15 INTRAUTERINE INSEMINATION USING FROZEN-THAWED BOAR SEMEN IN SPONTANEOUS AND INDUCED OVULATING SOWS UNDER FIELD CONDITIONS

Abstract

Intrauterine insemination (IUI) using frozen-thawed (FT) boar semen has yet to be reported. The objective of the present study was therefore to evaluate the 24-day nonreturn rate (NR), farrowing rate (FR), number of total piglets born/litter (TB), and number of live born piglets/litter (BA) after IUI with FT boar semen in spontaneous and induced ovulating sows. Ejaculates collected from each of 6 boars [3 Landrace (L) and 3 Yorkshire (Y)] were cryopreserved separately and used to produce LY crossbred offspring. Each batch of qualifying FT semen (≥30% motility) was divided and used in both groups, to minimize an individual boar variation effect. Thawed semen containing 1 × 10⁹ motile spermatozoa extended in 20 mL of Beltsville Thawing Solution extender was flushed into the uterine body (20 mm beyond the cervix) via IUI device (Deep goldenpig™ catheter, IMV Technologies, L’Aigle, France). Forty multiparous sows (20 L and 20 Y) with weaning to estrus interval of 3 to 7 days were randomly assigned to 1 of 2 groups: spontaneously ovulating sows (10 L and 10 Y) and hCG-induced ovulating sows (10 L and 10 Y). The sows with spontaneous ovulation did not receive any treatment. The induced ovulating sows were given 750 IUhCG i.m. at detection of estrus. Ovulation was investigated every 12 h using transrectal ultrasonography. Time of ovulation was determined as 6 h before the first time when preovulatory follicles were not found. Insemination was conducted at 24 h after the detection of estrus and repeated every 12 h until ovulation took place in the spontaneous ovulation group and at 36, 42, and/or 48 h after hCG administration in the induced ovulation group. The statistical analyses were carried out using SAS software (version 9.0, SAS Institute, Cary, NC, USA.). The interval from detection of estrus to ovulation (EOI), TB, and BA were compared between the groups using Student’s t-test; and NR and FR between groups were compared using chi-square test. P < 0.05 was considered statistically significant. The results revealed that sow breed and sow breed interacted with group had no influence on any parameter assessed (P > 0.05). The average EOI differed significantly between spontaneous ovulation (40.2 h) and induced ovulation groups (35.6 h; P = 0.01). Moreover, variation of EOI among sows within each group seemed to be lower in the induce ovulation (4.5 h SD) than in spontaneous ovulation (5.5 h SD; P = 0.5). The number of inseminations per sow was 2.9 ± 0.6 (2 to 4 times) in spontaneously ovulating sows and was 2.4 ± 0.5 (2 to 3 times) in induced ovulating sows. No significant differences (P > 0.05) were found in the NR (80 v. 85%), FR (60 v. 65%), TB (8.0 ± 2.8 v. 9.4 ± 3.7 piglets/litter), and BA (7.8 ± 2.8 v. 8.7 ± 3.7 piglets/litter) between spontaneous and induced ovulating sows. In conclusion, IUI with a low number of FT boar spermatozoa provided fairly good NR and reasonable FR and TB in both spontaneous and induced ovulating sows. The number of inseminations required to attain acceptable fertility tended to be lower in the weaned sows with induced ovulation.