Kiimaaika

Kiimaaika, also called kiima-aika in Finnish, refers to the phase in the reproductive cycle of female mammals when the animal is sexually receptive and fertile. It is part of the estrous cycle and is distinct from pregnancy and from human menstrual cycles in species that do not menstruate. The term kiima means heat or estrus, describing the behavioral and physiological state associated with this phase.

Signs and duration vary by species. Common indicators include increased activity, seeking or standing to be mounted, changes in vocalization or temperament, and swelling of the vulva or mild vaginal discharge in some species. The kiimaaika typically lasts from about one day to several days depending on the species. Typical durations are roughly cows 18–24 hours; sows 2–3 days; mares 4–7 days; bitches 7–10 days; ewes about 1–2 days; and queens about 4–8 days.

Biology and timing: Hormonal changes drive kiimaaika. Rising estrogen during proestrus increases receptivity, followed by an LH surge that commonly triggers ovulation near the end of kiimaaika. After ovulation, progesterone rises during diestrus. The precise timing of ovulation is species-specific and is a key consideration for breeding or artificial insemination.

Management and significance: In livestock and veterinary practice kiimaaika is monitored to plan mating or insemination, optimize fertility, and prevent unintended mating. Detection methods include behavioral observation and physical signs, with more precise timing achievable through hormonal assays or ultrasound in some cases. Understanding kiimaaika is important for reproductive efficiency, welfare, and breeding programs.