The anatomical and histological features of the genital tract of a six-year-old Haryana heifer, which had failed to show oestrus, are described. The heifer had a 60 XY karyotype in the leucocyte culture. The external genital organs were absent and a small opening at the ventral perineal border acted as the external urogenital opening. The ovaries were completely hypoplastic and a uterus didelphys opened into a single cervix. No male sex organs or their rudiment were observed.

The study was conducted on 30 true acyclic Sahiwal cows (15 cows, ≥90 days postpartum; 15 postpubertal heifers, ≥30 months of age) and a similar 20 untreated controls (10 cows, 10 heifers). An 'Eazi' breed Controlled Internal Drug Release (CIDR) device (containing 1.38 g progesterone) was inserted intravaginally for 7 days (days 0 to 7) followed by 500 IU eCG i.m. at CIDR removal in all the treated animals. Heifers also received 5 mg oestradiol valerate i.m at CIDR insertion. The reproductive performance of these animals was recorded in terms of oestrus induction response, conception and pregnancy rates. Plasma progesterone (P 4 ) and oestradiol-17β (E 2 ) profiles of 4 representative animals from each treatment group before, during and after CIDR treatment were also monitored. An oestrus induction response of 100% was observed in treated cows and heifers. The majority of cows (53.3%) and heifers (60%) were induced to oestrus within 24-36 and 36-48 h, respectively after CIDR withdrawal; with mean intervals of 44±3.18 and 48±2.35 h, respectively. The conception rate at induced oestrus was higher in cows (40%) than heifers (20%). The final pregnancy rates after 2 subsequent oestruses were 80 and 60% in cows and heifers, respectively (overall 70% for all treated animals). In comparison, only 10% of control animals (2 cows only, 2/20) showed oestrus and become pregnant (10%) during theentire study period. The pretreatment (day 0) mean plasma P 4 levels were statistically (p>0.05) similar in cows and heifers (0.40±0.04 and 0.49±0.11 ng/ml, respectively). The peak P 4 levels were observed on day 1 in cows (13.94±1.41 ng/ml) and day 2 in heifers (19.15±3.30 ng/ml) with a progressive decline up to the day of CIDR withdrawal (3.35±0.92 and 8.79±1.71 ng/ml, respectively). Mean P 4 levels on day 9 and 10 in cows and heifers did not differ significantly from their respective day 0 values and the lowest values were recorded on day 10 both in cows and heifers (0.13±0.03 and 0.14±0.02 ng/ml, respectively). Wide variations in individual pretreatment E 2 levels were observed both in the cows (range = 4-26, mean = 13.00±4.65 pg/ml) and heifers (range = 10-14, mean = 11.50±0.96 pg/ml). Thereafter also, E 2 levels in cows showed variation and reached a peak level (53.50±2.99 pg/ml) on day 8. In heifers, peak mean E 2 level (111.25±39.81 pg/ml) was recorded on day 1, followed by a non-significant decline on day 2, a significant fall on day 6 and a non-significant increase on day 9 and 10. However, mean E 2 levels on days 7 (p<0.05), 8 and 9 (p<0.01) were significantly higher in cows compared to heifers. The post-CIDR withdrawal mean highest P 4 and lowest E 2 levels coincided with the period when the majority of animals were induced to oestrus. CIDR and eCG treatment resulted in effective induction of oestrus with satisfactory pregnancy rates in true acyclic Sahiwal cows and heifers.

Sixteen female sheep of Degua breed were assigned to receive either the full dose of norgestomet ear implant and injectable solution containing norgestomet and estradiol valerate (n = 8) or half the dose (n = 8). The ear implants were removed in both groups on day 12. All ewes received an intramuscular administration of 500 IU PMSG at implant withdrawal. Synchronized ewes were individually hand mated twice at 48 and 60 hours after implant removal. One ewe in each group however refused mating on both occasions. Pregnancy diagnosis was conducted by bimanual external palpation 90 to 100 days post mating. The conception rates (3/7, 42.85%) and (5/7, 71.42%) were recorded in the two treatment groups, respectively. All eight ewes lambed between 145 to 153 days post mating. In group I ewes carried only singletons (prolificity rate 1.0) whereas in group II two ewes delivered twins, producing 7 lambs with prolificity rate of 1.4 (N.S). From this preliminary investigation it appears that the lower dose of norgestomet ear implants offers better option for estrus synchronization accompanied by higher fertility.

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