The success of any dairy reproductive program depends on well-observed and recorded estrus (heat). Low fertility in a herd can often be linked to heat detection failure and can be costly, causing extended calving intervals and wasted expense on semen and labor.
Observe for heat when cattle are more likely to mount during the early morning or evening hours, avoiding the hottest hours of the day, as well as feeding or cleaning times. All heats should be recorded whether or not she is to be bred, as this can help anticipate future heats. Train employees to recognize signs of heat. Use detection devices, such as heat patches, tailhead markings and electronic monitors, where appropriate to supplement visual observation.
Primary Signs of Estrus (Standing Heat)
When the cow stands to be mounted by another cow (on average 20-50 times)
Lasts for 15-18 hours.
Most accurate and consistent sign of heat
Secondary Signs Surrounding Estrus
Mounting other cows
Mucus discharge, vulvar swelling
Bellowing, restlessness
Chin resting, licking
Rubbed trailhead hair, dirty flanks.
Signs vary in duration and intensity and can occur before, during or after standing heat.
Factors Affecting Estrus Behavior
Footing surface: concrete that is icy or slick is a major hazard as well as an uninviting environment for estrus activity.
Feet and leg problems
Overcrowding in freestalls and holding pens prior to milking can discourage mounting behavior or falsely show a cow in standing heat because there is no room for her to move away.
Temperature greater than 85 degrees causes a decrease in mounting activity. During hotter weather, secondary signs of heat are more common.
Time of day: Cows tend to exhibit more signs of heat between 7 p.m. and 7 a.m., when they are not distracted by farm chores like feeding, milking and barn cleaning, and when the temperature is cooler.