author(s)
A Reshma, C Veerapandian, T Sathiamoorthy and N Arunmozhi

abstract
A total of ninety apparently healthy crossbred cows which failed to conceive in three or more inseminations with good quality semen and with a BCS of 2.5 to 3.5 and in their first to fourth parity were selected under field conditions to study the effect of controlled breeding using a progesterone device on fertility in repeat breeder cows which were brought to the Teaching Veterinary Clinical Complex, Veterinary College and Research Institute, Tirunelveli and infertility camps at nearby villages of Tirunelveli during the period of October 2016 to April 2017. The repeat breeder cows were randomly and equally assigned to one of the three groups. viz. control ( Group I; n=30) CIDR (Group II; n=30) and CIDR + post AI CIDR (Group III; n=30). The pregnancy verification was carried out in all the animals by rectal palpation after 60 to 90 days post insemination. The animals were conceived due to increasing the levels of plasma progesterone in relation to Controlled Internal Drug Release (CIDR) insertion on day 10 (10.23±0.11 ng/ml) and PGF₂α in combination with post insemination CIDR therapy (9.92±0.19 ng/ml) on 12 day or alone in repeat breeder cows under field conditions. Hence, the insertion of CIDR and post insemination CIDR led to increase in the plasma progesterone concentration and thereby improves the conception rate in repeat breeder cows.