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The objective was to determine the accuracy of a pregnancy test for predicting nonpregnant cattle based on the evaluation of corpus luteum (CL) blood flow at 20 d (CLBF-d20) after timed artificial insemination (TAI). Crossbred Holstein-Gir dairy heifers (n=209) and lactating cows (n=317) were synchronized for TAI using the following protocol: intravaginal implant (1.0 g of progesterone) and 2mg of estradiol benzoate i.m. on d -10, implant removal and 0.526 mg of sodium cloprostenol i.m. on d -2, 1mg of estradiol benzoate i.m. on d -1, and TAI on d 0. On d 20, animals underwent grayscale ultrasonography (US) to locate the CL and color flow Doppler to evaluate CLBF-d20 using a portable ultrasound equipped with a 7.5-MHz rectal transducer. Based only on a visual, subjective CLBF evaluation, the animals were classified as pregnant or not pregnant. On d 30 to 35, blinded from results of the previous diagnosis, the same operator performed a final pregnancy diagnosis using US to visualize the fetal heartbeat (gold standard; US-d30). A second evaluator also analyzed the CLBF-d20 in the same animals by watching 7-s recorded videos. Blood samples were collected from a subset of 171 females to determine, by RIA, plasma progesterone (P4) concentrations, which indicate CL function. The final pregnancy outcome (US-d30) was retrospectively compared with the CLBF-d20 diagnoses and then classified either as correct or incorrect. The number of true positive, true negative, false positive, and false negative decisions were inserted into a 2 × 2 decision matrix. The sensitivity, specificity, positive predictive value, negative predictive value, and accuracy of the CLBF-d20 test were calculated using specific equations. Binomial variables (pregnancy rate and proportions) were analyzed using Fisher's exact test for the effect of parity and to compare between evaluators and tests (CLBF-d20 vs. plasma P₄). The kappa values were calculated to quantify the agreement between CLBF-d20 and the gold standard (US-d30) and between evaluators. The performance parameters of CLBF-d20 test were as follows: sensitivity=99.0%, specificity=53.7%, positive predictive value=65.1%, negative predictive value=98.5%, and accuracy=74.8%. False negatives represented only 0.4% of the exams. No differences existed in these parameters between evaluators (no. 1 vs. no. 2) and tests (CLBF-d20 vs. plasma P4). Moreover, a high level of agreement was observed between evaluators (0.91). In conclusion, visual evaluation of CLBF-d20 represents a quick, reliable, and consistent diagnostic test that enables the early detection of nonpregnant cattle.

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The effects of different dietary energy levels [100 and 170% for maintenance (M) and high energy (1.7M), respectively] on metabolic, endocrine, and reproductive parameters were evaluated in nonlactating Bos indicus (Gir; n=14) and Bos taurus (Holstein; n=14) cows submitted to ultrasound-guided ovum pick-up followed by in vitro embryo production. The oocyte donor cows were housed in a tiestall system and fed twice daily (0800 and 1600 h). Twenty-one days before the beginning of the experiment, the animals were fed with a maintenance diet for adaptation followed by the experimental diets (M and 1.7M), and each cow underwent 9 ovum pick-up procedures 14 d apart. The recovered oocytes were cultured in vitro for 7 d. We measured glucose and insulin concentrations and performed glucose tolerance tests and the relative quantification of transcripts (PRDX1, HSP70.1, GLUT1, GLUT5, IGF1R, and IGF2R) from the oocytes recovered at the end of the experimental period. No interactions were observed between the effects of genetic groups and dietary energy level on the qualitative (viable oocytes, quality grade, and oocyte quality index) and quantitative (oocytes recovered) oocyte variables. There were no effects of dietary energy level on the qualitative and quantitative oocyte variables. However, Bos indicus cows had greater numbers of recovered structures, viable oocytes, and A and B oocyte grades as well as better oocyte quality index scores and lower DNA fragmentation rates compared with Bos taurus donors. In vitro embryo production (cleavage and blastocyst rates and number of embryos) was similar between diets, but the 1.7M diet reduced in vitro embryo production in Bos indicus cows after 60 d of treatment. Moreover, Bos indicus cows on the 1.7M diet showed lower transcript abundance for the HSP70.1, GLUT1, IGF1R, and IGF2R genes. All cows fed 1.7M diets had greater glucose and insulin concentrations and greater insulin resistance according to the glucose tolerance test. In conclusion, increasing dietary energy did not interfere with oocyte numbers and quality, but the 1.7M diet reduced in vitro embryo production in Bos indicus cows after 60 d of treatment. Finally, Bos indicus cows had greater oocyte quality, greater numbers of viable oocytes and greater in vitro embryo yield than Bos taurus.

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-The aim of this study was to investigate the follicular dynamics during estrous cycle in Gir breed (Bos indicus) cows. Follicular growth and atresia during estrous cycle were evaluated using a portable ultrasound device. Luteal activity was evaluated by serum progesterone levels. Cycles with two (6.67%), three (60.00%), four (26.67%) and five (6.67%) follicular waves were observed. There was no difference (P>0.05) in dominant or subordinate follicles growth or atresia rates among follicular waves. The maximum diameter of the ovulatory follicle was higher than the diameter of the other dominant follicles in cycles with four waves, and higher than the diameter of the second dominant follicle in cycles with three waves (P<0.05). There was no difference (P>0.05) in estrous cycle length (21.11±1.76 and 22.25±1.71 days) or progesterone levels during diestrous (4.48±1.45 and 5.08±1.40 ng/mL) between cycles with three or four waves. Follicular dynamics in Gir cattle is characterized by a higher incidence of cycles with three or four waves, associated with a low persistence of the dominant follicle.Index terms: bovines, Gir breed, oestrous cycle, ovaries, ovarian follicles, ultrasonics. DINÂMICA FOLICULAR EM VACAS ZEBUÍNAS RESUMO -Objetivou-se neste trabalho estudar a dinâmica folicular em vacas da raça Gir (Bos indicus).O crescimento e a atresia folicular foram monitorados diariamente ao longo de ciclos estrais completos (n = 15), utilizando-se um aparelho portátil de ultra-som. A atividade luteal em cada ciclo foi avaliada pela determinação do nível de progesterona plasmática. Foram observados ciclos com duas (6,67%), três (60,00%), quatro (26,67%) e cinco (6,67%) ondas de crescimento folicular. Não houve diferença significativa (P>0,05) nas taxas de crescimento e atresia de folículos dominantes ou subordinados, entre ondas. O diâmetro máximo do folículo ovulatório foi maior (P<0,05) que o dos demais folículos dominantes nos ciclos com quatro ondas e do que o diâmetro do folículo dominante da segunda onda nos ciclos com três ondas. Não houve diferença significativa (P>0,05) no comprimento do ciclo (21,11±1,76 e 22,25±1,71 dias) ou na concentração de progesterona durante o diestro (4,48±1,45 e 5,08±1,40 ng/mL), entre ciclos com três ou quatro ondas de crescimento. Esses resultados demonstraram que a dinâmica folicular na raça Gir é caracterizada pela predominância de ciclos com três ou quatro ondas de crescimento folicular, associados à baixa persistência dos folículos dominantes das ondas intermediárias.Termos para indexação: bovinos, raça Gir, ciclo estral, ovários, folículos ovarianos, ultra-som.

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