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On 26th of july 2007 a new case of bluetongue was notified in the Netherlands and on 2nd of august 2007 food and-mouth disease was diagnosed in Surrey, England, which raised the threat of having both infections simultaniously in one area. Bluetongue and foot-and-mouth disease have a different pathogenesis, but symptoms may resemble each other at a later stage of infection. The pathogenesis and possible clinical symptoms of both infections are discussed and illustrated with pictures.

Uitleg over de epidemiologie van maagdarmwormen bij schapen, en adviezen om de ontwikkeling van resistentie tegen wormmiddelen te voorkomen. De huidige praktijk van preventieve behandeling van ooien en lammeren werkt de ontwikkeling van resistentie juist in de hand. Om de selectiedruk voor resistentie bij de wormen te verlagen is het belangrijk om niet meer alle schapen tegelijk te behandelen en wormmiddelen uit de verschillende groepen (benzimidazolen; imidithiazoles; avermectines en milbemycines) af te wisselen. Ook een cocktail van middelen is effectief tegen resistentieontwikkeling

Mastitis is an inflammation of the udder, which leads to economic loss, mainly consisting of discarded milk, reduced milk production and quality, and increased health costs. Somatic cell count (SCC), and therefore somatic cell score (SCS), is widely used as indicator of mastitis. In this thesis, I focus on the genetic parameters of SCS as indicator of mastitis, and on the possibilities of using this trait for selection for mastitis resistance in the Valle del Belice dairy sheep. In Chapter 1, mastitis and SCS are defined and introduced. Chapter 2 deals with the estimation of genetic parameters for SCS and milk production traits in primiparous Valle del Belice ewes. Heritability estimates ranged from 0.09 to 0.14 for milk, fat and protein yields and contents. For SCS, the heritability of 0.14 was relatively high. SCS was genetically positively correlated to milk, fat and protein yields and contents. However, correlations were not extreme, so simultaneous improvement for milk yield and SCS seems possible. In Chapter 3, the level of SCC is included in a survival analysis to evaluate the effect of SCC on functional longevity. Results showed that an increase in SCC was associated with an increase in culling rate.Elevated SCC, therefore, play an indirect role in the culling decisions of Valle del Belice dairy sheep farmers, although, at present, farmers do not directly select for reduced SCC. In Chapter 4, the genetic parameters of the infection status and SCS, according to whether the samples were bacteria negative or positive are reported. Moreover, the impact of imperfect sensitivity and specificity on variance component estimates was investigated. The 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 (0.62) suggests that they may be genetically different traits, confirming that SCSfrom healthy and infected animals should be analyzed separately. Moreover, a positive genetic correlation between bacteria negative SCS and liability to mastitis was found, suggesting that the approach of selecting animals for decreased SCS will help to reduce the prevalence of mastitis. The results also showed that the 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. In Chapter 5, the diagnostic ability of SCCand California Mastitis Test (CMT) to detect intramammary infectionswas evaluated by using the Receiver-Operating Characteristic(ROC) curves, in order to identify a SCCthreshold that better discriminated healthy from infected udders. The results indicate that the CMT can only discriminate the udders infected from major pathogens. Nevertheless, in general SCS was the best indirect test for the bacteriological status of the udder. The final chapter explores and discusses the opportunities to use SCS as indicator of mastitis in a selection scheme to improve mastitis resistance for the Valle del Belice dairy sheep breed.

Mastitis is an inflammation of the udder, which leads to economic loss, mainly consisting of discarded milk, reduced milk production and quality, and increased health costs. Somatic cell count (SCC), and therefore somatic cell score (SCS), is widely used as indicator of mastitis. In this thesis, I focus on the genetic parameters of SCS as indicator of mastitis, and on the possibilities of using this trait for selection for mastitis resistance in the Valle del Belice dairy sheep. In Chapter 1, mastitis and SCS are defined and introduced. Chapter 2 deals with the estimation of genetic parameters for SCS and milk production traits in primiparous Valle del Belice ewes. Heritability estimates ranged from 0.09 to 0.14 for milk, fat and protein yields and contents. For SCS, the heritability of 0.14 was relatively high. SCS was genetically positively correlated to milk, fat and protein yields and contents. However, correlations were not extreme, so simultaneous improvement for milk yield and SCS seems possible. In Chapter 3, the level of SCC is included in a survival analysis to evaluate the effect of SCC on functional longevity. Results showed that an increase in SCC was associated with an increase in culling rate.Elevated SCC, therefore, play an indirect role in the culling decisions of Valle del Belice dairy sheep farmers, although, at present, farmers do not directly select for reduced SCC. In Chapter 4, the genetic parameters of the infection status and SCS, according to whether the samples were bacteria negative or positive are reported. Moreover, the impact of imperfect sensitivity and specificity on variance component estimates was investigated. The 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 (0.62) suggests that they may be genetically different traits, confirming that SCSfrom healthy and infected animals should be analyzed separately. Moreover, a positive genetic correlation between bacteria negative SCS and liability to mastitis was found, suggesting that the approach of selecting animals for decreased SCS will help to reduce the prevalence of mastitis. The results also showed that the 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. In Chapter 5, the diagnostic ability of SCCand California Mastitis Test (CMT) to detect intramammary infectionswas evaluated by using the Receiver-Operating Characteristic(ROC) curves, in order to identify a SCCthreshold that better discriminated healthy from infected udders. The results indicate that the CMT can only discriminate the udders infected from major pathogens. Nevertheless, in general SCS was the best indirect test for the bacteriological status of the udder. The final chapter explores and discusses the opportunities to use SCS as indicator of mastitis in a selection scheme to improve mastitis resistance for the Valle del Belice dairy sheep breed.

Het LEI is door LNV in overleg met het PVE gevraagd om een analyse te doen naar de financiële draagkracht van de schapen- en de geitenhouderij wat betreft de kosten van een centrale registratie van individuele dieren (I&R). De noodzaak of gewenstheid om met het oog op het diergezondheidbeleid een I&R stelsel in te voeren voor schapen en geiten is geen onderwerp van discussie; de dieren moeten getraceerd kunnen worden in geval van een ziekte-uitbraak. De centrale vraag is dan ook wat betekent de lastenverzwaring met (ruim) 2 mln. euro voor de sector schapen- en geitenhouderij en is hiervoor financiële draagkracht. Gevraagd wordt aan het LEI na te gaan met welke financieel-economische gegevens (kengetallen) de draagkracht in beeld gebracht kan worden. In deze notitie geeft het LEI een analyse op basis van gegevens met betrekking tot de structuur en de financiële gegevens en resultaten van de schapen- en geitenhouderij

Het LEI is door LNV in overleg met het PVE gevraagd om een analyse te doen naar de financiële draagkracht van de schapen- en de geitenhouderij wat betreft de kosten van een centrale registratie van individuele dieren (I&R). De noodzaak of gewenstheid om met het oog op het diergezondheidbeleid een I&R stelsel in te voeren voor schapen en geiten is geen onderwerp van discussie; de dieren moeten getraceerd kunnen worden in geval van een ziekte-uitbraak. De centrale vraag is dan ook wat betekent de lastenverzwaring met (ruim) 2 mln. euro voor de sector schapen- en geitenhouderij en is hiervoor financiële draagkracht. Gevraagd wordt aan het LEI na te gaan met welke financieel-economische gegevens (kengetallen) de draagkracht in beeld gebracht kan worden. In deze notitie geeft het LEI een analyse op basis van gegevens met betrekking tot de structuur en de financiële gegevens en resultaten van de schapen- en geitenhouderij

On 26th of july 2007 a new case of bluetongue was notified in the Netherlands and on 2nd of august 2007 food and-mouth disease was diagnosed in Surrey, England, which raised the threat of having both infections simultaniously in one area. Bluetongue and foot-and-mouth disease have a different pathogenesis, but symptoms may resemble each other at a later stage of infection. The pathogenesis and possible clinical symptoms of both infections are discussed and illustrated with pictures. Op 26 juli 2007 werd opnieuw bluetongue in Nederland vastgesteld en op 2 augustus 2007 brak in Engeland MKZ uit en ontstond de dreiging van introductie in Nederland. Bluetongue en MKZ hebben een verschillende pathogenese, maar de symptomen kunnen in een later stadium op elkaar gaan lijken. De pathogenese en mogelijke klinische symptomen van beide ziekten worden besproken en aan de hand van foto’s toegelicht

This research focuses on the genome-wide identification of new biomarkers (other than PrP) that might be useful to extend current TSE diagnostics especially in the preclinical phase. In addition this project might provide clues to better understand the TSE micro-pathogenesis. Specific aims: - generate a non-redundant sheep microarray from primary lymphoid tissues; − collect and preserve well documented material for RNA isolation from natural scrapie exposed or clean environments; − determine differential expressed genes between the collected samples and relate these to natural scrapie infection. These identified biomarkers might turn useful for the development of preclinical tests (at best on live animals) in the very early phase of natural scrapie infection. Such tests can support the control of scrapie in the field

This research focuses on the genome-wide identification of new biomarkers (other than PrP) that might be useful to extend current TSE diagnostics especially in the preclinical phase. In addition this project might provide clues to better understand the TSE micro-pathogenesis. Specific aims: - generate a non-redundant sheep microarray from primary lymphoid tissues; − collect and preserve well documented material for RNA isolation from natural scrapie exposed or clean environments; − determine differential expressed genes between the collected samples and relate these to natural scrapie infection. These identified biomarkers might turn useful for the development of preclinical tests (at best on live animals) in the very early phase of natural scrapie infection. Such tests can support the control of scrapie in the field

Is het in de Nederlandse situatie mogelijk om met goed management verantwoord schapen te houden zonder het couperen van de staarten? In dit onderzoek is met name ingegaan op de relaties tussen (wel of niet) couperen, het risico op het optreden van myiasis en verschillende managementmaatregelen.

Is het in de Nederlandse situatie mogelijk om met goed management verantwoord schapen te houden zonder het couperen van de staarten? In dit onderzoek is met name ingegaan op de relaties tussen (wel of niet) couperen, het risico op het optreden van myiasis en verschillende managementmaatregelen.

Uitleg over de epidemiologie van maagdarmwormen bij schapen, en adviezen om de ontwikkeling van resistentie tegen wormmiddelen te voorkomen. De huidige praktijk van preventieve behandeling van ooien en lammeren werkt de ontwikkeling van resistentie juist in de hand. Om de selectiedruk voor resistentie bij de wormen te verlagen is het belangrijk om niet meer alle schapen tegelijk te behandelen en wormmiddelen uit de verschillende groepen (benzimidazolen; imidithiazoles; avermectines en milbemycines) af te wisselen. Ook een cocktail van middelen is effectief tegen resistentieontwikkeling

Uitleg over de epidemiologie van maagdarmwormen bij schapen, en adviezen om de ontwikkeling van resistentie tegen wormmiddelen te voorkomen. De huidige praktijk van preventieve behandeling van ooien en lammeren werkt de ontwikkeling van resistentie juist in de hand. Om de selectiedruk voor resistentie bij de wormen te verlagen is het belangrijk om niet meer alle schapen tegelijk te behandelen en wormmiddelen uit de verschillende groepen (benzimidazolen; imidithiazoles; avermectines en milbemycines) af te wisselen. Ook een cocktail van middelen is effectief tegen resistentieontwikkeling