The Effect of Intravaginal Applied GnRH‐agonist on the Time of Ovulation and Subsequent Reproductive Performance of Weaned Multiparous Sows

Abstract

In order to prove the effect of 'fixed time insemination' and insemination at standing oestrus after post-weaning application of GnRH, in a Croatian large breeding unit, 502 sows were assigned to three groups and were artificially inseminated (AI) at their first post-weaning oestrus as many times as they stand, in 24-h intervals. The groups were treated as follows: group 1 (control, n = 160) were AI during their standing reflex; group 2 ['GnRH-fixed time insemination' (GnRH-FT-AI), n = 175] were AI, independent of detection of oestrus and following administration of GnRH-agonist at 96 h post-weaning; group 3 [GnRH insemination at standing oestrus (GnRH-OE-AI), n = 167] the animals were GnRH-agonist treated as group 2 and were AI at their standing reflex. Pre-trial daily average lactational feed intake, average daily feed intake from weaning to oestrus, oestrus within 6 days post-weaning (%), ovulation within 6 days post-weaning (%), weaning-to-oestrus interval (h), duration of oestrus (h), follicle size (mm), interval from oestrus to ovulation (h), subsequent day 24 pregnancy rate (%), farrowing rate (%) and total pigs born were evaluated. Pre-trial average daily lactational voluntary feed intake was 7.1 +/- 0.08 kg in group 1, 7.0 +/- 0.07 kg in group 2 and 7.1 +/- 0.17 kg in group 3 (p > 0.05). Average voluntary daily feed intake from weaning to oestrus was 5.1 +/- 0.3 kg in group 1, 5.2 +/- 0.5 kg in group 2 and 5.2 +/- 0.19 kg in group 3 (p > 0.05). Oestrus was detected within 6 days post-weaning in 134 (83.8%) in control, 164 (93.7%) in GnRH-FT-AI and 155 (92.8%) animals in GnRH-OE-AI groups (p = 0.05). Follicle size did not differ (p > 0.05) among the groups. In control 82.8%, in GnRH-FT-AI 91.5% and in GnRH-OE-AI 91.0% of the sows ovulated within 6 days post-weaning (p = 0.04), and had 80.6, 90.9 and 89.7% 24-day pregnancy rates (p = 0.16), respectively. In GnRH-FT-AI group 90.2%, in GnRH-OE-AI sows 89.7%, in control animals 79.9% farrowing rates were recorded (p = 0.17). Weaning to oestrus interval was 113.1 h in control, 114.1 h in GnRH-FT-AI and 112.6 h GnRH-OE-AI (p > 0.05). Duration of oestrus was significantly shorter in GnRH-FT-AI (44.9 h) and GnRH-OE-AI (48.1 h) animals, compared with the control (62.9 h) sows (p = 0.001). Similarly, the interval from oestrus to ovulation revealed significant (p = 0.004) differences between the groups (control 44.1 h, GnRH-OE-AI 34.1 h and GnRH-FT-AI 32.9 h). GnRH-FT-AI (12.5) and GnRH-OE-AI (12.6) sows had significantly higher (p = 0.01) number of total pigs born (n = 10.4) compared with control sows. GnRH-agonist-gel treatment to the sow shortens duration of oestrus, the interval from oestrus to ovulation, and may eliminate the need for oestrus detection in the hands of skilled personnel.

Effect of Insemination–Ovulation Interval and Addition of Seminal Plasma on Sow Fertility to Insemination of Cryopreserved Sperm

“…Further, other workers have indicated a GnRH‐to‐ovulation interval of 38 h (Langendijk et al. 2000) and 33–34 h (Baer and Bilkei 2004). Taken together, the present data and that in the literature suggest that the ovulation control protocol described herein likely resulted in ovulation consistently at about 38 h after the pLH injection.…”

Intra-uterine insemination with low numbers of frozen–thawed boar spermatozoa in spontaneous and induced ovulating sows under field conditions

“…approximately 6 h (Pursel et al, 1978;Soede et al, 1995;Weitze et al, 1994), the induction of ovulation before insemination with FT semen seems to be necessary for maximizing in vivo fertility (Huhn and Konig, 1989;Konig et al, 1977). The control of estrus and ovulation with exogenous hormones in gilts and sows has been demonstrated (Baer and Bilkei, 2004;Brussow et al, 1996;Roca et al, 2003;Wiesak et al, 1990). Roca et al (2003) using human chorionic gonadotrophin (hCG) for controlling ovulation reported that 77.5% FR and 9.31 TB were obtained in hormonally treated sow after a single deep AI using a low number of FT spermatozoa.…”

Advances in Breeding Management and Use of Ovulation Induction for Fixed‐time AI

“…Most recently, a gel for intravaginal application of the GnRH analogue triptorelin (OvuGel ® ; Elanco) is being promoted (Baer and Bilkei ; Stewart et al. ).…”

“…Most recently, a gel for intravaginal application of the GnRH analogue triptorelin (OvuGel Ò ; Elanco) is being promoted (Baer and Bilkei 2004;Stewart et al 2010). In a study by Knox et al (2011), weaned sows received 100 lg of triptorelin either 96 h post-weaning or at oestrus detection and were subsequently inseminated twice at fixed times.…”