الفهرس 
TitleOnly 14 pages are availabe for public view
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Abstract
Herd reproductive performance depends on cows being accurately detected in heat and achieving adequate conception rates when they are presented for artificial breeding to superior progeny tested bulls. Inadequate heat detection has been identified as a major limit to herd reproductive performance over many years. Each missed heat represents the loss of a complete estrus cycle of approximately 21 days that in a seasonally calving herd represents 21 days of lost potential production, so each missed heat has a significant financial consequence.
It is a tremendous task to detect standing estrus in a cow herd, and nothing can substitute for visually observing the cattle. Several estrous-detection aids are commercially available, but these are just aids. The more time spent with the cattle looking for standing estrus, the better. However, none of these techniques has yielded consistent, reproducible data that are easily obtained, and estrus detection still relies primarily on the observation of estrous behavior or on the results of a milk progesterone assay, neither of which afford high fertility rates and both of which are labor intensive. The production of a simple, reliable protocol to aid the herdsperson is still not available.
Changes in perincal odor as estrus is approached could form the basis of a new method of estrus detection. Recent advances in artificial olfaction technology have allowed us to monitor perineal odor through estrus. Electronic/artificial noses are being developed as systems for the automated detection and classification of odors, vapors, and gases. An electronic nose is generally composed of a chemical sensing system (e.g., sensor array or spectrometer) and a pattern recognition system (e.g., artificial neural network).
The present study include tow experiments each include 24 cows. Experiment I: comparison of perineal odor from cows in estrus and the luteal phase which include (group A): 15 non synchronized Holstein Friesian cows and (group C): 9 non synchronized Holstein Friesian cows. The stage of the estrous cycle was not synchronized, and cows come into estrus naturally on different days. Experiment II: longitudinal odor profiles which include (Group B): 15 synchronized Holstein Friesian cows and (Group D): 9 synchronized Holstein Friesian cow. Estrus was induced during the midluteal phase, using a single intramuscular injection of PGF2cc. Day of estrus was assessed on the basis of behavioral observations of estrus, rectal pulpation, GC measurements for acetaldehyde profile, and plasma hormone profiles were overlaid to confirm the timing of estrus daily for 9 day (Group B) and for 8 days (Group D).
In experiment I there was significant difference between the tow cluster of differentiation of the cows on estrus and cows in midluteal phase by PCA. In experiment II the EN proved it’s accuracy in comparison with the Acetaldehyde concentration measured with GC and plasma hormone profiles (ELISA) in detecting the changes in emanated pheromonal odor during estrus cycle.
The present study confirms the sensitivity of the EN to detect the changes in the pheromones through estrous cycle which facilitate the accurate detection of estrus phase leading to accurate timing of AI. Accurate timing of AI is important in reducing disease transmission, allowing for genetic selection, and ultimately increasing the health, longevity, and milk yield of dairy cattle.