Plasma progesterone levels during oestrous cycle and their relationship with the ovulation rate in Red Sokoto (Maradi) goats.

Twenty-five 2-3-year-old cycling does weighing 17-25 kg were obtained from semi-nomadic farmers and managed under controlled conditions while simulating the traditional management system. Oestrus was synchronized using progestogen impregnated vaginal pessaries. Blood samples were collected daily for progesterone assay from the day of pessary withdrawal up to one complete oestrous cycle. Oestrus was checked twice daily using vasectomized bucks. Ovulation rate was determined by direct observation of the ovaries following laparotomy on day 5-7 of the oestrous cycle. Following oestrus synchronization, mean ovulation rate was 1.68 +/- 0.13. Mean oestrous cycle length and duration of oestrus were 21.30 +/- 0.28 days and 21.37 +/- 0.24 hours respectively. Plasma progesterone concentrations ranged from non-detectable levels on the day of oestrus to 5.2 +/- 0.28 ng ml at mid-cycle. The duration of elevated progesterone level (greater than 2 ng/ml) was about 12 days. The peak progesterone values did not differ between animals with different ovulation rates. However, the plasma progesterone concentration during the early cycle (days 0-6) was significantly lower in the single ovulators compared with others. There were no major differences in plasma progesterone levels during the oestrous cycle of Red Sokoto does with different ovulation rates.

Use of plasma progesterone profiles for the assessment of reproductive functions in indigenous Nigerian Zebu cattle.

The reproductive performance of Zebu cattle is generally low. However, blood concentrations of progesterone may be of practical value in assessing the reproductive status of the Zebu female. This paper reviews recent findings regarding plasma progesterone profiles during different phases of the reproductive cycle of some Nigerian Zebu cattle. The reproductive phases examined include the estrous cycle, early pregnancy and the postpartum periods. Our findings describe variations in plasma progesterone profiles observed under field conditions. The practical implications of these findings in assessing reproductive functions in indigenous Nigerian Zebu cattle are examined.

Robertsonian translocation in a Zebu bull.

Karyotypes were prepared for ten Rahaji bulls using cultured peripheral blood lymphocytes. C-banded metaphases were prepared to identify the sex chromosomes and possible translocations. Out of the ten bulls, studied one bull had a 2n number of 59 chromosomes and carried a Robertsonian translocation. The possible importance of the Robertsonian translocation in Zebu cattle in Nigeria is discussed.

Concentration of gonadotrophins in the plasma of sheep given gonadal steroid antisera to raise ovulation rate.

The concentration of FSH and LH in peripheral plasma was studied in sheep from 8 h before to 17.5 h after injection (i.v.) with antisera to the steroids androstenedione, oestradiol, oestrone and testosterone. The fitted mean concentration of LH increases after all treatments and the increase was associated with a higher frequency of LH pulses. The greater concentration was evident for all groups by the period 3.5-6.5 h after injection, but by the end of the sampling period the concentration had returned to or towards the values in the controls. For FSH, significant change was limited to those animals given anti-oestrogen sera but it was more rapid than for LH, both groups receiving anti-oestrogen sera showing an increase during the period 0.5-3.0 h after injection. The ovulation rate was increased by treatment and an effect close to 0.75 corpora lutea per ewe was maintained by treatment in subsequent oestrous cycles. This declined to 0.25 corpora lutea after two oestrous cycles without treatment.

Early pregnancy diagnosis in buffaloes from plasma progesterone concentration.

Blood samples were collected from 84 buffalo cows 21 days after fixed time artificial insemination following oestrus synchronisation and cloprostenol. Progesterone concentration in plasma was determined by radioimmunoassay. The animals were examined for pregnancy by rectal palpation 60 to 90 days after insemination. Forty-two animals were predicted pregnant on the basis of progesterone concentration (more than 1.0 ng per ml), and 28 (66.7 per cent) of them were subsequently confirmed pregnant by rectal palpation. Thirty-five animals were predicted non-pregnant (progesterone less than 0.7 ng per ml), in 34 (97.1 per cent) this proved to be so. Of the total number, seven (8.3 per cent) were classified as doubtful because their progesterone concentrations were within the range 0.7 to 1.0 ng per ml: two of them were confirmed pregnant and the other five non-pregnant. Out of 31 animals diagnosed pregnant by rectal palpation, 28 (90.3 per cent) had been correctly detected by assay at 21 days. Thirty-four (64.2 per cent) of the 53 animals found non-pregnant had been correctly detected by assay. It was concluded that the determination of plasma progesterone concentration 21 days after insemination was an accurate method of predicting non-pregnancy in buffaloes.

Seasonal differences in plasma testosterone profiles in buffalo bulls.

Testosterone was measured by radioimmunoassay in blood samples collected hourly over 10 h from two adult buffalo bulls in April, May, August and December. The basal concentrations were below 0.2 ng/ml while peak concentrations ranged from 0.35 to 1.65 ng/ml, with not more than one complete peak occurring during a 10 h period. Both bulls had similar testosterone profiles within each sampling period but differences were evident between periods, the mean concentration being highest in August and falling through December and April to the lowest levels in May. Testosterone concentrations in buffaloes are therefore lower than those in other domestic species, and appear to vary during different times of the year.

Fertility in buffaloes after oestrus synchronisation with cloprostenol and fixed time insemination.

Fifty-seven cycling buffalo cows of the river type were treated with two doses of 0.5 mg cloprostenol intramuscularly given 11 days apart. Each animal was inseminated twice at 72 and 96 hours after the second injection of cloprostenol. The first service conception rate diagnosed by rectal palpation at 90 days was 38.6 per cent. At the time of insemination the cervix was easily penetrable on both days in only 39 (68.4 per cent) of the animals. They were inseminated at or beyond the internal cervical os, while the others were inseminated in the cervical canal. There was a marked difference in conception rate between those receiving deep inseminations (48.7 per cent) and the others (16.7 per cent). In relation to the interval from calving to insemination the conception rates for those which had calved 60 to 90, 90 to 120 and 120 to 150 days earlier were 16.6, 36.4 and 55.5 per cent respectively. The use of cloprostenol treatment and fixed-time insemination is a useful method of overcoming the problem of oestrus detection in buffaloes. Acceptable levels of fertility can be obtained in those animals which have a sufficiently relaxed cervix to permit semen deposition at the internal os, provided the interval from calving to insemination is more than 90 days.

Synchronisation of oestrus and fertility in buffaloes using a prostaglandin analogue.

Cloprostenol, a prostaglandin analogue, was administered intramuscularly to a total of 35 cycling buffalo cows and heifers in two doses, each of 0.5 mg, given 11 days apart. Out of five cows and 12 heifers subjected to observations after the second injection of cloprostenol (day 0), all except one heifer responded. Signs of oestrus were most marked on days 3 or 4. Eighteen treated heifers were kept with buffalo bulls for four days after the second injection while a control group of nine heifers was kept with bulls for 21 days. The first-service conception rate, diagnosed by rectal palpation at 60 days, was 33 1/3 per cent in both groups. Twelve treated heifers were artificially inseminated at 72 and 96 hours after the second injection of cloprostenol, using fresh semen diluted in egg yolk--citrate extender. The first service conception rate at 60 days was 30 per cent.

Synchronisation of oestrus in buffaloes (Bubalus bubalis) using prostaglandin F2alpha.

Prostaglandin F2alpha (PGF2alpha) was used intramuscularly in two preliminary trials to determine its effect in cycling buffalo cows. In the first trial, animals with corpora lutea in their ovaries responded to either two doses of 15 mg on two consecutive days, or to a single dose of 30 mg, by showing signs of oestrus commencing 31 to 55h after the initial injection. In the second trial two doses of 30 mg PGF2alpha given 11 days apart resulted in oestrus on the third day after the second injection.