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Regression analyses were performed on data from 48 Compton metabolic profile tests relating the concentrations of certain constituents in the blood of dairy cows to their milk yield, age and stage of lactation. The common partial regression coefficients for milk yield, age and stage of lactation were estimated for each blood constituent. The relationships of greatest statistical significance were between the concentrations of inorganic phosphate and globulin and age, and the concentration of albumin and milk yield.  相似文献   
3.
A cross-sectional study was carried out from July to September 1989 in Kaloleni Division, Coast Province, Kenya to estimate the prevalence of vector-transmitted diseases in small-holder dairy cattle and to identify the risk factors associated with different management systems. One hundred and thirty of the 157 herds with dairy cattle in Kaloleni Division were surveyed. These were from three agro-ecological zones (coconut-cassava, cashew nut-cassava and livestock-millet), comprised two management systems (stall-feeding and herded grazing) and were herds with either dairy cattle only or with Zebu and dairy cattle. A formal questionnaire sought answers to questions on cattle health and management practices. A total of 734 dairy and 205 Zebu cattle in 78 dairy and 52 mixed (dairy and Zebu) herds were sampled and screened for haemoparasites (Trypanosoma, Anaplasma, Babesia, and Theileria infections). Sera were tested for antibodies to Theileria parva, using the schizonts-antigen indirect fluorescent-antibody (IFA) test and to antibodies for Babesia bigemina and antigens to Anaplasma marginale by enzyme-linked immunosorbent assay (ELISA). Packed-cell volume (PCV) also was measured. Tick-control measures were practised by all except three of the farmers. Despite this, overall seroprevalence to T. parva was >70%--suggesting either that control practices were not strictly implemented or they were ineffective. The seroprevalence of T. parva in adult cattle kept in stall-feeding systems in the coconut-cassava zone was significantly lower (57+/-8% (S.E.)) than in herded-grazing systems (79+/-3%) and there was no association between antibody prevalence and age of cattle in this zone. Antibody prevalences in cattle in the cashew nut-cassava and the drier livestock-millet zone increased with age. Cattle in herded-grazing systems had an overall lower seroprevalence of T. parva infection in the livestock-millet zone (45+/-6%) than in the other two zones.Analysis was confined to the coconut-cassava zone for B. bigemina and to the coconut-cassava and cashew nut-cassava zones for A. marginale. Mean prevalences of B. bigemina were 40.9+/-9 and 73+/-6% for dairy cattle under stall-feeding and herded-grazing systems, respectively, and increased with age. Antigen prevalences of A. marginale were over 80% in all age groups of cattle in the coconut-cassava and cashew nut-cassava zones. Overall trypanosome prevalence in cattle was <1%. Trypanocidal treatment was uncommon. The variations in antibody prevalence associated with risk factors such as feeding system, agro-ecological zone and age of animal suggest that management system influenced exposure to tick-borne infection (particularly, T. parva infections) in small-holder dairy cattle in coastal Kenya.  相似文献   
4.
Two experiments were carried out to identify the target population of cattle for immunisation against East Coast fever (ECF) using the infection-and-treatment method. Firstly, a sentinel-calf study was used to determine the age window for ECF immunisation by determining ages at clinical detection of infection with Theileria parva. Six groups of five naive cross-bred (Bos taurus/Bos indicus) male calves, introduced at intervals of 2 months at a mean age of 26 days, were exposed to natural tick challenge on a high ECF-risk, small-holder farm in the coastal lowland, coconut-cassava agro-ecological zone of coastal Kenya. Secondly, a challenge study evaluated the relationship between the presence of T. parva antibodies and immunity. Ten indigenous adult Zebu cattle and nine Zebu young stock purchased from farmers in the same zone, and eight cross-bred calves (survivors of the sentinel-calf study) were challenged with 10 times the immunising dose of T. parva Marikebuni stock. Twenty-four of these 27 cattle had high antibody titres before challenge. Two cross-bred calves, obtained from an ECF-free area and seronegative to T. parva schizont antigen, also were challenged and used as susceptible controls. Twenty-five (83%) of the 30 sentinel calves contracted ECF over an age range of 36-116 days (mean 72 days). The remaining five calves died of other causes within 2 months of arrival on the farm. Fourteen of the 25 calves survived the infection and developed antibodies to T. parva. Despite tick control, seven of these 14 calves had a second episode of ECF and two died. In total, 13 of the 25 calves that contracted ECF died. Only one of 19 indigenous Zebu animals developed clinical ECF when challenged with T. parva Marikebuni (mild clinical signs with spontaneous recovery). Of the eight cross-bred survivors from the first experiment, only one succumbed to ECF when challenged and it died. Both susceptible cross-bred calves developed severe clinical signs of ECF and one died. The experimental studies show that in the high ECF-risk areas of the coconut-cassava zone of coastal Kenya, immunisation against ECF in cross-bred (B. taurus/B. indicus) cattle should be targeted at an early age (preferably within 1-2 months of birth).  相似文献   
5.
Inhibitors of cyclin‐dependent kinases, as roscovitine, have been used to prevent the spontaneous resumption of meiosis in vitro and to improve the oocyte developmental competence. In this study, the interference of oil overlay on the reversible arrest capacity of roscovitine in sheep oocytes as well as its effects on cumulus expansion was evaluated. For this, cumulus‐oocyte complexes (COCs) were cultured for 20 h in TCM 199 with 10% foetal bovine serum (Control) containing 75 μm roscovitine (Rosco). Subsequently, they were in vitro matured (IVM) for further 18 h in inhibitor‐free medium with LH and FSH. The culture was performed in Petri dishes under mineral oil (+) or in 96 well plates without oil overlay (?) at 38.5°C and 5% CO2. At 20 and 38 h, the cumulus expansion and nuclear maturation were evaluated under stereomicroscope and by Hoechst 33342 staining, respectively. No group presented cumulus expansion at 20 h. After additional culture with gonadotrophins, a significant rate of COCs from both Control groups (+/?) exhibited total expansion while in both Rosco groups (+/?) the partial expansion prevailed. Among the oocytes treated with roscovitine, 65.2% were kept at GV in the absence of oil overlay while 40.6% of them reached MII under oil cover (p < 0.05). This meiotic arrest was reversible, and proper meiosis progression also occurred in the Control groups (+/?). So, the culture system without oil overlay improved the meiotic inhibition promoted by roscovitine without affecting the cumulus expansion rate or the subsequent meiosis progression.  相似文献   
6.
Clostridium (C.) difficile is a common cause of nosocomial diarrhea in horses. Vancomycin and metronidazole have been used as standard treatments but are only moderately effective, which highlights the need for a novel alternative therapy. In the current study, we prepared antiserum of equine origin against both C. difficile toxins A and B as well as whole-cell bacteria. The toxin-neutralizing activities of the antibodies were evaluated in vitro and the prophylactic effects of in vivo passive immunotherapy were demonstrated using a conventional mouse model. The data demonstrated that immunized horses generated antibodies against both toxins A and B that possessed toxin-neutralizing activity. Additionally, mice treated with the antiserum lost less weight without any sign of illness and regained weight back to a normal range more rapidly compared to the control group when challenged orally with 107 C. difficile spores 1 day after serum injection. These results indicate that intravenous delivery of hyperimmune serum can protect animals from C. difficile challenge in a dose-dependent manner. Hence, immunotherapy may be a promising prophylactic strategy for preventing C. difficile infection in horses.  相似文献   
7.
Lameness in herds during one year was commonest in the first month of lactation (15 per cent of all cases). Leg lesions were particularly common at this time (24 per cent of all cases of leg lesions) but white line abscess and sole ulcer were more common a month later. Foul-in-the-foot was one of the two most common lesions at all stages of pregnancy and lactation, and white line abscess the most common (20 per cent of all lesions) in late lactation. Both sole ulcer and underrun heel had lower incidence in the second half of the year than the first. White line abscess was particularly common in March and November although there were significant interactions between month and veterinary practice; foul-in-the-foot was most common in October. Susceptibility to lameness increased with age; 10-year-old cows were over four times more likely to develop lameness than three-year-old cows. This was due particularly to increased incidence with age of white line abscess and sole ulcer and, to a lesser extent, underrun heel. In contrast, foul-in-the-foot and leg lesions showed little change with age. Whereas these lesions accounted for 68 per cent of the total in cows up to two years old, they accounted for only 15 per cent of all lesions in cows over 10 years old. White line abscess was slightly commoner in cows with large heart girths.  相似文献   
8.
Human histocompatibility antigens and susceptibility to disease   总被引:1,自引:0,他引:1  
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9.
The production of agglutinins to Salmonella typhi was studied in the opossum embryo in the period immediately before and after the development of thymic and lymph node lymphoid tissue. Antibody was found only in embryos older than 8 days which corresponds to an 8- to 10-week human embryo in terms of organogenesis and is the earliest stage at which antibody production has been recorded.  相似文献   
10.
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