Effects of neuropeptide Y as a feed additive on stimulating the growth of tilapia (Oreochromis niloticus) fed low fish meal diets

Abstract

Neuropeptide Y is known to stimulate food intake in fish. In this study, we investigated tilapia NPY (tNPY) both for its effects on the growth of tilapia (Oreochromis niloticus, GIFT) in low fish meal and for its thermal stability. Three diets were formulated containing 0, 3 and 10% fish meal (NF, LF and HF). From these diets, six experimental diets were prepared by spraying either tNPY solution (0.3\u2009μg/g feed) or distilled water (DW) onto the surface of formulated feeds (NF\u2009+\u2009DW, NF\u2009+\u2009tNPY, LF\u2009+\u2009DW, LF\u2009+\u2009tNPY, HF\u2009+\u2009DW and HF\u2009+\u2009tNPY). Tilapia were fed the six experimental diets for 8 weeks. Fish in the NF\u2009+\u2009tNPY, LF\u2009+\u2009tNPY and HF\u2009+\u2009tNPY groups showed increasing trends in the weight gain rate and specific growth rate compared to its corresponding control group. The feed coefficient of group HF\u2009+\u2009tNPY was significantly lower than that of the control group. The growth performance of the LF\u2009+\u2009tNPY approached that of the HF\u2009+\u2009DW group. The mRNA levels of npy in NF\u2009+\u2009tNPY were significantly higher than those in NF\u2009+\u2009DW. A field experiment in which tNPY was sprayed in feeds by the vacuum spray method with doses of 0, 0.2 and 0.4\u2009μg/g feed was performed for three months, and the FBW of tilapia receiving tNPY at 0.2 and 0.4\u2009μg/g feed was higher than that of the control group although not significantly. The bioactivity of tNPY was confirmed by its ability to reduce cAMP levels and activate the ERK1/2 pathway. These results demonstrated that tNPY could promote tilapia growth with oral administration low fish meal diets.