Heterosis, direct and maternal additive effects on rabbit growth and carcass traits from a Canadian experiment

A total of 479 male and female rabbits from the Californian (CA), American Chinchilla (CH) and New-Zealand White (NZ) breeds and nine crosses between them were used in this experiment. This study aimed to estimate heterosis and direct and maternal additive effects as well as some non genetic effects on rabbit growth and carcass traits in order to identify the most appropriate crossbreeding plan to use for rabbit meat production under Quebec conditions. Each rabbit was identified and weighed individually at weaning (35 d) and at slaughter (63 d). Rabbits were slaughtered after an 18 h fasting period from feed only. Statistical analyses were performed solving fixed models that allow different variances between genetic types. Significant statistical differences were obtained between genetic types for rabbit growth performance. Rabbits from purebred NZ females mated to CA and NZ males or from CAxNZ and NZxCH crossbred females mated to NZ males ranked first for live weight at 35 and 63 d body weight and for average daily gain (ADG). ADG of NZxNZ, NZx(NZxCH) and NZx(CAxNZ) rabbits reached around 50 g/d and their feed conversion ratio was about 3.4. Significant differences between genetic types were observed for all carcass traits except for meat/bone ratio. Rabbits from CH, NZ, CAxNZ and NZxCH does mated to NZ males, and from NZ does mated to CA males had the highest commercial carcass weight and the lowest commercial carcass yield (CCY), whereas CHxCA rabbits ranked first with a CCY higher by 4 to 8% than rabbits from other genetic types. The highest hind part yields were obtained with CHxCH, CHxNZ and NZxCH rabbits. Concerning the intermediate part percentages, the highest values corresponded to the highest CCY. The CH breed had unfavourable direct effects but favourable maternal effects on growth traits. The CA breed had negative maternal effects on weight traits from weaning to slaughtering. The CA and CH breeds had positive direct and negative maternal effects on intermediate part yield of the carcass compared to NZ. Direct heterosis effects were found for body weight traits, particularly in the crosses involving the NZ breed, with a magnitude ranging from 5 to 10% of the parental mean.Ouyed, A.; Rivest, J.; Brun, JM. (2011). Heterosis, direct and maternal additive effects on rabbit growth and carcass traits from a Canadian experiment. World Rabbit Science. 19(1). doi:10.4995/wrs.2011.783.SWORD19

Rendements et pratiques des cultures maraîchères en agriculture biologique au Sénégal

Les rendements en agriculture biologique font l'objet de controverses et sont considérés comme plus faibles qu'en agriculture conventionnelle. En Afrique, l'agriculture biologique recouvre une grande diversité de pratiques et les rendements présentent de fortes incertitudes. Les analyses des rendements et des itinéraires techniques en agriculture biologique sont présentées pour trois cultures maraîchères au Sénégal. Les résultats sont ensuite comparés aux rendements usuels de l'agriculture conventionnelle. Deux types de données sont utilisés, provenant de parcelles d'agriculteurs : i) suivi de champs conduits selon des itinéraires techniques d'agriculture biologique vs. itinéraires techniques conventionnels ; ii) résultats issus des actions de l'organisation non gouvernementale ENDA-PRONAT, suivant un cahier des charges copié sur celui de l'agriculture biologique. Les suivis comparatifs de parcelles de chou pommé et de tomate en saison des pluies mettent en évidence des ratios de rendement agriculture biologique/conventionnelle de 74 et 40 % respectivement. Ces valeurs confirment la tendance générale des résultats de la littérature. Elles sont expliquées par une fertilisation azotée plus faible et l'absence de mesures de protection efficace contre les maladies et ravageurs des cultures. Les rendements en oignon des parcelles d'agriculture biologique chez les producteurs sont très variables : en moyenne de 19,4 t/ha à 11,0 t/ha suivant les années dans la zone des Niayes, 21,0 t/ha dans le Bassin arachidier et seulement 8,6 t/ha dans la vallée du fleuve Sénégal. Les rendements de la culture d'oignon au Sénégal observés dans la littérature varient aussi dans de grandes proportions, de 10,7 à 32 t/ha. Dans certains cas, les rendements en agriculture biologique sont supérieurs à ceux des itinéraires techniques de l'agriculture conventionnelle. Ce constat, déjà observé dans la littérature scientifique, montre que l'agriculture biologique est une voie de développement de l'agriculture à ne pas écarter en Afrique

Classical and MgII-selected Damped Lyman-alpha Absorbers: impact on Omega_HI at z<1.7

The Damped Lyman-alpha systems (DLAs), seen in absorption in the spectrum of quasars, are believed to contain a large fraction of the neutral gas in the Universe. Paradoxically, these systems are more difficult to observe at z_abs<1.7, since they are rare and their HI feature then falls in UV spectra. Rao & Turnshek (2000) pioneered a method based on MgII-selected DLAs, that is absorbers discovered thanks to our knowledge of their MgII feature in optical spectra. We use new observations undertaken at the TNG as well as a careful literature & archival search to build samples of low redshift absorbers classified according to the technique used for their discovery. We successfully recover N(HI) and equivalent widths of FeII 2600, MgII 2796, MgII 2803 and MgII 2852 for a sample of 36 absorbers, 21 of which are MgII-selected. We find that the MgII-selected sample contains a marginally larger fraction of absorbers with log N(HI)>21.0 than seen otherwise at low redshift. If confirmed, this property will in turn affect estimates of Omega_HI which is dominated by the highest HI column densities. We find that log N(HI) does not correlate significantly with metal equivalent widths. Similarly, we find no evidence that gravitational lensing, the fraction of associated systems or redshift evolution affect the absorber samples in a different way. We conclude that the hint of discrepancies in N(HI) distributions most likely arises from small number statistics. Therefore, further observations are required to better clarify the impact of this discrepancy on estimates of Omega_HI at low redshift.Comment: 13 pages, 8 figures. Accepted for publication in MNRA

Quelle sélection fruitière pour une production durable, à faible niveau d’intrants ? Méthodologie pour un réseau de sélection variétale décentralisée

In France Fruit production is cultivated on 140 thousand hectares, mainly conducted on intensive training system. Very few elements are available on low input training systems while they have to integrate the Global rule under the frame of Ecophyto 2018. In order to evaluate if another system of cultivation will be possible, a project has been developed to highlight the main factors to be integrated in low input training system. A low input multilocal experimental design has thus been investigated on apricot in two main regions of production: Rhone valley and Roussillon. A set of 9 common cultivars with 20 replications each, planted in a complete single-tree randomization design has been established. As already observed in apple orchard, a larger set of disease has been observed in our experimental plots by comparison with conventional training orchards. A large genetic variability has been set-up among the observed cultivars, but if some of them expressed components of resistance against the observed diseases no one appeared widely resistant to all the diseases. Taking in consideration the longevity of the orchard, a huge concern exists with the tested germplasm because the observed dieback was in between 10 and 80% of the trees according to the cultivars after only 6 years of observation. On the methodological point of view, a clear optimization of the experimental design is expected on the base of the observed results

Intraplaque hemorrhage, a potential consequence of periodontal bacteria gathering in human carotid atherothrombosis

Periodontal diseases are multifactorial inflammatory diseases, caused by a bacterial biofilm involving both innate and adaptative immunity, characterized by the destruction of tooth-supporting tissues. In the context of periodontitis, the spread of weak pathogenic bacteria into the bloodstream has been described. These bacteria will preferentially localize to existing clot within the circulation. Atherothrombosis of the carotid arteries is a local pathology and a common cause of cerebral infarction. Intraplaque hemorrhages render the lesion more prone to clinical complications such as stroke. The main objective of this study is to explore the biological relationship between carotid intraplaque hemorrhage and periodontal diseases. This study included consecutive patients with symptomatic or asymptomatic carotid stenosis, admitted for endarterectomy surgical procedure (n=41). In conditioned media of the carotid samples collected, markers of neutrophil activation (myeloperoxidase or MPO, DNA-MPO complexes) and hemoglobin were quantified. To investigate the presence of DNA from periodontal bacteria in atherosclerotic plaque, PCR analysis using specific primers was performed. Our preliminary results indicate an association between neutrophil activation and intraplaque hemorrhages, reflected by the release of MPO (p&lt;0,01) and MPO-DNA complexes (p&lt;0,05). Presence of DNA from periodontitis-associated bacteria was found in 32/41 (78%) atheromatous plaque samples. More specifically, DNA from Pg, Tf, Pi, Aa was found in 46%, 24%, 34% and 68% of the samples, respectively. Hemoglobin levels were higher in conditioned media in carotid samples where the bacteria were found, but this was not statistically significant. Our data confirm the relationship between intraplaque hemorrhage and neutrophil activation. In addition, the presence of periodontal bacteria DNA in carotid atheromatous plaque, may contribute to this activation. Further analysis is needed to fully explore the raw data and specimens

Complexation du Ca++ par les substances humiques extraites de tourbe naturelle et de tourbe traitée aux oxydes d'azote

The study of the complexation of calcium by humic substances (SH) extracted from a natural peat (TN) and from a peat treated with nitrogen oxides (TT) was followed by conductimetry and potentiometry with pH variable and pH constant. The complexing capacity increases as the pH rises: complexed calcium is 130 cmol kg*[-1) SH (TN) and 135 cmol kg*[-1) SH (TT) with pH 5, and 330 cmol kg*[-1) SH (TN) and 410 cmol kg*[-1) SH (TT) with pH 9. These reactions involve various functional groupings of pKa1 < 4 for TN and TT, pKa2 = 5.9 for TN and pKa2 = 6.2 for TT; in all cases, the medium has exhibited an increase in acidity. The complexation of calcium by HS extracted from TT could then enhance the efficiency of the phosphatic nutrition of plants

Generation of 0.6 J pulses of 16 fs duration through high-repetition rate amplification of self phase modulated pulses

International audienceWe have generated optical pulses of 16fs duration in the submicrojoule range and at a repetition rate of 11 kHz. This was obtained by amplifying self-phase modulated pulses at the output of a fiber, using a couple of dyes to achieve gain covering a large spectrum around 620 n

From nonreciprocal to charge-4e supercurrents in Ge-based Josephson devices with tunable harmonic content

Hybrid superconductor(S)-semiconductor(Sm) devices bring a range of new functionalities into superconducting circuits. In particular, hybrid parity-protected qubits and Josephson diodes were recently proposed and experimentally demonstrated. Such devices leverage the non-sinusoidal character of the Josephson current-phase relation (CPR) in highly transparent S-Sm-S junctions. Here we report an experimental study of superconducting quantum-interference devices (SQUIDs) embedding Josephson field-effect transistors fabricated from a SiGe/Ge/SiGe heterostructure grown on a 200-mm silicon wafer. The single-junction CPR shows up to three harmonics with gate tunable amplitude. In the presence of microwave irradiation, the ratio of the first two dominant harmonics, corresponding to single and double Cooper-pair transport processes, is consistently reflected in relative weight of integer and half-integer Shapiro steps. A combination of magnetic-flux and gate-voltage control enables tuning the SQUID functionality from a nonreciprocal Josephson-diode regime with 27% asymmetry to a $\pi$-periodic Josephson regime suitable for the implementation of parity-protected superconducting qubits. These results illustrate the potential of Ge-based hybrid devices as versatile and scalable building blocks of novel superconducting quantum circuits.Comment: 8 pages, 5 figure