A study of the influence of the method of oral administration of ampicillin upon plasma drug levels in calves.

Ampicillin was given orally to five Holstein calves using the following four different methods of administration: via stomach tube, mixed and fed in the calf starter ration, dissolved in milk and pail fed and administered orally as 400 mg commercial calf tablets. In addition, ampicillin was dissolved in milk and pail fed 20 to 30 minutes following intramuscular atropine. Ampicillin was only detected in the plasma of calves which had received the drug, pail fed in milk. Atropine administration slowed the appearance of the drug in the plasma but did not decrease the efficiency of absorption.     

Anti-ttck grasses as the basis for developing practical tropical tick control packages

Summary Of six grass species analysed,Melinis minutiflora (molasses grass) showed the highest anti-tick deterrent properties whileAndropogon gayanus (Gamba grass) exhibited the ability to maintain a defined, constantly low, initial host tick infestation property and lengthy but low to moderate field tick population.It was concluded thatMelinis minutiflora is a species which would best be used in a tick control package within a marginal tick zone whileAndropogon gayanus has the advantage within an endemic tick zone.

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Pastos Anti-Garrapatas Como Base Para El Desarrollo Practico De Paquetes Para El Control De Garrapatas En El Tropico

Resumen De seis pastos analizados,Melinis minutiflora (pasto Gordura) tuvo las propiedades más altas para el control de garrapatas, mientras que elAndropogon gayanus (pasto Gamba), tuvo la abilidad de mantener una población inicial definida y constantemente baja de garrapatas en el huésped, y una prolongada, entre baja y moderada, población de garrapatas en el campo.Se concluyó, que el pasto Gordura, es la mejor especie para el control de garrapatas en una zona marginal, mientras que el pasto Gamba tiene mejores ventajas en zonas endémicas.

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Les Plantes Anti-Tiques Comme Base Du Développement Pratique De La Lutte Contre Les Tiques Dans Les Pâturages

Résumé Des six plantes étudiées c'est leMelinis minutiflora qui a montré l'activité préventive la plus élevée tandis queAndropogon gayanus (Gamba grass) a montré son aptitude à maintenir à un niveau constant et correct une infestation initiale peu élevée.En conclusionMilinis minutiflora est une espèce à utiliser de préférence pour le contrôle des tiques dans les zones où l'infestation est marginale tandis queAndropogon gayanus est à préférer pour lutter dans les zones où l'infestation par les tiques revêt un caractère endémique.

     

Comparison of three serological tests and an interferon-gamma assay for the diagnosis of paratuberculosis in experimentally infected sheep

OBJECTIVE: To compare the diagnostic performance of a complement fixation test, an agar gel immunodiffusion test, an enzyme-linked immunosorbent assay, and a whole-blood interferon-gamma assay for paratuberculosis in 14 sheep experimentally infected with Mycobacterium avium subsp paratuberculosis. EXPERIMENTAL DESIGN: Longitudinal study. RESULTS: The IFN-gamma assay detected more experimentally infected sheep, and earlier, than any of the serological tests. None of the antibody assays was able to detect all sheep with histologically confirmed paratuberculosis. CONCLUSIONS: The superior performance of the IFN-gamma assay in detecting infected sheep in this small experimental population warrants its further evaluation in a larger population of sheep naturally exposed to M a paratuberculosis.     

Lymphosarcoma of the pharyngeal region in a 7-month-old beef steer

A steer presented for retropharyngeal swelling and dyspnea. Biopsy of the swelling indicated lymphoblastic lymphosarcoma, and necropsy revealed involvement of regional veins and arteries. The tumor was classified as a non-T, non-B lymphoma based on CD3 polyclonal antibody stains. Lymphosarcoma is unusual in this location, but should be considered with retropharyngeal swelling.     

Association of serologic status for Neospora caninum with postweaning weight gain and carcass measurements in beef calves

OBJECTIVE: To determine the seroprevalence for Neospora caninum in a population of beef calves in a feedlot and the association of serologic status with postweaning weight gain and carcass measurements. DESIGN: Longitudinal observational study. ANIMALS: 1,009 weaned beef steers from 92 herds. PROCEDURE: Samples were obtained from all steers at time of arrival at a feedlot. Serologic status for Neospora spp was determined, using an agglutination test. Results of serologic testing were compared with calf growth and carcass data, using multivariate regression with generalized estimating equations. RESULTS: Of 1,009 calves, 131 (12.98%) were seropositive, and 54 of 92 (58.7%) consignments had > or = 1 seropositive calf. Median within-consignment prevalence for consignments in which there was > or = 1 seropositive calf was 20%. Seropositive status was associated with significant reductions in average daily gain, live body weight at slaughter, and hot carcass weight and an increase in ribeye area-to-hot carcass weight ratio. Seropositive status also was associated with significant increases in cost of treatment and significant reductions in income. Sick seropositive calves had the highest cost of treatment. An economic loss of $15.62/calf was projected for seropositive calves. CONCLUSIONS AND CLINICAL RELEVANCE: Significant reductions in postweaning weight gain, carcass weight, and economic return were associated with detection of antibodies to N caninum in beef calves in a feedlot.     

Cryptosporidium meleagridis in an Indian ring-necked parrot (Psittacula krameri)

OBJECTIVE: To perform a morphological and genetic characterisation of a Cryptosporidium infection in an Indian ring-necked parrot (Psittacula krameri) and to compare this with C meleagridis from a turkey. DESIGN: Tissue and intestinal sections from an Indian ring-necked parrot were examined microscopically for Cryptosporidium. The organism was also purified from the crop and intestine, the DNA extracted and a portion of the 18S rDNA gene amplified, sequenced and compared with sequence and biological information obtained for C meleagridis from a turkey as well as sequence information for other species of Cryptosporidium. RESULTS: Morphological examination of tissue sections from an Indian ring-necked parrot revealed large numbers of Cryptosporidium oocysts attached to the apical border of enterocytes lining the intestinal tract. Purified Cryptosporidium oocysts measured about 5.1 x 4.5 microns, which conformed morphologically to C meleagridis. The sequence obtained from this isolate was identical to sequence information obtained from a C meleagridis isolate from a turkey. CONCLUSION: Cryptosporidium meleagridis was detected in an Indian ring-necked parrot using morphological and molecular methods. This is the first time that this species of Cryptosporidium has been reported in a non-galliform host and extends the known host range of C meleagridis.     

Fatigue in wood-based panels. Part 1: The strength variability and fatigue performance of OSB, chipboard and MDF

Wood-based panels used as floor decking can be exposed to fatigue as well as creep loading. The strength and fatigue performances of three wood-based panel products OSB, chipboard and MDF have been determined in four-point bending. The mean bending strengths were found to decrease in the following order MDF>OSB>chipboard. The bending strength variation within the OSB was considerably greater than that for chipboard and MDF. Normalised with respect to the static strengths, the fatigue performance of the chipboard was superior to that of the OSB, although the two materials have very similar performances at low stress levels. Normalised with respect to the static strengths, the fatigue performance of the MDF was inferior to both materials and at lower stress levels the fatigue performance deteriorated to a greater extent. However, in terms of absolute applied stress, the fatigue performance of the MDF was superior to that of the OSB, which was superior to that of the chipboard. However, as the stress was reduced the difference between the three materials reduced. At low stresses the performances of the three materials were quite similar. Received 5 August 1999     

Effect of two relative humidity environments on the performance properties of MDF, OSB and chipboard

The static strength, stiffness and fatigue life of MDF, OSB and chipboard have been measured in a 65%RH environment and a 85%RH environment. Chipboard is commonly utilised as a flooring material and OSB is also used in structural applications, for example floor decking and webs of I-beams. The mean static strengths of MDF, OSB and chipboard at 65%RH were 47.9 MPa, 27.9 MPa and 21.0Mpa, respectively, compared with 34.59 MPa, 21.70 MPa and 10.61 MPa at 85%RH. However, MDF has mostly been used in non-structural applications, such as furniture, so its resistance to fatigue loads as a structural panel is of considerable interest. In a 65%RH environment dynamic modulus values showed that whilst MDF and chipboard exhibit similar stiffness values (4 GPa), OSB is approximately 50% stiffer. However, at 85%RH MDF was the stiffest of the three materials, followed by OSB and chipboard. The fatigue life performance of all three panel products was markedly lower at 85%RH compared with 65%RH. Overall, the high RH environment had a noticeably detrimental effect on the MOE (modulus of elasticity), MOR (modulus of rupture) and fatigue lives of OSB and chipboard. This is attributed to these panels retaining more of the original characteristics of the original wood, i.e. larger particle sizes (flakes/chips) compared with the homogeneous fibrous composition of MDF. Received 5 November 1999     

Fatigue and creep in chipboard

Summary Structural grade chipboard used as floor decking can be exposed to a combination of creep loading, and fatigue loading at a wide range of frequencies. Creep loads are produced by static masses such as machinery. Fatigue loads arise from intermittent loads such as fork lift trucks in motion, people in motion, or vibrating machinery.Four-point bend tests in fatigue and creep have been performed simultaneously on matched sets of four structural grade chipboard samples. The aim was to examine the effect of frequency on the fatigue performance of chipboard by following the rate of microstrain development in each case at the same peak stress. The ratio of the minimum to the maximum fatigue stress (the R ratio) was set at R = 0.1. Fatigue tests were performed at three different frequencies classified as low, medium and high, determined by the rate of application of stress.The performance of chipboard in flooring applications is shown to be highly dependent on the loading frequency. Increasing the frequency increased the number of cycles to failure as did reducing the stress level. Using hysteresis loop capture to monitor damage accumulation during testing indicates that there is a fatigue limit for chipboard loaded at constant amplitude at some point just below 20% of its static bending strength.This research was supported by the Building Research Establishment who also supported the postgraduate case award in conjunction with the Engineering and Physical Sciences Research Council (EPSRC)