Modulatory effects of various carbon sources on growth indices, digestive enzymes activity and expression of growth-related genes in Whiteleg shrimp, Litopenaeus vannamei reared under an outdoor zero-exchange system

In this study, we investigate the effect of the biofloc (BF) system using various carbon sources including sugarcane bagasse (SCB), rice bran (RB) and rice straw (RS) on growth parameters, hepatopancreatic digestive enzymes and the expression of growth-related genes of white-leg shrimp, Litopenaeus vannamei. Single-nucleotide polymorphisms (SNPs) in the haemocyanin gene in small- and large-sized Litopenaeus vannamei for 3 months reared in outdoor concrete ponds were also screened. The results showed that the growth and survival of shrimp in the RB and SCB groups were improved (p <= 0.05) and the same trend was observed for the digestive enzyme activities. The expression of different growth-related genes including growth hormone, insulin-like growth factor-I and II, myosin and paramyosin was significantly increased in all biofloc groups reaching the highest levels in the RB group. The SNPs recorded in the haemocyanin gene between the small- and large-sized L. vannamei revealed an insertion of Adenine at position 554 and a substitution at 1114 in large-sized RS shrimp. So far, the RB group was attained the best growth, digestive enzyme activity and expression of growth-related genes between different carbon sources. Furthermore, the haemocyanin gene can be used as a marker for the selection of large-sized shrimp.