• Journal of Embryo Transfer
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• v.18 no.3
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• pp.249-255
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• 2003

These studies were performed to improve the reproductive efficiency of gilts and we investigated the effects of puberty periods, first mating time and backfat thickness and will adapt to these results for early selection of excellent gilts. The main results were as follows; 1. First heats on birth season were showed 194.14 day, 163.25 day, 160.25 day and 157.92 day at birth of spring, summer, autumn and winter, respectively and birth of spring was significantly latest among other seasons (p<0.01). 2. First service on birth season were revealed 222.05 day in spring, 193.00 day in summer, 199.20 day in autumn and 190.11 day in winter. birth of spring was significantly latest among others (p<0.01). 3. First heat period of cadidated gilt had 13∼16 mm backfat thickness was 180.32 day, 171.24 day in 17∼20 mm and 162.20 day in 21∼23 mm and was showed delay in thin backfat gilts. There was no differences among backfat thickness. 4. First service of cadidate gilt had 13∼16mm backfat thickness was 211.12 day, 202.43 day in 17∼20 mm and 195.43 day in 21∼23 mm and was showed delay in thin backfat gilts. There was no differences among backfat thickness. 5. The litter size were 9.64 in gilts under 160 day of first heat, 10.14 in 161∼180 day, 9.56 in 181∼200 day and 9.13 in over 201 day. There showed the largest litter size in 161∼180 day of first heat but was no differences. 6. The litter size in gilts under 180 day of first service was 9.13, 9.75 in 181∼200 day, 10.13 in 201∼220 day and 9.45 in over 221 day. There showed the largest litter size in 201∼220 day of first service but was no differences. 7. The litter size of gilt had 13∼16 mm backfat thickness on first service was 9.33, 9.81 in 17∼20 mm and 10.17 in 21∼23 mm and was showed delay in thin backfat gilts. There was no differences among backfat thickness.