Antibiotic misuse in aquaculture causes several detrimental effects. Currently, non-antibiotic feed additives have been popularly applied in aquafeed to improve aquatic animal health and growth performance. Short-chain fatty acids, such as butyric acid, are among the most promising ones. To enhance its stability and bio-availability and decrease its unpleasant smell, butyric acid can be supplemented as butyrins (glycerol esters of butyric acid). The present study aimed to evaluate the effects of butyrins on growth performance, survival rate, and Vibrio spp. counts in Pacific white shrimp.
Pacific white shrimp (2-3 g) were randomly distributed into 30 tanks (40 shrimp/tank) with 200 L of water (29°C and 25-30 ppt). Ten experimental diets were formulated with different concentrations of soybean meal (SB) at 25 and 50%, and different formulations of butyrins, namely butyrins powder (BP, ProPhorce SR 130) at 0.05 and 0.10% and butyrins liquid formulations (BL, ProPhorce SR 730) at 0.03 and 0.07%. The two commercial products were obtained from Perstorp (Malmö, Sweden). These experimental diets were fed to the shrimp 4 times daily for 10 weeks. The shrimp body weight and survival rate of each group were recorded at the end of the feeding trial. At the end of growth trial, the intestinal and hepatopancreatic (HP) Vibrio spp. counts were also conducted using a spread plate method on TCBS agar.
Results revealed that the shrimp body weight was slightly improved by supplementation with BP and BL at both SB levels. The BP 0.10% group had highest survival rate at both 25% SB (87.50%) and 50% SB levels (62.5%), significantly (p<0.05) different from the control groups, which were 69.17% and 55.00%, respectively (Table 1). Regarding the Vibrio spp. count study, shrimp offered BP and BL supplemented diets had significantly lower (p<0.05) Vibrio spp. number in the HP, from about 8 ×103 CFU/g to about 4 ×103 CFU/g (Table 1) and the intestine, from about 8 ×102 CFU/g to about 5 ×102 CFU/g (data not shown) compared to the corresponding control groups. In conclusion, the benefit of butyrins feed additive in improving shrimp growth and survival as well as reducing Vibrio spp. counts in the laboratory condition were evident.