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Chlorella additive increased growth performance, improved appetite and immune response of juvenile crucian carp Carassius auratus

Luo, Zhi, Ye, Han‐Mei, Gao, Yan, Ling, Shi‐Cheng, Wei, Chuan‐Chuan, Zhu, Xiaoming
Aquaculture research 2018 v.49 no.10 pp. 3329-3337
Carassius auratus, Chlorella, alkaline phosphatase, appetite, aquaculture tanks, body weight, brain, crude protein, experimental diets, feed conversion, feed intake, fiberglass, food intake, gene expression, gene expression regulation, genes, growth performance, immune response, immunoglobulin M, juveniles, kidneys, lipids, liver, messenger RNA, muscles, specific growth rate, tissues, weight gain
This study was designed to investigate effects of dietary Chlorella meal (CM) additive on growth performance, immune responses and appetite regulation of juvenile crucian carp Carassius auratus (initial body weight: 1.27 ± 0.03 g). Four experimental diets were formulated to contain 0% (CM0), 1% (CM1), 2% (CM2) and 4% Chlorella meal (CM4), respectively. Each diet was randomly assigned to triplicate groups with 40 juvenile fish per fibreglass tank for 8 weeks. Weight gain rate, specific growth rate and feed intake increased with increasing dietary CM levels. In contrast, FCR (feed conversion rate) declined with dietary CM levels. No significant differences were observed in moisture, crude protein, crude lipid and ash contents of muscle and liver tissues. Dietary CM addition increased activities of acid and alkaline phosphatase in liver and kidney. Dietary CM up‐regulated the mRNA expression levels of NKEF‐B, MCHII and IgM in kidney, and increased the mRNA levels of NPY and agouti gene‐related protein in the brain, but down‐regulated mRNA levels of MC4R, LEP, LEPR, CART1, CART2 and CCK8 genes. Based on these observations above, this study indicated that dietary CM additive increased growth performance, immune responses and appetite of crucian carp. The results, for the first time, demonstrate a role for the central nervous system in the control of food intake in fish fed dietary Chlorella meal.