Comparative pharmacokinetics of fenbendazole in buffalo and cattle     

M. R. Knox  P. M. Kennedy  D. R. Hennessy  J. W. Steel  L. F. Le Jambre 《Veterinary research communications》1994,18(3):209-216

Swamp buffalo (Bubalus bubalis) and Droughtmaster cattle (Bos indicus × B. taurus), fitted with gastrointestinal cannulae, were dosed intraruminally with fenbendazole at 7.5 mg/kg liveweight, together with a chromium oxide capsule and a pulse dose of NaCoEDTA, to estimate the flow dynamics of the digesta in the rumen and duodenum. The concentrations of fenbendazole (FBZ) metabolites were measured in plasma and duodenal fluid collected over 120 h. In plasma, significantly lower peak concentrations and earlier disappearance of FBZ and its sulphoxide (OFZ) metabolite were observed in buffalo, which considerably reduced systemic availability in comparison with cattle. The availability of OFZ in the duodenal fluid of buffalo was significantly lower, whereas FBZ disposition was similar to that in cattle. The turnover rate of fluid in the rumen was higher in buffalo than in cattle, while the flow parameters for other digesta were similar in the two species. It is concluded that the decreased absorption of drug in buffalo was attributable to the shorter residence time of the dose in the rumen, and probably in the entire gastrointestinal tract. This may reduce the efficacy of treatment and indicate the need for higher dose rates for benzimidazole anthelmintics in buffalo than in cattle.Abbreviations AAS atomic absorption spectroscopy - AUC area under the concentration-versus-time curve - C _max maximum concentration - FBZ fenbendazole - FBZ.SO₂ fenbendazole sulphone - HPLC high-performance liquid chromatography - OFZ fenbendazole sulphoxide  相似文献   

Bioeconomic evaluation of sow longevity and profitability     

Rodriguez-Zas SL  Southey BR  Knox RV  Connor JF  Lowe JF  Roskamp BJ 《Journal of animal science》2003,81(12):2915-2922

Sow production indicators, including litter size, litter weight, and the length of time that sows remained in the herd (sow longevity), were used to characterize sow performance and profitability. Sow longevity and production records from 148,568 sows in 32 commercial herds from Central Illinois from January 1995 to May 2001 were analyzed using survival and repeatability models, respectively. The factors studied included sow genetics (32 genetic lines), with eight major lines present in multiple herds, and the combination of herd and year of entry in the herd. The largest difference in longevity between the major genetic lines was approximately one parity. There were differences (P < 0.05) in the instantaneous sow removal rate or hazard from the major lines. These differences constitute evidence that sow longevity could be improved by using replacements from specific genetic lines. The net present value per sow (present value of future cash flows and the present value of the sow) was used to evaluate the effect of sow longevity and production traits on economic returns. Assuming a zero discount rate per parity, genetic lines with longer herd life resulted in greater profit than genetic lines with shorter herd life. This difference was reduced with increasing discount rates and was reversed with high discount rates and low net income per litter. These results suggest that the magnitude of the economic improvement attained through the use of sow genetic lines with longer longevity depends on the economic context under which the evaluation is made.  相似文献   

Serum alpha-tocopherol concentrations in German shepherd dogs with chronic degenerative radiculomyelopathy     

Johnston PE  Knox K  Gettinby G  Griffiths IR 《The Veterinary record》2001,148(13):403-407

The concentration of serum alpha-tocopherol was measured in German shepherd dogs with chronic degenerative radiculomyopathy, and in German shepherd dogs and dogs of other breeds unaffected by the condition. The mean concentration was significantly higher in German shepherd dogs with the condition than in other breeds of dog unaffected by it, but it was not significantly higher than in unaffected German shepherd dogs. Estimates of components of variance indicated that the concentration varied more widely in individual affected dogs than in unaffected dogs, irrespective of breed. These results suggest that chronic degenerative radiculomyopathy in German shepherd dogs is unlikely to be due to uncomplicated vitamin E deficiency.  相似文献   

Biological control of field infections of nematode parasites of young sheep with Duddingtonia flagrans and effects of spore intake on efficacy   总被引：2，自引：0，他引：2  

Knox MR  Faedo M 《Veterinary parasitology》2001,101(2):155-160

A field study was undertaken to determine the effects of feeding Duddingtonia flagrans to young Merino sheep on pasture. A total of 60 mixed sex lambs 4-5 months old were divided into six even groups on the basis of liveweight. On Monday to Friday, each week for 6 months, three groups were offered barley grains on which D. flagrans had been cultured while the other three groups remained untreated. Every 4 weeks liveweights were recorded and faecal samples collected for nematode egg count estimation. Feeding D. flagrans reduced faecal egg counts and tended to improve liveweight gains, but considerable differences were observed between groups within treatment. These differences are thought to result from variations between the groups in consumption of the treated barley with the "best" consumers showing the greater effects of treatment.  相似文献   

Cattle identification     

Knox A 《The Veterinary record》1999,145(24):712

  相似文献   

Photosensitisers from plants     

Alan D. Dodge  J. Paul Knox 《Pest management science》1986,17(5):579-586

The absorption of solar radiation by certain phytochemicals leads to excitation to the singlet state. If unquenched, intersystem crossing occurs, and a longer-lived triplet state arises. Triplet states may directly induce damage to biological molecules by type I reactions, or by interaction with triplet or ground state oxygen (³O₂) generate singlet oxygen (¹O₂) in a type II reaction. ¹O₂ reacts with lipids, proteins and nucleic acids, and thus induces considerable cellular damage if unquenched. Chlorophyll is the most widespread plant photosensitiser, and damage to chloroplasts and plant cells will occur if, for example, photosynthesis is inhibited and excited chlorophyll unquenched. The endogenous formation of chlorophyll precursors from δ-aminolaevulinic acid fed to darkened leaves has been shown to have a phytotoxic effect in subsequently illuminated plants. In animals a number of breakdown products of chlorophyll, such as phylloerythrin, promote secondary sensitisation, and a condition in sheep known as geeldikkop is induced if these compounds are not metabolised further in the liver. Hypericism is a well-known case of primary photosensitisation in which the ingested molecule acts as the photosensitiser. The active compound hypericin is produced in the glands of various Hypericum species and is offensive to grazing animals and insect predators. Damage is promoted by the photosensitised generation of ¹O₂. A related compound, fagopyrin from buckwheat, is similarly toxic, as also are a number of fungal quinones such as cercosporin. This compound is produced by Cercospora species and promotes a leaf-spot disease in certain crop plants. A large number of furanocoumarins such as psoralen and xanthotoxin are particularly offensive to phytophagous insects. Phototoxicity may involve ultraviolet sensitised binding to DNA as well as type II reactions. Numerous other polyacetylenes and thiophenes are also activated by ultraviolet radiation, and have a role as plant protectants.  相似文献   

Effect of subcutaneous vs intramuscular administration of P.G. 600 on estrual and ovulatory responses of prepubertal gilts     

Knox RV  Tudor KW  Rodriguez-Zas SL  Robb JA 《Journal of animal science》2000,78(7):1732-1737

The effects of s.c. and i.m. administration of P.G. 600 on estrual and ovulatory responses of prepubertal gilts were investigated. One hundred eighty-four crossbred gilts between 159 and 174 d of age were assigned to receive P.G. 600 s.c. (s.c. P.G. 600) in the flank, P.G. 600 i.m. in the neck (i.m. P.G. 600), or no treatment (control). At the beginning of the study (d 0), animals were selected from a modified, open-front barn, regrouped, relocated to new pens, and exposed once daily to a mature boar to check for estrus. On d 17, ovaries were collected from all gilts and analyzed for the presence of corpora lutea (CL), cystic follicles, and cystic CL. A higher proportion of gilts expressed estrus with s.c. P.G. 600 (76%) than with i.m. P.G. 600 (52%, P < .01) or controls (15%, P < .01). The interval from initiation of treatment on d 0 to estrus was reduced (P < .01) by P.G. 600 (4.6 d) compared to controls (5.9 d), but there was no significant difference between P.G. 600 treatments. Both s.c. P.G. 600 (86%) and i.m. P.G. 600 (77%) induced more gilts to ovulate (P < .01) than controls (18%), but there was no significant difference between P.G. 600 treatments. No significant effect of treatment was detected on number of CL (17.9), number of cystic follicles (1.5), or number of cystic CL (2.1). Proportions of gilts that developed cystic follicles or cystic CL were not influenced by treatment. Results of this study indicated that s.c. administration of P.G. 600 significantly improved the induction of estrus in prepubertal gilts compared to i.m. administration.  相似文献   

Infection of pigs by Aujeszky's disease virus via the breath of intranasally inoculated pigs   总被引：2，自引：0，他引：2  

Gillespie RR  Hill MA  Kanitz CL  Knox KE  Clark LK  Robinson JP 《Research in veterinary science》2000,68(3):217-222

Aujeszky's disease is a worldwide problem in the pig industry. In this experiment, four pigs chosen to act as shedder pigs were intranasally infected with Aujeszky's disease virus. Next, on three consecutive days, eight recipient pigs were exposed to the breath of a pair of shedder pigs via a mask-to-mask module. Except for the virtual absence of CNS signs, shedder pigs expressed clinical signs that were similar to pigs infected naturally or experimentally. Only mild respiratory signs occurred in recipient pigs, but all were infected by aerosols of Aujeszky's disease virus as evidenced by seroconversion. The pig is a much more sensitive indicator of airborne virions than our aerosol collection methods. We conclude that the mild respiratory disease acquired by the aerogenous route in recipient pigs is an easily managed model for studying the transmission of airborne respiratory infections and the immune responses to this type of infection.  相似文献   

Malignant transformation of a giant congenital pigmented nevus (hamartoma) in a dog     

Valentine  McManus  & Knox 《Veterinary dermatology》1999,10(2):127-130

A male Golden Retriever was born with a large area of abnormal skin and hair on the distal pelvic limb. A tumour arose from the proximal margin of this area at 5 years of age. Histopathological examination of the abnormal area of skin revealed an area in which follicles were surrounded by nodular accumulations of densely packed round to spindle-shaped cells with fine granular intracytoplasmic melanin. Similar cells were present within the subcutaneous fat, and clusters of densely pigmented melanocytes were scattered within the basal epidermis, follicular epithelium, and dermis. A diagnosis of giant congenital pigmented nevus (hamartoma) was made. The tumour from the proximal end of this area was composed of densely packed, moderately pleomorphic, poorly differentiated and pigmented, spindle-shaped to epithelioid melanocytes, and was diagnosed as malignant melanoma. Metastasis of the malignant melanoma to the stifle and inguinal regions occurred within 6 months. To date, the authors are unaware of prior reports of a canine giant congenital pigmented nevus (hamartoma) with transformation to a malignant melanoma.  相似文献   

糖源对棉花花药培养的影响──Ⅰ 糖源对棉花花药愈伤组织诱导的影响     

张宝红  刘方  姚长兵  李付广  刘传亮  李凤莲 《江西农业大学学报》1998,(3)

糖源在棉花花药培养中起着重要作用,不同糖源所起的作用不同。可溶性淀粉、蔗糖和葡萄糖有利于棉花花药愈伤组织的诱导和生长;麦芽糖对花药愈伤组织的诱导和生长促进作用不大;乳糖不利于愈伤组织的诱导。甘露醇的添加抑制了愈伤组织的诱导和生长。不同糖浓度对棉花花药愈伤组织诱导和生长的影响也不同,一般低浓度糖易诱导形成愈伤组织和愈伤组织的快速增殖。蔗糖的最佳使用浓度为３０ｇ／Ｌ。在不含糖源的培养基上棉花花药不能诱导形成愈伤组织,继代培养的愈伤组织也不易生长。培养条件和基因型也影响着糖源的使用效果。当以淀粉为糖源时,其具有胞外水解作用。  相似文献