The Suitable Temperature to Stimulate the Immuno-Endocrine Interaction and Growth Improvement of Oreochromis niloticus Larvae

Khalil Et Al., Noha A.

doi:10.21608/ejabf.2024.361971

The Suitable Temperature to Stimulate the Immuno-Endocrine Interaction and Growth Improvement of Oreochromis niloticus Larvae

Document Type : Original Article

Author

Noha A. Khalil et al.

10.21608/ejabf.2024.361971

Abstract

The adrenocorticotropic homone (ACTH) and corticotropin-releasing factor (CRF) have functional roles during Oreochromis niloticus development. The present investigation looked at how temperature affected O. niloticus larval development regarding growth, survival rate, CRF and ACTH immunoreactivity, as well as mucous cell activity. Exposure to temperature enhanced larval growth, as demonstrated by the higher increases in terms of larval weight and length observed during the experiment at 30 and 35°C. Furthermore, compared to the group under control, the contact with these temperatures produced a noticeably higher larval survival rate. Temperature-exposed O. niloticus larvae produced more CRF in the fully formed stomach; the mucosal layer's synthetic and secretory activities increased, as evidenced by a strong immunoreaction and the existence of secretory vacuoles in CRF-immunoreactive cells. In addition, goblet cells within the growing intestine of treated larvae exhibited increased levels of both the quantity and strength of ACTH immunoreactivity. Furthermore, temperature exposure influences mucous cell activity. Mucous cell count in the alimentary canal increased after exposure to the previously mentioned environmental temperatures. In addition, qualitative alterations were demonstrated in the composition of mucus, which changed from being primarily neutral to having acid mucosubstances or a mix of acid and neutral mucosubstances. Hence, increased temperature-induced advanced digestive function improves immune-endocrine interaction, food intake during the critical period of initial feeding, primary stress response. Additionally, it enhances the protective functions of mucins, CRF and ACTH. Consequently, growth is increased and the mortality rate is lowered. These data imply that contact with the ideal temperature range of 30 to 35°C may be helpful for the spawning and growth of O. niloticus fingerlings.

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