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Biomedical subjects

A J Russel

Publications and source records attributed to A J Russel.

At least 19 recordsLinked to original sources
PubMed1996

Studies on caprine responsiveness to nematodiasis: segregation of male goats into responders and non-responders.

Eighty-three 2-4-year-old intact male goats exposed to a combination of artificial and natural challenge were segregated into responders and non-responders by ranking of weekly faecal egg counts (FECs). Retrospective analysis of samples over a 15-week-period showed responders had a statistically lower mean FEC than non-responders. Estimates of repeatability between consecutive egg counts were significant in both groups. The 6 top responders and bottom non-responders were subsequently given an artificial trickle challenge with Teladorsagia circumcincta and Trichostrongylus vitrinus. Mean faecal egg output was significantly lower in responders than non-responders. Peripheral eosinophil numbers following challenge were significantly greater in responder than non-responder goats. Abomasal and intestinal worm burdens were considerably lower in responders, with evidence of retardation of worm development compared to non-responders. Both abomasal and jejunal tissue eosinophil numbers were significantly higher in responders, although there was no difference in mucosal mast cell or globule leucocyte numbers. These results suggest that under temperate climatic conditions, it is possible to segregate male goats into responders and non-responders on the basis of simple parasitological criteria.

Abomasum↗
PubMed1996

The response of breeding doses to nematodiasis: segregation into "responders" and "non-responders".

Responder and non-responder does were identified from a flock of 95 Scottish cashmere 2-6 year-old does exposed to natural nematode infection over a 12-month period. Every 5 weeks, the does were faecal sampled for worm-egg counts prior to anthelmintic treatment. Responsive and non-responsive individuals were identified on the basis of their cumulative faecal egg count (FEC) rankings: the 8 lowest and 8 highest rankings were deemed to be responders and non-responders, respectively. Retrospective analysis showed that the mean egg count of the 8 responders was significantly lower than that of the 8 non-responders. The selected responders and non-responders were subsequently housed together with 8 randomly selected does from a control line, and given a mixed trickle challenge with Teladorsagia circumcincta and Trichostrongylus vitrinus larvae (L3). Mean responders FEC was significantly lower following artificial infection than that of non-responder and unselected does. Peripheral eosinophilia was significantly greater in responders in the first 3 weeks of this infection. On day 60, the infection was terminated with anthelmintic and 7 days later the goats were given a single challenge of 50,000 T. circumcincta L3. The mean responder worm burden was lower, and exhibited greater evidence of retardation of worm development, than those of non-responder and unselected does. Responders had significantly more mast cells and globule leukocytes post-challenge than did the other 2 groups. These results suggest that under the conditions encountered in this experiment, it is possible to segregate goats into responders and non-responders using simple parasitological criteria, as individual responsiveness is a relatively repeatable phenomenon.

Animal Feed↗
PubMed1994

The role of prolactin in the reactivation of hair follicles in relation to moulting in cashmere goats.

The effects of the suppression or elevation of plasma prolactin concentrations in spring on the timing of the reactivation of the hair follicles and the timing of the spring moult were investigated in cashmere goats. Thirty eight adult female goats, housed under conditions of natural photoperiod at 55 degrees 55'N from mid-December until May, were allocated to four groups starting on 5 January: ten served as untreated controls, eight received 2 mg ovine prolactin subcutaneously every 12 h for 7 weeks (PRL), twelve received 35 mg bromocriptine intramuscularly every 14 days for 17 weeks (BCR) and eight received injections of both ovine prolactin and bromocriptine at the above dose rates for 7 weeks (PRL+BCR). In the PRL group there was an earlier reactivation of the secondary hair follicles (PRL vs control, proportion of secondary follicles in antigen, weeks 1-5, P < 0.01) associated with an earlier moult of secondary fibres (cashmere) but no significant difference in the activity of the primary hair follicles. In the BCR group there was a delay in the reactivation of both the secondary and primary hair follicles (BCR vs control, proportion of secondary and primary hair follicles in anagen, weeks 5-13, P < 0.01) and a delay in the moult. In the PRL+BCR group there was an early reactivation and moult similar to the PRL group. Voluntary food intake (VFI) and liveweight were also measured. Only in the BCR group was there a decrease in VFI compared with the controls but with no effect on liveweight.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1992

Prevalence of anthelmintic-resistant nematodes in fibre-producing goats in Scotland.

Six cashmere goat herds in Scotland were surveyed to assess the prevalence of anthelmintic resistance and the species of nematode involved. Resistance was determined in vivo by a faecal egg count reduction test and in vitro using an egg hatch assay and specific faecal egg identification techniques. Benzimidazole resistance was present in five of the herds, insufficient eggs were obtained from the other herd to draw firm conclusions. Teladorsagia (Ostertagia) species predominated in four of the five herds in which resistance was detected and Haemonchus contorus was the dominant species in the other.

Animals↗
PubMed1988

Prediction of calving date in beef cows by real-time ultrasonic scanning.

Three hundred pregnant beef cows between 35 and 125 days of gestation were scanned ultrasonically and their calving dates were predicted from measurements of fetal parts. The mean difference between the actual and predicted calving dates was 0.9 day with a standard deviation of 9.0 days. The accuracy and precision of the prediction of calving date were sufficient to be of benefit in the management of cows in late pregnancy and at calving.

Animals↗
PubMed1985

Real-time ultrasonic scanning in the diagnosis of pregnancy and the estimation of gestational age in cattle.

Diagnoses of pregnancy were made on 110 Hereford cross Friesian and 69 blue grey (white shorthorn cross Galloway) cows between 92 and 202 days after last service using a real-time ultrasonic scanning instrument with a 3.5 MHz rectal transducer. Of the 174 cows which subsequently calved, one was wrongly diagnosed as non-pregnant. Of the five cows which did not subsequently calve two were diagnosed as pregnant and may in fact have been pregnant at the time of scanning. The overall level of accuracy of pregnancy diagnosis was 98.3 per cent. In further trials with 16 Hereford cross Friesian and 16 blue grey cows scanned at regular intervals between 20 and 140 days of gestation, pregnancy was diagnosed with confidence from 30 days, and relationships were established whereby gestational age could be estimated from measurements of certain uterine and fetal dimensions. Crown-rump length provided the most precise estimate of gestational age (residual sd +/- 4.5 days) and uterine diameter the least (+/- 12.6 days) with head length and the diameters of trunk, head and nose being intermediate (+/- 6.9 to 8.7 days).

Animals↗
PubMed1984

Real-time ultrasonic scanning in the diagnosis of pregnancy and the determination of fetal numbers in sheep.

Two trials were conducted on a total of 1120 ewes of four breeds to evaluate the use of real-time ultrasonic scanning as a means of diagnosing pregnancy, differentiating barren, single- and multiple-bearing ewes and determining actual fetal numbers in pregnant ewes. In trial 1 (566 ewes) the accuracy of an inexperienced operator, as judged against assessments of an experienced operator, improved from 81 to 100 per cent for the classification of ewes as carrying no, one or more than one fetus, and from 69 to 100 per cent for the determination of actual fetal numbers more than one. In trial 2 the accuracies of the same operator, judged against the lambing performance of 267 ewes, ranged from 90 to 97 per cent for both types of assessment, and for an experienced operator from 95 to 100 per cent (554 ewes). In both trials pregnancy was diagnosed with an accuracy of 100 per cent. It is concluded that real-time ultrasonic scanning of sheep between days 50 and 100 of gestation offers a safe and practicable means of diagnosing pregnancy and of determining fetal numbers. Accuracies of diagnosis of pregnancy of more than 99 per cent, of differentiation of barren, single- and multiple-bearing ewes of 98 per cent, and of determination of actual fetal numbers of 97 per cent can be achieved in practice at scanning rates of at least one ewe per minute. Some of the benefits to flock management and performance likely to result from the use of the technique are considered.

Animals↗
PubMed1983

Use of cupric oxide needles in the prophylaxis of induced copper deficiency in lambs grazing improved hill pastures.

Cuprix oxide needles as a single oral dose were administered to ewes in the prepartum period, and to one member of each pair of twin lambs at between three and five weeks of age when grazing hill pastures improved by liming and reseeding. Lambs derived from dosed or undosed ewes and treated at three to five weeks of age were maintained in normocupraemia and showed no signs of ill-thrift. Lambs derived from dosed or undosed ewes but not themselves dosed showed hypocupraemia and ill-thrift. The lambs derived from the dosed ewes took longer to become hypocupraemic, but showed only a transient benefit from the ewe treatment. The dosed ewes showed a delay in the onset of hypocupraemia compared with the undosed ewes but there were no definable differences in performance between the two groups.

Administration, Oral↗
PubMed1978

Effects of energy intake during late pregnancy and of genotype on immunoglobulin transfer to calves in suckler herds.

Blue-Grey (Shorthorn x Galloway) and Hereford x Friesian cows were given levels of feeding, during the last 12 weeks of pregnancy, varying between 75.2 per cent and 171.5 per cent of the maintenance requirements in one experiment and between 65 per cent and 125 per cent of the maintenance requirements in a second experiment. The concentrations of the immunoglobulin classes IgG1, IgG2 and IgM, in their colostrum and in their calves' serum were measured. The IG1 and IgM, but not the IgG2, concentrations were significantly higher in the Blue-Grey than in the Hereford x Friesian colostrum and serum. The relative concentrations of the three classes in the serum were almost identical to those in the colostrum, suggesting that absorption by the calves was non-selective. The amounts of immunoglobulin transferred to the calves were not affected by the cows' levels of feeding in the first year, but there was a small increase in transfer with increasing levels of feeding during the second year. Cows that transferred large amounts to their calves in the first year tended to do so in the second year. The milk intake and growth of the calves during the first 42 days were significantly correlated with their immunoglobulin concentrations.

Animals↗