Data/hora: 10/06/2024 00:46:41

Provedor de dados: | 5
País: | France
Título: | Domestication, sélection et comportement du bar: variabilité des aptitudes comportementales et de la tolérance au stress de groupes génétiquement distincts de bar, Dicentrarchus labrax
Autores: | Millot, Sandie.
Data: | 2008-10-08
Ano: | 2008
Palavras-chave: | Personality; Physiological status; Growth; Swimming behaviour; Feeding behaviour; Stress tolerance; Adaptation; Welfare; Chronic stress; Acute stress; Selection; Domestication; Dicentrarchus labrax; Personnalité; Statut physiologique; Croissance; Comportement natatoire; Comportement alimentaire; Tolérance au stress; Adaptation; Bien être; Stress chronique; Stress aigu; Sélection; Domestication; Dicentrarchus labrax.
Resumo: | The culture of aquatic species has grown much more rapidly in recent years than that of terrestrial species. Consequently, aquatic livestock welfare is a growing concern for society. However, unlike the many studies of terrestrial animal welfare, few scientific data exist concerning fish welfare. It is generally recognized that the aquaculture environment exposes fish to many repeated stress factors which affect their health, growth, reproductive performance and feeding behaviour. Even if stress responses do not highlight all welfare disturbances, it is generally admitted that they reveal a poor welfare. Among the solutions investigated to reduce fish stress, domestication and selection appear to be the favoured approaches. However, selection has generally focused on productivity and few fish selection programs have addressed adaptability or stress tolerance. The evolution of the latter under domestication pressure has also been little studied. This thesis has two main goals: 1) Identify the main behavioural characteristics of the European sea bass (Dicentrarchus labrax) in rearing conditions, and 2) Analyze behaviour disturbances induced by stress on animals, which genetic origin is known, to evaluate the influence of domestication and selection on adaptability and their welfare potential. Stress effects (acute or chronic) are studied using multi-criteria analyses of potential indicators including feeding and swimming behaviour, growth potential, physiological state, risk-taking behaviour and exploration of new territory, interpreted in terms of personality (shy or bold).  A first primary study, carried out on fish presenting the common domestication state found in sea bass farms in Europe, has allowed the long term characterisation of "standards" self-feeding behaviour, growth potential and physiological status i.e. variable feed demand activity and stable quantity of food intake over time, stress-related food wastage (e.g. biometrics), diurnal feeding, regularly increase of body weight and physiological characteristics in the usual published species range. This study has also highlighted the underlying principles of self-feeding behaviour and social structure in this species, i.e. in a group of 50 to 60 sea bass, about 5% are high-triggering fish (which realize more than 25% of all trigger actuations), 80% are low-triggering fish, and 15% are zero-triggering fish. Group self-feeding behaviour results not simply from the sum of individual feed demands, but is lead by the high-triggering fish feed demand rhythm and behaviour which is itself influenced by nutritional status. As a general rule, a single individual plays this role within the group for a continuous period of approximately 60 days before being replaced by another. Thus, more than its individuality, it is the role of leader that is essential to maintain a stable group social structure.  Studies on stress effects showed first of all a set of common responses for fish originating from different levels of domestication and/or selection for growth, i.e. a sudden increase in feeding motivation sometimes associated with wastage, a decrease of growth rate, a spontaneous change of feeding rhythm, a modification of spatial distribution, a decrease (or total cessation) of swimming activity, stereotyped behaviours (thigmotaxis, prostration), and an increase of blood glucose and lactate levels, an increase of serotonin activity and a decrease of liver glycogen concentration. The process of domestication seems to improve fish learning, and environmental adaptation (i.e. fast recovery of feeding, growth and normal physiological status following stress). The process of selection for growth seems to promote animals with regular feeding rhythms throughout the day, high exploration capacities in new environment (interpreted as a bold personality), and variable growth over time.  This work could be completed by (i) the acquisition of the relevant genetic bases of behaviour (genetic variability, heritability, genetic correlations with other phenotypic, physiological or behavioural characters), (ii) the acquisition of new indicators usable in a selective breeding program (non-invasive, inexpensive and easily implemented on a large number of individuals), and (iii) the study of further generations of domestication and selection to better understand their true relative influence on sea bass stress tolerance and welfare potential in aquaculture
Tipo: | Text
Idioma: | Francês
Identificador: | http://archimer.ifremer.fr/doc/2008/these-6272.pdf
Editor: | La Rochelle
Relação: | http://archimer.ifremer.fr/doc/00000/6272/
Formato: | application/pdf