Efficacy of CIDR in cosynch and oestrus synchronization protocols in lactating cows

Abstract

It was aimed to compare efficacy of CIDR in Cosynch and estroussynchronization protocols based on pregnancy rates following the firstservice at 45–160 days postpartum in lactating cows. In Group I(Cosynch-CIDR, n = 100), CIDRÒ(progesterone, 1.38 g) wasinserted intravaginally concurrently with GnRH injection (ReceptalÒ,buserelin acetate, 0.02 mg, i.m.). Seven days later CIDR was removedand PGF2a(DinolyticÒ, dinoprost tromethamine; 25 mg, i.m.) wasinjected followed by timed artificial insemination (TAI) and GnRHinjection 56 h later. In Group II (Control-CIDR, n = 81), CIDR wasadministered for 7 days. One day before CIDR removal, PGF2awasadministered. During 5 days following CIDR removal, artificialinsemination (AI) was performed following heat detection based onAM/PM rule. Pregnancies were diagnosed with transrectal ultraso-nography 40–45 days after AI or TAI. Pregnancy rates did not differbetween Cosynch-CIDR (35%; 35/100) and Control-CIDR (38.3%;31/81) groups. Submission rate for AI was higher (p < 0.01) inCosynch-CIDR group (100%; 100/100) compared to Control-CIDRgroup (82.7%, 67/81). In Control-CIDR group, frequencies of cowsdetected in heat following 1, 2, 3, 4, 5 days after CIDR removal were19.8% (16/81), 37.0% (30/81), 17.3% (14/81), 7.4% (6/81), 1.2% (1/81); respectively. Whereas, 17.3% (14/81) of cows were not detected inestrus during 5 days after CIDR removal in Group II. In conclusion,use of CIDR in Cosynch protocol provides similar pregnancy rates buthigher submission rate compared to CIDR based estrous synchroni-zation protocol in lactating cows.