Sexual dimorphism studies in tilapias, using two pure species, Oreochormis niloticus and Sarotherodon melanotheron, and their intergeneric hybrids (O. niloticus x S. melanotheron and S. malanotheron x O. niloticus)

This comparative study of growth performances and sexuel growth dimorphism was conducted with fish obtained from artificial reproduction. Growth was measured weekly. The levels of sexual steroids (11-KT) and thyroid hormones (T3 and T4) was measured after 74 rearing days and at the end of the experiment (103 days). Social interactions were examined with a video camera (three sequences of one hour for each group). #O. niloticus# and #S. melanotheron# achieved the best and worst growth rates, respectively, with their intergeneric hybrides standing in between. Tilapias originating from female #O. niloticus# (pure species and hybrid 1) exhibited a significant sexual growth dimorphism, which contrasted with the situation observed in the two other groups (originating from female #S. melanotheron#), where no significant difference was measured. Male tilapias from the two hybrid groups had similar growth rates, whereas hybrid females originating from female #S. melanotheron# (hybrid 2) grew faster than those coming from female #O. niloticus# (hybrid 1). The levers of 11-KT were highest in #O. nioticus# and lowest in #S. melanotheron#. The levels in the hybrid groups were similar and intermediate between those of the pure species. By contrast, the lever of T4 was highest in #S. melanotheron#. The levels of T3 at 74 days did not differ between groups but between sexes in all four groups. At the end of the experiment, this sex-related difference was still observed in the hybrid 2 group whilst it had vanished in the hybrid 1 group. The analysis of behavioural sequences indicated that aggressive behaviours (face to face or jaw to jaw interactions, attacks with or without poursuit) first emerged among faster growing fish (#O. niloticus# and hybrid 1)

Bibliographic Details

Main Authors:	Toguyeni, Aboubacar, Fauconneau, Benoît, Mélard, Charles, Fostier, Alexis, Lazard, Jérôme, Baras, Etienne, Kühn, Eduard R., Van Der Guyten, S., Baroiller, Jean-François
Format:	conference_item biblioteca
Language:	eng
Published:	s.n.
Subjects:	L52 - Physiologie animale - Croissance et développement, Tilapia, Oreochromis niloticus, Sarotherodon, hybride, dimorphisme sexuel, gain de poids, contrôle hormonal, http://aims.fao.org/aos/agrovoc/c_32720, http://aims.fao.org/aos/agrovoc/c_34687, http://aims.fao.org/aos/agrovoc/c_26668, http://aims.fao.org/aos/agrovoc/c_3707, http://aims.fao.org/aos/agrovoc/c_32659, http://aims.fao.org/aos/agrovoc/c_8350, http://aims.fao.org/aos/agrovoc/c_35764,
Online Access:	http://agritrop.cirad.fr/389863/
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