Fetal growth and reproductive performance in ewes administered GnRH agonist on day 12 post-mating.
Reproductive performance and fetal growth was determined in GnRH (4 microg synthetic GnRH agonist, Receptal) administered (i.m.) to ewes on day 12 post-mating (n = 103) compared to control ewes (n = 97) during the breeding season. Plasma progesterone and LH concentrations were analyzed. A total of 13 ewes was slaughtered on day 45 of pregnancy (six from control, seven from GnRH treated groups). GnRH administration on day 12 post-mating increased plasma progesterone concentration (4.39+/-0.25 ng/ml) compared to control group (3.43+/-0.15 ng/ml) on days 13-15 post-mating (P < 0.01). GnRH administration also increased plasma LH concentration between 1 and 4 h after GnRH administration (P < 0.01). Pregnancy rate was higher in GnRH treated group (84%) than control (66%) group (P < 0.05). The ewes in GnRH administered group had more twins (P < 0.05) than those in control group. The ovarian weights (P < 0.05) and the number of corpora lutea (CL) (P < 0.01) were greater in ewes slaughtered on day 45 of pregnancy in GnRH treated group than those in control group. GnRH administration on day 12 post-mating did not have any effect on products of conception at day 45 of pregnancy except on crown-rump length (CRL) of fetuses and cotyledon weight. CRL of fetuses and cotyledon weight in GnRH treated group was higher than those in control group (P < 0.05). In conclusion GnRH administration improved reproductive performance of ewes when administered on day 12 post-mating probably through its beneficial effect on embryo survival by enhancing luteal function, but not through stimulating fetal growth.
Cam
Mehmet Akif
MA
Ondokuz Mayis Universitesi, Ziraat Fakultesi, Kurupelit, 55139 Samsun, Turkey. makifcam@omu.edu.tr
Kuran
Mehmet
M
Yildiz
Sedat
S
Selcuk
Erdogan
E
D000818:Animals; D004622:Embryo, Mammalian / Q000187:drug effects / Q000502:physiology; D005314:Embryonic and Fetal Development / Q000187:drug effects* / Q000502:physiology; D005260:Female; D005300:Fertility Agents, Female / Q000008:administration & dosage / Q000819:agonists; D007987:Gonadotropin-Releasing Hormone / Q000008:administration & dosage* / Q000819:agonists*; D007273:Injections, Intramuscular / Q000662:veterinary; D008098:Litter Size / Q000187:drug effects; D007986:Luteinizing Hormone / Q000097:blood; D010053:Ovary / Q000033:anatomy & histology / Q000187:drug effects; D011247:Pregnancy; D011374:Progesterone / Q000097:blood; D011897:Random Allocation; D012098:Reproduction / Q000187:drug effects* / Q000502:physiology; D012756:Sheep / Q000502:physiology*
D005300:Fertility Agents, Female; D007987:Gonadotropin-Releasing Hormone; D011374:Progesterone; D007986:Luteinizing Hormone