Acta Veterinaria Eurasia
Research Article

The AFFECTS of OVSYNCH STARTED in DİFFERENT PHASES of OESTRUS CYCLE on OESTRUS SYNCHRONİZATİON in COWS

1.

Bahri Daûdaş Uluslararası Tarımsal Araştırma Enstitüsü Müdürlüğü, Büyükbaş Hayvan Yetiştirme Bölümü, Konya

2.

Tarım ve Kırsal Kalkınmayı Destekleme Kurumu, Konya

Acta Vet Eurasia 2009; 35: 7-17
Read: 675 Downloads: 452 Published: 22 December 2019

In this study the effects of ovsynch protocol started in different phases of oestrus cycle on oestrus synchronization in Brown Swiss cows were examined. A total of 41 cows were randomly allocated into four groups. According to observation of the oestrus and ovulation, ovsynch protocol was began during oestrus (Group I, n=12), metoestrus (Group II, n=9), dioestrus (Group III, n=10) or proestrus (Group IV, n=10). All cows received 10 µg buserelin acetate intramuscularly and, 500 ng cloprostenol 7 d and a second GnRH 9 d after the first GnRH injection and AI 16 h after the second GnRH application. Ovarian structures were monitored daily during the experiment and pregnancies were diagnosed by ultrasound 28 d after AI. Ovulation or luteinization and new follicle development rates (%) after first GnRH injection are 100%, 78%, 100% and 90% in groups I, II, III and IV, respectively. On PGF2α injection day, 83.3%, 88.9%, 100% and 100% cows had large follicle (>8 mm) and 91.7%, 100%, 90% and 100% cows had lutein tissue in groups I, II, III and IV, respectively. Luteolytic responses to PGF2α, were 81.8%, 77.8%, 66.7% and 80% and ovulation responses to second GnRH were 83.3%, 66.7%, 80% and 70% in groups I, II, III and IV, respectively. Pregnancy rates were 58.3%, 44.4%, 40% and 50% in groups I, II, III and IV, respectively. There was only a significant difference for average diameter of corpus luteum on PGF2a injection day between groups II and IV (p<0.05). It is concluded that, ovsynch protocol could be began regardless of the phase of oestrus cycle.

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