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Biomedical subjects

J H Dufty

Publications and source records attributed to J H Dufty.

At least 37 records · Page 2Linked to original sources
PubMed1983

The effect of Tritrichomonas foetus infection on calving rates in beef cattle.

The effect of Tritrichomonas foetus var. brisbane infection on calf production by Hereford cows was determined. The mean number of calves produced by cows that were kept continuously with bulls infected with T. foetus for 3 years was 17.6% less than the mean number produced by cows kept with a non-infected bull. Losses in production due to trichomoniasis occurred each year, but were greatest in the first 2 years in cows experiencing infection for the first time.

Animals↗
PubMed1983

Immunisation of bulls against trichomoniasis.

Studies into the immunisation of bulls against infection with Tritrichomonas foetus showed that subcutaneous administration of vaccines containing killed cells of T foetus in a mineral oil adjuvant prevented the eliminated genital infection in most bulls up to the age of 5 years. Immunisation did not effectively prevent or cure infection in bulls older than 5.5 years.

Age Factors↗
PubMed1981

Surface markers for characterisation of bovine blood lymphocyte populations and changes in these from birth to maturity.

A sheep erythrocyte (E) rosette technique was developed for use with cattle lymphocytes. This involved the use of 17 per cent Ficoll 400 and preservative-free heparin (84 iu/ml) in the saline-erythrocyte mixture. Using this technique, 83 per cent of peripheral blood lymphocytes in cattle aged between six and 10 years were found to form E rosettes. The remaining cells (17 per cent) were B-cells, so that no cells remained unmarked. Lymphocytes from very young calves contained a population of unmarked or null cells, but these rapidly diminished as the animals matured. A peak of total lymphocytes recovered from blood, as well as E rosette-forming cells, occurred in calves aged four to six months. The non-E rosette-forming cells were mostly B-cells and it was suggested that this was associated with calf weaning. The total number of lymphocytes recovered, as well as E rosette-forming cells, gradually fell with the age of the cattle sampled. Null cells were virtually absent from the blood of cattle six years and older. Bovine T-cells could be further subdivided into Fc mu, Fc gamma and C' receptor-bearing subpopulations on the basis of overlap with R rosette-forming cells. Some further separation of these cells from B-cells was achieved using density gradient centrifugation on Percoll. Separation of E rosette-forming cells with Fc receptors from E rosette-forming cells without Fc receptors was achieved by nylon wool columns, to which the Fc receptor bearing cells were adherent. It was concluded that bovine blood lymphocytes had blood T-lymphocyte populations with markers which may correspond to the 'helper' (Fc mu ) and 'suppressor' (Fc gamma ) populations described for the human.

Aging↗
PubMed1980

Assessment of vaginal impedance measurements as an indicator of oestrus in cattle.

A study was made in cattle of the variation of vaginal impedance with respect to the placement of probe, time after insertion, and stages of the oestrous cycle. Impedance values were lowest and least variable when determined in the ventral sector of the vaginal fornix. Allowing the probe time to warm up improved results. Vaginal impedance declined by approximately 30% during pro-oestrus, oestrus and metoestrus when compared with dioestrus. The time at which the lowest values were reached varied between animals, in 2 cases being a day before oestrus, in another 2 on the day of oestrus, and for 1, the day after oestrus. The method described was not suitable for determining the peak of behavioural oestrus.

Animals↗
PubMed1977

Studies on the transmission of Tritrichomonas foetus.

Although 2 experiments showed that non-infected bulls can passively transmit Tritrichomonas foestus from infected to non-infected cows during mating, the rates of transmission were low. The results of the second experiment, in which time intervals between services were recorded, suggested that T. foetus was most likely to become established in previously non-infected cows when the interval was less than 20 minutes. Application of 2 X 10(6) active cells of T. foetus to the vulva failed to cause genital infection in 10 cows.

Animals↗
PubMed1977

Anoxia in the bovine foetus.

Laparohysterotomies were performed, under local analgesia, on 18 plurigravid Herefore cattle and the response of their foetuses to anoxia was examined. All control and 4 of 6 foetuses subjected to 4 minutes of anoxia survived whereas all others died when the umbilical cord was clamped for 6 or 8 minutes. Death mostly occurred just before or soon after delivery, which was undertaken immediately following release of the umbilical clamp. In 2 cases, however, the calves survived for at least 2 days before being slaughtered when death appeared imminent. During the intervening period both animals failed to suck although one was able to stand temporarily following the oral administration of glucose and milk. Studies on the blood-gas and acid-base status of the foetuses while the umbilical cord was clamped revealed a decline in pH, pO2 and standard bicarbonate levels, the development of a base deficit and an increase in pCO2 and lactate levels. Clamping of the umbilical cord usually resulted in some foetal movement and the release of meconium. Clamping of the imbilical cord also caused an almost immediate fall in the pulse rate, which gradually increased after several minutes and became irregular and weak. Post-mortem examination of foetuses or calves dying from anoxia revealed haemorrhages throughout the body, these always being found on the heart, usually in the thymus and spleen, and occasionally in other sites throughout the body.

Animals↗
PubMed1977

A dual vaccine for the immunisation of cattle against vibriosis.

Single subcutaneous injections of a mineral oil adjuvant vaccine containing 20 mg dry weight of Campylobacter fetus subsp fetus biotype venerealis cells and 20 mg dry weight of C. fetus subsp fetus biotype intermedius cells per 5 mil dose protected 2- and 3-year-old heifers and 3- and 4-year-old cows against genital infection with either organism.

Animals↗
PubMed1977

Elective caesarean operation in Hereford cattle.

An elective left flank Caesarean operation was performed on 56 Hereford cattle and the influence of various surgical techniques on the postoperative progress assessed. A paravertebral nerve block produced effective analgesia in all layers of the abdominal wall of all cattle. In contrast, tissue infiltration, in the form of an inverted L block, did not produce analgesia of the peritoneum and was generally only partly effective in the muscle layers of fat animals. The use of spasmolytic drug facilitated handling of the uterus. Xylazine, when given to unmanageable animals, noticeably increased uterine tone even when used in conjunction with a spasmolytic. Three animals (5.4%) died from generalised peritonitis. Peritoneal adhesions developed in 29 animals (51.8%) and minor wound dehiscence and/or suture infection occurred in 8 animals (14.1%). Postoperative subcutaneous emphysema developed in ;23 cattle (41%). The absence of sutures in the peritoneum was associated with a significant increase in the occurrence of subcutaneous emphysema. Although the prevalence of retained foetal membranes was high this did not seem to influence the postoperative progress of the animal.

Anesthesia, Obstetrical↗
PubMed1977

The plasma zinc concentration of nonpregnant, pregnant and parturient Hereford cattle.

Studies were made on several groups of Hereford cattle to determine the plasma zinc concentration at various phases of their reproductive life. In nonpregnant heifers a major cause of variation was due to differences between individual animals. Seasonal changes were also evident but little difference was noted in the zinc levels of cattle sampled at particular stages of the oestrous cycle or over a 24-hour period. Following conception, the plasma zinc levels remained relatively constant until late in pregnancy when a decline occurred. A more marked decline occurred during the periparturient period although the trends observed differed between animals that calved normally and those that suffered from dystocia. Samples obtained from calves approximately 24 hours after delivery contained zinc at concentrations of more than double that recorded for their dams.

Animals↗
PubMed1975

Studies on veneral transmission of Campylobacter fetus by immunised bulls.

Temporary contamination of the penis and prepuce with Campylobacter fetus subsp. venerealis and Campylobacter fetus subsp. venerealis biotype intermedius may occur when immunised bulls mate with infected heifers. However, 2 experiments showed that this contamination was not a significant cause of genital infection in susceptible heifers that subsequently mated with bulls.

Animals↗
PubMed1975

The influence of age on the susceptibility of bulls to Campylobacter fetus subsp venerealis.

Observations were carried out on 22 Hereford bulls to determine the age at which they bacame carriers of C. fetus. During preliminary investigations, 5 bulbs were repeatedly exposed to the organism by artificial or natural means from the age of 18 months. All animals became longterm carriers on reaching an age of between 40 and 70 months. Prior to this, a temporary carrier state lasting from 4 to 29 days was produced in 4 bulls. In a subsequent experiment, 17 bulls of 3 different age groups were artificially exposed to C. fetus on 5 occasions over a 2-year period. Thirteen bulls became long-term carriers, including 9 (53%) when less than 4 years old. A transient carrier state occurred in 4 bulls, 2 of which subsequently became long-term carriers. It usually lasted 1-2 weeks, although in 1 animal the organism persisted for 11 weeks. These results are discussed in relation to the findings of other workers and it is concluded that the use of young bulls to limit the spread of C. fetus in infected herds is of dubious value.

Age Factors↗