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    Veterinary Herd Health Management in Ugandan smallholder pig farms
    (Swedish University of Agricultural Sciences, Department of Clinical Sciences, 2020) Gertzell, Elin
    Animal health research often focus on single, specific diseases such as e.g. African swine fever. However, animal health usually depends on multiple factors. In the present thesis, the overall herd health and productivity in 20 smallholder pig farms were assessed by the use of veterinary herd health management, an iterative approach using both interviews, observations, clinical examinations and targeted sampling to obtain a holistic view on the herd. Further, certain problems were identified that likely affected many herds, and the presence of ecto- and endoparasites, parvoviral antibodies, and antibiotic resistance of Staphylococcus spp. and E. coli, were screened for in all herds. The main constraints to the production were identified as inadequate feeding, poor reproduction, poor biosecurity, and infectious diseases, although the problems varied considerably among the herds. Low quantity and quality of feed and water caused poor growth rates and poor health, and contributed to increased mortality rates. Suboptimal management was likely one of the main causes of the poor reproductive performance, but pathogens, inadequate nutrition, heat stress, low parity numbers, and inferior breeds probably also contributed to the poor results. Parasites were very common, and apart from pruritus, mainly caused by lice, endoparasites were the most commonly identified cause of clinical disease. In herds of all sizes, coccidia and nematodes caused diarrhea in suckling piglets and growing pigs, resulting in emaciation and even deaths. The two largest herds experienced post-weaning diarrhea associated with enterotoxigenic E. coli, resistant to tetracycline that was commonly used to treat the disease. Methicillin-resistant Staphylococcus aureus was found in a healthy pig in one herd. African swine fever was not diagnosed, but differential diagnoses such as Erysipelothrix infection were suspected. Despite the lack of vaccination programs, parvoviral antibodies were commonly found and parvovirus was thus suspected to be the cause of the high number of mummified fetuses in two herds, and possibly associated with the small litters in several herds. In conclusion, many different factors affect the health and productivity of smallholder pig herds in Uganda. Efforts to improve health and productivity need to take into consideration both the smallholder context and the situation of the individual herd, as the conditions and motivations differ from those in intensive farms in high-income countries.
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    Infection dynamics of Cryptosporidium bovis and Cryptosporidium ryanae in cattle
    (Department of Clinical Sciences, Swedish University of Agricultural Sciences, 2019) Åberg, Malin
    In order to investigate the infection dynamics of the protozoan parasites Cryptosporidium bovis and Cryptosporidium ryanae in cattle, a Swedish dairy farm known to be free of C. parvum was recruited. Two sampling regimes were utilized; a cross-sectional study of pre-weaned calves over one year (study I), and a two-year prospective cohort study (study II). In study I, feces samples were collected from up to twenty calves once a month (13 occasions). In study II samples were collected from 16 heifers from birth to calving. They were sampled once a week for two months, and then monthly until calving. The samples were cleaned using a flotation method and examined with immunofluorescence microscopy to quantify the shedding. The Cryptosporidium positive samples were further processed with molecular species determination.In study I, a total of 238 samples were examined and oocysts were found in 92 samples, of which 72 were successfully species determined: 87.5% were C. bovis, 9.7% were C. ryanae and 2.8% were a mix of both species. In the cohort (study II), a total of 455 samples were collected and for calves up to nine weeks old, C. bovis was found in 58.5% of the samples, C. ryanae in 9.2%, and both C. bovis and C. ryanae in 3.1%. No parvum was found in either study.The prevalence of shedding calves was at its highest at ages four and five weeks in both studies: 54.8% and 56.7% in study I, 81.3% and 87.5% in study II. The cumulative incidence in the cohort reached 100% when the calves were five weeks old, which is earlier than what many international studies have shown for C. bovis.The highest oocysts per gram feces count (OPG) were 1.1 × 106 and 3.6 × 106 in study I and study II, respectively. The youngest calf in which C. bovis was identified was 5 days old, and the youngest calf in which C. ryanae was identified was 15 days old. In four calves in study II, the detected species changed from C. bovis to C. ryanae or the other way around, and two samples were a combination of both species. Several individuals shed oocysts sporadically up to 16 months of age. Calf housing type and seasonality were not associated with differences in the shedding of oocysts (I). There was no association between the presence of diarrhea and oocyst shedding.