Resposta superovulatória de vacas em lactação tratadas com diferentes concentrações de progesterona

Abstract

The efficiency of superovulation protocols with different levels of progesterone in dairy cows was evaluated on the ovulated follicles rate. Twenty five high producing female were distributed in control group (n = 5), and four treatments with progesterone device (CIDR). Used CIDR for 4 and 5 days, new CIDR for 4 and 5 days (n=5 in each treatment). All cows received a pre synchronization with prostaglandin F2α (PGF) and GnRH. On Day 10 of the estrous cycle started the follicle stimulating hormone (FSH) treatment in nine decreasing doses for 4.5 days. Two applications of PGF were also used along with the 5th and 6th FSH injection. Ovaries were evaluated daily by transrectal ultrasonography to determine the start of the second follicular wave, evaluation of recruitment, follicles growth, also for monitoring the ovulation. Superovulation with used CIDR 4 resulted in a higher ovulation rate between 36-60h after device removal (94.9%, P <0.0001) compared to the control group (49.5%), used CIDR 5 (68.3%), new CIDR 4 (52.8%), or new CIDR 5 (70.6%). Thus, artificial insemination could be performed within 24-36h after removal the used 4 days CIDR. The number of follicles in control cows (38 ± 9.27) was similar (P=0.739) to used CIDR 4 (31.4 ± 6.8), new CIDR 4 (31 ± 4.6), used CIDR 5 (33.4 ± 8.4), or new CIDR 5 (38.6 ± 10.6). Our finds supported the hypothesis that low levels of exogenous progesterone during superovulation were sufficient to allow pulses of luteinizing hormone to enable ovulation induction.