Wheat bran addition methods in Pacific white shrimp (Litopenaeus vannamei) biofloc systems

Incorporating non-starch polysaccharides (NSP) as a slowly degradable carbohydrate source in pelleted feed can simplify biofloc system management, compared to external carbon addition. NSP-containing ingredients like wheat bran synchronizes carbon input with the system organic matter dynamics compared to simple sugars. This study evaluated the effect of two methods of addition of an NSP-rich carbon source, wheat bran, to a Pacific white shrimp (Litopenaeus vannamei) biofloc system; supplementation via feed (wheat bran diet; WBdiet) and direct addition to the water (CONdiet+WB). The amount and composition of the total nutrient input to each mesocosm of the treatments was the same. A digestibility and a growth experiment were carried out separately for 35 and 42 days, respectively. The nutrient digestibility was overall lower in shrimp fed the WBdiet compared to the CONdiet, but without an effect on shrimp final weight, production, and survival. When comparing the methods of addition, neither of the approaches altered the shrimp nutritional quality. As expected, a difference in faecal C:N ratio was observed; 21 vs. 17 for WBdiet and CONdiet, respectively. The difference in faeces composition did not affect biofloc quantity, quality, and chlorophyll-a concentrations, and resulted in comparable water quality and microbial activity. Our study concluded that both NSP-addition methods, either via feed or via the water, were equally effective. When compared to the traditional addition of carbohydrate to the water, supplementing NSP-containing carbon sources via the feed can be a more efficient approach in terms of labour and feeding management practices.