups showed significantly higher survival than that of VA0 group. Based on broken line regression with WG, the dietary requirement of VA level for post-larval Pacific white shrimp is likely to be 3.42 mg/kg.
The results of the gene expression related with immunity and antioxidant capacity will be further presented.