Ovulation rate and embryonic migration in cross-bred gilts

Area of Science:

• Reproductive biology
• Swine reproduction
• Ovarian physiology

Background:

• Understanding ovarian activity and embryonic migration is crucial for optimizing swine reproduction.
• Previous research has not fully elucidated the comparative activity of left versus right ovaries in gilts concerning ovulation and embryonic development.

Purpose of the Study:

• To compare the ovulation activity between the left and right ovaries in gilts.
• To investigate the relationship between embryonic migration and the total number of fetuses.
• To analyze ovarian function across different oestrous cycles in gilts.

Main Methods:

• Examination of 254 crossbred gilts post-insemination (AI) with frozen semen.
• Slaughtering gilts 5-8 weeks after AI and examining genital tracts within two hours.
• Recording the number of corpora lutea and normally developed fetuses to assess ovulation and pregnancy rates.

Main Results:

• The left ovary demonstrated a significantly higher ovulation rate (P < 0.001) and was heavier than the right ovary (0.01 < P < 0.05).
• Corpora lutea count increased from the 2nd to 4th oestrous cycle (P < 0.05), while fertilization rate was not significantly influenced by oestrous number.
• Embryonic migration incidence positively correlated with the total number of fetuses (P < 0.05), with equal migration frequencies between ovaries.

Conclusions:

• The left ovary is more active in ovulation compared to the right ovary in gilts.
• Embryonic migration is influenced by litter size, suggesting a compensatory mechanism in uterine capacity.
• Ovarian function and embryonic development in gilts are complex, influenced by factors like oestrous cycle and ovulation rates.