الفهرس 
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Abstract
Fertility is one of the most important factors affecting the economic success of dairy farms. Therefore, early and accurate estrus detection is crucial, particularly in farms using artificial insemination. In fact, in the last decades, several automated sensor-based technologies for estrus detection have been developed. Nevertheless, accurate estrus detection is still a challenge. The ability of an electronic nose (EN) technology (MENT-EGAS prototype) to detect estrus by direct sampling of odor from the perineal headspace in 49 Holstein Frisian dairy cows was assessed. Statistical analyses (PCA) were applied and revealed high discrimination between proestrus and estrus and between estrus and metestrus in cycling cows. In addition, high discrimination between estrus in cycling cows and pregnant ones was perceived. Contrarily, low discrimination between proestrus and metestrus in cycling animals was detected. Similarly, when comparing pregnant cows with cycling cows in proestrus or metestrus no significant discriminations were noticed. Based on these findings and for the first time that is possible to recognize with accuracy estrus in dairy cattle by direct sampling on the perineal headspace using an EN device during milking. The MENT-EGAS prototype could be used in the future routinely on farms as a non-invasive, accurate method for estrus detection in cattle.