19 LOW-DOSE DEEP INTRAUTERINE INSEMINATION IN SOWS UNDER CONDITIONS: INCIDENCE OF UNILATERAL FERTILIZATIONS

Abstract

A new procedure for nonsurgical deep intrauterine insemination (DUI) in non-sedated sows has recently been reported (Martinez et al. 2002 Reproduction 123, 163–170). In comparison to traditional artificial insemination (AI), using this procedure, a 20-fold reduction in the number of spermatozoa inseminated can be used without a decrease in fertility when hormonally treated post-weaning estrous sows are used. The aim of the present study was to evaluate the effectiveness of DUI under field conditions. In Experiment 1, crossbred sows (2–6 parity) were weaned at 20.75 ± 0.06 days. Estrous detection was performed once per day, beginning 3 days after weaning. Sows with a weaning to estrus interval of 4–5 days were selected to be inseminated. A total of 190 sows were inseminated at 12, 24, and 36 h after onset of estrus using one of the following two regimes: (1) DUI with 150 × 106 fresh spermatozoa in 5 mL of BTS (n = 95) and (2) Traditional AI with 3 × 109 fresh spermatozoa in 100 mL of BTS (n = 95) prepared from the same semen samples used for the DUI group. Farrowing rates (FR) and litter sizes (LTS; mean ± SEM) from both groups were compared using chi-squared test and ANOVA, respectively. There was no significant difference in the FR between groups (83.2 and 86.3% for DUI and AI groups, respectively). However, a decrease (P < 0.001) in the LTS was observed in sows inseminated by the DUI procedure (9.8 ± 0.29 and 10.9 ± 0.17, respectively). In Experiment 2, seventy one natural post-weaning estrus sows were used. Fifty-five sows were DUI inseminated three times with 150 (n = 17), 300 (n = 19), or 600 (n = 19) × 106 spermatozoa in 5, 10, or 20 mL of BTS, respectively. The remaining sows (n = 16) were traditionally inseminated. On Day 6 after estrus, sows were subjected to laparotomy and the tips of both uterine horns were flushed in order to evaluate pregnancy rate (PR: percentage of sows with at least 4 viable embryos) and fertilization rate (ratio of viable embryos to the total number of embryos and oocytes). PR was similar in all the groups, ranging from 84.2% (DUI 300 × 106 spermatozoa group) to 94.7% (DUI 600 × 106 spermatozoa group). Fertilization rate and the percentage of bilateral fertilization after DUI with 600 × 106 spermatozoa did not differ from those of the AI group (97.8 and 100% vs. 98.4 and 100%, respectively), but a significant decrease in both parameters (P < 0.05; chi-square test) was observed in sows inseminated with 300 (94.3 and 87.5%) or 150 (84.4 and 66.7%) × 106 spermatozoa. In conclusion, DUI with 150 × 106 spermatozoa offers similar FR but a lower LTS in sows with natural estrus in comparison with those parameters obtained when traditional AI is used. The lower litter size could be related to the low percentage of bilateral fertilization observed in that group. This work was supported by CDTI 020003.