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.

ABSTRACT
INTRODUCTION
MATERIALS AND METHODS
RESULTS
DISCUSSION
CONFLICTS OF INTEREST
ACKNOWLEDGEMENTS
AUTHOR CONTRIBUTIONS
AUTHOR’S POSITION AND ORCID NO
REFERENCES

• Pankaj Kumar Jha(Department of Surgery and Obstetrics, Bangladesh Agricultural University, Mymensingh-2202, Bangladesh, Nepal Agricultural Research Council (NARC), Khumaltar, Lalitpur-44703, Nepal) Corresponding author
• Golam Shahi Alam(Department of Surgery and Obstetrics, Bangladesh Agricultural University, Mymensingh-2202, Bangladesh)
• Abdullah Al Mansur(Department of Surgery and Obstetrics, Bangladesh Agricultural University, Mymensingh-2202, Bangladesh)
• Mohammad Rafiqul Islam Talukder(Department of Surgery and Obstetrics, Bangladesh Agricultural University, Mymensingh-2202, Bangladesh)
• Nazmun Naher(Department of Surgery and Obstetrics, Bangladesh Agricultural University, Mymensingh-2202, Bangladesh)
• A. K. M. Anisur Rahman(Department of Medicine, Bangladesh Agricultural University, Mymensingh-2202, Bangladesh)
• David C. Hall(Department of Ecosystem and Public Health, University of Calgary, Calgary-T2N 4Z6, Canada)
• Farida Yeasmin Bari(Department of Surgery and Obstetrics, Bangladesh Agricultural University, Mymensingh-2202, Bangladesh)