The effects of the number of frozen-thawed ram sperm per single and double intra-cervical artificial insemination (AI) on fertility in ewes were studied. A total of 89 non-pregnant ewes were synchronized for oestrus with two doses of 100 μg PGF2α (Cloprostenol) 9 days apart. The ewes were randomly assigned to one of four groups; D200 (n = 23; double AI with 200 × 106 sperm), S200 (n = 24; single AI with 200 × 106 sperm), D100 (n = 24; double AI with 100 × 106 sperm) and S100 (n = 18; single AI with 100 × 106 sperm). Ewes were inseminated within 12 to 18 h for single AI and, within 10 to 12 h and 16 to 18 h for double AI after the onset of oestrus. The onset of oestrus ranged from 28 to 76 h (54.33 ± 1.28 h). The high percentage (29.2%) of ewes showed oestrus between 51 to 60 h. The non-return rates were highest in group D200 (56.5%) and differed significantly (p < 0.05) from group S100 (11.1%). No ewes were pregnant in group S100, and the pregnancy rates among the remaining groups did not differ. The mean gestation period was 152.8 ± 0.5 days and no difference was observed among the groups. The lambing and multiple birth rates were 100% in group D200. The single and twin lambing was highest in group D100 (33.3%) and group D200 (83.3%), respectively. Only one triplet lambing and the highest lambing size (2.2 ± 0.2) was recorded in group D200. In conclusion, double AI with 200 × 106 sperm showed comparatively most practical for achieving high pregnancy rates and lambing performances in Bangladeshi ewes under field conditions.

The pregnancy rate in indigenous ewes inseminated with frozen-thawed Suffolk semen following natural and synchronized estrus was determined. The serum Progesterone and Estrogen concentration and vaginal electrical resistance (VER) of ewes at the time of Artificial Insemination (AI) were observed as successful pregnancy determinants. 21 healthy ewes were selected for this experiment during January-April, 2017. 10 ewes were inseminated in natural estrus. Whereas, 11 ewes were inseminated after estrus synchronization using intravaginal sponges containing 60 mg medroxyprogesterone acetate. Trans-cervical Al (TCAI) was performed in all ewes within 12-16 hours of observed heat. Prostaglandin E1 analogue impregnated vaginal sponge was used for cervical relaxation 6-8 hours before insemination. Pregnancy was diagnosed through trans-abdominal ultrasonography after 40 days of AI. The pregnancy rate of ewes in synchronized estrus was higher (54.5%) than in natural estrus (30%). Higher serum Progesterone level (0.90 ± 0.02 ng/mL) and significantly (p < 0.001) lower VER (257.78 ± 10.11 ohm) were observed at the time of AI in ewes becoming pregnant. Results suggest that higher Progesterone concentration and lower VER could be considered as pregnancy indicators. Oestrous synchronization could be implemented to increase the pregnancy rate in ewes.

A study was carried out on 16 indigenous ewes in Bangladesh in order to assess the reproductive physiology, the pattern of vaginal cell exfoliation and progesterone profiles during the estrous cycle period. The mean estrous cycle length and duration of estrus were 15.8±0.12 days and 31.1±0.57 h respectively. The exfoliated epithelial cells were categorized into parabasal, intermediate, superficial and keratinized and their relative occurrences. The percentages of parabasal, intermediate and superficial cell type during proestrus were similar. The percentage of superficial cell type during estrus was 61.7%, which was significantly (p<0.01) differ from other types of cells and stages of estrus cycle. Metoestrus was predominant with neutrophils in addition with other cell types. Dioestrus was dominated by neutrophils. On days 0 to 5 of the cycle the progesterone concentration was 0.09 to 1.6±0.07 ng/ml. The length of diestrus was 5∼10 days with a range of mean progesterone level of 1.6±0.07 to 2.8±0.11 ng/ml. Progesterone levels increased significantly (p<0.01) after Day 5 and maximum level was 2.8±0.11 ng/ml observed on Day 10 of the estrous cycle. Thereafter it dropped rapidly to basal level of 0.11±0.04 ng/ml on Day 0 (p<0.01). These results indicate that the pattern of exfoliation of vaginal cells along with progesterone concentration could be used to determine the reproductive stages of indigenous ewe.

The present study was designed to observe the oestrus responses in the indigenous ewe induced by cloprostenol sodium manufactured by two different companies (Ovuprost®, BOMAC, Newzealandand Prostenol®, Techno, Bangladesh). Twelve local ewes were divided into 3 groups (n= 8). The ewes in Group I and II were induced by intramuscular injection of 100 μg (0.4 ml) of cloprostenol sodium (Ovuprost® and Prostenol®), respectively. The 2nd injection in each group was given at 9 days apart. The ewes in Group III were kept as control for observing natural oestrus characteristics and comparing the responses with induced oestrus. Hundred and 75% ewes showed oestrus following 2nd injection of Ovuprost® and Prostenol®, respectively. The average time of onset of oestrus following 1st and 2nd injection of Ovuprost® and Prostenol® were 50.5 ± 3.5 vs 48.0 ± 0.0 h and 49.9 ± 1.9 vs 49.5 ± 1.7 h, respectively. There was no significant difference between the two types of cloprostenol sodium group on the onset of oestrus. The average duration of oestrus was 27.5 ± 0.7 vs 27.5 ± 0.0 h and 25.9 ± 3.3 vs 24.2 ± 0.3 h in Ovuprost® and Prostenol® treated ewes, respectively. For natural oestrus, the duration of oestrus was 25.2 ± 3.3 h. There was no significant difference among the cloprostenol sodium produced by two different companies and natural oestrous ewes on the duration of oestrus. The higher percentages of cornified cells were present in induced oestrus (90 and 85%) compared with natural oestrus (80%), although there was no significant difference among them. The pregnancy rates were 75, 66.7 and 100% in Ovuprost®, Prostenol® and natural oestrous ewes, respectively. The above results indicate the suitability of using cloprostenol sodium for synchronization of oestrus in indigenous ewes in Bangladesh.