Document Type


Publication Date



estrus detection, mares, reproductive cycles

Extension Number

ExEx 2077


Agricultural and Biosystems Engineering


In a successful horse-breeding program, it is im¬portant to understand the reproductive cycles and be¬haviors of a mare. The reproductive cycle of a mare is called the estrous cycle and lasts an average of 21 days from one ovulation to the next. Estrus is a period of time within the estrous cycle when the mare is recep¬tive to being bred and typically lasts from 5 to 8 days. The efficiency of your breeding program can be af¬fected by your ability or inability to detect estrus in a mare. When a mare is in estrus, it is often referred to as being in “heat” or standing to be bred. Today there are a wide variety of methods used for detection of estrus in the mare. Before discussing the methods and signs of estrus, some background information about the es¬trous cycle must be given. Developing a thorough un¬derstanding of estrus and the estrous cycle in the mare during the breeding season is crucial for improving current breeding practices.


June 2011.