Comparing CIDR with progesterone injections and eCG with human recombinant FSH for synchronizing estrous cycle in ewes

It is desirable in estrus synchronization in sheep to avoid intravaginal devices and to shorten the program from 14 to 6 days. Moreover, replacement of eCG with safe, cheap, and efficient gonadotropin is in worldwide demand.

This study investigates the possibility of replacing eCG with human recombinant FSH (hrFSH) and CIDR with progesterone injections for estrous synchronization in ewes.

Assaf and Lacaune ewes (n=170) were divided into two groups and synchronized with either progesterone injections for 6 days or CIDR for 14 days. Ewes assigned in the injection group, received progesterone (37.5 mg; SC) and GnRH analogue (7.5 µg Alarelin acetate; IM) on day 0 of the experiment. On days 3 and 6, ewes received 25 and 12.5 mg progesterone (SC), respectively. On day 6, ewes in both groups received prostaglandin F2α (250 µg Cloprostenol; IM), and were divided into two subgroups to receive either hrFSH (75 IU Follitropin alfa; SC) or eCG (400 IU; IM). On day 7, fertile rams were introduced to ewes for 21 days. Data were analyzed using GLM and Glimmix.

There was no difference in the respective lambing rates, prolificacy, and fecundity between CIDR (71.1, 1.63, and 1.16%) and injections (66.7, 1.55, and 1.03%); between eCG (71.4, 1.60, and 1.14%), and hrFSH (66.3, 1.58, and 1.05%, P>0.05).

In conclusion, 6-day progesterone injection-based protocol produced similar results to 14-day CIDR program and hrFSH could be an effective alternative for eCG during estrus synchronization in ewes.