Ovulatory and Reproductive Characteristics of Sows Treated with an Intravaginal GNRH Agonist Gel

Abstract

This study was designed to test the reproductive and ovulatory characteristics of sows treated with Ovugel® (EIEICO, Radnor, PA), a gel containing a GnRH agonist (Triptorelin) administered intravaginally. The treatment groups received 100μg of GnRH agonist intravaginally in varying viscosities of the gel, .6%(n=12), .9%(n=12), 1.2%(n=12), and 1.5%(n=12) respectively. A positive control group (n=11) received saline containing 100μg of GnRH agonist while the control sows (n=12) received a vehicle of the 1.2% gel and at 96h post weaning. Jugular cannulas were placed 48 hours before administration of the treatment. Blood samples were taken every 6 hours before treatment, then every 2 hours for the first 12 hours after treatment, then every 6 hours for the next 18 hours. Estrus detection occurred every 6 hours through the entire study. Real time ultrasonography was conducted every 4 hours to determine the time of ovulation. Control sows were bred based on the onset of estrus and treatment sows were bred at +8 and +32 h after the gel was administered. All data was analyzed using SAS and the proc GLM procedure.

Treatment Saline + GnRH

Control 0.6% + GnRH

0.9% + GnRh

1.2% + GnRH

1.5% + GnRH

Ovulation time (h)

46.5±1.2

43.8±5.4 43.8±2.0 41.2±3.3 43.5±1.8 44.5±1.5

Estrus length (h)

45.8±3.4 45.6±3.8 49.0±3.8 47±3.2 46.9±3.9 55.1±3.9

LH surge (0-30h post treatment) 7/10 5/8 7/10 9/11 8/10 8/9

Farrowing Rate 8/8

9/9 11/12 10/12 11/12 10/11

Litter Size

12.9±0.7 9±3.1.2 11±1.3 11.6±1.0 11±0.5 10.6±1.4

There were no differences in treatments in ovulation time from the onset of estrus or administration of Ovugel® (p=0.28), estrus length (p=.60), farrowing rate (p=0.80), litter size (p=0.35), or LH surge (p=0.49). However, variation associated with ovulation time was significantly reduced (p=0.01) for saline, 1.2%, and 1.5% treatments compared with controls. The duration of estrus was greater for the 1.5% gel with the triptorelin than the sows receiving only the 1.2% gel (p=0.04). The intravaginal absorption of GnRH in Ovugel® or saline along with a timed insemination program is an effective method to reduce the interval over which ovulation occurs without overtly decreasing fertility.

KEY WORDS: ovulation, GnRH agonist, swine