The effect of post-mating hCG or progesterone administration on reproductive performance of Afshari × Booroola-Merino crossbred ewes.
To investigate the efficiency of hCG/CIDR after breeding to increase the reproductive performance, 35 synchronized ewes were mated with fertile rams and were assigned to three treatment groups. Ewes in hCG group (n = 12) received 400 IU hCG on day 11 post-mating, and ewes in CIDR group (n = 11) received CIDR from day 7 until day 19 post-mating. Ewes in the control group (n = 12) did not receive any treatment. Blood samples were collected on days 7, 12, 17, and 22 post-mating. Plasma P4concentrations were higher on days 12 and 17 post-mating in hCG- and CIDR-treated groups (P < 0.05). However, the concentrations of P4on day 22 post-mating in hCG and control groups were higher than that in CIDR group (P < 0.05). Ewes in hCG group produced more quadruplets (P < 0.05) and triplets, and as a result, they had a larger litter size (P < 0.05). The lamb mortality rate by weaning in hCG group (3.6%) was less than that in control (11.8%; P < 0.05) and CIDR (9.1%; P > 0.05) groups. Post-mating administration of hCG or CIDR did not affect the lamb birth weight in single and quadruplet births (P > 0.05), but the birth weight of twin lambs was higher in the hCG and CIDR groups (P < 0.05). Weaning weights of twin lambs were higher in the hCG and CIDR groups (P < 0.05). In conclusion, hCG/CIDR administration post-mating increased the maternal P4concentrations and enhanced reproductive performance.
Department of Animal Science, Faculty of Agriculture, University of Zanjan, P.O. Box 313, Zanjan, Iran. brostami@znu.ac.ir.
Behnam
B
Rostami
Department of Animal Science, Faculty of Agriculture, University of Zanjan, P.O. Box 313, Zanjan, Iran.
Rahman
R
Hajizadeh
Department of Animal Science, Faculty of Agriculture, University of Zanjan, P.O. Box 313, Zanjan, Iran.
Mohammad-Hossein
MH
Shahir
Department of Animal Science, Faculty of Agriculture, University of Zanjan, P.O. Box 313, Zanjan, Iran.
Davood
D
Aliyari
D000282:Administration, Intravaginal; D000818:Animals; D001724:Birth Weight / Q000187:drug effects; D006063:Chorionic Gonadotropin / Q000008:administration & dosage*; D005260:Female; D005306:Fertilization / Q000187:drug effects*; D007273:Injections, Intramuscular / Q000662:veterinary; D007492:Iran; D008098:Litter Size / Q000187:drug effects*; D008136:Longevity / Q000187:drug effects; D011374:Progesterone / Q000008:administration & dosage* / Q000097:blood*; D011897:Random Allocation; D012756:Sheep / Q000502:physiology*; D013997:Time Factors
D006063:Chorionic Gonadotropin; D011374:Progesterone
CIDR; Ewe; Post-mating; Reproductive performance; hCG