Evaluation of different protocols for synchronization of estrus and ovulation in postpartum subestrus lactating dairy cows [electronic resource].

Includes references.

Thirty three Friesian cows in postpartum subestrus were used in this study to compare two protocols for synchronization ofestrus and ovulation with that of standard, 1 or 2 injections ofPGF2a Cows were divided randomly into three treatment groups as fo nows: Group 1(OvSynch): GnRH (Day 0, 50J.1J.1g im), PGF2"., (Day 7, 500 J.1J.1g im), GnRH (Day 9, 50uug im), TAl 8-20h later; Group 2 (GnRH- PGF2".,): cows were synchronized using the same manner however, the second nyection ofGnRH was eliminated, AI 12h after exhIbiting estrus or at 80-96 h for cows which not displayed estrus: Group 3 (pGF2aa): (Day 0, 500uug im), AI 12 h after detection of estrus or, if estrus not observed, cows received a second PGF2aa., injection on Day 14, and AI 12 h after observed estrus or, at 80-96 h when estrus was absent. The results showed that, conception rates at d 35 post AI was significantly (P < 0.05) higher for cows in Group 2 (77. 8%) than in Group 1 (63.6%) and Group 3 (50%). Similarly, Group 2 had a higher pregnancy rate (66.7; P<0.05) at d 65 post AI than Group 1 (54.6 %) and Group 3 (40%). However, pregnancy losses did not differ among treated groups. Estimated saving in hormone costs required for synchronizing estrus and ovulation was LE 4.17 and LE 15.75 per pregnancy for Group1 and 2, respectively. It could be concluded that GnRH- PGF2aa or GnRH-PGF2a- GnRH treatment was effective method for synchronizing a fertile estrus in postpartum subestrus lactating dairy cows. But, the better reproductive performance was observed in cows treated with GnRH- PGF2aa protocol.

Summary in Arabic.

1