Your browser doesn't support javascript.
Mostrar: 20 | 50 | 100
Resultados 1 - 6 de 6
Mais filtros

Base de dados
Tipo de estudo
Intervalo de ano de publicação
Vet Parasitol ; 277: 109018, 2020 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-31896020


Control of sheep gastrointestinal nematode (GIN) infections mostly relies on the use of anthelmintics. Refugia-based control strategies as targeted selective treatments (TST) can delay anthelmintic resistance development, but the optimal decision criteria for selecting individuals to be treated in subclinical infection scenarios remain unclear. The present study aimed to evaluate the suitability of body condition score (BCS) and faecal egg counts (FEC) as treatment indicators and to determine their optimized threshold values for treatment in TST by determining the relationships of BCS, FEC and anthelmintic treatment with several productive parameters in pre-mating and pre-partum periods at an individual level. Deworming in pre-mating period increased BCS gain, but its magnitude was directly associated with strongyle FEC before treatment. Deworming also increased fertility in ewes with BCS < 2.75 and the proportion of lambing ewes that got pregnant during the first ovulation cycle. Nevertheless, treatment did not yield productive benefits in ewes with higher BCS values. On the other hand, deworming in the pre-partum lowered lamb peri-partum mortality and increased lamb weight at birth and the growth of lambs during lactation, especially in lambs born from ewes with strongyle FEC > 400 epg before treatment. These results showed that FEC and especially BCS can be potential decision criteria for the implementation of TST in these types of scenarios. The TST scheme derived from the present results on the control of GIN infections should include anthelmintic treatment of ewes with BCS lower than ≈ 3 approximately five weeks before mating and lambing. In the pre-lambing period, treatment may be unnecessary if flock mean strongyle FEC is lower than ≈ 200 epg, as the proportion of ewes with individual FEC > 400 epg would be very low. The results suggest that implementation of this TST scheme would provide benefits, such as the improvement of productivity, a rational management of parasites in refugia, and preservation of future efficacy of anthelmintics, in comparison to traditional deworming schemes.

Gastroenteropatias/veterinária , Infecções por Nematoides/veterinária , Doenças dos Ovinos/tratamento farmacológico , Doenças dos Ovinos/prevenção & controle , Animais , Infecções Assintomáticas , Feminino , Gastroenteropatias/tratamento farmacológico , Gastroenteropatias/prevenção & controle , Infecções por Nematoides/tratamento farmacológico , Infecções por Nematoides/prevenção & controle , Gravidez , Ovinos
Phys Rev E ; 94(3-1): 032302, 2016 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-27739797


In a recent work [Phys. Rev. E 91, 022808 (2015)PLEEE81539-375510.1103/PhysRevE.91.022808] it was reported that placing an obstacle in front of a gate has a beneficial effect in the flow of sheep through it. Here, we extend such results by implementing three different obstacle positions. We have observed that the flow is improved in two cases, while it worsens in the other one; the last instance happens when the obstacle is too close to the door. In this situation, the outcomes suggest that clogging develops between the doorjamb and the obstacle, contrary to the cases when the obstacle is farther, in which case clogging always occurs at the very door. The effectiveness of the obstacle (a strategy put forward to alleviate clogging in emergency exits) is therefore quite sensitive to its location. In addition, the study of the temporal evolution of the flow rate as the test develops makes evident a steady behavior during the entire duration of the entrance. This result is at odds with recent findings in human evacuation tests where the flow rate varies over time, therefore challenging the fairness of straightforward comparisons between pedestrian behavior and animal experimental observations.

Artigo em Inglês | MEDLINE | ID: mdl-26764754


The "faster-is-slower" (FIS) effect was first predicted by computer simulations of the egress of pedestrians through a narrow exit [D. Helbing, I. J. Farkas, and T. Vicsek, Nature (London) 407, 487 (2000)]. FIS refers to the finding that, under certain conditions, an excess of the individuals' vigor in the attempt to exit causes a decrease in the flow rate. In general, this effect is identified by the appearance of a minimum when plotting the total evacuation time of a crowd as a function of the pedestrian desired velocity. Here, we experimentally show that the FIS effect indeed occurs in three different systems of discrete particles flowing through a constriction: (a) humans evacuating a room, (b) a herd of sheep entering a barn, and (c) grains flowing out a 2D hopper over a vibrated incline. This finding suggests that FIS is a universal phenomenon for active matter passing through a narrowing.

Fricção , Animais , Humanos , Cinética , Movimento (Física) , Movimento , Ovinos/fisiologia , Vibração
Vet Dermatol ; 26(1): 49-52, e15-6, 2015 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-25354687


BACKGROUND: Dermatosparaxis (Ehlers-Danlos syndrome in humans) is characterized by extreme fragility of the skin. It is due to the lack of mature collagen caused by a failure in the enzymatic processing of procollagen I. We investigated the condition in a commercial sheep flock. HYPOTHESIS/OBJECTIVES: Mutations in the ADAM metallopeptidase with thrombospondin type 1 motif, 2 (ADAMTS2) locus, are involved in the development of dermatosparaxis in humans, cattle and the dorper sheep breed; consequently, this locus was investigated in the flock. ANIMALS: A single affected lamb, its dam, the dam of a second affected lamb and the rams in the flock were studied. METHODS: DNA was purified from blood, PCR primers were used to detect parts of the ADAMS2 gene and nucleotide sequencing was performed using Sanger's procedure. Skin samples were examined using standard histology procedures. RESULTS: A missense mutation was identified in the catalytic domain of ADAMTS2. The mutation is predicted to cause the substitution in the mature ADAMTS2 of a valine molecule by a methionine molecule (V15M) affecting the catalytic domain of the enzyme. Both the 'sorting intolerant from tolerant' (SIFT) and the PolyPhen-2 methodologies predicted a damaging effect for the mutation. Three-dimensional modelling suggested that this mutation may alter the stability of the protein folding or distort the structure, causing the protein to malfunction. CONCLUSIONS AND CLINICAL IMPORTANCE: Detection of the mutation responsible for the pathology allowed us to remove the heterozygote ram, thus preventing additional cases in the flock.

Proteínas ADAM/genética , Síndrome de Ehlers-Danlos/veterinária , Mutação de Sentido Incorreto/genética , Doenças dos Ovinos/genética , Animais , Simulação por Computador , Síndrome de Ehlers-Danlos/genética , Feminino , Heterozigoto , Masculino , Dobramento de Proteína , Estrutura Terciária de Proteína/genética , Ovinos/genética
Can J Vet Res ; 78(3): 237-40, 2014 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-24982557


Ovine pulmonary adenocarcinoma (OPA) is a transmissible lung cancer caused by Jaggsiekte sheep retrovirus (JSRV). It is difficult to identify animals infected with JSRV but are clinically healthy. The virus does not induce a specific antibody response and, although proviral DNA sequences of JSRV can be found in mononuclear blood cells, the detection is inconsistent. The aim of this study was to investigate the presence of JSRV in the bone marrow of infected sheep and develop a more consistent screening method. Immunohistochemical examination of bone marrow samples from 8 asymptomatic JSRV-infected sheep revealed the presence of positively labelled cells. However, JSRV could not be detected by a highly sensitive polymerase chain reaction (PCR) in bone marrow aspirates periodically collected from these animals. Results suggest that JSRV-infected cells may be present in the bone marrow of symptomless animals, but the number is below the detectable level for PCR. Therefore, this technique does not seem to be helpful for preclinical diagnosis of OPA.

Células da Medula Óssea/virologia , Retrovirus Jaagsiekte de Ovinos/fisiologia , Adenomatose Pulmonar Ovina/virologia , Animais , Retrovirus Jaagsiekte de Ovinos/isolamento & purificação , Reação em Cadeia da Polimerase/veterinária , Sensibilidade e Especificidade , Ovinos , Latência Viral
Can Vet J ; 47(12): 1208-9, 2006 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-17217091


A 9-year old, Rasa Aragonesa ewe was presented with a left-sided, facial, soft fluctuant swelling. The postmortem examination showed grass awns filling the entire length of the parotid gland duct. The presence of parotid duct obstruction with Horner's syndrome, previously unreported in sheep, is discussed.

Síndrome de Horner/veterinária , Glândula Parótida/patologia , Doenças dos Ovinos/diagnóstico , Animais , Evolução Fatal , Feminino , Síndrome de Horner/diagnóstico , Síndrome de Horner/patologia , Ovinos , Doenças dos Ovinos/patologia