Effect of Repeated Administration of hCG on Ovarian Response in PMSG-superovulated Ouled Djellal Ewes (Algeria)

TROPICULTURA, 2014, 32, 1, 10-15 Effect of Repeated Administration of hCG on Ovarian Response in PMSG-superovulated Ouled Djellal Ewes (Algeria) R. Lamraoui1, F. Afri-Bouzebda1*, Z. Bouzebda1, M. Franck2 & D.E. Gherissi1 Keywords : Superovulation- Progesterone- hCG- Ewe- Ouled-Djellal- Algeria Summary Résumé The objective of this study was to evaluate the effect of repeated administration of hCG on ovarian response in PMSG-superovulated ewes. Intravaginal pessaries containing 40 mg fluorogestone acetate (FGA) were inserted in all ewes (n=9) and remained in situ for 14 days. Two days prior to pessary removal, all ewes were treated with 1000 IU of PMSG. On the day of sponge removal (day 0), the females were randomly assigned to 2 treatments. The first group (n=3) did not receive any hCG, while the second group (n=6) treated inter-muscular with hCG (500 IU) during days 0-2. On day 8, laparotomy was performed to assess numbers of corpora lutea (CL) and anovulatory follicles (AF). Blood samples were collected for analysis of serum progesterone (P4) using radioimmunoassay (RIA) method. The results obtained for first and second group was in number of CL (6.33±1.15 and 10.50±5.54), number of AF (2 ±3.46 and 4.16±5.70), then the levels of P4 (5.75± 4.45 and 13.22±6.80 ng/ml), respectively. These results indicate that the repeated administration of hCG post-sponge removal increases number of CL and improves luteal function in ewes after PMSGsuperovulatory treatment. Effet de l’administration répétée de l’hCG sur la réponse ovarienne chez la brebis « Ouled Djellal » superovulée avec de la PMSG (Algérie) Introduction Superovulation plays an important role in the embryo transfer (ET) programs. It aims at inducing a high number of ovulations and a high yield of embryos of good quality (4). Any treatment regimen designed to induce multiple follicular development L’objectif de cette étude est de déterminer l’effet de l’administration répétée de l’hCG sur la réponse ovarienne chez la brebis « Ouled Djellal » superovulée avec de la PMSG. Après synchronisation des chaleurs, par des éponges vaginales de 40 mg de FGA pendant 14 jours, 2 jours avant le retrait des éponges toutes les brebis (n=9) reçoivent une injection de PMSG (1000 UI). Au jour de retrait des éponges (J0), les brebis ont été réparties en 2 lots, le premier (n=3) n’a reçu aucune injection de l’hCG, cependant le deuxième lot (n=6) a reçu une double injections de l’hCG (500 UI) au jour 0-2. Le contrôle de la réponse ovarienne est effectué au 8e jour, par comptage des structures ovariennes par laparotomie : Corps Jaune (CJ), Follicules Anovulatoires (FA) et par un dosage radio immunologique de Progestérone (P4). Les résultats obtenus dans le 1er et le 2e lot sont respectivement en nombre de CJ (6,33±1,15 et 10,50±5,54), en nombre de FA (2±3,46 et 4,16± 5.70), et les niveaux moyens de P4 (5,75±4,45 et 13,22±6,80 ng/ml). Les résultats obtenus dans cette étude montre que l’administration répétée de l’hCG après le retrait des éponges vaginales augmentent le nombre de CJ et améliore la fonction lutéale chez la brebis superovulée avec de la PMSG. must override a physiologic system operating to permit only a single follicle to mature for ovulation. Thus, treatment must be initiated prior to the emergence of the dominant follicle. Additionally, the stimulation must not only promote follicular development but must also provide normal 1 University of El-Tarf, Institute of Veterinary Science. Laboratory of Animal Production, Biotechnology and Health. El-Tarf, Algeria 2 National Veterinary School of Lyon, Lyon, France * Corresponding author: E-mail: Received 4.02.2013 and accepted for publication on 12.08.2013 10 TROPICULTURA, 2014, 32, 1, 10-15 development of granulosa and thecal cells so that luteal function being normal (12). Superovulation protocols allow taking advantage of the relatively short gestation length of sheep and utilize the ewe to her fullest potential (5). One of the more problematic aspects of the ET procedure is the variable response by the donor to superovulatory treatment and the percentage of embryos available for transfer from each donor (4). The pregnant mare’s serum gonadotrophin (PMSG) act as analog to the hypophyseal gonadotropin FSH (10). Human chorionic gonadotropin (hCG), which is similar to LH in function, causes ovulation in female animals. Due to its high content of sialic acid, the half life of hCG (about 8 hours) is much longer than that of LH, ranged between 12 to 50 min. hCG produces an effect similar to LH on luteal cells since it managed by the same receptors as hypophyseal gonadotropin (10). Thus, possibility of utilizing hCG associated with PMSG for inducing superovulation has to be verified. Four gonadotropic preparations (human menopausal gonadotropin, human follicle stimulating hormone, pregnant mare's serum gonadotropin, and porcine FSH), in combination with human chorionic gonadotropin, are successful in inducing multiple follicular develop. Treatment with these gonadotropin preparations, in combination with hCG, results in multiple follicular development (12). The aim of the present study was to test the hypothesis that the repeated administration of hCG at a dose level of 500 IU after sponge removal, in PMSG-superovulated Ouled Djellal ewes, may improve ovarian response and enhance serum P4 concentration at the time of embryo collection. Materials and Methods Animals and treatments This trial was carried out in Ras El Aioun town, Department of Batna, Algeria. The present study was performed during the reproductive season (September) for ewes. Adult non-lactating, nonpregnant and clinically healthy Ouled Djellal ewes (n=9) were used. They averaged 25 months old, 55 kg mean body weight and raised in a semi-intensive system under a natural lighting. None of these females has previously received a superovulation treatment. Estrus was synchronized (during the breeding season) using intravaginal sponges that contained 40 mg fluorogestone acetate (Synchropart), which was inserted for 14 days. The ewes were superovulated using an administration of a single dose of 1000 IU PMSG (Folligon®, Intervet International, Netherlands), two days before sponge withdrawal (1). On the day of sponge removal (day 0) females were randomly assigned to two treatments, the first group (n=3) did not receive any hCG treatment, while the second group (n=6) received a double injection of hCG (500 IU) (Chorulon®, Intervet International, Boxmeer, PaysBas) at days 0 and 2 (Figure 1) (7). Control of ovarian response a. Laparotomy Ovarian response was performed through an anterior mid-ventral laparotomy, on day 8 postsponge removal. After the reproductive tract was exposed, the superovulatory response was assessed, by counting CL and AF. b. Hormone analysis Blood samples (10 ml) were taken by jugular venipuncture into vacutainers on day 8 post-sponge removal. The samples were centrifuged for 10 min at 2000×g, t (...truncated)