Effects of personality traits on growth and physiology of Oreochromis niloticus juveniles

ABSTRACT: To evaluate hematological and biochemical parameters after testing in a new environment, and the zootechnical performance of Oreochromis niloticus classified as proactive or reactive. In experiment 1, male Nile tilapia with an average weight of 128.33 ± 34.17 g were kept in a recirculating aquaculture system (RAS). Immediately after classification, blood samples were collected from 20 reactive and 20 proactive animals. In experiment 2, 60 proactive and 60 reactive males were classified, with an average weight of 88.23 ± 21.59 g, which were divided into the following treatments: PT (40 proactive animals), RT (40 reactive) MT (20 proactive + 20 reactive ). Animals were fed twice daily for 90 days. In experiment 1, reactive animals had higher amounts of hemoglobin and cortisol and lower amounts of leukocytes detected. In experiment 2, weight gain was greater in proactive animals (PT) and reactive animals (RT); however, the best feed conversion was obtained in reactive animals. The survival rate was lower in the MT treatment group of animals. Hemoglobin and glucose had lower values for proactive animals and for those that were mixed, in the MT group. Cholesterol was higher in animals PT. It is concluded that variables such as hemoglobin, cortisol, leukocytes and cholesterol are more likely to undergo changes between personality traits. Furthermore, it can be concluded that reactive and proactive O. niloticus, grown in separate environments, have the same potential for weight gain; however, the food conversion of reactive ones is better.