A field study on reproductive efficiency of mares maintained predominately on native pasture     

P.G. Gibbs  K.E. Davison 《Journal of Equine Veterinary Science》1992,12(4)

A field study utilizing 145 mares of various age and breeding status was conducted to determine reproductive performance under native range conditions with only limited supplemental feeding. All mares had an average initial body condition score of 4.5 and a final score of 5.1 by the time breeding was completed and mares returned to pasture. Average foaling rate was 80%, and mares that had not conceived during the previous breeding season had a foaling rate of 94%, which was higher (P<.05) than 74% for lactating mares. Mares 16 years and older had a significantly lower foaling rate (P<.05) than younger mares. Old mares that were lactating at time of breeding had only a 37% foaling rate, which was less (P<.05) than for young lactating mares. The 94 mares bred by natural cover or artificial insemination that actually foaled required 1.43 cycles per conception. Lactating mares in the oldest age group required more cycles per conception (P<.05) than open mares, and these older, lactating mares also required more cycles per conception than younger mares with foals at side. Those mares diagnosed as pregnant or open at 45 days post breeding had a pregnancy rate of 97%. Average pregnancy loss for all mares was 7.7%. These data indicate that lactating mares in moderate body condition tended to skip a breeding season and that a body condition score of 5 was only marginally acceptable, especially in the case of lactating mares. Authors' address: Equine Science Program, Department of Animal Science, Texas Agricultural Extension Service, Texas A&M University, College Station, TX 77843. Technical Article Number 30023, Texas Agr. Exp. Sta.  相似文献   

Use of cyproterone acetate to lower circulating corticosterone and its effects on lymphocytes in domestic fowl     

T F Davison  A R Ezzat  J Rea 《Research in veterinary science》1989,46(1):105-109

Chickens were given daily injections of cyproterone acetate (CA) and the effects on plasma corticosterone, bodyweight, weights of the adrenals and lymphoid organs, numbers of circulating peripheral blood lymphocytes and their proliferation in the presence of lectins, concanavalin A (Con A) and phytohaemagglutinin (PHA), were investigated. Five daily doses of 10 or 30 mg CA kg-1 bodyweight each week over a three-week period caused a decrease in weight gain and a reduction in the relative weights of the bursa and thymus but not the spleen. There was a small decrease in the adrenals after treatment with 10 mg CA kg-1. When daily injections of CA were given over a seven-day period doses of 6 and 10 mg CA kg-1 bodyweight caused a significant (P less than 0.05) decrease in plasma corticosterone concentration after four days. However, after eight daily injections of CA a single injection of corticotrophin (10 iu ACTH kg-1) increased circulating corticosterone indicating CA had not completely blocked adrenal synthesis. CA had no effect on numbers of circulating peripheral blood lymphocytes or their ability to proliferate in the presence of Con A or PHA. The results indicate that CA is effective in lowering circulating corticosterone in the fowl but this did not affect the numbers or responsiveness of peripheral blood lymphocytes.  相似文献   

Mercapturic acid formation in the metabolism of propachlor,CDAA, and fluorodifen in the rat     

Gerald L. Lamoureux  Kenneth L. Davison 《Pesticide biochemistry and physiology》1975,5(6):497-506

When [¹⁴C]F₃-fluorodifen (2,4′-dinitro-4-trifluoromethyl diphenylether), carbonyl-[¹⁴C]CDAA (N,N-diallyl-2-chloroacetamide), and carbonyl-¹⁴C-propachlor (2-chloro-N-isopropylacetanilide) were fed to rats, 57 to 86% of the ¹⁴C was excreted via the urine within 48 hr. Although very little radioactivity was excreted in the feces of CDAA-treated rats, 15–22% of the ¹⁴C was excreted in the feces of propachlor- of fluorodifentreated rats and an average of 8% of the ¹⁴C remained in these rats 48 hr after treatment. Oxidation of the ¹⁴C label to [¹⁴C]O₂ was not a major process in the metabolism of these herbicides. The only major radioactive metabolite present in the 24-h urine of fluorodifen-treated rats, 2-nitro-4-trifluoromethylphenyl mercapturic acid, accounted for 41% of the administered dose of ¹⁴C. In the metabolism of CDAA, the corresponding mercapturic acid accounted for 76% of the dose; it was the only major metabolite present in the 24-h urine. In contrast, three major metabolites were detected in the 24-h urine of propachlortreated rats, and the mercapturic acid accounted for only 20% of the dose. The mercapturic acid of each herbicide was identified by mass spectrometry.  相似文献   

Isolation of a parainfluenza virus from sentry dogs with upper respiratory disease   总被引：1，自引：0，他引：1  

R A Crandell  W B Brumlow  V E Davison 《American journal of veterinary research》1968,29(11):2141-2147

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Evaluation of two point-of-care analysers for measurement of fructosamine or haemoglobin A1c in dogs     

Davison LJ  Podd SL  Ristic JM  Herrtage ME  Parnham A  Catchpole B 《The Journal of small animal practice》2002,43(12):526-532

Measurement of glycosylated proteins such as fructosamine and haemoglobin A1c (HbA1c) can be used to assess glycaemic control in canine diabetic patients. Two point-of-care analysers, designed for human diabetics, were evaluated for use in dogs. Blood samples were collected from 50 normoglycaemic dogs, 100 diabetic patients and five dogs with insulinoma and tested using the In Charge fructosamine meter and the Haemaquant/Glycosal HbA1c meter. Readings were obtained in all cases except for 21 of 50 diabetics, which were above the upper limit of the In Charge meter. Diabetic dogs had higher fructosamine and HbA1c concentrations compared to controls. However, there was poor agreement between the In Charge meter readings and serum fructosamine concentrations, suggesting that there are problems associated with the use of this device in dogs. HbA1c concentrations showed a high degree of correlation with glycosylated haemoglobin measured at an external laboratory, suggesting that the Haemaquant/Glycosal meter warrants further evaluation for veterinary use.  相似文献   

Regional brain monoamine concentrations and their alterations in bovine hypomagnesaemic tetany experimentally induced by a magnesium-deficient diet     

McCoy MA  Young PB  Hudson AJ  Davison G  Kennedy DG 《Research in veterinary science》2000,69(3):301-307

Monoamines are important brain neurotransmitters. An investigation was carried out to determine if hypomagnesaemic tetany was associated with alterations in regional brain monoamine concentrations in bovines. The results, established in cows with normal magnesium status, demonstrated that regional differences existed in the distribution and concentration of brain monoamines in the adult bovine, which were similar to those in other species. In magnesium-deficient cows, severe hypomagnesaemia and lowered cerebrospinal fluid (CSF) magnesium concentrations were associated with significant alterations in monoamine concentrations in some brain regions. Alterations in 3,4-dihydroxyphenylalanine (DOPA) and dihydroxyphenylacetic acid (DOPAC) concentrations in the corpus striatum, and dopamine (DA) in the cerebral cortex and cerebellum were recorded. These regions play an important role in both voluntary and involuntary motor function, and therefore these alterations may play a role in the aetiology of hypomagnesaemic tetany. However, there was no significant change in DA concentrations in the corpus striatum (the main dopaminergic region in the brain) associated with hypomagnesaemia. In addition, a significantly lower norepinephrine (NE) concentration in the corpus striatum of hypomagnesaemic animals was also recorded. Norephinephrine is generally excitatory and therefore lowered NE concentrations would be expected to result in depression rather than stimulation of motor function.  相似文献   

A CONTRIBUTION TO THE PROBLEM OF COON BUTTE     

Davison JM 《Science (New York, N.Y.)》1910,32(829):724-726

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Oxygen uptake in the Antarctic teleost Pagothenia borchgrevinki. Limitations imposed by X-cell gill disease   总被引：1，自引：0，他引：1  

William Davison  Craig E. Franklin  Peter W. Carey 《Fish physiology and biochemistry》1990,8(1):69-77

Fish in a population of Pagothenia borchgrevinki in McMurdo Sound, Antarctica, are affected by a gill disease (X-cell disease) which causes tissue hyperplasia that results in a decreased gill surface area and an increased water/blood diffusion distance. P. borchgrevinki acquires 95% of its oxygen via the gills, but damage to the gills by X-cell disease did not affect this function. There was no compensatory shift to cutaneous respiration. X-cell disease reduced the ability for oxygen uptake at low ambient P_{O 2} and the decreased uptake was related to the extent of the disease. _{O 2} max was greatly reduced in X-cell affected fish and substantially reduced their aerobic potential. This effect may impair the ability of diseased fish to catch prey and avoid predators.  相似文献   

Cryptosporidium infection in a dugong (Dugong dugon)     

BD HILL  IR FRASER  HC PRIOR 《Australian veterinary journal》1997,75(9):670-671

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Use of the IDEIA ELISA to detect Chlamydia psittaci (ovis) in material from aborted fetal membranes and milk from ewes affected by ovine enzootic abortion     

R Thomas  H C Davison  A J Wilsmore 《The British veterinary journal》1990,146(4):364-367

The IDEIA ELISA was used to detect Chlamydia psittaci (ovis) antigen in ewes' milk to which were added serial dilutions of chlamydiae titrated as inclusion forming units (ifus) in McCoy cell tissue culture. The test was able to detect as few as 35 ifus/ml of the organism. The ELISA was then used to detect chlamydial antigen in fetal membranes and milk from ewes clinically affected with ovine enzootic abortion (OEA). The results were compared with results of isolation of chlamydiae in McCoy cell tissue culture from the same material. The fetal membranes of 17 of 19 ewes were positive for chlamydia when tested with the ELISA but chlamydia could be cultured from only 15 of them. Milk samples from 26 ewes which had aborted between 1 and 34 days previously were tested: chlamydiae could not be cultured from any of them and only one was positive when tested by the ELISA. The results show that the IDEIA ELISA is a sensitive test for the detection of C. psittaci (ovis) antigens. The positive results to this test for the three samples from which chlamydiae could not be cultured suggest that the test is not as specific as culture or that it detected dead organisms. Chlamydiae do not appear to be excreted in the milk of ewes affected with OEA.  相似文献