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A comparison of estradiol 17β and gnrh in synchronizing follicle wave emergence on superovulatory response in holstein cows
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Theriogenology
A COMPARISON OF ESTRADIOL 17/3 AND GNRH IN SYNCHRONIZING FOLLICLE WAVE EMERGENCE ON SUPEROVULATORY RESPONSE IN HOLSTEIN COWS B.R. Mitchell, M. Martinez, D.M. Bentley and R.J. Mapletoft Department of Herd Medicine and Theriogenology, W.C.V.M., University of Saskatchewan, Saskatoon, Sask. S7N 5B4, Canada An experiment was designed to compare the effect of estradiol-17e (E-17P) or gonadotropin releasing hormone (GnRH) in synchronizing follicle wave emergence on the superovulatory response in Holstein cows. Thirty non-lactating Holstein cows at mid-luteal phase, and 3 to 6 d after an injection of GnRH (previous experiment), were assigned randomly to one of 2 treatment groups in 3 replicates. On Day 0, CIDR-B implants (Vetrepharm Can. Inc., London, ON) were inserted in all cows and 15 were given 2.5 mg of E-17P and 50 mg of progesterone intramuscularly (Sigma Chemical Co., St. Louis, MO) in canola oil. The remaining 15 were administered 100 p.g of GnRH intramuscularly (Cystorelin, Merial, Victoriaville, PQ) on Day 2. Cows were superstimulated with 400 mg NIH-FSH-Pl of Folltropin-V (Vetrepharm Can. Inc.) divided into a twice daily decreasing intramuscular dose schedule over 4 d starting on Day 4, the expected day of follicle wave emergence. Prostaglandin (PGF; 2 ml Estrumate; Mallinckrodt Vet Inc., Ajax, ON) was administered to all cows in the morning of Day 6 and CIDR-B implants were removed in the evening. Cows were timed-inseminated 60 and 72 h after PGF treatment and ova/embryos were collected by a non-surgical technique and sent to slaughter for CL counts 7 d later. The effect of treatment on the number of CL was analyzed by a 2 sample t-test. Percentages were compared between groups by chi-square analysis. Reproductive tracts from 4 cows were lost at slaughter and these animals were removed from the experiment. There was no difference in superovulatory response or in any of the other parameters examined between groups pretreated with either E-17p or GnRH (Table 1). Table 1. Superovulatory
response as represented by means (+SEM) and percentages.
n No. of CL Total ova/embryos Recovery rate 1%) Fertilized ova Fertilization rate (%) Transferable embryos Transferable rate (%)
E-17P 14 23.7k2.1 7.4kl.6 1031332 (34.5) 4.0fl.3 56003 (50.0) 2.9f0.7 41/103 (41.3)
Probability GllRH 12 20.3k3.2 ns 4.2fl.7 ns 50/243 (19.9) ns 2.8kO.9 ns 33/50 (49.1) ns 2.4kO.7 ns 29150 (45.6) ns
Results suggest that superovulatory response in Holstein cows implanted with CIDR-B will not differ whether cows are pretreated with E-17P or GnRH in the growing phase of a follicle wave and superstimulated at the expected time of the subsequent follicle wave emergence.
Theriogenology
A COMPARISON OF ESTRADIOL 17/3 AND GNRH IN SYNCHRONIZING FOLLICLE WAVE EMERGENCE ON SUPEROVULATORY RESPONSE IN HOLSTEIN COWS B.R. Mitchell, M. Martinez, D.M. Bentley and R.J. Mapletoft Department of Herd Medicine and Theriogenology, W.C.V.M., University of Saskatchewan, Saskatoon, Sask. S7N 5B4, Canada An experiment was designed to compare the effect of estradiol-17e (E-17P) or gonadotropin releasing hormone (GnRH) in synchronizing follicle wave emergence on the superovulatory response in Holstein cows. Thirty non-lactating Holstein cows at mid-luteal phase, and 3 to 6 d after an injection of GnRH (previous experiment), were assigned randomly to one of 2 treatment groups in 3 replicates. On Day 0, CIDR-B implants (Vetrepharm Can. Inc., London, ON) were inserted in all cows and 15 were given 2.5 mg of E-17P and 50 mg of progesterone intramuscularly (Sigma Chemical Co., St. Louis, MO) in canola oil. The remaining 15 were administered 100 p.g of GnRH intramuscularly (Cystorelin, Merial, Victoriaville, PQ) on Day 2. Cows were superstimulated with 400 mg NIH-FSH-Pl of Folltropin-V (Vetrepharm Can. Inc.) divided into a twice daily decreasing intramuscular dose schedule over 4 d starting on Day 4, the expected day of follicle wave emergence. Prostaglandin (PGF; 2 ml Estrumate; Mallinckrodt Vet Inc., Ajax, ON) was administered to all cows in the morning of Day 6 and CIDR-B implants were removed in the evening. Cows were timed-inseminated 60 and 72 h after PGF treatment and ova/embryos were collected by a non-surgical technique and sent to slaughter for CL counts 7 d later. The effect of treatment on the number of CL was analyzed by a 2 sample t-test. Percentages were compared between groups by chi-square analysis. Reproductive tracts from 4 cows were lost at slaughter and these animals were removed from the experiment. There was no difference in superovulatory response or in any of the other parameters examined between groups pretreated with either E-17p or GnRH (Table 1). Table 1. Superovulatory
response as represented by means (+SEM) and percentages.
n No. of CL Total ova/embryos Recovery rate 1%) Fertilized ova Fertilization rate (%) Transferable embryos Transferable rate (%)
E-17P 14 23.7k2.1 7.4kl.6 1031332 (34.5) 4.0fl.3 56003 (50.0) 2.9f0.7 41/103 (41.3)
Probability GllRH 12 20.3k3.2 ns 4.2fl.7 ns 50/243 (19.9) ns 2.8kO.9 ns 33/50 (49.1) ns 2.4kO.7 ns 29150 (45.6) ns
Results suggest that superovulatory response in Holstein cows implanted with CIDR-B will not differ whether cows are pretreated with E-17P or GnRH in the growing phase of a follicle wave and superstimulated at the expected time of the subsequent follicle wave emergence.