Theses and Dissertations Collection

Permanent URI for this collectionhttp://10.10.97.169:4000/handle/123456789/118

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Browsing Theses and Dissertations Collection by Author "Bunyaga, A. S."

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    Cryopreservation of dog semen as an alternative method to improved fertility in bitches: A review article
    (Tanzania Veterinary Association, 2018-02-01) Bunyaga, A. S.; Kashoma, I. P.
    Cryopreservation of dog semen facilitates the exchange of genes between populations and makes it possible to preserve genes from valuable males for an extended time. Although AI in dogs can help avert sexually transmitted diseases and reducing the chances of inbreeding, the technique is not routinely practised in most developing countries including Tanzania. Among the reasons are problems associated with cryopreservation. Cryopreservation of semen has a number of problems limiting its success and thus, affecting fertility in dogs as a whole. The common assisted reproductive technologies like AI in dogs are constrained by challenges in semen cryopreservation which partly is caused by freezing temperature, cryoprotectants and lifespan of spermatozoa. The purpose of this review is to study the possible ways which can improve cryopreservation of semen in dogs. Improving semen cryopreservation is not a one process; it involves a combination of factors with the ultimate goal of improving the outcome of semen cryopreservation in terms of conception rates in bitches, and thus, fertility in general. Cryopreservation parameters to improve include: type of ejaculate, insemination technique, storage, post thawing procedures, extenders, cryoprotectants, collection method and antioxidants. Several approaches have been recommended, including cryopreservation protocols, for instance freezing rates should be slow enough to allow the cells to minimize chemical potential and osmolality gradients across the plasma membrane, but fast enough to dehydrate the cell without exposing it to lethal salt concentrations. Moreover, the first ejaculates and the ejaculates from old dogs are to be discouraged if we need to improve fertility output under cryopreservation method. Thawing temperature of 70°C and above within a few seconds, have shown promising results. Possibly, this temperature is helpful to reduce the toxic nature of cryoprotectants. However, this review suggests the use of intrauterine method, and possibly innovation of new modification and training expertise would help to improve fertility in bitches. Nevertheless, more work is needed to accurately predict fertility of cryopreserved canine semen.
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    Prevalence and antimicrobial resistance in Campylobacter from different stages of the chicken meat supply chain in Morogoro, Tanzania
    (Tanzania Veterinary Journal, 2015-01-12) Kashoma, I. P.; Mkomba, F. D.; Bunyaga, A. S.
    Poultry are recognized as a main reservoir of Campylobacter spp. However, longitudinal studies investigating the persistence of Campylobacter on broilers and retail chciekn meat in Tanzania are rare. The aim of the current work was to evaluate the prevalence and antimicrobial susceptibility of Campylobacter spp. isolated from broiler farms and retail chicken meat. Eight hundred samples were collected from broilers aged 1 week to slaughter and retail chicken carcasses, consisting of 600 fecal droppings and 200 carcass rinses. The overall Campylobacter prevalence was 43.3% (381/880). The isolation rate of Campylobacter from chicken faeces was 41.5%, from carcasses at the farm was 51.0% and from carcasses from retail stores was 37.5%. Biochemical testing by hippurate hydrolysis identified 72.4% of all isolates as C. jejuni, 20.5% as C. coli, and 7.1% as other Campylobacter spp. Multiplex polymerase chain reaction confirmed 75.1% of all isolates as C. jejuni, 17.8% as C. coli, 4.2% as both, and 2.9% as other Campylobacter spp. Antimicrobial susceptibility testing using disk diffusion assay and broth micro-dilution method revealed resistance to: ampicillin (41% and 44%, respectively), ciprofloxacin (56 and 59%), erythromycin (17 and 18%), gentamicin (6% and 12%), streptomycin (20 and 23%), and tetracycline (62 and 63%). Resistance to azithromycin (9%), chloramphenicol (7%) and nalidixic acid (72%) was determined using the disk diffusion assay only. Up to 5% and 4% of all isolate tested were pan-susceptible, while, 67% and 40% showed multidrug resistance using the disk diffusion assay and the broth microdilution method, respectively. These results reinforce the need of efficient strategy implementation to control and reduce Campylobacter in chickens at production and slaughter levels, and the necessity to reduce the use of antimicrobials in poultry sector.