Evaluation of attributes sonographic (mode-B and doppler) of corpus luteum after puberty induction in Nellore heifers and its relation with functionality

Abstract

The aims of this study are: study the dynamics of development of corpus luteum (CL) through Mode-B and Doppler ultrasound attributes, formed after puberty induction in Nelore heifers; studying the plasma profile of progesterone (P4) before and after puberty induction to confirm the cyclicity animal, following the duration of CL formed and; study blood flow rates of ovarian arteries to relate with the functionality of CLs. The work will be performed at the Instituto de Zootecnia, located in the Sertãozinho city, state of São Paulo, during the period of March to July 2016. The close heifers to enter puberty be assessed once a week for two weeks. These evaluations will be conducted weighing the animals, assessment of body condition score (BCS), blood samples for hormone progesterone dosing and ultrasonography (US) of the female reproductive tract. After these initial assessments (D-19 e D-12), the aim will be to identify 60 prepubertal heifers, which are those with absence CL in the ovary, reproductive tract score less than or equal to 3, dosage P4 < 1 ng/mL, 65% weight of an adult animal and BCS between 7 and 8.The sixty heifers are divided into two treatment groups for the induction of puberty: using ovulation induction (OIG) and other with progesterone device and ovulation induction (IPG), thirty for each groups. For IOG induction will be performed with 0.02 mg of Buserelin Acetate in D0. For the other group is used third use of progesterone device on D-12, remaining this device for 10 days. In D-2 this device will be removed and in D0 made application of 0.02 mg de Buserelin Acetate. Sonographic evaluations after puberty induction begin at the D2 for the two treatment groups, with the confirmation of ovulation. Studies of CL begin at the D4 to the D16, with an interval of two days between assessments. All CLs detected by conventional ultrasound will be quantified and measured their diameters. Later the analysis of ultrasound images and dosage of P4, the aim will be detect differences between CLs formed of a normal estrous cycle and short-cycle. Also be made blood samples for determination of serum P4 on the same day of the US in order to confirm the functionality of the luteal structures. For the evaluation and comparison of echogenicity and echotexture of the ultrasound images of CLs will be held quantification of pixels via software. For evaluation in Doppler, other software will be used to measure the area of the blood flow of CLs. Blood samples will be proceeded by puncturing the coccygeal vein using vaccum tubes labeled with the animal number and date of collection. After collection, the tubes are centrifuged and the serum obtained will be transferred to polypropylene tubes in 2 micro-aliquots of the same volume, and kept at -20ºC for subsequent hormone analysis by performing solid phase radioimmunoassay. Statistical analyzes will be performed using SAS software version 9.3 (2002-2015). The variables considered for inclusion in the model are: treatments (induction of puberty with ovulation induction or progesterone device and ovulation induction), duration of the functionality of the corpus luteum (normal or premature regression) and interaction treatment and duration of functionality. In the absence of interaction and effect of treatment, the data is grouped for the purpose of comparing the groups regarding the duration of the functionality of corpus luteum. The level of significance will be 5%. (AU)