Direct and indirect measurement of somatic cell count as indicator of intramammary infection in dairy goats

<p>Abstract</p> <p>Background</p> <p>Mastitis is the most important and costly disease in dairy goat production. Subclinical mastitis is common in goats and is mainly caused by contagious bacteria. Several methods to diagnose subclinical mastitis are available. In this study indirect measurement of somatic cell count (SCC) by California Mastitis Test (CMT) and direct measurement of SCC using a portable deLaval cell counter (DCC) are evaluated. Swedish goat farmers would primarily benefit from diagnostic methods that can be used at the farm. The purpose of the study was to evaluate SCC measured by CMT and DCC as possible markers for intramammary infection (IMI) in goats without clinical symptoms of mastitis. Moreover to see how well indirect measurement of SCC (CMT) corresponded to direct measurement of SCC (DCC).</p> <p>Method</p> <p>Udder half milk samples were collected once from dairy goats (n = 111), in five different farms in Northern and Central Sweden. Only clinically healthy animals were included in the study. All goats were in mid to late lactation at sampling. Milk samples were analyzed for SCC by CMT and DCC at the farm, and for bacterial growth at the laboratory.</p> <p>Results</p> <p>Intramammary infection, defined as growth of udder pathogens, was found in 39 (18%) of the milk samples. No growth was found in 180 (81%) samples while 3 (1%) samples were contaminated. The most frequently isolated bacterial species was coagulase negative staphylococci (CNS) (72% of all isolates), followed by <it>Staphylococcus aureus </it>(23% of all isolates). Somatic cell count measured by DCC was strongly (p = 0.000) associated with bacterial growth. There was also a very strong association between CMT and bacterial growth. CMT 1 was associated with freedom of IMI while CMT ≥2 was associated with IMI. Indirect measurement of SCC by CMT was well correlated with SCC measured by DCC.</p> <p>Conclusions</p> <p>According to the results, SCC measured with CMT or DCC can predict udder infection in goats, and CMT can be used as a predictor of the SCC.</p

Reduced Lentivirus Susceptibility in Sheep with TMEM154 Mutations

Visna/Maedi, or ovine progressive pneumonia (OPP) as it is known in the United States, is an incurable slow-acting disease of sheep caused by persistent lentivirus infection. This disease affects multiple tissues, including those of the respiratory and central nervous systems. Our aim was to identify ovine genetic risk factors for lentivirus infection. Sixty-nine matched pairs of infected cases and uninfected controls were identified among 736 naturally exposed sheep older than five years of age. These pairs were used in a genome-wide association study with 50,614 markers. A single SNP was identified in the ovine transmembrane protein (TMEM154) that exceeded genome-wide significance (unadjusted p-value 3×10−9). Sanger sequencing of the ovine TMEM154 coding region identified six missense and two frameshift deletion mutations in the predicted signal peptide and extracellular domain. Two TMEM154 haplotypes encoding glutamate (E) at position 35 were associated with infection while a third haplotype with lysine (K) at position 35 was not. Haplotypes encoding full-length E35 isoforms were analyzed together as genetic risk factors in a multi-breed, matched case-control design, with 61 pairs of 4-year-old ewes. The odds of infection for ewes with one copy of a full-length TMEM154 E35 allele were 28 times greater than the odds for those without (p-value<0.0001, 95% CI 5–1,100). In a combined analysis of nine cohorts with 2,705 sheep from Nebraska, Idaho, and Iowa, the relative risk of infection was 2.85 times greater for sheep with a full-length TMEM154 E35 allele (p-value<0.0001, 95% CI 2.36–3.43). Although rare, some sheep were homozygous for TMEM154 deletion mutations and remained uninfected despite a lifetime of significant exposure. Together, these findings indicate that TMEM154 may play a central role in ovine lentivirus infection and removing sheep with the most susceptible genotypes may help eradicate OPP and protect flocks from reinfection

RT-PCR detection of lentiviruses in milk or mammary secretions of sheep or goats from infected flocks

Using Smart Source ParsingIn this study we evaluated a reverse transcriptase polymerase chain reaction (RT-PCR) technique for detecting lentiviral infection in milk or mammary secretions from small ruminants. Initial observations on seven goats infected with cloned caprine arthritis-encephalitis virus (CAEV) showed that RT-PCR on milk cells is as reliable as coculture for detecting viral infection, and is quicker and simpler. With a suitable choice of redundant primers followed by a semi-nested amplification, it proved possible to detect the virus in milk samples from naturally infected French sheep (8/8) or goats (9/9), and viral sub-groups could be identified by hybridization with discriminatory probes. All seropositive animals gave positive amplifications, as did one seronegative goat from a contaminated herd, suggesting greater sensitivity for RT-PCR. None of eight goats from a long-established seronegative herd ever gave a positive RT-PCR amplification. This technique provides a simple means for rapidly identifying potentially infectious animals and for epidemiological investigations, as long as the primers are selected according to the genetic structure of the local viral population

L'hormone de croissance recombinante : intérêt et risques potentiels de son utilisation pour la production laitière bovine

Chantier qualité spécifique "Auteurs Externes" département de Génétique animale : uniquement liaison auteur au référentiel HR-AccessNational audienceThe administration of recombinant bovine growth hormone (rbGR) increases milk yield by 26 kg/d, according to cow age, lactation stage and nutrional status, injected dose and slow release formulation of the hormone. Effects on milk composition and body reserves depend on the duration of trials and the kind of diets used. GH increases activity and/or longevity of mammary secretory cells, probably via IGI-I produced by the liver and/or the mammary gland. Simultaneously, GH orients adipose tissue and muscle metabolism towards increased fatty acid mobilization and oxidation, and glucose sparing. The administration of rbGH has few direct effects on the reproductive function, but tends indirectly to delay it, when starting before fecondation, due to the transient decrease in energy balance of the cows. The milk processing ability does not seem to be changed per rbGH, nor the increase in milk IGF-I secretion to create a risk for consumers, GH is probably stimulating immunological responses of animals, and hence increasing the milk cell count, On the other hand, a trend towards increased mastitis frequency seems to result indirectly from the increased milk yield, GH at high concentra tion can stimulate viral yield in some in vitro models in monogastric species, but there are until now only few data obtained in dairy ruminants, Furthermore, the clearance rate of xenobiotics (antibiotics,..) by the liver could be decreased. A putative commercial use of rbGH mould decrease the efficiency (or increase the cost) of genetic selection, and would be of limited economic value for farmers in a milk quota system, However, its use in other countries without quotas could decrease the cost of milk yield and increase the competition on the world market of dairy products, despite the risks of decreasing the image of these products for the consumers.L’administration d’hormone de croissance bovine recombinante (rbGH) accroît la production laitière de 2 à 6 kg/j, de façon variable selon l’âge des vaches, leur stade de lactation et leur état nutritionnel, la dose de GH injectée et la forme de présentation de l’hormone. Les effets sur la composition du lait et les réserves corporelles dépendent de la durée des expériences et de la nature des rations distribuées. La GH stimule l’activité et/ou la durée de vie des cellules sécrétrices mammaires, probablement par l’intermédiaire de l’IGF-1 produit par le foie et/ou la glande mammaire. Simultanément, la GH oriente le métabolisme du tissu adipeux et du muscle vers une mobilisation et une oxydation accrues des acides gras, et une épargne du glucose. L’administration de rbGH a peu d’effets directs sur la fonction de reproduction, mais tend indirectement à la retarder, lorsqu’elle est initiée avant la fécondation, en raison de la diminution transitoire du bilan énergétique des vaches. L’aptitude du lait à la transformation ne semble pas être modifiée par l’administration de rbGH, ni l’élévation de la sécrétion d’IGF-1 dans le lait entraîner de risque pour le consommateur. La GH pourrait stimuler les réponses immunitaires des animaux, et de ce fait accroître le nombre de cellules dans le lait. La tendance à augmenter l’incidence des mammites semble par contre résulter indirectement de l’élévation de la production laitière. La GH à très forte concentration peut stimuler la production virale dans certains modèles in vitro chez les espèces monogastriques, mais il n’existe pour l’instant que très peu de données chez les ruminants laitiers. Par ailleurs, la vitesse d’élimination des xénobiotiques (antibiotiques,...) par le foie pourrait être diminuée. Une éventuelle utilisation commerciale de la rbGH diminuerait l’efficacité (ou augmenterait le coût) de l’amélioration génétique, et serait d’un intérêt économique limité pour les éleveurs placés dans un système de quotas laitiers. Toutefois, son utilisation dans des pays tiers sans quotas pourrait diminuer le coût de production du lait et accroître la compétition sur le marché international des produits laitiers, malgré les risques de dégradation qui pèseraient alors sur l’image de ces produits pour les consommateurs

La hormona de crecimiento recombinante : Interes y riesgos potenciales de su utilizacion para la produccion de leche bovina

152 ref. 6 graph. Chantier qualité spécifique "Auteurs Externes" département de Génétique animale : uniquement liaison auteur au référentiel HR-AccessInternational audienc

Predicting the responses of soil nitrite-oxidizers to multi-factorial global change: A trait-based approach

Soil microbial diversity is huge and a few grams of soil contain more bacterial taxa than there are bird species on Earth. This high diversity often makes predicting the responses of soil bacteria to environmental change intractable and restricts our capacity to predict the responses of soil functions to global change. Here, using a long-term field experiment in a California grassland, we studied the main and interactive effects of three global change factors (increased atmospheric CO2 concentration, precipitation and nitrogen addition, and all their factorial combinations, based on global change scenarios for central California) on the potential activity, abundance and dominant taxa of soil nitrite-oxidizing bacteria (NOB). Using a trait-based model, we then tested whether categorizing NOB into a few functional groups unified by physiological traits enables understanding and predicting how soil NOB respond to global environmental change. Contrasted responses to global change treatments were observed between three main NOB functional types. In particular, putatively mixotrophic Nitrobacter, rare under most treatments, became dominant under the 'High CO2+Nitrogen+Precipitation' treatment. The mechanistic trait-based model, which simulated ecological niches of NOB types consistent with previous ecophysiological reports, helped predicting the observed effects of global change on NOB and elucidating the underlying biotic and abiotic controls. Our results are a starting point for representing the overwhelming diversity of soil bacteria by a few functional types that can be incorporated into models of terrestrial ecosystems and biogeochemical processes. © 2016 Le Roux, Bouskill, Niboyet, Barthes, Dijkstra, Field, Hungate, Lerondelle, Pommier, Tang, Terada, Tourna and Poly