The Research Of Ovulating Time In Weaned Sows

Sow potential reproductive is huge, healthy and adult sow can ovulate about 20-30 oocytes, however, Chinese average litter size is only about 10, about 30-40% of the oocytes die eventually due to various causes unfertilized. Predict the time of ovulation accurately is the key to improve sow conception rate and litter size. However, the time of ovulating in weaned is affected by a variety of factors. Through statistical analysis of data to determine the factors of ovulating time in weaned sows, and establish an optimal regression formula to predict the time of ovulating in weaned sow, improving farrowing rate and litter size.This study has observed a large pig widely purebred Yorkshire sows weaning to estrus interval, visualizing the follicles of swine by external transabdominal real-time ultrasonography in Guangdong one farm, and recording the appropriate time, lactation length, total number born, the number of born alive, the number of sucking pig, parity before weaning. Statistical analysis methods are mainly single-factor analysis of variance and multiple regression with SAS 9.1.Present study found, season, lactation, parity can affect weaning to estrus interval and estrus to ovulation interval. Weaning to estrus interval, duration of estrus, estrus to ovulation interval in summer were higher than winter(5.35 h, 5.38 h, 2.56 h and 1.61 h, respectively). Overall, the greater lactation in weaned sows weaning to estrus interval decreased first, then increased, while the duration of estrus and estrus to ovulation interval decreased first and then increased, duration of ovulating decreased first and then increased and decreased finally. Larger parities weaning to estrus interval showed a decreasing trend, and the duration of estrus reduced and estrus to ovulation interval increased, duration of ovulating has no difference between parity 1 to 5, but reduced gradually in ? 6. The longer weaning to estrus interval, the duration of estrus and estrus to ovulation interval was shorter, namely duration of estrus and estrus to ovulation interval was negatively correlated with weaning to estrus interval.The results of data analysis for the optimal regression equation: estrus to ovulation interval = 2.924415 ? lactation length- 0.049982 ? lactation length 2, R~2 = 0.940820.