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Auteur de Verdal, H.; Mekkawy, W.; Lind, C.E.; Vandeputte, M.; Chatain, B.; Benzie, J.A.H.
Titre Measuring individual feed efficiency and its correlations with performance traits in Nile tilapia, Oreochromis niloticus Type Article scientifique
Année 2017 Publication Revue Abrégée Aquaculture
Volume 468 Numéro Pages 489-495
Mots-Clés bream sparus-aurata; compensatory growth; conversion efficiency; diet environments; Feed conversion ratio; Feed efficiency; Feed intake; fish-meal; food; genetic-improvement; growth; Nile tilapia; rainbow-trout; Repeatability; salmon salmo-salar; selection; Sex
Résumé Estimating individual feed intake of fish held in groups has long been a challenge precluding precise knowledge of the individual variation of feed efficiency (FE) in fish. In this study, counts of the number of feed pellets (1.63 mg on average) eaten by individual tilapia (Oreochromis niloticus) held in 8 mixed sex groups of 15 fish were measured from video recordings made over a period of 10 days where fish were fed twice daily to achieve compensatory growth after 10 days of fasting. The initial body weight of the fish was 9.77 +/- 2.03 g. Accumulated measures of feed intake (FI) over 11 meals were found to achieve 95% repeatability and a high accuracy of estimation of FI. During the FI measurement period, the average fish growth was 12.0 +/- 3.6 g, feed intake was 0.99 g day (-1), and feed conversion ratio (FCR) was 0.86 +/- 0.20. FI differences accounted for 56% of the observed individual growth variations, and 44% was related to individual variations of FE. On average males grew 24.2% faster than females but consumed 12.1% more feed. Males showed an 11.7% better FCR than females, whereas residual feed intake (RFI) differences were not significant between sexes. FCR and RFI were moderately and significantly correlated (0.58 +/- 0.06) but FCR and FI, and body weight gain (BWG) and RFI, were not, highlighting the complex relationships between feed efficiency traits. The approach described here demonstrates a means to accurately investigate FE traits in fish and to assess the potential for their genetic improvement. Statement of relevance: Feed efficiency has strong economic and environmental impact. (C) 2016 Elsevier B.V. All rights reserved.
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ISSN 0044-8486 ISBN Médium
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Numéro d'Appel MARBEC @ alain.herve @ collection 1713
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Auteur de Verdal, H.; O'Connell, C.M.; Mekkawy, W.; Vandeputte, M.; Chatain, B.; Begout, M.-L.; Benzie, J.A.H.
Titre Agonistic behaviour and feed efficiency in juvenile Nile tilapia Oreochromis niloticus Type Article scientifique
Année 2019 Publication Revue Abrégée Aquaculture
Volume 505 Numéro Pages 271-279
Mots-Clés Agonstic behaviour; arctic charr; atlantic salmon; brain serotonergic activity; brown trout; conversion ratio; Correlation; dominance relationships; Feed efficiency; food acquisition; genetic-improvement; Nile tilapia; Performances; salvelinus-alpinus; social-status
Résumé Given the strong effects of behavioural hierarchies on growth in many cultured species and the key role of feed efficiency in aquaculture economics, understanding the nature of the interaction of these variables is important for the sustainability of aquaculture. The relationship between agonistic behaviour, growth and feed efficiency in Nile tilapia, Oreochromis niloticus, was studied by rearing 120 fish in eight aquaria. Fish were video-recorded to estimate the occurrence of agonistic behaviour during a fasting and a refeeding period. Growth, feed intake and feed conversion efficiency (FCE – calculated as the inverse of feed conversion ratio (FCR)) were subsequently measured individually for each fish. Fish showed 58% less agonistic traits during the fasting period compared to the feeding period, but generally, an aggressive fish during the fasting period was also aggressive during the refeeding period. The nature of agonistic behaviours between individuals was used to assess the presence of hierarchical relationships between fish. There were dominance hierarchies established in each experimental aquarium that despite minor shifts were maintained throughout the experiment. Agonistic behaviours were strongly correlated with each other, the aggression Index (AI) and with hierarchy rank. PCA analysis of the agonistic behaviours summarising the behavioural information showed little or no correlation between agonistic behaviour, fish growth or FCE. FCE was correlated with body weight gain (BWG). These results suggest that agonistic interactions in juvenile Nile tilapia do not have a large impact on growth and feed conversion efficiency.
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Langue English Langue du Résumé Titre Original
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Volume de collection Numéro de collection Edition
ISSN 0044-8486 ISBN Médium
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Numéro d'Appel MARBEC @ isabelle.vidal-ayouba @ collection 2583
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Auteur McKenzie, D.J.; Blasco, F.R.; Belão, T.C.; Killen, S.S.; Martins, N.D.; Taylor, E.W.; Rantin, F.T.
Titre Physiological determinants of individual variation in sensitivity to an organophosphate pesticide in Nile tilapia Oreochromis niloticus Type Article scientifique
Année 2017 Publication Revue Abrégée Aquatic Toxicology
Volume 189 Numéro Supplement C Pages 108-114
Mots-Clés Critical swimming speed; Individual variation; Metabolic rate; Nile tilapia; Respirometry; Trichlorfon
Résumé Individual variation in sub-lethal sensitivity to the organophosphate pesticide trichlorfon was investigated in Nile tilapia, using critical swimming speed (Ucrit) as an indicator. Tilapia exposed for 96h to 500μgl−1 trichlorfon at 26°C (Tcfn group, n=27) showed a significant decline in mean Ucrit, compared to their own control (pre-exposure) performance in clean water (−14.5±2.3%, mean±SEM), but also compared to a Sham group (n=10) maintained for 96h in clean water. Individuals varied in their relative sensitivity to the pesticide, with the decline in Ucrit after exposure varying from 1 to 41%. The Ucrit of the Tcfn group did not recover completely after 96h in clean water, remaining 9.4±3.2% below their own control performance. The decline in performance was associated with a significant increase in net cost of aerobic swimming, of +28.4±6.5% at a sustained speed of 2bodylengthss−1, which translated into a significant decline in swimming efficiency (Eswim) of −17.6±4.0% at that speed. Within the Tcfn group, individual Eswim was a strong positive determinant of individual Ucrit across all trials, and a strong negative determinant of individual% decline in Ucrit after pesticide exposure (P<0.001, linear mixed effect models). Trichlorfon had no effects on standard metabolic rate or active metabolic rate (AMR) but, nonetheless, individual Ucrit in all trials, and% decline in Ucrit after exposure, were strongly associated with individual AMR (positively and negatively, respectively, P<0.001). Individual Ucrit under control conditions was also a strong positive determinant of Ucrit after trichlorfon exposure (P<0.001), but not of the% decline in Ucrit performance. In conclusion, the OP pesticide impaired Ucrit performance by reducing Eswim but individual tilapia varied widely in their relative sensitivity. Intrinsic individual physiology determined effects of the pesticide on performance and, in particular, good swimmers remained better swimmers after exposure.
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ISSN 0166-445x ISBN Médium
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Numéro d'Appel MARBEC @ isabelle.vidal-ayouba @ collection 2225
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