Detection of subclinical mastitis in ewes

Maisi, Päivi; Junttila, Jaana; Seppänen, Jaana

doi:10.1016/0007-1935(87)90017-0

Cited by 49 publications

(26 citation statements)

References 5 publications

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“…Evidence has been published that healthy ewes normally have higher SCC than healthy cows [18-20]. Bufano et al [21] have shown that high SCC (> 1 million/mL) do occur in healthy sheep's milk, especially towards the end of lactation.…”

Section: Discussionmentioning

confidence: 99%

Genetic parameters for somatic cell score according to udder infection status in Valle del Belice dairy sheep and impact of imperfect diagnosis of infection

et al. 2010

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BackgroundSomatic cell score (SCS) has been promoted as a selection criterion to improve mastitis resistance. However, SCS from healthy and infected animals may be considered as separate traits. Moreover, imperfect sensitivity and specificity could influence animals' classification and impact on estimated variance components. This study was aimed at: (1) estimating the heritability of bacteria negative SCS, bacteria positive SCS, and infection status, (2) estimating phenotypic and genetic correlations between bacteria negative and bacteria positive SCS, and the genetic correlation between bacteria negative SCS and infection status, and (3) evaluating the impact of imperfect diagnosis of infection on variance component estimates.MethodsData on SCS and udder infection status for 1,120 ewes were collected from four Valle del Belice flocks. The pedigree file included 1,603 animals. The SCS dataset was split according to whether animals were infected or not at the time of sampling. A repeatability test-day animal model was used to estimate genetic parameters for SCS traits and the heritability of infection status. The genetic correlation between bacteria negative SCS and infection status was estimated using an MCMC threshold model, implemented by Gibbs Sampling.ResultsThe heritability was 0.10 for bacteria negative SCS, 0.03 for bacteria positive SCS, and 0.09 for infection status, on the liability scale. The genetic correlation between bacteria negative and bacteria positive SCS was 0.62, suggesting that they may be genetically different traits. The genetic correlation between bacteria negative SCS and infection status was 0.51. We demonstrate that imperfect diagnosis of infection leads to underestimation of differences between bacteria negative and bacteria positive SCS, and we derive formulae to predict impacts on estimated genetic parameters.ConclusionsThe results suggest that bacteria negative and bacteria positive SCS are genetically different traits. A positive genetic correlation between bacteria negative SCS and liability to infection was found, suggesting that the approach of selecting animals for decreased SCS should help to reduce mastitis prevalence. However, the results show that imperfect diagnosis of infection has an impact on estimated genetic parameters, which may reduce the efficiency of selection strategies aiming at distinguishing between bacteria negative and bacteria positive SCS.

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Section: Discussionmentioning

confidence: 99%

Genetic parameters for somatic cell score according to udder infection status in Valle del Belice dairy sheep and impact of imperfect diagnosis of infection

et al. 2010

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“…Avaliando amostras de leite de fê-meas ovinas, Domingues et al (2006) observaram que das 88 amostras positivas ao teste CMT, 14 (16,0%) apresentaram resultados negativos no cultivo microbiológico. O uso do CMT também apresenta limitações quando aplicado na espécie ovina, já que o teste foi inicialmente desenvolvido para espécie bovina, apresentando melhor conjunto de sensibilidade e especificidade quando empregado nesta espécie (Maisi et al 1987). Nunes et al (2008) recomendam o escore 1+ do CMT para a discriminação entre as fêmeas ovinas positivas e negativas para a mastite subclínica, considerando que este escore apresenta boa especificidade sem comprometer demasiadamente a sensibilidade.…”

Section: Methodsunclassified

Etiologia e perfil de sensibilidade antimicrobiana dos isolados bacterianos da mastite em pequenos ruminantes e concordância de técnicas empregadas no diagnóstico

et al. 2010

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Mastitis is an inflammation of mammary gland, that are important in milking breed as well in meat ones. It is associated with serious reduction in milk production and quality, lambs weight gain reduction and mortality The goal of this work was determine the major etiologic agents of goat and sheep mastitis, as well as antimicrobial drug-resistance patterns and the agreement between two different diagnostic tools. We visit 25 goat, sheep, and goat and sheep farms in Pernambuco and Bahia State, and a total of 439 goats and 76 sheep milk samples were collected. To diagnose of small ruminant mastitis were compared two tests: Milk culture and California Mastitis Test (CMT). The bacterial drug-resistance pattern was determined by Kirby Bauer test. Staphylococcus spp. was the most frequent bacteria isolated from goat and sheep mastitis cases. Streptococcus spp., Corynebacterium spp. and gram-negative bacilli were isolated. It was possible to observe the high sensitivity to antimicrobial drugs in all tested bacteria, being the lower sensitivity percentage determined to nalidixic acid. Considering caprine mastitis diagnostic the comparative analysis between microbiologic culture and shown a concordance degree of K=0,17, although to ovine species these value was K=0,22. The use of CMT to subclinical mastitis diagnostic in goat and ewes must be associated to milk bacterial culture.INDEX TERMS: Pathogens, antimicrobial sensitivity, diagnostic, mastitis.RESUMO.-A mastite é a inflamação da glândula mamária que acomete raças de aptidão leiteira como também aquelas voltadas para produção de carne. Esta enfermidade ocasiona sérias alterações na produção de leite e na sua qualidade, redução no ganho de peso e mortalidade de cordeiros. O presente estudo teve por objetivo conhecer os principais agentes causadores de mastite em ovinos e caprinos, bem como a sua susceptibilidade aos agentes antimicrobianos, além de avaliar o grau de concordância entre testes diagnósticos. Aceito para publicação em 12 de abril de 2010.

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“…Some evidence has been provided that healthy ewes have normally higher SCC than cows (Maisi et al, 1987;Fthenakis et al, 1991;González-Rodríguez et al, 1995). Bufano et al (1996) showed that a high SSC (>1 million/mL) occurs in healthy sheep and goat milk, especially towards the end of lactation.…”

Section: Scc In Sheepmentioning

confidence: 99%

Genetic selection for reduced somatic cell counts in sheep milk: A review

Riggio

Portolano

2015

Small Ruminant Research

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a b s t r a c tMastitis is an inflammation of the udder, mainly caused by bacteria, and leads to economic loss, due to discarded milk, reduced milk production, reduced milk quality and increased health costs in both dairy sheep and cattle. Selecting for increased genetic resistance to mastitis can be done directly or indirectly, with the indirect selection corresponding to a prediction of the bacteriological status of the udder based on traits related to the infection. The most frequently used indirect method is currently milk somatic cell count (SCC) or somatic cell score (SCS). This review reports the state of the art relating to the genetic basis of mastitis resistance in sheep and explores the opportunities to use SCC as selection criterion in a breeding programme to improve resistance to mastitis in sheep, discussing the actual situation and prospects for improvement. It has been stressed, in particular, that although it is unlikely that selection for mastitis resistance by the farmers on their own will be successful, there is good prospect for genetic improvement if reliable pedigree and performance recording is implemented across flocks, combined with breeding value estimation. To achieve this, a strong and well-structured organization to implement and support the programme is essential.

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Detection of subclinical mastitis in ewes

Cited by 49 publications

References 5 publications

Genetic parameters for somatic cell score according to udder infection status in Valle del Belice dairy sheep and impact of imperfect diagnosis of infection

Genetic parameters for somatic cell score according to udder infection status in Valle del Belice dairy sheep and impact of imperfect diagnosis of infection

Etiologia e perfil de sensibilidade antimicrobiana dos isolados bacterianos da mastite em pequenos ruminantes e concordância de técnicas empregadas no diagnóstico

Genetic selection for reduced somatic cell counts in sheep milk: A review

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