Investigation of the effects of recombinant human growth hormone on growth indices, expression of GHR and IGF1 genes, and intestinal pathology in rainbow trout fry (Oncorhynchus mykiss)

Document Type : scientific research article

Authors

1 Department of Fisheries, Faculty of Natural Resources and Environment, Ferdowsi University of Mashhad, Mashhad, Iran

2 Department of Animal Science, Faculty of Agriculture, Ferdowsi University of Mashhad

3 Department of Pathobiology, Faculty of Veterinary Medicine, Ferdowsi University of Mashhad, Mashhad, Iran

4 Department of Fisheries, Faculty of Natural Resources and Environment, Ferdowsi University of Mashhad

Abstract

Studies on the oral application of growth hormone can enhance fish growth and aquaculture development by improving feed efficiency. This study was designed to investigate the effects of different levels of human growth hormone on growth indices, the expression of two genes (GHR and IGF1), and intestinal pathology in rainbow trout fry (75 fish with an initial weight of 1.469 ± 0.251 grams).The experiment was conducted over 30 days using a completely randomized design with 3 treatments and 2 replicates. The experimental treatments included a control group (without hormone), fish fed a diet containing 0.2 mg of growth hormone per gram of feed, and fish fed a diet containing 0.4 mg of growth hormone per gram of feed. The results indicated that human growth hormone significantly increased body weight, specific growth rate, and liver index (P<0.05), while the feed conversion ratio in the control group was significantly higher than in the groups receiving 0.2 and 0.4 mg of growth hormone (P<0.05). Additionally, hormone consumption did not have a significant effect on the expression of the GHR and IGF1 genes. Histopathological examinations of the intestines of rainbow trout fry showed a normal intestinal condition in the control group, with mild infiltration of inflammatory cells in the subepithelial layer of the intestinal tissue in the hormone-treated groups. Therefore, based on the data obtained from this research, it seems that the use of human growth hormone in the diet of rainbow trout fry not only improves growth indices and stimulates intestinal immunity but also does not cause damage to the intestinal tissue.

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