<div>Background: Success of any estrous synchronization protocol to optimize production and reproduction in goats requires deeper insight of dynamic regulation of hormones progesterone and estradiol-17&beta;. Surti goats reared mostly by marginal livestock owners are native to Gujarat. Present study was conducted to study rhythmic changes in serum progesterone and estradiol-17&beta; in Surti goats under different synchronization protocols. 
 
Methods: 18 Surti goats were divided equally (n=6) in 3 groups viz. G1, G2 and G3 (control). G1 and G2 groups were injected with GnRH analogue (day 0 and 11) and PGF2&alpha; analogue (day 9). Progestogen sponge was kept intravaginal in G1 group (day 0) and removed (day 11) before GnRH analogue injection. G3 group (control) received placebo of 2 ml normal saline simultaneous to treatment groups. 
 
Result: Levels were higher at estrus and lower at day 30 for Estradiol-17&beta; and vice versa for progesterone. Coefficient of variation for estradiol-17&beta; at estrus and for progesterone at day 30 was lower for G1 and higher in control. It was concluded that GPG synchronization protocol with intravaginal progestogen was better to synchronize estrus and establish reproductive cyclicity in Surti goats as it effectively minimized variability of progesterone during pregnancy and estradiol-17&beta; at estrus.</div>

Rhythmic Changes in Serum Progesterone and Estradiol-17β in Surti Goats under Different Synchronization Protocols