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A prospective longitudinal study was carried out from September 2001 to June 2004 in three adjacent villages in a semi-arid area of Tanzania. The objectives of this study were to measure the intervals between calving and either resumption of cyclical activity or confirmation of pregnancy, to estimate calving intervals, and to investigate the effect of factors assumed to be related to postpartum reproductive performance. A total of 275 lactation periods from 177 Tanzanian Shorthorn Zebu cows managed in a traditional pastoral system in 46 households were initially included. Animals were initially screened for brucelosis and thereafter examined by palpation per rectum at 2-week intervals. Body condition score (scale 1 to 5) was assessed and girth measurement (cm) taken. Occurrence of other reproductive events such as calving, abortion, death of calf, culling and reason for culling were recorded. In a subset of 98 lactation periods from 91 cows milk samples for progesterone (P4) determination were collected twice per week from day 7 after calving to the time of confirmed pregnancy or until milk production ceased before pregnancy. The data were analysed both univariately and in multivariable Cox proportional hazard (frailty) models. The mean (+/-S.E.M.) calving interval was 500+/-13.6 days. Positive reactors in the brucellosis test were 15.6% of the tested animals. Milk P4 analysis showed the rate of abortion/late embryo loss to be 14.3%. Calf mortality rates varied between 14.6 and 17.4%. A positive relationship was found between the outcome variables likelihood of cyclical activity and likelihood of pregnancy in the Cox model, and the explanatory variables: parity and body condition score (BCS) at calving. A negative relationship was found between the outcome variables, and the explanatory variables: maximum BCS loss and calf survival/mortality. Calving in the rainy season was associated with an increased likelihood of pregnancy.

Eighty-two subestrous cattle were treated with different doses of cloprostenol through intramuscular (i.m.) and intravulvo-submucosal (i.v.s.m.) injections to study hormonal profile and fertility. The study was divided into two experiments. In Experiment I, 13 cows were treated with one of three doses of cloprostenol (500 mug i.m., 125 and 62.5 mug i.v.s.m.) to measure response of progesterone (P(4)) and estradiol (E(2)). P(4) decreased abruptly and E(2) levels increased from basal levels following injections of the two larger doses of cloprostenol. P(4) decreased to<5 nmol/l approximately 72 h after treatment. E(2) levels increased to >300 pmol/l 24 h after cloprostenol injections except in cows treated with 62.5 mug dose. Close agreement was observed between P(4) profiles and clinical findings following 500 and 125 mug of cloprostenol treatment. In Experiment II, 69 subestrous cows were treated with either 500 mug i.m. or 250, 125 or 62.5 mug i.v.s.m. doses of cloprostenol. The percent of cows in estrus 96 h following treatment were 60, 80, 67.8 and 18%, respectively. A total of 29 cows were artificially inseminated and 41.3% conceived. We concluded that i.v.s.m. injections of cloprostenol at the dosage of 125 mug and above causes luteolysis, induces estrus and establishes fertility in subestrous cattle. The method is economical but time consuming when compared to the intramuscular route.

The starch grain and phenolsulphonphthalein (PSP) tests were used to investigate the patency of the fallopian tubes in five "repeat breeder" cows. Evidence of tubal lesions was determined in three cows on rectal palpation. Using the starch grain test, bilateral occlusion was determined in three animals, left sided occlusion was determined in one and right sided occlusion in another. Using the PSP test there was evidence of bilateral occlusion in two of the four coes which were tested. In four cows the genital organs were examined visually and by palpation at laparotomy and in two cows tubal occlusion was confirmed when they were flushed with saline, and patency restored. In one animal both ovaries were almost completely encapsulated, while in the fourth adhesions involving the fimbriae occluded the ostia. There were broken down and this cow was the only one which subsequently conceived.

A total of 2000 bovine reproductive tracts (1000 parous and 1000 nulliparous) from freshly slaughtered animals were examined for uterine tube abnormalities and lesions. Tubal lesions were recorded in 180 tracts (9.0 per cent). More parous tracts (6.4 per cent) had tubal lesions than nulliparous tracts (2.6 per cent). The most frequently identified lesion was ovarobursal adhesions which comprised 80 per cent of all abnormalities and were identified in 6.85 per cent of all the genital tracts examined. The uterine tubes were insufflated with carbon dioxide gas to a maximum pressure of 300 mm Hg; 22 were found to be occluded even though they were macroscopically normal.

Two experimental procedures were investigated in order to assess their usefulness in diagnosing occlusion of the equine uterine tube. The starch grain test, which involves the injection of a starch suspension onto the ovary and the subsequent recovery of starch from the cervix, proved to be safe and reliable. Each tube could be investigated separately. It was found that when starch was injected onto the ovulating ovary on the day of ovulation, there was a delay of four to seven days before starch was recovered from the cervix. The phenolsulphonphthalein (PSP) test, which involves the deposition of dye solution into the uterus and its subsequent identification in urine after peritoneal absorption, was not reliable. Contamination of the urine occurred per vaginum, and the test was not unilaterally specific.

The starch grain test was studied in two ewes to determine the effect of the stage of the oestrous cycle on their transport through the Fallopian tubes. There was very little difference when the test was performed at oestrus or day 10 of the oestrous cycle. Bilateral ovariectomy had very little effect on the transport of starch grains. When progesterone in oil was administered by intramuscular injection to a bilaterally ovariectomised ewe and an intact ewe there was a marked increase in the number of grains which were recovered. Oestradiol benzoate in oil delayed the recovery of grains and reduced their numbers.