Portail Hal-l'Institut Agro Rennes-Angers
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Colonization and spatiotemporal distribution of bruchid pests in lentil and faba bean fields
No full textInternational audienceBACKGROUND: Lentils (Lens culinaris Medikus, 1787) and faba beans (Vicia faba Linnaeus, 1753) are important crops in France facing threats from Bruchus spp. We analyzed 59 lentil and 45 faba bean fields across four French regions over three growing seasons (2019-2020 to 2021-2022). We investigated the diversity, colonization patterns and spatiotemporal distribution of bruchids at different crop phenological stages and distances from field edges. RESULTS: Bruchus rufimanus Boheman, 1833 and Bruchus signaticornis Gyllenhal, 1833 were the only species emerging from faba beans (97.8%) and lentils (99.5%), respectively. B. rufimanus colonization was concentrated during pod development, maintaining a balanced male-female ratio throughout. B. signaticornis exhibited a colonization period of ≈1 month, with a gradual increase in female proportion over time. The spatial distribution of bruchids and damage were relatively uniform within fields, indicating strong dispersal capabilities. A significant positive correlation, with a high degree of dispersion, was identified between female abundance and bruchid-damaged grains. CONCLUSION: We confirmed that B. rufimanus and B. signaticornis were the only species damaging faba beans and lentils in France, respectively. The homogeneous spatial distribution suggests a strong dispersal ability of bruchids. The high degree of dispersion in the relationship between female abundance and bruchid-damaged grains highlights the importance of regulatory factors influencing larval and egg survival. These results, together with the presence of B. signaticornis in faba beans, emphasize the need for species-specific, phenology-based and spatially informed integrated pest management strategies, to mitigate the impact of bruchids and reduce reliance on chemical in their control
On-farm validation of a feeding strategy improving nutritional and technological quality of meat from Duroc crossbred pigs and contributing to relocating feed resources
No full textInternational audienceThere is an increasing demand from consumers and pork chain actors for farming practices improving simultaneously the intrinsic (e.g. sensory, nutritional, etc.) and the extrinsic (i.e. production-related: type and origin of feed resources, environmental impacts, etc.) quality attributes of pork. In this context, the present study was undertaken in a commercial farm to validate a feeding strategy designed to jointly improve intrinsic and extrinsic quality attributes of pork. The experiment included a total of 102 growing pigs (Danbred dams × Duroc sires) with females (n = 52) and castrated males (n = 50) over three replicates. At an average body weight (BW) of 32 kg, pigs were assigned to either a control (C) or an experimental diet based on ''relocation of feed resources" (R). They were fed ad libitum one of the two diets according to a three-phase feeding programme until slaughter, when pigs achieved around 125 kg BW. The C diet was based on oilseed meals as a source of proteins and the R diet included extruded faba bean as the main source of proteins and extruded linseed as a source of n-3 polyunsaturated fatty acids (FAs). The average growth rate and slaughter BW tended to be higher (P < 0.1) in R than in C pigs, but hot carcass weight and lean meat content did not differ between the two feeding regimens. Ultimate pH in the Longissimus (LM) and ham (Semimembranosus, Adductor, Gluteus medius (GM) and Gluteus superficialis) muscles was higher (P < 0.01) in R than in C pigs. Drip loss in LM was lower (P < 0.001) in R than in C pigs. With respect to meat colour, L*, b*, C* and h° values measured 24 h after slaughter were lower (P < 0.01) in the LM and GM, indicating less light and redder meat (due to lower h°) from R compared with C pigs. Compared with the C diet, the R diet did not affect LM protein and lipid content but markedly reduced (P < 0.001) the n-6:n-3 and saturated:n-3 FA ratios in both LM and backfat. The current study confirms that in commercial conditions, feeding crossbred pigs with a faba beanbased diet enriched with extruded linseed is a favourable strategy to jointly improve the technological and nutritional properties of pork, while contributing to the relocation of feed resources
Changes in physical properties of growing media constituents according to biodegradation
No full textInternational audienceThe use and exploration of more sustainable materials for growing media, in response to the search for alternatives to peat, are expanding. Many locally available organic resources are currently under study for this purpose. However, their biological stability remains a major limitation. Understanding the effect of biodegradation on the physical properties of these materials, in order to assess their long-term suitability for ensuring water supply and root system respiration, remains largely unexplored. The objectives of this research were to evaluate the biological stability of various organic materials over a 6-week biodegradation process; to investigate how biodegradation alters key physical properties; and to determine whether these alterations stem from changes in particle size distribution. Initial and post-biodegradation physical properties and particle size distribution were analyzed. Biodegradation was measured via respirometry. The protocol employed aerobic conditions, fertilizer addition, and a temperature of 35°C to reach a substantial biodegradation rate. As a result, the methodology employed led to biodegradation rates comparable to, or exceeding, those reported in the literature. No significant changes were observed in particle size distribution after biodegradation, probably due to overall low biodegradation rates coupled with heterogeneous particle sizes. No significant changes were observed in total porosity or available water either. The significant changes observed were a decrease in air-filled porosity, resulting from a general increase in water retention properties at suctions of -10 cm and above. These observations therefore suggest the hypothesis of a change in the integrity of the particle surface, with the formation of fine pores, rather than fragmentation leading to changes in particle size and organization. These observations highlight the importance of assessing changes in physical properties during relatively long biodegradation processes for potentially biologically unstable raw materials, in order to adapt agronomic practices to the changing properties of the materials
Inferring cellular heterogeneity with mixture models for DNA methylation rates (SMPGD 2026)
No full textInternational audienceCellular heterogeneity in biological tissues reflects progression of disease state and is therefore valuable for improving diagnostic and prognosis. Cellular composition of tissues is however difficult to assess from bulk molecular profiles. Specifically, the recorded signals represent aggregated contributions from all constituent cell types. Cell deconvolution is a common approach to unravel the heterogeneous molecular profiles observed in bulk tissues, by inferring the underlying relative abundance of constituent cell populations. % Part 0: definition of cell deconvolution/heterogeneityExisting approaches assume that bulk omic profiles result from weighted sums of so-called signature cell-specific omic profiles, where weights represent the unknown proportions of those cell types. Consistently, most statistical methods used for cellular deconvolution are based on extensions of the Ordinary Least Squares (OLS) optimization algorithm, under non-negativity and sum-to-one constraints on the estimated mixing coefficients. % Part 1.1: first problem of deconvolution: constraints (enforcing/under)Using OLS implicitly assumes independence, homoscedasticity and normality of the residual errors, conditions under which OLS optimization guarantees optimal estimation. In cellular deconvolution applied to bulk molecular profile, all three assumptions are highly questionable. Indeed, strong violations of those assumptions may be due to the intrinsic nature of omics data: genomic features are generaly overdispersed and dependencies among them arise from underlying gene regulatory networks.The goal of this work is to provide a well-defined statistical framework for deconvolution that respects the inherent characteristics of biological data. Among available omics data types, RNA-seq gene expression and DNA methylation are most frequently used for deconvolution. We focus here on DNA methylation data, which provide complementary information to gene expression and are particularly useful when RNA quality is limited or degraded. Whole-genome cell-type specific distributions of DNA methylation rates actually show a latent group structure, that can explain poor estimation accuracy when fitting deconvolution models on the whole genome. Therefore, we propose a mixture of non-negative beta regression models, estimated via an EM (Expectation-Maximization) algorithm, explicitly accounts for this latent structure. In this framework, selecting the optimal mixture component corresponds to an implicit gene selection step. Therefore, identifying the best latent component is decisive. We propose a component selection criterion that balances two objectives: (i) within-component improvement of the fit of the cell deconvolution model, and (ii) estimation stability evaluated by the condition number of the asymptotic variance-covariance matrix of the cell type proportions estimator. We evaluate the proposed approach through an extensive comparative study on several benchmark datasets: an \textit{in vitro} mixtures of isolated pancreatic cancer cell populations, an \textit{in vitro} mixtures of isolated immune blood cell populations, and \textit{in vivo} blood cell data. Our results demonstrate the strong sensitivity of deconvolution performance to the latent component choice and highlight the significant accuracy gains achieved when using genes from the best-performing component compared to whole-genome deconvolution. Results confirm both the marked sensitivity of cell deconvolution performance to the latent component choice, and highlight the significant accuracy gains using the geneset within the best latent component compared to whole-genome deconvolution. These findings establish mixture modeling of whole-genome methylation data as a promising methodological perspective that enhances both the accuracy and interpretability of cellular deconvolution
Seasonal variations in goat milk composition: a comprehensive review
No full textInternational audienceAmong the numerous factors influencing goat milk composition, seasonality has a major impact, reflecting changes in lactation stage, diet, and weather. This review aims to synthesize studies comparing the nutrient content of goat milk in summer and winter. Studies reporting on lipids, fatty acids, phospholipids, cholesterol, proteins, urea, lactose, oligosaccharides, minerals and vitamins were included. Data on physicochemical and organoleptic properties were as well reviewed. Various breeds and countries were considered, with particular focus on the Alpine breed. Despite heterogeneity between studies, consistent trends emerged. Compared to winter milk, summer goat milk contained lower concentrations of lipids, proteins and total solids but higher levels of lactose. Summer milk fat showed higher levels of saturated fatty acids and lower levels of unsaturated fatty acids, possibly driven by changes in monounsaturated fatty acids. Summer milk had lower linoleic/alpha-linolenic acid ratios and trans fatty acid levels.Casein content was lower in summer. Summer milk contained lower concentrations of Ca, P, Mg, Na, and Mn, but higher levels of K and Cl than winter milk. Summer milk may be richer in vitamins A, B1, B2 and oligosaccharides. pH and titratable acidity may be lower in summer, whereas the freezing point tended to be higher. After homogenization and heat treatment, summer milk showed lower viscosity, serum-protein denaturation, and serum-protein-casein interactions. Summer milk tended to have a milder flavor than winter milk.</p
Locating enzyme activities and nutrients in the rhizosphere: Combining zymography and DET methods
No full textInternational audienceOrganic fertilization is a recognized sustainable practice in agriculture and represents a major nutrient source for microbes and plants in these systems. Microbes produce hydrolytic enzymes to mineralize nutrients from organic forms into mineral forms to satisfy their own needs, and thus can compete with plants for these mineralized nutrients. Thus, interactions between plants and microbes in the rhizosphere determine nutrient availability and flows. We investigated these relations, using a spatial approach that combined zymography with the method of diffusive equilibrium in thin films (DET) to localize enzyme activity and N and P availabilities simultaneously. Basil (Ocimum basilicum L.) was grown in rhizoboxes filled with an organo-mineral crop soil (MS) or 100 % organic peat soil (OS) that was unfertilized or fertilized locally with horn meal for 20 days. In general, enzyme activities were higher in MS than in OS, but the stimulation of leucine aminopeptidase (LAP) activity and associated decrease in nutrient availability was 2 times as strong in OS as in MS. A rhizosphere effect, in which rhizodeposits stimulated enzyme activity, was clearly observed in OS. Fertilization increased LAP activity and nutrient availability near the location of fertilization, which increased basil growth in OS but not in MS. β-glucosidase, acid phosphatase and N-acetyl-glucosaminidase activities responded weakly to fertilization and the rhizosphere. By relating enzyme activities mapped by zymography to nutrient availability mapped by DET, we identified microbial hotspots in the rhizosphere where most nutrient mobilization processes and competition between plants and microbes occurred
Monitoring changes in body reserves in gestating dairy heifers with 3D imaging technology: a potential tool to prevent early culling?
No full textInternational audienceThe use of 3-dimensional (3D) imaging technology to monitor dairy cows enables the acquisition of morphological, surface, and volume data, which can then be employed to estimate body weight (BW) or body condition score (BCS). Accurate tracking of morphological changes in these animals could lead to better management of the gestation and parturition periods, which are especially critical for primiparous cows. Indeed, BCS values that are too low or too high are associated with reproductive disorder and/or early culling after calving. To assess the potential utility of precise and continuous recordings in gestating animals, we studied BW and morphological changes in 13 gestating Holstein heifers from 3 mo of gestation until the start of lactation. BCS was estimated using both 3D imaging technology (BCS3d) and manual scores determined by trained technicians (BCSm). From mid-April (start of experiment) until the end of August (start of calving season) in 2021, average BW increased from 515 (±standard deviation, 40.5) kg to 604 (±49.4) kg, while average BCS3d decreased slightly, from 2.50 (±0.19) to 2.32 (±0.30). A similar decrease was noted for BCSm, from 2.63 (±0.19) to 2.11 (±0.24). Linear regression between the 2 estimates of BCS indicated that the technicians usually gave a higher BCS value than the imaging device (BCS3d = 0.97 x BCSm; R 2 = 0.58). Because of the small number of observations and the fact that the experiment ended after the first calving, we are not able to draw any conclusions about the long-term effects of changes in BCS during gestation on the overall longevity of cows. Nevertheless, using our system it was possible to detect small changes in BCS during the first gestation of nulliparous cows. Such information could be employed to adapt the diet of heifers to avoid inadequate, insufficient, or excessive fatness at parturition, thus potentially ameliorating calving difficulties (dystocia) and poor starts to lactation. The precise evolution of BCS in the pregnant heifer is of great interest, and the next step will be to examine larger groups of animals to shed more light on the potential value of this technology
Fatty acid profiles of muscle and liver reveal ontogenetic shifts in diet and reproductive investment in an undulate ray from the Bay of Biscay (northeast Atlantic)
No full textInternational audienceElasmobranchs, with their slow growth, long lifespans and low reproductive output, are particularly sensitive to fluctuations in nutritional status and energy availability throughout ontogeny. Fatty acids serve as valuable biomarkers for studying trophic ecology, ontogenetic dietary shifts and energy allocation during key life periods such as growth and reproduction. This study examined fatty acid profiles in Raja undulata by analysing muscle and liver tissues to investigate ontogenetic dietary shifts, assess niche breadth and overlap between juveniles and adults, and explore how reproductive development influences fatty acid allocation after sexual maturity. The muscle fatty acid profiles of R. undulata varied across life stages, with adults showing a reduced trophic niche and a diet composed of higher-trophic-level prey compared to juveniles. This pattern suggested a dietary shift from a diverse, invertebrate-based diet in juveniles to more specialized predation on fish and larger crustaceans in adults. The liver fatty acid profiles varied across reproductive stages, with an increasing proportion of omega-3 (C22:6n-3, docosahexaenoic acid [DHA]; 22:5n-3, docosapentaenoic acid) and omega-6 polyunsaturated (C20:4n-6, arachidonic acid [ARA]) fatty acids, alongside a marked decline in eicosapentaenoic acid (C20:5n-3), likely reflecting its direct allocation to the ovaries. Additionally, the elevated monounsaturated fatty acids levels in adults and their decline during gametogenesis highlighted their key role as energy sources for oocyte development, supporting previous findings on reproductive energy mobilization in elasmobranchs. While DHA and ARA proportions increased, their stable absolute values suggested a different allocation pattern compared to viviparous species, potentially due to R. undulata's oviparous strategy. Our findings, in line with previous studies, showed that analysing different tissues is key to understanding how diet and energy use are linked in elasmobranchs
Régulation du commerce international et enjeux de santé et d'environnement Des clauses miroir sont-elles pertinentes pour protéger le marché européen de l'usage de pesticides interdits dans l'UE ?
No full textInternational audienceDans son « Point de vue », Catherine Laroche donne à voir ce que l’on peut espérer et craindre des règles commerciales en ce qui concerne la prise en compte des effets sanitaires et environnementaux des échanges internationaux. Dans une sorte d’exercice de prospective fondé sur l’analyse de présents conflits commerciaux, l’autrice s’attache à saisir l’espace des possibles de futures clauses miroir qui se donneraient comme ambition de renforcer les objectifs du Pacte vert européen sans pour autant remettre en cause les accords internationaux multilatéraux mis en œuvre dans le cadre de l’OMC
