Aquaculture Reports (Oct 2022)
Zootechnical performance, immune response, and resistance to hypoxia stress and Vibrio harveyi infection in Pacific white shrimp (Litopeneaus vannamei) fed different fishmeal diets with and without addition of sodium butyrate
Abstract
The dietary effect of a chemically protected sodium butyrate, Butirex®C4 (BU), on growth performance, digestive enzymes activity, immunity, gut microflora, and resistance against hypoxia stress and infectious disease were studied in Pacific white shrimp fed different levels of fishmeal (FM) diets in earthen outdoor ponds. Nine isonitrogenous and isolipidic experimental diets were formulated to contain different levels of FM (45 %, 30 %, and 15 %) and enriched with the incremental levels of BU (0, 0.3%, and 0.6%). After 60 days, the shrimp fed diets containing 45% and 30 % FM along with 0.3 % and 0.6 % BU, respectively, showed higher levels of final weight and weight gain, while, the group fed diet with 15 % FM free from BU showed the highest level of feed conversion ratio. The levels of protease and trypsin activity significantly decreased in the group fed 15 % FM without BU, while the administration of BU improved the digestive enzymes activity in low FM diets. The total hemocyte count, phenoloxidase, and lysozyme were negatively affected by decreasing levels of FM in the diets, but BU-supplemented diets improved these parameters. The dietary administration of BU increased lactic acid bacteria and decreased total Vibrio sp. counts in the intestine of shrimp fed different levels of FM. Although the diets with low levels of FM had no significant effect on the hypoxia stress tolerance, the cumulative mortality was decreased in the low FM groups fed with different BU levels. The mortality of shrimp against Vibrio harveyi infection was notably decreased in BU-added groups compared to the groups that did not receive BU in their diets. Overall, dietary BU administration at 0.6 % mitigates the adverse impacts of the diets with the lowest FM (15 %) on overall performance and immunity in Pacific white shrimp.
