Investigation of the Efficiency of CIDR-PG for Dehong Dairy Buffaloes under Thermoneutral and Heat Stress Conditions

The study investigated the efficiency of CIDR-PGF2 a-based protocol under thermoneutral (spring) and heat stress (summer) conditions. Dehong dairy buffaloes (128) were utilized to analyze the effects of the intravaginal progesterone-releasing insert (i.e., controlled internal drug release [CIDR]) and prostaglandin F2 a (PGF2 a) injection on reproductive performance under high temperatures. Each buffalo received a CIDR with 1.38 g progesterone (day 0) and a 0.6 mg PGF2 a injection on day 10 after CIDR insertion. The CIDR was removed on day 13 and then two artificial inseminations (AI) at 48 hr and 72 hr after the CIDR removal occurred. Average temperature-humidity index exceeding 72 during summer was greater than that in spring. Estrous rates of buffaloes were not significantly different between spring and summer. No difference in day 90 pregnancy/AI (pregnancy status at 90 d after AI) was found in multiparous buffaloes under thermoneutral and heat stress conditions; however, heifers (51.7%) showed greater day 90 pregnancy/AI in spring than in summer (39.6%) (p < 0.05). In total, buffalo day 90 pregnancy/AI in summer (34.1%) was lower than in spring (40.6%) (p <0.05). In conclusion, the administration of progesterone by CIDR and PGF2 a injection improve estrous response and day 90 pregnancy/AI in summer.