Regulation of feed intake, intestinal enzymes activity and growth in response to live feed and prepared diet during early rearing of Labeo rohita

A 35 day feeding trial in a replicate of five was conducted to evaluate the impact of partial and total replacement of live feed (LF) with nanoparticulate-prepared diet (ND) on early rearing of rohu ( Labeo rohita (Hamilton, 1822)). Larvae 3 days after hatching (DAH) were evenly distributed into three groups; T1 was reared exclusively on LF, T2 was on ND, and T3 was co-fed both LF and ND (1:1). All groups showed a feed-dependent increase in growth and the expression of genes involved in feed intake and growth with age DAH. The T3 group showed significantly higher weight gain, specific growth rate, and expression of insulin-like growth factor-1 followed by the T2 group, while the highest expression of ghrelin and growth hormone secretagogue receptor was observed in T3 followed by T1. Furthermore, leptin showed the highest expression in the T2 followed by the T1 group. The intestinal enzymes showed variable trends, with the highest activity of cellulase, amylase, and protease in the T1, T2, and T3 groups, respectively. Moreover, in all groups, cellulase increased continuously with age DAH, while amylase and protease showed a positive correlation up to 30 DAH and then declined. The results of this study could be helpful in larval nutrition programming.