Timing of eCG injection in hormonal treatment program of estrus induction in Torki-Ghashghaei ewes during deep anestrus

The objectives of this study were to detect appropriate time of eCG injection in estrus induction program for seasonally deep anestrous Torki-Ghashghaei ewes and to examine its effect on reproductive and economic efficiency in the nomadic sheep production system of Fars province of Iran. Three hundred ewes were identified by ear tags and their ages and BCSs were recorded. Then 270 of them treated by progesterone CIDR + eCG, in March. Hormonal treated ewes were assigned to three groups based on injection time of eCG, including: Group1- 48 h, Group2- 24 h, or Group3- 0 h before CIDR removal. The 4th group including 30 ewes as the control was under no hormonal treatment. Injection of eCG, 24 h vs. 0 h before CIDR removal significantly (P≤0.05) increased and 48 h vs. 0 h before CIDR removal tended (P≤0.10) to increase pregnancy and parturition rates, fecundity, weaned lamb production rate, born and weaned lamb crops, grass and net incomes from lamb production per ewe. All of these reproductive and economic parameters were significantly (P≤0.05) higher in three hormonal treated groups in comparison with control group. There was no pregnancy in control group at all, that indicating a deep anestrus period for Torki-Ghashghaei ewes during March. In conclusion, the best time of eCG injection to induce estrus in Turki-Ghashghaei ewes during deep seasonal anestrus (in March and April) is 24 h before finishing progesterone treatment.