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Biomedical subjects

W R Ward

Publications and source records attributed to W R Ward.

At least 73 records · Page 4Linked to original sources
PubMed1976

Effect of continuous infusion of gonadotrophin-releasing hormone in ewes at different times of the year.

Gn-RH (3 mug/hr for 8 hr) evoked a surge of LH in ewes during the anoestrous season which was of similar peak height to that found at oestrus but of shorter duration. When Gn-RH was given on 3 consecutive days, the response was considerably reduced on the 2nd and 3rd day. Follicles grew as a result of Gn-RH infusion but peripheral plasma oestrogen concentration did not increase. During the anoestrous season 9/18 ewes ovulated but only 1/6 did so at mid-anoestrus. Mature follicles or a CL were found in 15/18 ewes that had increased peripheral plasma progesterone concentrations for 1-5 days (11 ewes) or 9-14 days (4 ewes). The concentrations of progesterone found were always lower than those observed during the normal cycle. In the breeding season 10/11 ewes ovulated but there was no evidence that the induced CL were maintained.

Anestrus↗
PubMed1976

Concentration of steroids in bovine peripheral plasma during the oestrous cycle and the effect of betamethasone treatment.

Testosterone, oestradiol and progesterone were measured in peripheral plasma during the oestrous cycle of 6 heifers. Oestradiol and progesterone results confirmed earlier reports. Concentration of testosterone on the day of oestrus was 40+/-3 pg/ml (mean+/-S.E.M.), and two peaks were detected during the cycle, one 7 days before oestrus (1809+/-603 pg/ml) and the other (78+/- 7 pg/ml) on the day before the onset of oestrus. The concentration of progesterone declined in most cases 1 day after the maximum concentration of testosterone. Betamethasone treatment in 5 heifers extended luteal function by an average of 10 days: plasma androstenedione and oestradiol concentrations were unaltered; cortisol values were depressed for at least 16 days after treatment; testosterone concentrations were lowered by 13+/-2-4% during treatment, and except in one heifer the peak on Day -7 was abolished.

Adrenal Glands↗
PubMed1976

Changes in steroid hormones in plasma and myometrium and uterine activity in ewes during late pregnancy and parturition.

In 7 ewes during late pregnancy, peripheral plasma concentrations of oestrogens were correlated with uterine activity (P less than 0-01; r=+0-47). In myometrial tissue, the concentration of progesterone was similar to that in plasma; it rose to a plateau from Days 115 to 130 of pregnancy and then fell, but was still detectable during parturition. Myometrial oestrogen concentration was much higher than in plasma; from a peak at Days 100-115 it decreased, but rose sharply just before parturition.

Animals↗
PubMed1976

Parturition in the goat: plasma concentrations of prostaglandin F and steroid hormones and uterine activity during late pregnancy and parturition.

Changes in plasma concentrations of hormones and uterine activity associated with spontaneous parturition in the goat were examined. No change in oestradiol-17beta concentration was detected during the experimental period, but oestradiol-17alpha consistently increased in concentration 3-4 days before parturition. This was followed by an increase in prostaglandin F two days later, while a pre-partum decline in progesterone concentration occurred 18-20 h after the significant increase in prostaglandin F. The onset of uterine contractions coincided with a significant decline in progesterone concentration and a period of continually rising prostaglandin F and oestradiol-17alpha concentrations. Uterine activity expressed in Montevideo units did not change until 10-8 h before foetal expulsion. These results support the hypothesis that in the goat the elevated prepartum concentration of prostaglandin F brings about luteolysis and a subsequent decline in progesterone concentration.

Animals↗
PubMed1975

Treatment of clinical mastitis: two intramammary formulations compared.

Two hundred cases of mild clinical mastitis were treated on two farms using two intramammary preparations in quick release bases. One preparation contained penicillin and streptomycin, the other contained lincomycin, neomycin and prednisolone. Fifty-eight per cent of cases were clinically and bacteriologically cured using the first preparation; and 61 per cent of cases, with a similar range of organisms, using the second. The main infections were Streptococcus uberis and coliform; all but three of the infections were sensitive in vitro to one or both of the antibiotics in the preparations. On the farm with 100 cows, 69 per cent of cases were cured, while only 52 per cent were cured on the farm with 300 cows. It is suggested that it is more difficult to detect and treat cases in the larger herd. A number of reservations about the interpretation of the results are discussed.

Animals↗
PubMedDate not supplied

The relationship between milk yield and cystic ovarian disease in cattle.

Studies were conducted to understand the relationship, if any, between the amount and pattern of milk yield and the occurrence of cystic ovarian disease (COD) in dairy cattle. More than 70 cows with cysts were compared with herd mates of similar lactation number. Total milk yield in lactations when cysts occurred and in the preceding lactations were not different from the corresponding lactations in control cows. Patterns of monthly milk yield did not differ between the two groups of cows. However, weekly analysis in early lactation revealed differences. Both groups of cows achieved peak yields at a similar time (5.4 +/- 1.2 vs 5.7 +/- 1.9 weeks post partum in normal vs cows with COD). However, owing to an early decline in yield of cows with COD, their duration of peak yield was significantly shorter (P less than 0.05) than in the control cows (3.2 +/- 2.2 vs 5.6 +/- 2.4 weeks). Both the attainment and the decline of peak yield occurred 5.6 (range = 2-15) weeks before the cysts were diagnosed. It is concluded that COD is not particularly a disease of higher yielding cows and that COD has no discernible effect on the milk yield or its pattern. It is speculated, however, that some cows in early lactation, while trying to meet the requirements of sustained peak milk production, are more susceptible to minor environmental changes (such as new social interactions, or changes in diet). These events may lead to a drop in milk production and disruption of events controlling normal ovulation, resulting in the formation of ovarian cysts.

Animals↗
PubMedDate not supplied

An angiographic evaluation of vascular changes in sole lesions in the hooves of cattle.

In an angiographic study of vascular changes in sole lesions in cattle hooves, it was shown that hooves with sole haemorrhage at the ulcer site in the outer hind claw had constriction of the lumen of the terminal part of the proper digital artery. Severe constriction or occlusion of the lumen of the terminal part of the proper digital artery was seen in hooves with a developing sole ulcer. An avascular area at the ulcer site was seen in hooves with an early or a fully developed sole ulcer. It is concluded that vascular changes caused by hoof pathology may have an important role in the development of sole ulcers and white line lesions in cattle.

Angiography↗