Detection of Estrus in Sheep (Ovis aries) by Salivary Fern Pattern and Vaginal Cytological Examination with Relation to Estrogen

Tamilnadu is known for domestication of farm animals and home of many recognized sheep breeds, among them, Ramnad white is one of the breed of hardy and best suitable for the migratory system of rearing which were declining due to cross breeding. To retain the indigenous breed, many assisted reproduction technologies were used, but most of them are failed due to the detection of accurate estrus stage. Many researches are working in farm animals in order to develop a successful method to detect the estrus very accurately for successful reproduction. Based on the above information, the present study is planned and made an attempt to identify the accurate estrus stage by using salivary fern pattern, vaginal cytology along with the level of feacal estrogen in Ramnad white sheep. The stages of the estrous cycle were carefully examined for two to three consecutive cycles and the samples like saliva, vaginal mucus and feaces samples were collected for analysis. A drop of saliva was placed on a clean glass slide for smear preparation and observed under light microscope and there was no uniform fern pattern. A clear crystallized fern was observed during estrus period whereas it was not clear in other stages. Likewise, the vaginal mucus was also smeared on a glass slide and stained with papanicolaous and analyzed under microscope. The cytological study clearly showed that nucleated epithelial cells are highly present during proestrus and cornified cells during estrus. In metestrus period, the cornified cells were replaced by leuocytes and then leads to diestrus period which are having only leuocytes. The presence of various cells during different periods are based on the level of estrogen and it was estimated by RIA method. Interestingly, the levels of estrogen was high during the estrus stage. Due to the high level of estrogen, the vaginal epithelium becomes cornified and the surface cells become large and flattened, with small or absent of nuclei. Likewise, the increase in estrogen also causes sodium levels to rise, which resultant a clear crystallized fern during estrus. It is therefore concluded, that the clear salivary fern pattern and vaginal cytology (cornified cells) can be applied in the detection of appropriate time of estrus in farm animals.