Simple SummarySheep managed extensively can be exposed to several welfare challenges during the year, and the risk of some diseases can increase in warmer and wetter seasons. In this study, the welfare of Merino ewes was examined over a calendar year. The welfare of these animals, kept on a single farm with consistent management, varied substantially. Overall, the largest number of ewes experienced compromise and risk to welfare at weaning, indicating that this was the most vulnerable time. The main welfare issues identified were under and over feeding, ewe mortality, lameness, ecto-parasites (flystrike) and mastitis, all of which could be improved by modifying management practices, such as improved nutritional management and monitoring and better tail docking procedures. Future research must consider that significant variation in the on-farm welfare of ewes occurs during a calendar year, which needs to be accounted for when conducting on-farm assessments.AbstractThis study examined variation in the welfare of extensively managed ewes and potential welfare risks. A total of 100 Merino ewes (aged 2–4 years) were individually identified and examined at three key stages: pregnancy, lactation and weaning. Eight animal-based welfare measures were used to assess welfare: flight distance, body condition score (BCS), fleece condition, skin lesions, tail length, dag score, lameness and mastitis. Data were analysed by ANOVA and McNemar’s statistics. Overall, the average BCS of the group was in agreement with industry recommendations. However, a number of animals were classified with inadequate condition (either too thin or too fat) across the three observation periods. The presence of heavy dags was greatest at mid-lactation (87%, P < 0.0001), lameness was greatest at weaning (14%, P = 0.01), clinical mastitis was 1% annually, and five ewes were lost from the study. Ewes had better health at mid-pregnancy compared to mid-lactation and weaning. The main welfare issues identified were under and over feeding, ewe mortality, lameness, ecto-parasites (flystrike) and mastitis, all of which have the potential to be reduced with improved management practices. Future welfare assessment programs must consider that significant variation in on-farm welfare will occur in extensively managed systems and this needs to be accounted for when evaluating farms.

This study evaluates the comparative serum disposition kinetics of injectable formulations of doramectin (DRM), ivermectin (IVM) and moxidectin (MXD) in Australian Merino sheep. Thirty-six, 2-year-old sheep were allocated by weight into six groups of six animals. Animals in each group received 200 microg/kg of DRM, MXD, IVM or a combination of two of these drugs by subcutaneous (s.c.) injection. Blood was collected at designated intervals (between 1 h and 40 days after treatment) and the serum analysed by high performance liquid chromatography (HPLC) using fluorescence detection. The results indicated that MXD administration produced a significantly higher maximum serum concentration and a more rapid absorption as compared with DRM and IVM. MXD and DRM had a significantly larger area under the concentration vs. time curve (AUC) than IVM, suggesting a more persistent effect for the former two products in sheep. The AUC for DRM was significantly higher when administered alone as compared with that observed when given in combination with MXD or IVM, suggesting preferential elimination of DRM compared with IVM and MXD from concurrent s.c. administration.

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Mannheimia glucosida, M. haemolytica, and M. ruminalis were isolated from cases of acute mastitis in ewes. M. glucosida was found to be a common cause of clinical mastitis in sheep. Selected phenotypic tests in addition to genotyping were needed to definitively identify Mannheimia species causing ovine mastitis.Mastitis is an important disease of sheep in dairy, wool, and meat production systems. Several studies have found that the prevalence of Mannheimia haemolytica as a cause of ovine mastitis is similar to or greater than that of Staphylococcus aureus (6,7,13,14). In a preliminary study, our laboratory also demonstrated the significance of this species in mastitis in Poll Dorset ewes in southeastern Australia (7).The genus Mannheimia contains several species from the family Pasteurellaceae that have been recently reclassified (4). The five named species within this genus are M. haemolytica, M. glucosida, M. ruminalis, M. varigena, and M. granulomatis (4). There are also several unnamed taxa that are distinct from these named species (2).M. haemolytica is regarded as the most important species in this genus, as it is the major organism involved in pneumonia in feedlot cattle (10) and can cause pneumonia and mastitis in sheep (10,14). The former species Pasteurella haemolytica was separated into two biotypes, A and T, based on the capacity to ferment arabinose or trehalose and the results of some other phenotypic tests (19). Sixteen serotypes within these two biotypes were originally defined using indirect hemagglutination assays (10), with a new serotype, A17, added later (22). Biotype A was divided into 9 biogroups (1). Biogroup 1 of the former P. haemolytica was later renamed M. haemolytica and includes serotypes 1, 2, 5 to 9, 12 to 14, and 16 (4, 5). Serotypes 3, 4, 10, and 15 of biotype T of the former P. haemolytica were classified as P. trehalosi (20) and later as Bibersteinia trehalosi (9).Serotype A11, as well as biogroups 3A to H and 9 of the former P. haemolytica, were reclassified as M. glucosida (1), which is a heterogeneous species that has been isolated from in ruminants case of pneumonia (2) and from the nasal cavities of healthy sheep (2, 18).M. ruminalis has not been associated with disease and can be isolated from the rumen of sheep (2), and M. ruminalis-like organisms have been isolated from the nasal cavities of healthy sheep (18).This study investigated the phenotypic and genetic characteristics of Mannheimia species isolated from cases of clinical mastitis in sheep, with the aim of definitively identifying the most prevalent species responsible for this disease.Twenty-four bacterial isolates from cases of mastitis, mainly in Poll Dorset ewes, were used in this study. The isolates were all Gram-negative rods with no significant growth on MacConkey agar and produced mucoid, gray colonies on sheep blood agar (SBA). Seventeen were from a previous survey of mastitis in Poll Dorset ewes (7), and the other seven isolates were collected from ewes with mastitis in 2008. The isolates were from 8...

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