RESUMEN

Bovine respiratory diseases (BRDs) have major socioeconomic impacts in the beef sector. Antimicrobials have been traditionally used to prevent the development of BRDs upon arrival in fattening units. Currently, from a "One Health and One Welfare" perspective, alternative solutions are being investigated. Preconditioning programmes that aim at reducing stress and reinforcing immune functions have been proposed to decrease BRDs incidence. In this study, we assessed the effect of a preconditioning protocol set up in nine commercial beef herds on young bulls' behaviour, health, and performance. Preconditioned bulls (PREC) were weaned indoors 50 days before departure, and progressively fed a concentrate diet supplemented with vitamins and trace elements. They also received an anthelmintic treatment, and two doses of a trivalent vaccine against respiratory pathogens at 4-week intervals. In contrast, controls (CTRL) were kept on pasture with their dams with no vaccination or particular diets. All calves were transported together to a single sorting facility to be sorted by experimental groups, origins, and BW, forming new groups before dispatch to four fattening units. At arrival, CTRL were treated with anthelmintic drugs and received one injection of the same BRDs vaccine. No intervention was performed on PREC bulls. BRD-scores were 0.73 in PREC versus 0.07 in CTRL (P = 0.01) during the preconditioning period and 0.96 in PREC versus 0.54 in CTRL (P = 0.41) after 15 days in the fattening units. Morbidity estimates were 18% in PREC versus 1% in CTRL (P < 0.001) during the preconditioning period and 32% in PREC versus 19% (P = 0.07) in CTRL after 15 days in the fattening units. Poor housing conditions during preconditioning and a different aetiology could partly explain these results. At arrival to fattening, the average daily gain (ADG) was 1 605 g for PREC versus 1 140 g (P = 0.012) for CTRL. After fattening for 180 days, differences in BW, ADG, carcass weight and conformation were inconclusive. In Europe, preconditioning programmes including vaccination must be set up coherently with good husbandry practices and with a global adaptation of batch management of the beef sector otherwise, they may be less effective than expected.

Asunto(s)

Crianza de Animales Domésticos , Animales , Bovinos , Masculino , Crianza de Animales Domésticos/métodos , Conducta Animal , Bienestar del Animal , Complejo Respiratorio Bovino/prevención & control , Enfermedades de los Bovinos/prevención & control , Antihelmínticos/administración & dosificación

RESUMEN

The need to integrate more clearly societal expectations on livestock farming has led the authors of this article to consider that livestock farming systems must be redesigned to position health and welfare at the heart of their objectives. This article proposes a vision of the advances in knowledge required at different scales to contribute to this transformation. After defining health and welfare of animals, the article emphasises the need to consider health in a broader perspective, to deepen the question of positive emotional experiences regarding welfare, and raises the question of how to assess these two elements on farms. The positive interactions between health and welfare are presented. Some possible tensions between them are also discussed, in particular when improving welfare by providing a more stimulating and richer environment such as access to outdoor increases the risk of infectious diseases. Jointly improving health and welfare of animals poses a number of questions at various scales, from the animal level to the production chain. At the animal level, the authors highlight the need to explore: the long-term links between better welfare and physiological balance, the role of microbiota, the psycho-neuro-endocrine mechanisms linking positive mental state and health, and the trade-off between the physiological functions of production, reproduction and immunity. At the farm level, in addition to studying the relationships at the group level between welfare, health and production, the paper supports the idea of co-constructing innovative systems with livestock farmers, as well as analysing the cost, acceptability and impact of improved systems on their working conditions and well-being. At the production chain or territory levels, various questions are raised. These include studying the best strategies to improve animal health and welfare while preserving economic viability, the labelling of products and the consumers' willingness to pay, the consequences of heterogeneity in animal traits on the processing of animal products, and the spatial distribution of livestock farming and the organisation of the production and value chain. At the level of the citizen and consumer, one of the challenges is to better inter-relate sanitary and health perspectives on the one hand, and welfare concerns on the other hand. There is also a need to improve citizens' knowledge on livestock farming, and to develop more intense and constructive exchanges between livestock farmers, the livestock industry and citizens. These difficult issues plead for interdisciplinary and transdisciplinary research involving various scientific disciplines and the different stakeholders, including public policy makers through participatory research.

Asunto(s)

Crianza de Animales Domésticos , Ganado , Animales , Humanos , Granjas , Bienestar del Animal , Agricultores

RESUMEN

This study aimed to determine the effect of lipopolysaccharide (LPS)-induced mastitis with or without nonsteroidal anti-inflammatory drug (NSAID) on dairy cows' clinical, physiological, and behavioral responses in the milking parlor and freestalls as well as the specificity (Sp) and sensitivity (Se) of behavioral responses in detecting cows with LPS-induced mastitis. Twenty-seven cows received an intramammary infusion of 25 µg of Escherichia coli LPS in 1 healthy quarter. Following LPS infusion, 14 cows received a placebo (LPS cows), and 13 cows received 3 mg/kg of body weight of ketoprofen i.m. (LPS+NSAID cows). Cow response to the challenge was monitored at regular intervals from 24 h before to 48 h postinfusion (hpi) through direct clinical observations, markers of inflammation in milk, and via point-in-time direct behavioral observations in the barn and at milking. In LPS cows, infusion induced a significant increase of plasma cortisol levels at 3 and 8 hpi, milk cortisol levels at 8 hpi, somatic cell counts from 8 to 48 hpi, IL-6 and IL-8 at 8 hpi, milk amyloid A (mAA) and haptoglobin at 8 and 24 hpi, rectal temperature at 8 hpi, and respiratory rate at 8 hpi. Their rumen motility rate decreased at 8 and 32 hpi. Compared with before the challenge, significantly more LPS cows stopped feeding/ruminating and pressed their tail between their legs at 3 and 5 hpi, increased feeding/ruminating at 24 hpi, and had the tendency to be less responsive, dropping their head, and dropping their ears at 5 hpi. At milking, compared with before challenge, significantly more LPS cows lifted their hooves at forestripping at 8 hpi. The 2 groups showed similar patterns of response for milk cortisol, somatic cell count, respiratory rate, mAA, haptoglobin, and IL-6, IL-1ß, and IL-8. Compared with LPS cows, LPS+NSAID cows had significantly lower plasma cortisol levels at 3 hpi, their rectal temperature decreased at 8 hpi, their rumen motility rate increased at 8 and 32 hpi, and their heart rate increased at 32 hpi. Compared with LPS cows, a significantly larger proportion of LPS+NSAID cows were feeding/ruminating, a lower proportion had ears down at 5 hpi, and a larger proportion lied down at 24 hpi. At milking, whatever the phase of milking, for "hoof to belly," 9 out of 14 cows did not show this behavior before infusion (Sp = 64%) and 14/14 did not kick during pre-infusion milking (Sp = 100%). Regarding sensitivity, at maximum, 5 cows out of 14 (Se = 36%) displayed "hoof to belly" after infusion. For "lifting hoof," 14/14 did not show hoof-lifting before infusion (Sp = 100%) and 6/14 displayed it after infusion (Se = 43%) at forestripping only. In the freestall barn, 9 behaviors had a Sp >75% (at minimum, 10/14 did not show the behavior) whatever the time point but Se < 60% (at maximum, 8/14 displayed the behavior). Finally, "absence of feeding and ruminating" had Sp of 86% (12/14 ate/ruminated) and Se of 71% (10/14 did not eat/ruminate) at 5 hpi. This study shows that feeding/ruminating, tail position, and reactivity at forestripping could be used as behavioral indictors for early detection of mastitis-related pain in dairy cows.

Asunto(s)

Enfermedades de los Bovinos , Mastitis Bovina , Femenino , Bovinos , Animales , Lipopolisacáridos/farmacología , Interleucina-8/efectos adversos , Hidrocortisona , Haptoglobinas , Técnicas de Observación Conductual , Interleucina-6 , Mastitis Bovina/tratamiento farmacológico , Dolor/tratamiento farmacológico , Dolor/veterinaria , Leche , Antiinflamatorios no Esteroideos/uso terapéutico , Escherichia coli , Proteína Amiloide A Sérica/uso terapéutico , Enfermedades de los Bovinos/tratamiento farmacológico

RESUMEN

The reproductive parameters of dairy cattle have continuously declined worldwide over the last 50 years. Nutritional imbalances are identified as risk factors for this decrease of reproductive performance. The present paper aims to quantify the decrease in the pregnancy per artificial insemination (P/AI) in the case of high milk ketones before and after AI. A total of 388,731 test-day from the Brittany Milk Recording Program in France from 226,429 cow-lactations were provided for this trial. For each test-day, information about lactation characteristics, date of AI, date of the following calving, and acetone and ß-hydroxybutyrate (BHB) values were included. Ketones were predicted by Fourier transform mid-infrared spectroscopy using MilkoScan Foss analyzers (Foss, Hillerød, Denmark). Many thresholds were evaluated to define cows with hyperketolactia. Hyperketolactia statuses were then categorized into 1 of 4 possible classes according to the milk ketone dynamics for each AI and each threshold of acetone or BHB values (low-low, high-low, low-high, and high-high) within 20 d before and after AI. Similarly, the dynamics of udder health were characterized by changes in somatic cell counts measured at the same test day as ketone bodies. A logistic regression with a Poisson correction was performed to explain the relationship of P/AI with milk ketones and somatic cell count dynamics. Predicted acetone and BHB ranged from -0.51 to 4.92 mM (mean = 0.08 mM, SD = 0.10 mM) and -0.62 to 5.85 mM (mean = 0.07 mM, SD = 0.1 mM), respectively. Hyperketolactia defined by high acetone levels before AI was not associated with decreased P/AI, but high acetone levels after AI were associated with a >10% reduction in P/AI for all thresholds >0.10 mM. Hyperketolactia, defined by high BHB values before, after, or before and after AI, was associated with a 6 to 14% reduction in P/AI compared with cows with low BHB values. These associations are lower than those reported in previous trials in which blood ketones were used. High ketones in advanced lactation are likely to be the result of various primary disorders (secondary ketosis). Because the present work demonstrated that this situation is considered a risk factor for deteriorated reproductive performance, we suggest that high ketones in early and advanced lactation should be of interest to farm advisors.

Asunto(s)

Ácido 3-Hidroxibutírico/sangre , Bovinos/metabolismo , Inseminación Artificial/veterinaria , Cetonas/análisis , Leche/química , Animales , Femenino , Lactancia , Embarazo , Índice de Embarazo , Resultado del Tratamiento

RESUMEN

The objective was to assess effects of experimentally induced undernutrition on responses to an intramammary lipopolysaccharide (LPS) challenge in early-lactation cows. Starting at 24 ± 3 d in milk, multiparous Holstein cows either received a ration containing 48% straw for 96 h to restrict nutrient intake (REST, n = 8) or were allowed ad libitum intake of a lactation diet (CONT, n = 9). After 72 h on diet or after an equivalent period for CONT, 50 µg of LPS (Escherichia coli 0111:B4) was injected into one healthy rear mammary quarter to induce an acute inflammation response. Blood samples were collected weekly until 7 wk of lactation, daily during feed restriction (or control), before and at 1, 2, 4, 6, 10, and 24 h relative to LPS injection. Foremilk quarter samples were collected before and at 4, 6, 10, and 24 h after LPS injection. Dry matter intake, milk yield, energy balance, plasma glucose, nonesterified fatty acids (NEFA), and ß-hydroxybutyrate (BHB) concentrations did not differ between CONT and REST immediately before nutrient restriction in REST (least squares means at d -1 were 21.8, 39.0 kg/d, -2.5 MJ/d, and 3.78, 0.415, 0.66 mM, respectively) but were significantly altered at 72 h of nutrient restriction (9.8, 28.3 kg/d, -81.6 MJ/d, and 2.77, 1.672, and 2.98 mM, respectively), when the LPS challenge was performed. The rectal temperature increment from baseline values in response to LPS did not differ, but cortisol increment was greater and cortisol response area under the curve (AUC) tended to be greater [202 vs. 122 (ng/mL) × 10 h] for REST than CONT. No treatment differences were observed in foremilk IL-8, IL-1ß, tumor necrosis factor-α, and chemokine (C-X-C motif) ligand 3 concentrations in response to LPS injection. Composite milk somatic cell count per milliliter (6.919 × 106 vs. 1.956 × 106 cells/mL) and total number of somatic cells secreted in milk per day were greater for REST than CONT during the day following LPS. Plasma glucose, urea, and insulin concentrations increased after the LPS challenge, suggesting establishment of insulin resistance and modifications of glucose metabolism to support acute inflammation in both CONT and REST. Nonetheless, nutrient-restricted cows had delayed plasma insulin and glucose responses to LPS, smaller insulin AUC but greater glucose AUC compared with CONT, despite the limited nutrient availability to sustain an inflammation response. Undernutrition altered peripheral metabolic responses to an intramammary LPS challenge but had limited effects on selected indicators of inflammation response in early-lactation cows.

Asunto(s)

Metabolismo Energético/efectos de los fármacos , Inflamación/veterinaria , Desnutrición/veterinaria , Leche/metabolismo , Ácido 3-Hidroxibutírico/sangre , Animales , Glucemia/efectos de los fármacos , Bovinos , Dieta/veterinaria , Ingestión de Alimentos/efectos de los fármacos , Escherichia coli/química , Ácidos Grasos no Esterificados/sangre , Femenino , Inflamación/inducido químicamente , Inflamación/metabolismo , Insulina/sangre , Resistencia a la Insulina , Lactancia/efectos de los fármacos , Lipopolisacáridos/efectos adversos , Desnutrición/metabolismo

RESUMEN

An enduring controversy exists about low milk cell counts and susceptibility to mastitis. The concentration of milk leukocytes, or somatic cell count (SCC), is a well-established direct indicator of mammary gland inflammation that is highly correlated with the presence of a mammary infection. The SCC is also used as a trait for the selection of dairy ruminants less prone to mastitis. As selection programs favor animals with less SCC, and as milk cells contribute to the defense of the mammary gland, the idea that susceptibility to mastitis could possibly be increased in the long term has been put forward and is still widely debated. Epidemiological and experimental studies aimed at relating SCC to susceptibility to mastitis have yielded results that seem contradictory at first sight. Nevertheless, by taking into account the immunobiology of milk and mammary tissue cells and their role in the defense against infection, along with recent studies on SCC-based divergent selection of animals, the issue can be settled. Apparent SCC-linked susceptibility to mastitis is a phenotypic trait that may be linked to immunomodulation but not to selection.

Asunto(s)

Recuento de Células/veterinaria , Mastitis Bovina/diagnóstico , Leche/citología , Animales , Bovinos , Femenino , Glándulas Mamarias Animales

RESUMEN

During the transition from late gestation to early lactation ruminants experience a negative energy balance (NEB), which is considered to increase susceptibility to mammary infections. Our previous study in 2 divergent lines of sheep selected for high and low somatic cell score (SCS) suggested an association between the response to NEB and genetic susceptibility to mastitis. Forty-eight early-lactation primiparous dairy ewes from the 2 SCS genetic lines were allocated to 2 homogeneous subgroups-an NEB group, which was energy restricted and received 60% of the energy requirements for 15 d, and a control-fed group-to obtain 4 balanced groups of 12 ewes: high-SCS positive energy balance, low-SCS positive energy balance, high-SCS NEB, and low-SCS NEB. High-SCS ewes showed greater weight loss and increased plasmatic concentrations of ß-hydroxybutyrate and nonesterified fatty acids than low-SCS ewes when confronted with an induced NEB. The aim of this study was to further characterize this interaction by combining transcriptomic and phenotypic data with a generalized partial least squares discriminant analysis using mixOmics package framework. A preliminary analysis using 3 blocks of phenotypes (fatty acids, weight and production, blood metabolites) revealed a high correlation between fat-to-protein ratio, ß-hydroxybutyrate, and nonesterified fatty acids concentrations with milk long-chain fatty acid yields. These phenotypes allowed good discrimination of the energy-restricted high-SCS ewes and confirmed a high level of adipose tissue mobilization in this group. A second analysis, which included RNA-seq data, revealed high correlations between the long-chain fatty acid yields in milk and PDK4, CPT1A, SLC25A20, KLF10, and KLF11 expression, highlighting the relationship between mobilization of body reserves and enhanced fatty acids utilization for energy production in blood cells. Finally, analysis of milk composition measured in 1,025 ewes from the 2 genetic lines over 10 yr confirmed significant higher fat-to-protein ratio in high-SCS ewes in early lactation. Altogether, our results strongly confirmed a genetic link between susceptibility to mastitis and metabolic adaptation to energy shortage. Improving genetic resistance to mastitis using SCS should be accompanied by a favorable effect on the response to metabolic stress, especially in highly stressful early lactation. Moreover, this study suggests that the fat-to-protein ratio could be used as a low-cost tool for monitoring energy balance and ketosis during this critical phase of lactation.

Asunto(s)

Recuento de Células/veterinaria , Metabolismo Energético/genética , Lactancia/fisiología , Leche/citología , Ovinos/genética , Ácido 3-Hidroxibutírico/sangre , Tejido Adiposo/metabolismo , Animales , Peso Corporal , Ácidos Grasos/análisis , Ácidos Grasos no Esterificados/sangre , Femenino , Predisposición Genética a la Enfermedad/genética , Mastitis/genética , Mastitis/veterinaria , Leche/química , Proteínas de la Leche/análisis , Embarazo , Enfermedades de las Ovejas/genética

RESUMEN

This study assessed knowledge gaps and suggested research priorities in the field of Staphylococcus aureus mastitis. Staphylococcus aureus infecting the mammary gland remains a major problem to the dairy industry worldwide because of its pathogenicity, contagiousness, persistence in the cow environment, colonization of skin or mucosal epithelia, and the poor curing efficacy of treatments. Staphylococcus aureus also constitutes a threat to public health due to food safety and antibiotic usage issues and the potential for bidirectional transmission of strains between humans and dairy animals (cows and small ruminants). Gaps have been identified in (i) understanding the molecular basis for pathogenesis of S. aureus mastitis, (ii) identifying staphylococcal antigens inducing protection and (iii) determining the cell-mediated immune responses to infection and vaccination. The recommended priorities for research are (i) improved diagnostic methods for early detection of infection and intervention through treatment or management, (ii) development of experimental models to investigate the strategies used by S. aureus to survive within the mammary gland and resist treatment with anti-microbials, (iii) investigation of the basis for cow-to-cow variation in response to S. aureus mastitis, (iv) identification of the immune responses (adaptive and innate) induced by infection or vaccination and (v) antibacterial discovery programmes to develop new, more effective, narrow spectrum antibacterial agents for the treatment of S. aureus mastitis. With the availability and ongoing improvement of molecular research tools, these objectives may not be out of reach in the future.

Asunto(s)

Mastitis Bovina/prevención & control , Infecciones Estafilocócicas/veterinaria , Staphylococcus aureus/patogenicidad , Animales , Antibacterianos/farmacología , Investigación Biomédica , Bovinos , Femenino , Conocimientos, Actitudes y Práctica en Salud , Mastitis Bovina/microbiología , Leche/microbiología , Infecciones Estafilocócicas/microbiología , Infecciones Estafilocócicas/prevención & control , Staphylococcus aureus/inmunología , Vacunación/veterinaria

RESUMEN

Dietary proteins play an important role in reproduction, and increased dietary crude proteins, increased degradability of dietary proteins, and elevated blood or milk urea have been associated with decreased conception and pregnancy in many studies. The aim of this work was to provide a meta-analysis on the relationship between high milk or blood urea and pregnancy or conception, with a focus on defining the appropriate urea threshold associated with this issue. The meta-analysis included 61 different models from 21 papers. The thresholds of urea tested in the various models were built by steps of 1 mM urea. This constructed variable reduced heterogeneity by 61% in the meta-regression. The meta-analysis showed 43% lower odds of pregnancy or conception (odds ratio = 0.57; 95% confidence interval = 0.45-0.73) in cases where urea was ≥7.0 mM in the blood (plasma urea nitrogen = 19.3 mg/dL) or where urea was ≥420 mg/L in the milk compared with where urea values were lower. This threshold is the most suitable with regard to pregnancy or conception success, even if a threshold of 6.5 mM cannot be excluded with certainty. The results also highlighted the possibility of a stronger association between high urea concentrations and pregnancy or conception when high nitrogen exposure occurs before artificial insemination compared with after artificial insemination, but this possibility needs to be further studied. Whether the present results also apply to extensively pasture-based countries remains to be determined.

Asunto(s)

Fertilización , Leche/química , Preñez , Urea/análisis , Animales , Bovinos , Femenino , Inseminación Artificial/veterinaria , Lactancia , Embarazo , Preñez/sangre , Urea/sangre

RESUMEN

Dietary protein levels are a risk factor for poor reproductive performance. Conception is particularly impaired in cases of high blood or milk urea. The objective of this study was to investigate the association between conception and low milk urea or changes in milk urea around artificial insemination (AI). Data were obtained from the French Milk Control Program for a 4-yr period (2009-2012). Milk urea values between 250 and 450 mg/kg (4.3 and 7.7 mM) were considered intermediate (I), and values ≤150 mg/kg (2.6 mM) were considered low (L). Milk urea values before and after each AI were allocated into 4 classes representing the dynamics of milk urea (before-after; I-I, I-L, L-I, and L-L). Subclinical ketosis was defined using milk fat and protein contents before AI as proxies. A logistic regression with a Poisson correction and herd as a random variable was then performed on data from Holstein or all breeds of cows. The success of conception was decreased [relative risk (95% confidence interval) = 0.96 (0.94-0.99)] in low-urea cows compared with intermediate-urea cows after AI; no significant association was found for urea levels before AI. When combining data on urea before and after AI, I-L urea cows exhibited a 5 to 9% decrease in conception compared with I-I urea cows, and L-I urea cows showed no difference in conception success compared with I-I urea cows. A decreased conception success for L-L urea cows compared with I-I urea cows was observed for the analysis with cows of all breeds. This work revealed that a decrease in urea from intermediate (before AI) to low (after AI) is a risk factor for conception failure. Surveys of variation in milk urea in dairy cows close to breeding are highly recommended.

Asunto(s)

Leche , Urea , Animales , Cruzamiento , Bovinos , Femenino , Fertilización , Inseminación Artificial/veterinaria , Lactancia

RESUMEN

Agroecology uses ecological processes and local resources rather than chemical inputs to develop productive and resilient livestock and crop production systems. In this context, breeding innovations are necessary to obtain animals that are both productive and adapted to a broad range of local contexts and diversity of systems. Breeding strategies to promote agroecological systems are similar for different animal species. However, current practices differ regarding the breeding of ruminants, pigs and poultry. Ruminant breeding is still an open system where farmers continue to choose their own breeds and strategies. Conversely, pig and poultry breeding is more or less the exclusive domain of international breeding companies which supply farmers with hybrid animals. Innovations in breeding strategies must therefore be adapted to the different species. In developed countries, reorienting current breeding programmes seems to be more effective than developing programmes dedicated to agroecological systems that will struggle to be really effective because of the small size of the populations currently concerned by such systems. Particular attention needs to be paid to determining the respective usefulness of cross-breeding v. straight breeding strategies of well-adapted local breeds. While cross-breeding may offer some immediate benefits in terms of improving certain traits that enable the animals to adapt well to local environmental conditions, it may be difficult to sustain these benefits in the longer term and could also induce an important loss of genetic diversity if the initial pure-bred populations are no longer produced. As well as supporting the value of within-breed diversity, we must preserve between-breed diversity in order to maintain numerous options for adaptation to a variety of production environments and contexts. This may involve specific public policies to maintain and characterize local breeds (in terms of both phenotypes and genotypes), which could be used more effectively if they benefited from the scientific and technical resources currently available for more common breeds. Last but not least, public policies need to enable improved information concerning the genetic resources and breeding tools available for the agroecological management of livestock production systems, and facilitate its assimilation by farmers and farm technicians.

Asunto(s)

Crianza de Animales Domésticos/métodos , Cruzamiento/métodos , Aves de Corral/fisiología , Rumiantes/fisiología , Porcinos/fisiología , Animales , Ecología , Genotipo , Ganado/genética , Ganado/fisiología , Fenotipo , Aves de Corral/genética , Rumiantes/genética , Porcinos/genética

RESUMEN

Agroecology uses natural processes and local resources rather than chemical inputs to ensure production while limiting the environmental footprint of livestock and crop production systems. Selecting to achieve a maximization of target production criteria has long proved detrimental to fitness traits. However, since the 1990s, developments in animal breeding have also focussed on animal robustness by balancing production and functional traits within overall breeding goals. We discuss here how an agroecological perspective should further shift breeding goals towards functional traits rather than production traits. Breeding for robustness aims to promote individual adaptive capacities by considering diverse selection criteria which include reproduction, animal health and welfare, and adaptation to rough feed resources, a warm climate or fluctuating environmental conditions. It requires the consideration of genotype×environment interactions in the prediction of breeding values. Animal performance must be evaluated in low-input systems in order to select those animals that are adapted to limiting conditions, including feed and water availability, climate variations and diseases. Finally, we argue that there is no single agroecological animal type, but animals with a variety of profiles that can meet the expectations of agroecology. The standardization of both animals and breeding conditions indeed appears contradictory to the agroecological paradigm that calls for an adaptation of animals to local opportunities and constraints in weakly artificialized systems tied to their physical environment.

Asunto(s)

Crianza de Animales Domésticos/métodos , Cruzamiento/métodos , Objetivos , Ganado/fisiología , Aves de Corral/fisiología , Rumiantes/fisiología , Porcinos/fisiología , Aclimatación/genética , Animales , Ecología , Ambiente , Aves de Corral/genética , Rumiantes/genética , Selección Genética , Porcinos/genética

RESUMEN

Dairy ruminants experiencing a severe postpartum negative energy balance (NEB) are considered to be more susceptible to mastitis. Although the genetic variability of mastitis resistance is well established, the biological basis of the link between energy metabolism and resistance is mostly unknown. The aim of this study was to characterize the effect of NEB on metabolism and immune response according to the genetic background for mastitis resistance or susceptibility. Forty-eight ewes from high and low somatic cell score (SCS) genetic lines were allocated to 2 homogeneous subgroups 2 wk after lambing: one group (NEB) received an energy-restricted diet to cover 60% of their energy requirements, and the other group received a control (positive energy balance: PEB) diet. Both diets met the protein requirements. After 10 d on either the NEB or PEB diet, all ewes were injected with a Pam3CSK4/MDP solution in one half-udder to induce an inflammatory response. The ewes were monitored for milk production, somatic cell count (SCC), body weight (BW), body condition score (BCS), and blood metabolites. Differential milk cell counts were determined by flow cytometry. Plasma concentrations of glucose, insulin, nonesterified fatty acids (NEFA), ß-hydroxybutyrate (BHB), and triiodothyronine were determined. Energy restriction resulted in an increased fat:protein ratio in milk and decreased milk yield, BW, and BCS. The NEB ewes had significantly higher NEFA and BHB and lower plasma glucose concentrations than PEB ewes, reflecting a mobilization of body reserves and ketone body synthesis. High-SCS ewes had a higher SCS than low-SCS throughout the experiment, except after the inflammatory challenge, which resulted in similar SCS in all 4 groups. A noteworthy interaction between genetic background and diet was evidenced on metabolic parameters and BW. Indeed, high-SCS ewes subjected to NEB showed greater decrease in BW and increased NEFA and BHB concentrations compared with low-SCS ewes. Thus, NEB in early lactation led to extensive mobilization of body reserves and intense ketone body synthesis in mastitis-susceptible sheep. These results reinforce the hypothesis of a genetic association between mastitis susceptibility and energy metabolism and open the way to further studies on the biological basis for this association.

Asunto(s)

Ingestión de Energía/fisiología , Metabolismo Energético , Mastitis/veterinaria , Leche/metabolismo , Enfermedades de las Ovejas/inmunología , Ácido 3-Hidroxibutírico/sangre , Animales , Peso Corporal , Dieta/veterinaria , Susceptibilidad a Enfermedades/veterinaria , Ácidos Grasos no Esterificados/sangre , Femenino , Insulina/sangre , Lactancia , Glándulas Mamarias Animales/metabolismo , Mastitis/inmunología , Leche/citología , Periodo Posparto , Ovinos , Triyodotironina/sangre

RESUMEN

Excess dietary nitrogen (EDN) is commonly expected in dairy herds, but no data are available regarding its consequences on cattle immunity. In this study neutrophil functions were assessed during EDN in steers. In experiment 1, 4 one-month periods, 4 diets [16% crude protein (CP; DM basis), 20% CP based on soybean meal, 20% CP based on urea, and 24% CP based on urea and soybean meal], and 4 steers were included in a crossover design to determine the effects of a chronic excess. In experiment 2, the repercussions of an acute excess were assessed with 2 periods of 10 d, the same 4 steers, and 2 diets containing 14 and 20% CP. Sampling was done during the fourth week of each period in experiment 1, and on d 0, 1, 2, 3, 7, and 9 of each period in experiment 2. Individual blood biochemistry parameters were measured and neutrophil factors, such as counts, recovery after isolation, surface expression of CD11b and CD62L, phagocytosis, diapedesis, reactive oxygen species (ROS) production, and bacteria killing, were determined. Data were analyzed by general linear models of R, with period, diet or biochemical component, and animal as explanatory variables. The outcome variables were biochemical or immune variables. The variables diet, period, and animal were forced as fixed effects. Data collected over the entire period of experiment 2 were pooled. Several multiples linear regressions or ANOVA were performed and a Bonferroni correction was applied. In experiment 2 (acute EDN), neutrophil counts were negatively associated with nitrogen intake, conversely to CD62L expression. The observed relative neutropenia may be due to neutrophil margination because CD62L-expressing neutrophils are more likely to stick to endothelium. Interestingly, ROS production was changed by EDN: chronic EDN (experiment 1) was negatively associated with opsonized zymozan (OZ)-induced ROS production and acute EDN (experiment 2) with spontaneous ROS production. For chronic EDN, ROS production upon phorbol 12-myristate 13-acetate was not modified, in contrast to OZ stimulation. Decreased ROS production during chronic EDN probably involves the early events leading to ROS production, as OZ acts through membrane receptors and phorbol 12-myristate 13-acetate directly activates protein kinase C. This is the first study to provide evidence that the modifications of neutrophil functions produced by excess nitrogen depend on the intensity and duration of the excess. Further studies, including epidemiological studies during risk periods, are needed to resolve the issues linked to EDN.

Asunto(s)

Bovinos/inmunología , Proteínas en la Dieta/administración & dosificación , Neutrófilos/efectos de los fármacos , Nitrógeno/farmacología , Amoníaco/sangre , Animales , Bovinos/sangre , Bovinos/fisiología , Estudios Cruzados , Dieta/veterinaria , Proteínas en la Dieta/inmunología , Proteínas en la Dieta/metabolismo , Hematócrito/veterinaria , Masculino , Neutrófilos/inmunología , Nitrógeno/administración & dosificación , Nitrógeno/inmunología , Glycine max/química , Urea/sangre

RESUMEN

Recombinant myxoma virus (MYXV) can be produced without a loss of infectivity, and its highly specific host range makes it an ideal vaccine vector candidate, although careful examination of its interaction with the immune system is necessary. Similar to rabbit bone marrow-derived dendritic cells (BM-DCs), ovine dendritic cells can be infected by SG33, a MYXV vaccine strain, and support recombinant antigen expression. The frequency of infected cells in the nonhost was lower and the virus cycle was abortive in these cell types. Among BM-DC subpopulations, Langerhans cell-like DCs were preferentially infected at low multiplicities of infection. Interestingly, ovine BM-DCs remained susceptible to MYXV after maturation, although apoptosis occurred shortly after infection as a function of the virus titer. When gene expression was assessed in infected BM-DC cultures, type I interferon (IFN)-related and inflammatory genes were strongly upregulated. DC gene expression profiles were compared with the profiles produced by other poxviruses in interaction with DCs, but very few commonalities were found, although genes that were previously shown to predict vaccine efficacy were present. Collectively, these data support the idea that MYXV permits efficient priming of adaptive immune responses and should be considered a promising vaccine vector along with other poxviruses.

Asunto(s)

Células Dendríticas/inmunología , Células Dendríticas/virología , Portadores de Fármacos , Expresión Génica , Vectores Genéticos , Myxoma virus/inmunología , Vacunas Virales/inmunología , Animales , Células Cultivadas , Evaluación de Medicamentos/métodos , Perfilación de la Expresión Génica , Myxoma virus/genética , Conejos , Ovinos , Vacunas Atenuadas/genética , Vacunas Atenuadas/inmunología , Vacunas Sintéticas/genética , Vacunas Sintéticas/inmunología , Vacunas Virales/genética

RESUMEN

A comparative experimental study was performed between Barbados Black Belly (resistant) and INRA-401 (susceptible) breeds of sheep in which primary infection with Haemonchus contortus was terminated on day 16. Measurements of parasite burden, abomasal tissue eosinophilia, IL-4, IL-5 and IL-13 mRNA transcripts in abomasal mucosa, and in vitro larval killing abilities of blood eosinophils were performed. The results show that: (1) worm burden was significantly lower and blood eosinophilia higher in the Black Belly than in the INRA breed. (2) Abomasal cytokine expression was noticed but no difference existed between the two breeds. (3) Three out of four Black Belly sheep had higher tissue eosinophil numbers compared to the INRA sheep (more eosinophils observed in the pyloric than in the fundic region in both breeds). (4) No significant difference was observed in the in vitro larval immobilizing potential of eosinophils between the two breeds. Collectively, abomasal eosinophil number and larval killing abilities of blood eosinophils do not seem to explain the difference in worm burden between the two breeds.

Asunto(s)

Abomaso/parasitología , Eosinófilos/inmunología , Predisposición Genética a la Enfermedad , Hemoncosis/veterinaria , Haemonchus/fisiología , Enfermedades de las Ovejas , Animales , Regulación de la Expresión Génica/inmunología , Hemoncosis/genética , Hemoncosis/inmunología , Hemoncosis/parasitología , Haemonchus/inmunología , Interleucinas/inmunología , Larva , Ovinos , Enfermedades de las Ovejas/genética , Enfermedades de las Ovejas/inmunología , Enfermedades de las Ovejas/parasitología

RESUMEN

A divergent selection experiment in sheep was implemented to study the consequences of log-transformed somatic cell score (SCS)-based selection on resistance to natural intramammary infections. Using dams and progeny-tested rams selected for extreme breeding values for SCS, we created 2 groups of ewes with a strong divergence in SCS of approximately 3 genetic standard deviations. A survey of 84 first-lactation ewes of both the High and Low SCS lines indicated favorable responses to SCS-based selection on resistance to both clinical and subclinical mastitis. All clinical cases (n = 5) occurred in the High SCS line. Additionally, the frequency of chronic clinical mastitis, as detected by the presence of parenchymal abscesses, was much greater in the High SCS line (n = 21) than in the Low SCS line (n = 1). According to monthly milk bacteriological examinations of udder halves, the prevalence of infection was significantly greater (odds ratio = 3.1) in the High SCS line than in the Low SCS line, with predicted probabilities of 37 and 16%, respectively. The most frequently isolated bacteria responsible for mastitis were staphylococci: Staphylococcus auricularis (42.6% of positive samples), Staphylococcus simulans, Staphylococcus haemoliticus, Staphylococcus xylosus, Staphylococcus chromogenes, Staphylococcus lentus, Staphylococcus warneri, and Staphylococcus aureus. The incidence of positive bacteriology was greater in the High SCS line (39%) than in the Low SCS line (12%) at lambing, indicating that High SCS line ewes were especially susceptible to postpartum subclinical mastitis. Negativation of bacteriological results from one sampling time point to the next was markedly different between lines after weaning (e.g., 41 and 84% in the High and Low SCS lines, respectively). This result was consistent with differences in the duration of infection, which was much greater in the High SCS line compared with the Low SCS line. Finally, ewes from the High SCS line consistently had greater SCS in positive milk samples than did ewes from the Low SCS line (+2.04 SCS, on average), with an especially large difference between lines during the suckling period (+3.42 SCS). Altogether, the preliminary results suggest that the better resistance of Low SCS line ewes, compared with High SCS line ewes, was principally characterized by a better ability to limit infections during the peripartum period, to eliminate infections during lactation, and quantitatively to limit the inflammation process and its clinical consequences.

Asunto(s)

Inmunidad Innata/genética , Mastitis/veterinaria , Leche/citología , Selección Genética , Ovinos/genética , Animales , Cruzamiento , Recuento de Células , Femenino , Modelos Logísticos , Masculino , Glándulas Mamarias Animales/microbiología , Mastitis/microbiología , Leche/microbiología , Enfermedades de las Ovejas/microbiología

RESUMEN

Placentae from scrapie-affected ewes are an important source of contamination. This study confirmed that scrapie-incubating ewes bearing susceptible genotypes could produce both abnormal prion protein (PrPSc)-positive and -negative placentae, depending only on the PRP genotype of the fetus. The results also provided evidence indicating that scrapie-incubating ARR/VRQ ewes may be unable to accumulate prions in the placenta, whatever the genotype of their progeny. Multinucleated trophoblast cells appeared to play a key role in placental PrPSc accumulation. PrPSc accumulation began in syncytiotrophoblasts before disseminating to uninucleated trophoblasts. As these result from trophoblast/uterine epithelial cell fusion, syncytiotrophoblast cells expressed maternal and fetal PrPC, whilst uninucleated trophoblast cells only expressed fetal PrPC. In ARR/VRQ scrapie-infected ewes, expression of the ARR allele by syncytiotrophoblasts appeared to prevent initiation of PrPSc placental deposition. The absence of prions in affected ARR/VRQ sheep placentae reinforces strongly the interest in ARR selection for scrapie control.

Asunto(s)

Placenta/química , Proteínas PrPSc/análisis , Complicaciones del Embarazo/veterinaria , Scrapie/metabolismo , Alelos , Animales , Femenino , Feto , Genotipo , Inmunohistoquímica , Placenta/patología , Embarazo , Complicaciones del Embarazo/metabolismo , Complicaciones del Embarazo/patología , Scrapie/patología , Ovinos , Trofoblastos/química

RESUMEN

Because variant Creutzfeldt-Jakob disease (vCJD) in humans probably results from consumption of products contaminated with tissue from animals with bovine spongiform encephalopathy, whether infectious prion protein is present in ruminant muscles is a crucial question. Here we show that experimentally and naturally scrapie-affected sheep accumulate the prion protein PrP(Sc) in a myocyte subset. In naturally infected sheep, PrP(Sc) is detectable in muscle several months before clinical disease onset. The relative amounts of PrP(Sc) suggest a 5,000-fold lower infectivity for muscle as compared to brain.

Asunto(s)

Fibras Musculares Esqueléticas/metabolismo , Proteínas PrPSc/metabolismo , Scrapie/metabolismo , Animales , Bovinos , Ensayo de Inmunoadsorción Enzimática , Humanos , Inmunohistoquímica , Fibras Musculares Esqueléticas/citología , Fibras Nerviosas/metabolismo , Proteínas PrPSc/patogenicidad , Ovinos

RESUMEN

Th1 and Th2 cells produce different cytokines and have distinct functions. Th1/Th2 cell differentiation is influenced, among other factors, by the nature of TCR-MHC interactions. However, how the TCR transduces a signal resulting in IFN-gamma or IL-4 production is a matter of debate. For example, some authors reported a loss of calcium signaling pathway in Th2 cells. We used a T cell hybridoma producing IL-4 upon weak TCR stimulation and both IL-4 and IFN-gamma for strong TCR engagement as a model to study how TCR signaling pathways are differentially activated in both conditions of stimulation and how this influences the production of cytokines. We show that: (1) the calcium response is identical following weak and strong TCR stimulation; (2) mitogen-activated protein kinase(MAPK) activation is a gradual phenomenon depending upon the strength of TCR activation; (3) a calcium response, even weak, triggers IL-4 expression; (4) IFN-gamma synthesis requires not only a calcium response but also MAPK activation. The MAPK pathway is dispensable for IL-4 production, although it amplifies IL-4 synthesis upon strong TCR stimulation; (5) TCR-induced IL-4 production also depends on calcium signaling in Th2 cells, while IFN-gamma synthesis is dependent, in addition, on MAPK activation in Th1 cells.

Asunto(s)

Señalización del Calcio , Quimiocinas CC , Interferón gamma/biosíntesis , Interleucina-4/biosíntesis , Sistema de Señalización de MAP Quinasas , Receptores de Antígenos de Linfocitos T/metabolismo , Linfocitos T/metabolismo , Animales , Western Blotting , Calcio/metabolismo , Señalización del Calcio/efectos de los fármacos , Línea Celular , Quimiocina CCL11 , Citocinas/farmacología , Activación Enzimática/efectos de los fármacos , Regulación de la Expresión Génica/efectos de los fármacos , Hibridomas/efectos de los fármacos , Hibridomas/metabolismo , Interferón gamma/genética , Interferón gamma/inmunología , Interleucina-4/genética , Interleucina-4/inmunología , Sistema de Señalización de MAP Quinasas/efectos de los fármacos , Ratones , Ratones Endogámicos BALB C , Proteínas Quinasas Activadas por Mitógenos/metabolismo , Fosforilación/efectos de los fármacos , ARN Mensajero/genética , ARN Mensajero/metabolismo , Receptores de Antígenos de Linfocitos T/inmunología , Linfocitos T/efectos de los fármacos , Linfocitos T/enzimología , Linfocitos T/inmunología , Acetato de Tetradecanoilforbol/farmacología , Células TH1/efectos de los fármacos , Células TH1/enzimología , Células TH1/inmunología , Células TH1/metabolismo , Células Th2/efectos de los fármacos , Células Th2/enzimología , Células Th2/inmunología , Células Th2/metabolismo , Tapsigargina/farmacología