Study on Reproductive Performance of Breeding Sows and Ultrasound Monitoring of Ovarian Follicle Activity and Ovulation of Post-Weaning Sows in a Commercial Pig Farm of Central Ethiopia

Abstract

Introduction: The aim of the study was to assess the reproductive performance of breeding
sows under farm conditions and to identify the factors affecting it, as well as performing the
ultrasound monitoring of ovarian follicle activity and determining the time of ovulation in postweaning sows.
Materials and Methods: Retrospective study was conducted to analyze the reproductive
performance of 1200 primiparous and multiparous sows (experiment I) under tropical
condition in a commercial pig farm of central Ethiopia. Reproductive data including weaning
-to-estrus interval (WEI), age at first service (AFS), litter size (LS), farrowing rate (FR) and
number of litters per sow and year of sows were collected and analyzed. Moreover, a regular
observation of 25 randomly selected post-weaning sows (experiment II) was undertaken for
estrus detection and for performing the transabdominal ultrasound (US) monitoring of ovarian
follicle development and ovulation.
Result: Gilts are usually bred at the age of 7 to 8 months. Lactation period for the sows in the
farm was fixed; the piglets were weaned at the age of 30 days. About 69.6% of females showed
estrus between 3 and 6 days post-weaning. The average WEI was 5.6 (±1.7) days and the
percentage of females showing estrus within the 2 days after weaning was 5.8%. The overall
average FR was 86.1%. In both the primiparous and multiparous females, the WEI of 1-2, 7-9
and 10-12 days resulted in a lower FR (p<0.05) than those observed for WEI of 3-6 days. Mean
LS, number of litters per sow and year and total piglets born per sow and year of the farm
were 9.07 (±2.1), 1.90 (±0.2), and 17 (±3.7), respectively. In both the parity classes, the lowest
LS was observed in females with WEI of 1-2 days (p<0.05). In primiparous and multiparous
females, LS increased significantly (p<0.05) from WEI of 1-2 days to WEI of 3-6 days, it
decreased in females with WEI of 7-12 days and increased again in females with WEI of 13 to
20 days. The mean diameter of the pre-ovulatory follicles was 6.91 (±1.28) mm ranging from 6
to 10 mm. Ovulation lasted between 2-6 hours, with an average duration of 4.82 (±1.69) hours.
Conclusion: The current study revealed that the reproductive performance indicators, FR and LS
were affected in sows with WEI of 1-2 and 7-12 days post-weaning. Ultrasound examination of
the ovaries facilitated the detection and monitoring of pre-ovulatory follicles and the ovulation
process during the estrus period.