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Vaginal cytology analysis has been used to evaluate the different stages of estrous cycle of several species; it presents a direct correlation with the animal’s hormonal state and provides essential information about the female reproductive tract conditions. Two staining methods were tested to evaluate the vaginal epithelial cell morphology of nulliparous and multiparous ewes during the estrus period. An intravaginal device impregnated with medroxyprogesterone acetate was kept into 10 nulliparous and 10 multiparous ewes for 14 days for estrus synchronization. Then, the progesterone device was withdrawn, and 300 IU of eCG was administered intramuscularly. Vaginal smears were prepared for posterior staining with Panotico or Giemsa stains when estrus was detected. The cells were classified into nucleated superficial, anucleate superficial, intermediate, parabasal, and basal. The Panotico and Giemsa staining of the different cell types studied were satisfactory. A predominance of intermediate epithelial cells (p<0.05) was found after staining. No difference in percentages of the different types of vaginal epithelial cells between nulliparous and multiparous ewes were found. Therefore, both staining methods were efficient, and a predominance of intermediate cells is found in nulliparous and multiparous ewes during the estrus period.

The objective of the experiment was to evaluate the effects of recombinant bovine somatropin (rbST), and the reuse of the progesterone (P4) releasing devices in resynchronization, on the pregnancy rates of Nellore cows submitted to fixed-time artificial insemination. A group of 123 multiparae Nellore cows, was submitted to a resynchronization protocol: on day 0 a Bovine Intravaginal Device (DIB® ) with 1,0g of P4 was implanted, associated with intramuscular administration of 2,0mg of estradiol benzoate (IM); on day 8 DIB was removed; and 1,0mg of estradiol cypionate, 0,15mg of prostaglandin F2? and 300 UI of equine chorionic gonadotropin were administered; on day 10, fixed-time artificial insemination was conducted (FTAI). The cows were randomized into G1 (n=12) – without rbST / with used Bovine Intravaginal Device, G2 (n=50) – without rbST / with new DIB, G3 (n=11) - with rbST / with used DIB and G4 (n=50) – with rbST/ with new DIB. rbST was introduced on the eighth day of the protocol. Sixty days after TAI, pregnancy diagnoses were conducted, via rectal palpation. Blood samples were taken on day 0, 8 and 10 of the protocol, in order to assess P4 plasma concentrations. Pregnancy rates were statistically evaluated through Generalized Linear Models Theory and their significance was tested with Analysis of Deviance. Pregnancy rates were 58%, 40%, 81% and 48% for G1, G2, G3 and G4, respectively, with significant statistical difference for G3. Plasma concentrations of P4 were not statistically different among groups, or collections. In view of the results obtained, we concluded that the administration of rbST in association with P4 DIB, used for the third time, improves pregnancy rates. Estrus resynchronization and re-insemination positively impacted pregnancy rates.

Morphological evaluation of the corpus luteum before embryo transfer is a method commonlyused for the selection of the bovine receptients. The present study evaluated the relation betweenthe corpus luteum and the estrous synchronization protocol on pregnancy rates in recipientsimplanted with in vitro-produced bovine embryos (IVP). 260 crossbred females were selected andsynchronized using two different hormonal protocols: G1 (n=110), with sodium cloprostenol, andG2 (n=150), with norgestomet associated with estradiol benzoate, equine chorionic gonadotrophinand sodium cloprostenol. Corpus luteum (CL) were evaluated on the day of the transfer of theembryos, through rectal palpation, and classified into four types: CL-1 (small), CL-2 (medium), CL-3(large) and CL-4 (enclosed). All transfers were conducted transcervically, in the horn ipsilateral tothe ovary containing the corpus luteum. Pregnancy was confirmed, 30 days after the transfer, byultrasound. The total pregnancy rate was 35,77%, distributed as follows: 17,69% in the recepients withCL-1 (n=46), 30,77% in the recepients with CL-2 (n=80), 43,85% in those with CL-3 (n=114) and 7,69% inrecepients with CL-4 (n=20), resulting in 16 (34,78%), 29 (36,25%), 41 (35,96%) and 7 (35,00%) pregnantfemales, respectively. The results suggest that there is no correlation between corpus luteum sizeand synchronization protocol and the pregnancy rates of bovine recepients implanted with PIVembryos., A avaliação morfológica do corpo lúteo antes da inovulação é um método comumente utilizado na seleção de receptoras bovinas. Objetivou-se verificar a relação entre o protocolo de sincronização de estro e o tamanho de corpo lúteo sobre a taxa de fertilidade em receptoras bovinas inovuladas com embriões produzidos in vitro (PIV). Foram selecionadas 260 fêmeas mestiças e sincronizadas com dois diferentes protocolos hormonais: G1 (n=110), com cloprostenol sódico e G2 (n=150), com norgestomet associado a benzoato de estradiol, gonadotrofina coriônica eqüina e cloprostenol sódico. No dia da inovulação avaliaram-se os corpos lúteos (CL), por palpação retal, sendo classificados em quatro tipos: CL-1 (pequeno), CL-2 (médio), CL-3 (grande) e CL-4 (incluso). As inovulações foram realizadas por via transcervical, no corno ipsilateral ao ovário que continha corpo lúteo. O diagnóstico de gestação foi realizado por ultrassonografia aos 30 dias pós-inovulação. A taxa de fertilidade para os dois tratamentos foi de 35,77%, sendo 17,69% nas receptoras que apresentaram CL-1 (n=46), 30,77% nas que apresentaram CL-2 (n=80), 43,85% nas que apresentaram CL-3 (n=114) e 7,69% nas que apresentaram CL-4 (n=20), resultando em 16 (34,78%), 29 (36,25%), 41 (35,96%) e 7 (35,00%) fêmeas gestantes, respectivamente. Esses resultados sugerem não haver relação entre o tamanho do corpo lúteo e o protocolo de sincronização sobre os índices de prenhez de receptoras bovinas inovuladas com embriões PIV.Influence of the estrus synchronization protocol and the size of the corpus luteum onthe fertility rate in recipients implanted with embryos produced in vitro.