Research Information System
REVUE DE MEDECINE VETERINAIRE, vol.157, no.3, pp.158-162, 2006 (SCI-Expanded)
The objective of the present study wits to evaluate the effect of parity on pregnancy rate in lactating Holstein cows Subjected to different synchronization protocols. A total of 96 cows (49 primiparous and 47 multiparous) were allocated randomly into four groups containing primiparous and multiparous COWS. In the PRID group (n=23), progesterone releasing intravaginal device (PRID) was inserted into anterior vagina of the cows. The devices Were removed 12 days later and 500 mu g of cloprostenol was intramuscularly administered the day before PRID withdrawal. In the Implant group (n=25), ear implants releasing norgestomet were Subcutaneously g inserted in the Car of each cow for 9 days and 500 mu g of cloprostenol was intramuscularly administered the day before the implant removal. In the GnRH group (n=24), buserelin, a GnRH analogue 10 mu g was given oil day 0 followed by the administration of 500 mu g of cloprostenol, 7 days later. In the PGF(2 alpha) group (n=24), two intramuscular administrations of 500 mu g of cloprostenol were performed at an 11-day interval. All cows exhibited oestrus signs between 36 and 124 h after the last PGF(2 alpha) administration.