Nucleotide promotes feed intake and protein utilization via regulating the gene expression of feeding and nitrogen metabolism in juvenile Chinese perch ( <i>Siniperca chuatsi</i> )
Liwei Liu, Jinguang Fang, Xu‐Fang Liang, Shan He
Abstract
Nucleotide (NT) could enhance growth, feeding and immunity in higher vertebrate and fish. Chinese perch (Siniperca chuatsi) refuse artificial diet in natural water, whereas the NT might promote its feeding of domestication diet. The present study was designed to investigate the effect of dietary NT on growth, feed intake, feed utilization, body composition, serum biochemistry and nitrogen metabolism in juvenile Siniperca chuatsi. 0, 0.5, 1.0, 1.5, 2.0 and 4.0 g NT kg−1 diet were supplemented in each diet, respectively. Triplicate groups of Chinese perch (36.21 ± 0.98 g) were fed twice a day to apparent satiation for 8 weeks. The results showed that fish fed with 1.5 g NT kg−1 diet had the highest weight gain (WG), specific growth rate, feed efficiency, feed intake, protein efficiency ratio and protein retention efficiency. The crude protein content in whole body was highest in fish fed the diet containing 1.5 g NT kg−1 diet. Dietary NT supplementation significantly increased the neuropeptide Y gene expression and significantly decreased the agouti-related protein and pro-opiomelanocortin gene expressions in brain. NT supplementation decreased urea nitrogen content, aspartate aminotransferase (AST) and alanine aminotransferase activities in serum. The hepatic AST activity was increased first and then decreased, and the highest activity was observed in fish fed with 1 g NT kg−1 diet. Inversely, the activity of glutamate dehydrogenase (GDH) in liver and adenosine 5′-monophosphate deaminase in muscle decreased first and then increased, and the lowest activity was observed in fish fed with 1.5 g NT kg−1 diet. Similarly, the gene expression levels of GDH and arginase in liver were lowest in fish fed with 1.5 g NT kg−1 diet. Based on the broken-line regression analysis of WG in the present experimental condition, 1.44 g NT kg−1 diet was the optimum supplementation level in juvenile Siniperca chuatsi.