No abstract

Efeito de diferentes concentrações de progesterona em dispositivos vaginais sobre a dinâmica folicular de novilhas Holandesas (Bos taurus) submetidas à IATFPalavras-Chave: puberdade; folículo dominante; sincronização de estro; ovulação. AbstractThe work evaluated the effect of different P 4 concentrations [0.75g (T1) and 1.00 g (T2)] on follicular dynamics of prepuberal heifers subject to TAI. On D0 of the protocol, heifers of both T1 (n=10) and T2 (n=9) received P 4 in intravaginal devices and, by intramuscularly, 2mg of EB. On D7, heifers received 530μg of cloprostenol and 300 IU of eCG, while on D8 the devices were removed, and on D9 received 1 mg of EB and on D10 were subject to TAI. The synchronization of the follicular wave occurred in 100% of heifers. The diameter (mm) of the dominant follicle (DF), evaluated on D9, the maximum diameter of the DF, and the o maximum diameter of the ovulatory follicle (OF) did not differ (P>0.05) among groups. The mean daily follicular growth was greater (P<0.05) on T1 (1.6±0.12) than T2 (1.0±0.18). The diameter of the DF in T1 and T2 heifers did not differ (P<0.05), both in heifers that ovulated and those that did not. The DF diameter among heifers that ovulated was greater (P<0.05) than those that did not ovulate, both on T1 (14.8±0.6 vs 9.6±0.7) and T2 (11.2±1.6 vs 7.7±0.03). The pregnancy rate did not differ between T1 and T2. The results indicate that both P 4 devices are efficient to induce the emergence of the new follicular wave, control follicular growth, and ovulation synchronization in puberal heifers.