Repeated oestrus synchronisation of beef cows with progesterone implants and the effects of a gonadotrophin-releasing hormone agonist at implant insertion.

A group of 97 spring-calving beef cows were initially oestrus synchronised with controlled internal drug release (CIDR) intravaginal progesterone implants inserted for nine days and a prostaglandin injection on day 7. Approximately half the cows were given 10 microg buserelin when the implants were inserted, and they all received a single fixed-time artificial insemination (AI) 56 hours after the withdrawal of the implants. The overall pregnancy rate to the first synchronised AI was 55 per cent, the buserelin-treated cows having a pregnancy rate of 63 per cent compared with 47 per cent in the untreated cows (P>0.05). Sixteen days after the first synchronised AI all the cows were re-implanted with used CIDR implants which were removed five days later, and the cows received a second synchronised AI on days 23 to 24. Cows which received the second AI were implanted with new CIDR devices 16 days later and these were removed after five days and the non-pregnant cows received a third synchronised AI. The pregnancy rates to the second and third synchronised services were 74 per cent and 75 per cent, respectively.

Repeated oestrus synchrony and fixed-time artificial insemination in beef cows.

The feasibility of breeding spring-calving, single-suckled beef cows without the use of natural service was investigated over two breeding seasons by using repeated oestrus synchrony and fixed-time artificial insemination (AI). Initially, cows were oestrus-synchronised with subcutaneous norgestomet implants inserted for 10 days, with an injection of prostaglandin before the implants were removed. The cows were inseminated once 56 hours after the implants were removed, and 12 days later they were re-treated with norgestomet implants to allow a second synchronised service. Twenty-one days after the first synchronised AI, milk samples were taken for progesterone assay and the norgestomet implants were removed. The cows received a second service 56 hours later if the 21-day milk progesterone assay suggested that they were not pregnant. All the cows receiving a second service were retreated with norgestomet implants to allow a third synchronised service as necessary. Pregnancy was later confirmed by rectal palpation. In the first year, 48 cows entered the programme and the pregnancy rates to the first, second and third synchronised services were 56, 69 and 40 per cent, respectively, with 17 per cent of cows barren at the end of the breeding period. In the second year, 69 cows entered the programme and the pregnancy rates were 58, 48 and 33 per cent to the successive services with 20 per cent of cows barren at the end of the breeding period. The accuracy of milk progesterone assay for pregnancy diagnosis was 84 per cent and 87 per cent in the first and second years, respectively.

Use of tilmicosin in a severe outbreak of respiratory disease in weaned beef calves.

Severe respiratory disease, associated with seroconversion to bovine respiratory syncitial virus (BRSV), caused the death of two cattle and necessitated antibiotic treatment of 70 calves (rectal temperature of 39.6 degrees C or greater) from a group of 96 (73%) during an 8-day period. Tilmicosin injection resulted in a reduction in median rectal temperature from 40.3 degrees C to 39.2 degrees C and 39.0 degrees C for the first and second days after treatment. The rectal temperature was 39.5 degrees C or lower in 72% (48 of 67) and 96% (64 of 67) of cattle 1 and 2 days after tilmicosin treatment, respectively. Ten cattle were re-treated with tilmicosin 6 to 16 days after the first treatment. Our study demonstrated that bovine respiratory syncytial virus infection could cause severe respiratory disease in a beef herd that had no previous history of BRSV-related disease. Secondary bacterial invasion after BRSV infection was controlled effectively by tilmicosin treatment but repeat antibiotic treatments were occasionally necessary due to bacterial re-infection of the respiratory tract.

Management aspects of induced twinning in beef suckler cows using in vitro fertilised embryos.

Twin and single pregnancies were induced in two groups of oestrus-synchronised beef cows by using a combination of artificial insemination and the transfer of in vitro fertilised (IVF) embryos. Single IVF embryos transferred non-surgically to the uterine horn contralateral to the corpus luteum of 43 previously inseminated cows resulted in a calving rate of 72 per cent with a twinning rate of 38.7 per cent. In 45 cows, two IVF embryos were transferred non-surgically to one uterine horn resulting in a calving rate of 51.1 per cent with a twinning rate of 39.1 per cent. The median gestation length for cows bearing twins was 10 days shorter than that of cows bearing single calves (P < 0.001). The proportions of cows that received assistance at calving were similar for twin and single births (57 per cent vs 45 per cent, P > 0.05), but the incidence of retained fetal membranes was much higher after the birth of twins (62 per cent vs 3 per cent, P < 0.001). Nineteen per cent of twin calves were stillborn compared with 6 per cent of single calves (P > 0.05). The median birthweight of the twin calves was 32 kg (68 per cent of the median weight of single calves). The nutrition of twin-bearing cows in late pregnancy was adequate when assessed in terms of their plasma glucose, non-esterified fatty acid and beta-hydroxybutyrate concentrations. Serum immunoglobulin concentrations were similar in single and twin calves suggesting that the passive transfer of antibody was not compromised in the twin calves.

An evaluation of some breeding management options in beef herds in the United Kingdom.

The feasibility of replacing natural service in the suckler herd with artificial breeding (artificial insemination or embryo transfer), following synchronisation of oestrus in breeding animals, was investigated. In 1991 a herd of 143 spring-calving beef cows, matched for date and ease of calving, sex of calf, parity, body condition score and liveweight, were assigned to one of five controlled breeding programmes: natural service (group 1); single oestrus synchronisation using a norgestomet implant and fixed time insemination followed by natural service (group 2); double synchronisation with two consecutive norgestomet implants each with fixed-time insemination followed by natural service (group 3); synchronised as for group 2, but subjected to a movement stress two days after insemination (group 4); and cows synchronised by intravaginal progesterone/prostaglandin regimen with non-surgically transferred in vitro fertilised embryos followed by natural service (group 5). The percentage pregnancy rates to the first and second heats and overall were, respectively: group I, 55.5, 66.7 and 92.6; group 2, 44.4, 71.4 and 89.9; group 3, 52.0, 78.0 and 96.0; group 4, 55.0, 58.3 and 81.5, and group 5, 40.0, 68.2 and 85.7 per cent. In groups 2, 3, 4 and 5 the costs per pregnancy for artificial insemination or embryo transfer were 40.50 pounds, 56.62 pounds, 32.40 pounds and 149.98 pounds, respectively, and the calf weaning weights for groups 1, 2, 3, 4 and 5, adjusted for date of calving, were 250 kg, 255 kg, 252 kg, 261 kg and 259 kg, respectively.

Nematodirus infection in lambs on an alternate grazing system of husbandry.

The epidemiology of Nematodirus battus infection under a husbandry system based on an annual alternation of sheep and cattle was studied from 1983 to 1985. Pasture larval levels and sheep and cattle worm egg outputs were monitored from April to September each year. The level of N battus contamination on the sheep pasture and the number of clinically affected lambs increased over the three years despite grazing with cattle in the intervening year. Examination of cattle faeces demonstrated that six-month-old calves excreted moderate numbers of N battus eggs in June and July, thus contaminating next season's sheep grazing.

Feeding in relation to suckler cow management and fertility.

Profitable suckled calf production, like any other business, depends on the balance between costs and output (Fig 1). The major costs incurred in suckled calf production are feed costs to the cow. Output is simply the weight of weaned calf sold per cow put to the bull, coupled with planned marketing of good quality, cull cows. To maintain this balance at an optimum level requires correct herd management. This can only be achieved with all cows in the herd being at a similar stage of production--a compact two-month calving period. In the long term, a compact two month calving period can only be maintained with correct management of bulling and first-calved heifers. Day-to-day management decisions must be based on the current condition of the cows in relation to the target condition scores set for the system. Understanding this model allows a simple management system to be implemented and achieve the high levels of fertility and suckled calf output required for a profitable enterprise in today's economic climate.

The correction of cerebrovascular insufficiency by transluminal dilatation: a preliminary report.

Transluminal angioplasty is being extensively utilized to dilate arteriosclerotic lesions. However, this technique has not been widely used for the treatment of cerebrovascular insufficiency. This report describes the application of transluminal angioplasty to relieve cerebral ischemia secondary to extracranial arterial stenosis. A total of 10 patients presented with symptoms of vertebrobasilar insufficiency. Bilateral upper extremity pressures were measured prior to the performance of arteriography on all patients. Significant stenoses were found in the subclavian artery (9) and in the innominate artery (1). Dilating catheters were passed retrograde through surgically exposed brachial and common carotid arteries. Transluminal angioplasty under fluoroscopic control was attempted. Anatomic correction of all lesions was achieved without hemorrhagic or embolic complications. The mean increase in brachial systolic pressure was 38.2 mm Hg postdilatation. Initial symptomatic relief was total in seven patients, partial in two, and absent in one. It is believed that associated small vessel brain stem disease accounted for the less than total relief of symptoms of these three patients. Average follow-up for all patients was 13 months with one recurrent subclavian artery stenosis occurring at three months postangioplasty. Preliminary results suggest that some patients with cerebral ischemia secondary to extracranial arterial stenosis can be treated safely by transluminal angioplasty.

Influence of time of feeding on time of parturition in beef cows.

The influence of time of feeding pregnant beef cows on the timing of parturition was investigated. The results suggest that the distribution of calvings between 'day' and 'night' can be altered by time of feeding. The calculations, based on a small quantity of data, suggest that feeding at 22.00 would result in 79 per cent of cows calving between 06.00 and 22.00. On the same basis of calculation the traditional 09.00 time of feeding would result in 57 per cent of cows calving during the 'day' period. There appears to be some evidence that by feeding pregnant beef cows in the evening better supervision of calving with a smaller proportion of cows calving at night can be achieved.

Transluminal angioplasty during vascular reconstructive procedures: a preliminary report.

A total of 16 isolated arterial lesions were dilated intraoperatively in conjunction with primary vascular reconstructive procedures. Of these, eight involved the iliac vessels and eight the femoropopliteal segment. All angioplasties were successful and no catheter-related complications were noted. Hemodynamic improvement was confirmed by intraoperative pressure measurements and/or noninvasive Doppler segmental pressures.

Milk progesterone profiles and the double injection of cloprostenol in post partum beef cows.

The time to resumption of ovarian cycles was determined in 27 post partum beef suckler cows by twice weekly milk progesterone analysis and was 24.5 +/ 1.6 (SEM) days. Treatment of 87 cows with a double injection of 500 micrograms cloprostenol at an interval of 11 days resulted in 55 cows (63.2 per cent) responding by a fall in progesterone levels and ovulation. Thirty-eight of these cows (43.7 per cent of total) subsequently conceived to a timed double insemination. Eight (9.2 per cent) had high progesterone levels at the second injection had failed to respond; three (3.4 per cent) had a prolonged period of low progesterone levels after the first injection which were still low when the second was given. A further 21 cows (24.1 per cent) had low progesterone levels at the time of the second injection but could not be categorised further with certainty because of lack of previous samples. These cows were treated at a significantly earlier stage post partum than the rest and in fact were treated earlier than the recommended day 42. However, four of the 21 cows conceived to the timed insemination resulting in a total conception rate of 48.3 per cent.

Clinical application of milk progesterone in the diagnosis of subfertility in suckled cows.

The potential value of milk progesterone profiles in conjunction with rectal examination in the diagnosis of subfertility in beef suckler cows was investigated. Ten of 20 cows suckled their calves three times per day and the other 10 suckled their calves continuously. Milk samples were collected twice weekly during the 21 days prior to first service and up to day 50 post mating in cows confirmed pregnant. The uterine and ovarian states of the cows were examined per rectum weekly between calving and first service. Progesterone profiles of cows conceiving to first service showed a typical smooth curve, while those of cows failing to conceive were irregular and indicated disturbances in the normal functioning of the corpus luteum.

Pregnancy test and evaluation of embryonic and fetal mortality based on progesterone concentrations fore-milk.

PIP: Results of fore-milk progesterone estimations from suckler beef cows using radioimmunoassay for pregnancy diagnosis and, with manual examination per rectum, the measurement of embryonic fetal mortality are reported. 79 milk samples from 47 multiparous Hereford cross-British-Friesian cows were assayed. Milk was sampled on Day 22 postmating. Both ovaries were examined per rectum to identify the presence of absence of a corpus luteum verum. After a draw of milk to clean the teat sinuses, 5 ml from each quarter were collected. Potassium dichromate was used as a preservative and milk stored at 5 degrees C until examined. Milk progesterone levels were 60% lower than those reported for dairy herds. Butter fat content of the fore-milk was 1%. Mean milk progesterone levels for positive cows was 9.6 ng/ml (range, 3.4-23.6) and for negative cows 2.0 ng/ml (range, 1.0-4.3 mg/ml). A level of 3.2 ng/ml was arbitrarily taken as the dividing line between positive and negative reports. There were 3 false positive reports. During lactation, progesterone levels and fat content continued to rise. The fore-milk samples from suckler beef cows were of value in the early detection of nonpregnant cows. The embryonic fetal mortality limited the value for pregnant cows but indicated the incidence of this condition.^ieng