Measuring individual feed efficiency and its correlations with performances and agonistic behaviours in juvenile Nile tilapia Oreochromis niloticus reared in groups

Estimating individual feed intake of fish held in groups has long been a challenge precluding precise knowledge of the individual variation in feed efficiency (FE). In this study, we measured individual feed conversion ratio (FCR) of 100 juvenile Nile tilapia Oreochromis niloticus held in groups and estimated the correlations between FCR, performance and agonistic behavioural traits. For this purpose, fish were video-recorded to estimate the occurrence of agonistic behaviour during a fasting and a refeeding period, occurring just before the individual feed intake (FI) measurement. To measure FI, we counted the number of feed pellets eaten by each individual tilapia using video recordings made over a period of 10 days where fish were fed twice daily. Accumulated measures of FI over 11 meals were found to achieve 95% repeatability and a highly accurate FI estimate. Thus, with this approach, we can accurately investigate FI and FCR in fish. During the FI measurement period, average fish growth was 12.0 ± 3.6 g and FCR was 0.86 ± 0.20. FCR was negatively correlated with body weight gain (BWG, r = -0.62 ± 0.06) but not with FI (r = -0.02 ± 0.10). Conversely, residual feed intake (RFI) was positively correlated with FI (r = 0.60 ± 0.06) but not with BWG (r = -0.03 ± 0.10). These findings highlight the complex relationships between the main feed efficiency traits, FCR and RFI. Fish were 58% less aggressive during the fasting period compared to the refeeding period, but generally, an aggressive fish during the fasting period was also aggressive during the refeeding period. The correlations between agonistic behaviour and growth and feed conversion ratio were low, and in most cases not significant. We conclude that the hierarchical rank and agonistic behaviour should not affect Nile tilapia growth and feed conversion ratio. Consequently, a dominant fish should not necessarily be more efficient than a subordinate fish

Croiser une approche compréhensive des systèmes d'élevage piscicole et leur diagnostic génétique - de l'ambition aux résultats

La carpe est le premier poisson de pisciculture à Madagascar ; sa population est issue d'introductions dont la première date de 1912. Partant d'un souci de recenser les ressources génétiques actuelles de cette espèce d'élevage au niveau national, des poissons de plusieurs bassins versants du milieu naturel et d'éleveurs variés ont été analysés. En parallèle, les producteurs d'alevins ont été enquêtés afin de comprendre si leurs pratiques étaient susceptibles d'avoir conservé des populations avec des caractéristiques spécifiques. Ce travail montre que la présentation habituelle des différentes variétés ne résiste pas à l'analyse génétique. Un réseau très actif d'écloseries incluant de nombreux producteurs de taille variable et donc un très grand nombre de géniteurs s'est montré en capacité d'entretenir une souche avec une bonne potentialité. Ce vaste réseau de producteurs d'alevins, de tailles différentes, constitue une ressource précieuse pour le développement de cet élevage qu'il convient de mettre en valeur. Les résultats obtenus sur le tilapia sont présentés en parallèle soulignant l'intérêt de s'interroger sur les ressources génétiques présentes. (Résumé d'auteur

Experiments Reveal That Search Image Might Be Responsible for Seasonal Variation in Nest-Predation Rates

Investigations of seasonal variations in nest predation rates yield highly variable results. Some investigations argue that search image is responsible for some of the nest-predation patterns, but as far as we know, this study is the first in which search image in connection with seasonal variation in nest-predation rate has been experimentally tested. We used 1457 artificial nests placed in an identical way during the months of March to August, either in the two months consecutively or early and late within one of the two months, between the years 2000 and 2023. In addition, we compared the change in nest-predation rates at 113 artificial and 460 natural nests between the same two months. We estimated the seasonal variation in the abundance of breeding birds in the study area with 140 point counts to find the abundance of different species at the times when they normally breed. We found a strong and consistent seasonal variation in the nest-predation rate, with the highest predation rate in the middle of the breeding season. There was a similar change in the predation rate on natural and artificial nests between May and June. From July to August, the predation rate on artificial nests decreased significantly, while the search-image experiment revealed a significant increase between the same two months. A generalized linear mixed-effect model analysis found that the variation in nest-predation rates on artificial nests was significantly affected by seasonal variation in the estimated number of natural nests, that nests in trees were predated more often than nests on the ground, and that nests in the open landscape and on forest edges suffered higher predation rates than nests inside a forest. Mammals were nest predators significantly more often inside forests and on forest edges than in the open landscape, but birds were much more common nest predators than mammals independent of placement and habitat. Our experiment shows that search image explains the seasonal variation in nest-predation rates. However, more investigations are needed to find the reasons for the variation in published results on seasonal variation. Further, experimental testing on search image to find its contribution to the seasonal variation in nest-predation rates in other areas is also needed.publishedVersio

Genomic Selection and Genome-wide Association Study for Feed-Efficiency Traits in a Farmed Nile Tilapia (Oreochromis niloticus) Population

International audienceNile tilapia is a key aquaculture species with one of the highest production volumes globally. Genetic improvement of feed efficiency via selective breeding is an important goal, and genomic selection may expedite this process. The aims of this study were to 1 ) dissect the genetic architecture of feed-efficiency traits in a Nile tilapia breeding population, 2 ) map the genomic regions associated with these traits and identify candidate genes, 3 ) evaluate the accuracy of breeding value prediction using genomic data, and 4 ) assess the impact of the genetic marker density on genomic prediction accuracies. Using an experimental video recording trial, feed conversion ratio (FCR), body weight gain (BWG), residual feed intake (RFI) and feed intake (FI) traits were recorded in 40 full-sibling families from the GIFT (Genetically Improved Farmed Tilapia ) Nile tilapia breeding population. Fish were genotyped with a ThermoFisher Axiom 65 K Nile tilapia SNP array. Significant heritabilities, ranging from 0.12 to 0.22, were estimated for all the assessed traits using the genomic relationship matrix. A negative but favourable genetic correlation was found between BWG and the feed-efficiency related traits; −0.60 and −0.63 for FCR and RFI, respectively. While the genome-wide association analyses suggested a polygenic genetic architecture for all the measured traits, there were significant QTL identified for BWG and FI on chromosomes seven and five respectively. Candidate genes previously found to be associated with feed-efficiency traits were located in these QTL regions, including ntrk3a , ghrh and eif4e3 . The accuracy of breeding value prediction using the genomic data was up to 34% higher than using pedigree records. A SNP density of approximately 5,000 SNPs was sufficient to achieve similar prediction accuracy as the full genotype data set. Our results highlight the potential of genomic selection to improve feed efficiency traits in Nile tilapia breeding programmes

Probing the unusual anion mobility of LiBH_4 confined in highly ordered nanoporous carbon frameworks via solid state NMR and quasielastic neutron scattering

Particle size and particle–framework interactions have profound effects on the kinetics, reaction pathways, and even thermodynamics of complex hydrides incorporated in frameworks possessing nanoscale features. Tuning these properties may hold the key to the utilization of complex hydrides in practical applications for hydrogen storage. Using carefully synthesized, highly-ordered, nanoporous carbons (NPCs), we have previously shown quantitative differences in the kinetics and reaction pathways of LiBH_4 when incorporated into the frameworks. In this paper, we probe the anion mobility of LiBH_4 confined in NPC frameworks by a combination of solid state NMR and quasielastic neutron scattering (QENS) and present some new insights into the nanoconfinement effect. NMR and QENS spectra of LiBH_4 confined in a 4 nm pore NPC suggest that the BH_4− anions nearer the LiBH_4–carbon pore interface exhibit much more rapid translational and reorientational motions compared to those in the LiBH_4 interior. Moreover, an overly broadened BH_4− torsional vibration band reveals a disorder-induced array of BH_4− rotational potentials. XRD results are consistent with a lack of LiBH_4 long-range order in the pores. Consistent with differential scanning calorimetry measurements, neither NMR nor QENS detects a clear solid–solid phase transition as observed in the bulk, indicating that borohydride–framework interactions and/or nanosize effects have large roles in confined LiBH_4

Entanglement, local measurements, and symmetry

A definition of entanglement in terms of local measurements is discussed. Viz, the maximum entanglement corresponds to the states that cause the highest level of quantum fluctuations in all local measurements determined by the dynamic symmetry group of the system. A number of examples illustrating this definition is considered.Comment: 10 pages. to be published in Journal of Optics

Prosjektrapport. Innsatsteam - "Aktiv i eget liv"

Rapport fra forprosjekt for å utvikle modell for kompetanseutvikling innen habilitering og rehabilitering. Utvikle modell for tverrfaglig ambulant innsatsteam.Helsedirektorate

Politiets Fellesforbunds bevæpningsvedtak fra landsmøte i 2012: Rasjonelt, forhandlingsbasert eller tilfeldig? : En kvantitativ studie i hva som kjennetegner beslutningsprosessen som ledet til vedtaket om å arbeide for generell bevæpning av norsk politi

Master's thesis in Management (ORG917)Formålet med denne studien er å diskutere hva som kjennetegnet beslutningsprosessen under Politiets Fellesforbunds landsmøte i 2012 som ledet til vedtaket om å arbeide for generell bevæpning av norsk politi. Landsmøtevedtaket brøt med en lang tradisjon om et generelt ubevæpnet politi, en tradisjonelt som hadde stor oppslutning i politiorganisasjonen og samfunnet ellers. Oppgavens problemstillinger er som følger: « Hva kjennetegner beslutningsprosessen som ledet til at et flertall av delegatene under Politiets Fellesforbunds landsmøte i 2012 stemtefor generell bevæpning av norsk politi til tross for at et flertall blant medlemmer gjennom to spørreundersøkelser, forbundsstyre og et internt bevæpningsutvalg ikke ønsket generell bevæpning?»

The fishing system

This chapter is part of Result 3 “Supply of alternative protein is improved” of the Sustainable Wildlife Management (SWM) Programme. It reviews and characterizes the livestock production and grazing management systems in the three community conservancies (CCs) of Mucheni in Zimbabwe, and Inyasemu and Simalaha in Zambia, with a view to explore opportunities in the supply of alternative protein to resident communities in agreement with the theory of change of the SWM Programme in KaZa. Information and data were collected through literature reviews, qualitative and quantitative studies and surveys and general observation within the three CCs. The findings reveal that the farmers' major source of livelihood is livestock production with cattle, goats and poultry featuring as predominant species. The production systems are basic, “low input low output”