The growing interest in rotational crossbreeding in Western countries is due to its potential to improve reproductive and health performances of cows. Although a large amount of research focuses on ...assessing crossbred cows’ performances, how to manage the transition from purebred to rotational crossbred herds is under-explored. Based on a retrospective analysis of French dairy herd case studies, we aimed to identify and characterise technical pathways to make such a transition. In 2018, we performed semi-directive interviews on 26 commercial dairy farms. Data were collected to describe changes in breeding, replacement and culling management practices from the first crossbred mating with purebred cows to the management of a mainly crossbred herd in 2018. Based on a multivariate analysis, we identified two main guidelines structuring technical pathways to move towards rotational crossbred herds: (i) the depth and scale of change (i.e. farm v. herd) associated with the introduction of rotational crossbreeding in the whole-farm dynamics and (ii) the changes in herd replacement and breeding practices to adapt to the evolution of herd demographics induced by the evolution of the dairy crossbred mating rate over time (high from the beginning v. distributed over time). Hierarchical clustering discriminated three groups of farmers differing in their technical pathway to move towards a rotational crossbred herd. In pathway 1, farmers customised one or several rotational crossbreeding schemes to support whole-farm transition towards an organic or grass-based system. Once the scheme stabilised, they quickly implemented it and had to readjust replacement and culling practices to regulate imbalance in herd demographics induced by the improvement in cow fertility. In pathway 2, farmers also customised one or several rotational crossbreeding schemes to support whole-farm redesign but they implemented it more gradually in the herd, which induced no major imbalance in herd demographics. In pathway 3, farmers predefined a relatively well-known rotational crossbreeding scheme to correct fertility issues of purebred cows without any changes at the farm level. They implemented it quickly from the beginning and had to adapt herd replacement and culling to regulate imbalance in herd demographics induced by the improvement in cow fertility. These first empirical evidences on how dairy farmers manage the transition from a purebred to rotational crossbred herd provide original scientific and operational contributions.
Full text
Available for:
GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
•Effects of dairy crossbreeding on animal performances at herd level are yet unknown.•We analysed changes in animal performances of herds using rotational crossbreeding.•Crossbreeding improves ...reproductive performance and decreases milk productivity.•Crossbreeding has a variable influence on udder health and longevity of cows.•Rate of implementing crossbreeding in herds is key in trends in cow performance.
Three-breed rotational crossbreeding can improve the functional traits of dairy cows, but few farmers in most Western countries use it. This could be due to a lack of knowledge of its medium- and long-term effects on animal performances at the herd level, regardless of the initial states of the farm and herd, the crossbreeding programme(s) used and changes in farm management and structure while transitioning to it. We aimed at assessing changes in animal performance of dairy cattle herds transitioning towards three-breed rotational crossbreeding and at identifying factors that explained them. We sampled 13 French dairy cattle farms for which animal performance data were available for a 9-year period (2009–2017) and described their trends in herd management and the farming system when introducing crossbreeding. We calculated five herd performance variables: mean milk productivity per cow-year (MilkCow), mean Milk solids content (FatProtCont), and the percentages in the herd of cows with no more than 117 days open (FertileCow), with mean somatic cell score less than 4 over the lactation period (HealthyLact) and with four lactations or more (L4+). We defined 15 variables related to herd and farm structure and management. We applied linear regression to each variable over the study period and used the intercept and slope to describe their initial values in 2009 and their trends, respectively. We performed partial least squares (PLS) regression to assess relationships between the trends in herd performance variables and potential explanatory variables, including the initial values of herd performance variables and the initial values of and trends in herd and farm structure and management variables. Linear regressions showed that within herds, median MilkCow decreased (–177 kg/cow per year), FertileCow increased (+1.5%/year) and FatProtCont either remained stable or increased (+0.1 g/kg per cow). Conversely, changes were less distinct for HealthyLact and L4+. From 2009 to 2017, herd size increased in most farms (med = +1.2 LU/year). The PLS regression highlighted that herds in which MilkCow decreased the most over time were those in which HealthyLact and L4+ decreased and increased the most, respectively. Moreover, for herds in which FertileCow increased the most, FatProtCont either decreased, or increased less. Based on association scores from the PLS, changes in the genetic composition of the herd influenced changes in herd performance variables more than did changes in overall farm management (|0.28|–|0.59| vs |0.26|–|0.50|). Our findings suggest that dairy crossbreeding is relevant to rebalance herd performance between production and functional traits.
Full text
Available for:
GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
•Livestock systems are subjected to climate change and weather variability.•We simulate changes in diversity and so in redundancy within livestock systems.•Changes increase self-sufficiency for ...forage of livestock systems.•Changes do not increase and sometimes reduce animal feeding costs.•Changes reduce the vulnerability of livestock systems against weather variability.
Greater diversity (i.e., variety, balance and disparity) within agricultural systems is often suggested as a solution to promote redundancy within such systems and therefore increase their adaptive capacity and reduce their vulnerability against climate change and variability. Yet this assumption relies upon the gathering and integration of field- and herd-scale results at the farm scale. We have conducted a farm-scale simulation-based study to evaluate the potential for increasing adaptive capacity and reducing vulnerability of livestock systems to weather variability through increase of their agricultural diversity. We manipulate in the simulation, factors of change in the livestock systems resulting in less diverse and more diverse livestock systems to be simulated. We assume, a priori, that certain combinations of the factored system components bring redundancy in the system and in turn increase its adaptive capacity and reduce its vulnerability against weather variability. Simulated factors of change are: F1: a change in the ratio of the area mechanically harvested (vs. grazed) to the whole farm area; F2: a change in the crops and grassland types grown or in the distribution of the area between crops and/or grassland types; F3: a change in calving periods from one season to another. The simulation plan includes a baseline scenario without changes and scenarios corresponding to all possible combinations of F1–F3. These scenarios are applied to four livestock systems located on a diagonal across France over a succession of four years with varying weather conditions. In these systems, self-sufficiency for forage is jeopardized by unfavorable years, and this may increase animal feeding costs. Thus we consider that adaptive capacity increases and vulnerability decreases as long as self-sufficiency for forage is achieved without increasing animal feeding costs. Results confirm the potential for increasing adaptive capacity and reducing vulnerability of livestock systems to weather variability through increase of their agricultural diversity. For instance, F2 has three main kinds of impacts on self-sufficiency for forage: (i) it yields significant average improvements by 34%, 43%, 36% and 36% across livestock systems for the four successive years, (ii) it buffers year-to-year variations and (iii) the final level of self-sufficiency is higher than the initial one even after two years with unfavorable weather conditions. Moreover, simulated changes do not increase animal feeding costs. Thus our results provide empirical evidence at the farm scale to supplement literature reviews based on field- and herd-scale results. They also confirm that through easily implementable on-farm changes, adaptive capacity can be increased and vulnerability of agricultural systems to weather variability decreased.
Full text
Available for:
GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK
A Compton camera is being developed for the purpose of ion-range monitoring during hadrontherapy via the detection of prompt-gamma rays. The system consists of a scintillating fiber beam tagging ...hodoscope, a stack of double sided silicon strip detectors (90 Â 90 Â 2 mm 3 , 2 Â 64 strips) as scatter detectors, as well as bismuth germanate (BGO) scintillation detectors (38 Â 35 Â 30 mm 3 , 100 blocks) as absorbers. The individual components will be described, together with the status of their characterization.
Full text
Available for:
GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK
Finding ways of increasing animal production with low external inputs and without compromising reproductive performances is a key issue of livestock systems sustainability. One way is to take ...advantage of the diversity and interactions among components within livestock systems. Among studies that investigate the influence of differences in animals' individual abilities in a herd, few focus on combinations of cow breeds with contrasting features in dairy cattle herds. This study aimed to analyse the performances and management of such multi-breed dairy cattle herds. These herds were composed of two types of dairy breeds: 'specialist' (Holstein) and 'generalist' (e.g. Montbeliarde, Simmental, etc.). Based on recorded milk data in southern French region, we performed
(i) to compare the performances of dairy herds according to breed-type composition: multi-breed, single specialist breed or single generalist breed and (ii) to test the difference of milk performances of specialist and generalist breed cows (n = 10 682) per multi-breed dairy herd within a sample of 22 farms. The sampled farmers were also interviewed to characterise herd management through multivariate analysis. Multi-breed dairy herds had a better trade-off among milk yield, milk fat and protein contents, herd reproduction and concentrate-conversion efficiency than single-breed herds. Conversely, they did not offer advantages in terms of milk prices and udder health. Compared to specialist dairy herds, they produce less milk with the same concentrate-conversion efficiency but have better reproductive performances. Compared to generalist dairy herds, they produce more milk with better concentrate-conversion efficiency but have worse reproductive performances. Within herds, specialist and generalist breed cows significantly differed in milk performances, showing their complementarity. The former produced more milk for a longer lactation length while the latter produced milk with higher protein and fat contents and had a slightly longer lactation rank. Our results also focus on the farmers' management of multi-breed dairy herds underlying herd performances. Three strategies of management were identified and structured along two main axes. The first differentiates farmers according to their animal-selection practices in relation with their objectives of production: adapting animal to produce milk with low-feeding inputs v. focussing on milk yield trait to intensify milk production. The second refers to the purpose farmers give to multi-breed dairy herds: milk v. milk/meat production. These initial insights on the performances and management of multi-breed dairy herds contribute to better understanding the functioning of ruminant livestock systems based on individual variability.
Full text
Available for:
GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
Molecular epidemiology studies further our understanding of migrations of phytopathogenic bacteria, the major determining factor in their emergence. Asiatic citrus canker, caused by Xanthomonas citri ...pv. citri, was recently reported in Mali and Burkina Faso, a region remote from other contaminated areas. To identify the origin and pathways of these emergences, we used two sets of markers, minisatellites and microsatellites, for investigating different evolutionary scales. Minisatellite typing suggested the introduction of two groups of strains in Mali (DAPC 1 and DAPC 2), consistent with microsatellite typing. DAPC 2 was restricted to Bamako district, whereas DAPC 1 strains were found much more invasive. The latter strains formed a major clonal complex based on microsatellite data with the primary and secondary founders detected in commercial citrus nurseries and orchards. This suggests that human activities played a major role in the spread of DAPC 1 strains via the movement of contaminated propagative material, further supported by the frequent lack of differentiation between populations from geographically distant nurseries and orchards. Approximate Bayesian Computation analyses supported the hypothesis that strains from Burkina Faso resulted from a bridgehead invasion from Mali. Multi‐locus variable number of tandem repeat analysis and Approximate Bayesian Computation are useful for understanding invasion routes and pathways of monomorphic bacterial pathogens.
Full text
Available for:
BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SAZU, SBCE, SBMB, UL, UM, UPUK
Multilocus variable-number tandem-repeat analysis (MLVA) is efficient for routine typing and for investigating the genetic structures of natural microbial populations. Two distinct pathovars of ...Xanthomonas oryzae can cause significant crop losses in tropical and temperate rice-growing countries. Bacterial leaf streak is caused by X. oryzae pv. oryzicola, and bacterial leaf blight is caused by X. oryzae pv. oryzae. For the latter, two genetic lineages have been described in the literature. We developed a universal MLVA typing tool both for the identification of the three X. oryzae genetic lineages and for epidemiological analyses. Sixteen candidate variable-number tandem-repeat (VNTR) loci were selected according to their presence and polymorphism in 10 draft or complete genome sequences of the three X. oryzae lineages and by VNTR sequencing of a subset of loci of interest in 20 strains per lineage. The MLVA-16 scheme was then applied to 338 strains of X. oryzae representing different pathovars and geographical locations. Linkage disequilibrium between MLVA loci was calculated by index association on different scales, and the 16 loci showed linear Mantel correlation with MLSA data on 56 X. oryzae strains, suggesting that they provide a good phylogenetic signal. Furthermore, analyses of sets of strains for different lineages indicated the possibility of using the scheme for deeper epidemiological investigation on small spatial scales.
Polymeric cytotoxic conjugates are being developed with the aim of preferential delivery of the anticancer agent to tumour. MAG-CPT comprises the topoisomerase I inhibitor camptothecin linked to a ...water-soluble polymeric backbone methacryloylglycynamide (average molecular weight 18 kDa, 10% CPT by weight). It was administered as a 30-min infusion once every 4 weeks to patients with advanced solid malignancies. The objectives of our study were to determine the maximum tolerated dose, dose-limiting toxicities, and the plasma and urine pharmacokinetics of MAG-CPT, and to document responses to this treatment. The starting dose was 30 mg m(-2) (dose expressed as mg equivalent camptothecin). In total, 23 patients received 47 courses at six dose levels, with a maximum dose of 240 mg m(-2). Dose-limiting toxicities were myelosuppression, neutropaenic sepsis, and diarrhoea. One patient died after cycle 1 MAG-CPT at the maximum dose. The maximum tolerated dose and dose recommended for further clinical study was 200 mg m(-2). The half-lives of both MAG-CPT and released CPT were prolonged (>6 days) and measurable levels of MAG-CPT were retrieved from plasma and urine 4 weeks after treatment. However, subsequent pharmacodynamic studies of this agent have led to its withdrawal from clinical development.
Full text
Available for:
DOBA, EMUNI, FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, IZUM, KILJ, KISLJ, MFDPS, NLZOH, NUK, OILJ, PILJ, PNG, SAZU, SBCE, SBJE, SBMB, SBNM, SIK, UILJ, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
Farmers have been slow to adopt decision support system (DSS) models and their outputs, mainly owing to (i) the complexity of the data involved, which most potential users are unable to collect and ...process; and (ii) inability to integrate these models into real representations of their informational environments. This situation raises questions about the way farm management researchers have modelled information and information management, and especially about the quality of the information assessed by the farmers. We consider that to review advisory procedures we need to understand how farmers select and use farm management-related information, rather than focusing on decisions made in particular situations. The aim of this study was to build a conceptual model of the farmer-targeted farm management-related information system. This model was developed using data collected in commercial beef cattle farms. The design structure and operational procedures are based on (i) data categories representing the diversity of the informational activity; and (ii) selected criteria for supporting decisions. The model is composed of two subsystems, each composed of two units. First, an organizational subsystem organizes, finalizes and monitors informational activity. Second, a processing subsystem builds and exploits the informational resources. This conceptual model makes it possible to describe and understand the diverse range of farmers’ informational activity by taking into account both the flow of information and the way farmers make sense of that information. This model could serve as a component of biodecisional DSS models for assigning information in the decision-making process. The next task will be to take into account the broad range of farmers’ perceptions of the management situations in DSS models.
Full text
Available for:
GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
PDF
