Length of oestrus and timing of the LH surge was measured in six British White does, housed with a vasectomized buck (experiment 1). The following breeding season, pulsatile LH release during the cycle was measured in eight does and the pattern of behavioural and vaginal traits in relation to onset of oestrus (time 0) determined (experiment 2). In experiment 1, the interval to first oestrus after introduction of the buck on 1st October was 10.3 +/- 3.0 days (n = 6) but in experiment 2, when the buck was put in on 1st September, first oestrus occurred after 39.3 +/- 3.4 days in 7/8 does and 7 days in 1/8 does indicating that adequate exposure to short days is needed before the buck can initiate ovarian activity. LH pulse frequency increased from 0-1 pulses/8 h to 3 pulses/8 h after luteolysis, with no change in pulse amplitude, suggesting that progesterone regulates LH pulse frequency. Mean LH values rose from basal to 102.1 +/- 7.8 ng/ml, 12 +/- 1.5 h after the onset of oestrus, which was 16.3 +/- 1.7 h in length. Does sought out the buck and displayed tail wagging, bleating and restlessness from -60 h to +36 h relative to the onset of oestrus (time 0). The incidence of these activities rose at -12 h and peaked at 0 h. Tail wagging, but not bleating or restlessness, also increased in intensity at 0 h, as did the intensity with which the doe actively sought out the buck. Vulval redness and swelling and onset of a clear thin vaginal discharge were first observed 1-2 days before oestrus, becoming maximal on day 0. It was concluded that onset of frequent tail wagging was the most useful trait for detecting onset of oestrus.

Ten Boran (Bos indicus) cows were studied over 64 oestrous cycles. Alterations in sexual behaviour and of the ovaries palpated per rectum were related to the plasma progesterone profiles detemined using an extracted double antibody radioimmunoassay. The mean cycle length in the cows was 23 ± 0 · 4 days. Oestrus detection efficiency using standing to be mounted, was 27 percent. Restlessness, where observed, reliably indicated that a cow was in the period of basal progesterone concentration. Mounting, sniffing, head-butting, being sniffed, being mounted with avoidance behaviour, although shown by 50 percent of cows during the basal progesterone period were not confined solely to this part of the cycle. Use of Kamar heat-mount detectors in conjunction with standing to be mounted identified 44 percent of oestrous animals. However, the occurrence of false positives during the rest of the cycle precluded their use as sole indicators of oestrus. Accuracy of palpation of corpora lutea was 61 percent during periods of elevated and 98 percent in periods of basal progesterone concentrations.

A group of 12 first-calved Boran cows was infected with Trypanosoma congolense transmitted by Glossina morsitans centralis and another 10 uninfected cows kept as controls. Routine monitoring of oestrous behaviour, palpation of the ovaries per rectum and determination of plasma progesterone profiles was carried out until day 180 post-infection to assess the cyclical status of each animal. Two cows died of trypanosomiasis on days 51 and 54 post-infection. The remaining cows were divided into two groups. Group A (five infected and five controls), which showed the most severe clinical symptoms, was selected for treatment around day 60 and given a curative dose of diminazene aceturate (Berenil). Group B (five infected and five controls) was treated on day 90.

Five ovariectomized cows were treated with 1, 10 and 500 μg adrenocorticotrophic hormone (ACTH). Administration of 10 and 500 μg ACTH gave significantly higher mean plasma progesterone concentrations than those of control cows receiving saline (P < 0·001). It is probable that these doses of ACTH are capable of releasing sufficient adrenal progesterone to result in lowering of fertility in cows.

Combinations of oestrus detection, ovarian palpation and milk progesterone assays were used to monitor pre-service reproductive status of cows in two dairy herds over two successive years. Non-cyclical cows were identified as having no luteal tissue in their ovaries on two occasions 10 days apart. Absence of luteal tissue was determined by the presence of basal mild progesterone initially followed either by a repeat of this result or by failure to palpate a corpus luteum per rectum. In the period 32 to 56 days post partum the number of non-cyclical cows on farm A years 1 and 2 was eight out of 31 (25 . 5 per cent), and 10 out of 62 (16 . 1 per cent) and on farm B years 1 and 2 was 10 out of 68 (14 . 7 per cent) and 11 out of 85 (12 . 9 per cent) respectively. The farm A herd was high yielding, (average lactation 6380 litres), whereas the farm B herd was of average yield (4717 litres). In both herds 60 day milk yield was not related to cyclical status of pre-service cows. There was however a trend toward a greater proportion of young cows being non-cyclical. With the exception of a prolonged calving to conception interval for farm A in year 1, whether a pre-service cow was cyclical or not had no effect on when the cow was first served or on when the animal conceived. The routine incorporation of pre-service monitoring to herd fertility control programmers may however be of value in recognising the incidence of non-cyclical cows and giving an early indication of oestrus detection efficiency.

The nature of the infertility in 19 bitches was investigated: 10 animals were considered to be normal on the basis of their sexual behaviour, vaginal cytology and plasma oestrogen and progesterone concentrations. Successful conception and whelping occurred for 6 of the 10 bitches. The previous apparent infertility was probably attributable to defective mating management by the owners. Although follicular development and ovulation occurred in 4 of the remaining bitches, oestrus was not exhibited: AI resulted in 3 conceptions. The other 5 animals exhibited only some of the normal characteristics of pro-oestrus. Another group of 10 anoestrous bitches (normal and pathological) was treated with PMSG or stilboestrol. PMSG induced follicular development in 5 of 6 bitches treated. The magnitude of the induced plasma oestrogen peak varied considerably. Delay in the initiation of oestrous behaviour occurred relative to the plasma gonadal steroid pattern in 2 of the 3 bitches that showed oestrus. Stilboestrol induced a sequence of behavioural changes and plasma steroid concentrations and patterns similar to those found in the normal oestrous bitch, but none conceived.

Daily milk progesterone concentrations were determined in two dairy cows from calving until first insemination. Numerous transient peaks of milk progesterone of one to four days duration were recorded in both cows. In some instances these concentrations reached values indicative of the presence of a corpus luteum on the ovaries.

A test of oviduct patency was developed, based on instillation of dye to the uterine horn through a two-way catheter. In 23 cows, two cases of bilateral and five cases of unilateral blockage were detected. Of 69 cow genital tracts collected from an abattoir, nine of 138 oviducts (7 per cent) did not permit the passage of dye. Fourteen of the remaining oviducts were found to blocked using a suspension of 80 micrometer pollen grains. This suggested that some animals showing patency to the dye test in vivo may in fact have abnormalities of the oviduct sufficient to prevent the passage of the ovum. In five cows, superovulation and embryo recovery were carried out as an investigation of oviduct patency and function. Although in one of the five cows, subsequently found to have a blocked oviduct, no embryos were recovered, ambiguous results were obtained in the other animals. The unpredictable response to superovulation may limit the application of this latter technique in investigation of oviduct patency and function.

The relationship between palpation of the ovaries per rectum as a means of detecting corpora lutea and the presence of luteal tissue as monitored by milk progesterone concentration was investigated in 83 post-partum dairy cows. In addition corpora lutea size and consistency were compared both to each other and to the corresponding milk progesterone concentrations. In 47 of 55 cows (85%) with evidence of functional luteal tissue in their ovaries a corpus luteum was palpated. There was no significant relationship between corpora lutea sizes and milk progesterone concentrations. In addition corpora lutea sizes and consistencies did not appear to be related. Cows with soft corpora lutea had significantly (P < 0·05) higher milk progesterone levels than animals with hard corpora lutea.

A male miniature rough-haired dachshund, presented with episodic haematuria, was found to be a female pseudohermaphrodite. A littermate also had an abnormality of the urogenital tract and their dam had received a progesterone implant during pregnancy. Chromosome analysis of the intersex revealed XX/XY mosaicism in certain tissues.

Using a range of positive and negative sexual behaviour components, proceptivity of cycling, non-lactating mares and postpartum, lactating Pony mares was quantified around ovulation. Behavioural observations were compared to plasms concentrations of progesterone, total oestrogens and androstenedione. In addition, in cycling mares, comparison with plasma testosterone concentrations was carried out. Overall rejection behaviour by the mare was apparent both during dioestrus and during periods of basal plasma progesterone concentrations. Within cycling, non-lactating mares, and between postpartum ovulation associated with silent as opposed to overt oestrus, no consistent relationship existed between net behavioural scores and the circulating concentrations of oestrogens or androgens. The findings are taken to suggest that regulation of the signs of oestrus occurs to a large extent independently of circulating steroid concentrations.