Ewe milk samples from different ovine dairy farms from the Castilla-La Mancha region of Spain were collected from bulk tanks to estimate the occurrence of antibiotic residues in raw and heated (82 degrees C, 10 min) milk by the Delvotest SP test. The month of collection, somatic cell counts, and bacteriology were analyzed and examined by means of a logistic regression model. The screening of a total of 2686 raw milk samples showed 1.7% "positive" and 2.1% "doubtful" results, which decreased after heating treatment to 1.3% and 0.4%, respectively. "Positive" and "doubtful" samples were identified by penicillinase and p-aminobenzoic acid solutions, and the majority of them corresponded to antimicrobials different than beta-lactams or sulfonamides. By applying a logistic regression model, a significant effect of month of collection and bacteriology was observed in the initial screening and after the heat treatment. The highest percentages of "positive plus doubtful" results were observed in late summer-early autumn. A slight peak was also observed in spring in raw milk samples. Bacteriology was positively correlated with "positive plus doubtful" results.

Milk collected at 12-h intervals throughout 6 days from three groups of Manchega ewes (n = 12 per group), treated intramuscularly with beta-lactams (benzyl penicillin procaine, ampicillin, and amoxicillin, respectively), was evaluated for antibiotic residue persistence with four microbial inhibitor tests (BRT MRL, CH ATK P&S, Delvotest SP, and Eclipse 100ov) and one enzymatic test (Penzym 100). Antibiotic depletion time was established using a logistic regression model. A clear effect (P < 0.0001) of milking order on the response of all tests was observed with the three antibiotics, but no significant effects were found for milk yield. Except with Eclipse 100ov, positive tests were observed after the recommended withdrawal period of benzyl penicillin procaine (five milkings) from 2% (Delvotest SP) to 11% (CH ATK P&S). There were almost no positive responses beyond the withdrawal period (six milkings) of ampicillin, except for the Penzym 100 test (7%). Residues of amoxicillin were found to persist beyond the six milkings established as the withdrawal period, from 2.8% (Eclipse 100ov) to 72.4% (CH ATK P&S) of positive cases. Higher frequencies of doubtful cases were found with BRT MRL and Delvotest SP assays with the three beta-lactams. Positive and doubtful results could be obtained when milk samples from individual ewes were analyzed using BRT MRL, CH ATK P&S, Delvotest SP, and Penzym 100 tests, even if farmers follow the antibiotic withdrawal periods.

Bulk ewes' milk from Spanish dairy farms in the Castilla-La Mancha region and destined for production of protected denomination of origin (PDO) Manchego cheese were analysed each month for antimicrobial residues during the course of 1 year. A microbiological assay specific for ewes' milk (Eclipse '100ov') was used. The number of positive samples by the Eclipse '100ov' test was 2.6%. A second examination of positives following heat treatment at 82 degrees C for 10 min showed a reduction of up to 0.9% (i.e. 63% of the samples detected corresponded to 'false-positives'). Of the confirmed positives, 25% were identified as beta-lactams by a penicillinase solution; the remainder corresponded to antimicrobial compounds that could not be identified. The month of collection was related to the probability of positive results, but to no other factors such as somatic cell counts, bacteriology or composition (fat and protein). The highest rates of positives were observed in September and October. Finally, the results were compared with those obtained by the Delvotest SP method, which showed the detection of a higher number of positive samples compared with the Eclipse '100ov' method.

This study was done to establish relationships between management and sanitary practices on ewe dairy farms and the quality of milk produced. For this purpose, a survey was carried out on 118 farms and a total of 121,117 animals in the Castilla-La Mancha region (Southeast Spain) in which the veterinarians of the Association of Sanitary Defence participated. Flocks varied considerably in size, ranging from 120-7,200 sheep, with an average milking period lasting 3-5 months and milk yields of between 50 and 150 litres per lactation by mechanical systems on 75.0% of farms. Sanitary practices during milking are still not commonplace; 53.3% performed post milking teat disinfection, 37.0% did the California mastitis test, 31.1% had a dry therapy programme and only 18.6% of farms kept records of animals with clinical mastitis. Nonetheless, the results revealed that 42.7% of the farms surveyed showed good quality hygienic milk (bulk milk somatic cell count, BMSCC < 600 × 10 3 cells mL -1 ). On most farms, the rate of animals with clinical mastitis was less than 5.0%, while that of subclinical mastitis cases was less than 5.0% on 25.6% of farms. Certain factors like mechanical milking, post milking teat disinfection, recording animals with clinical mastitis and controlling the frequency of animals with subclinical mastitis did not exceed 5.0%. Those risk factors for increased BMSCC levels were significant. Therefore, farmers are recommended to bear these factors in mind, and to instil the importance of carrying out these practices when implementing a good dairy farm practices system. Additional key words: ewe milk, good dairy farming practices, milk quality. Resumen Prácticas de manejo e higiénico-sanitarias en las explotaciones lecheras y recuento de células somáticas en leche de tanqueEl trabajo se llevó a cabo para conocer las condiciones higiénico-sanitarias de las explotaciones de ovino manchego, y su posible relación con la sanidad de la ubre y la calidad de la leche obtenida. Para ello se elaboró una encuesta que se dirigió a los veterinarios responsables de Agrupaciones de Defensa Sanitaria de Castilla-La Mancha. Se analizaron las encuestas de 118 explotaciones, que incluyen un total de 121.117 animales de ordeño. Los resultados obtenidos mostraron que, a pesar de la enorme variabilidad en el tamaño de las explotaciones (desde 120 hasta 7.200 ovejas), la mayoría de ellas poseen sala de ordeño (75%), siendo la duración media del ordeño entre 3-5 meses y la producción de leche por oveja y lactación entre 50-150 L. Las prácticas sanitarias durante el ordeño no están muy extendidas, ya que el 53,3% realiza sellado postordeño, el 37,0% lleva a cabo el test de California, el 31,1% sigue la terapia de secado y el 18,6% de las explotaciones registra a los animales con mastitis. Del total de explotaciones encuestadas, 42,7% producen leche con un recuento de células somáticas < 600 × 10 3 células mL -1 . La mayoría de ellas posee valores por

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