Heat Detection

Written by: MaryAnn Holloway

Whether you AI your cattle or use natural service, you should be aware of the estrus cycles of your cows and keep a record of them. Cattle come into estrus at all times of the day, may not be very active in extreme hot or cold weather, and remain in heat for only a short period of time (roughly 12–18 hours). The best indicator of a cow or heifer in estrus, or heat, is when she allows other herd mates to mount her while she remains “standing”. Usually the animal in heat is restless and will ride other animals in the vicinity; however, only animals that remain standing in one place when mounted are in estrus.

Secondary signs of heat that a producer may observe when an animal is in heat include: roughened tail head (if a cow has been ridden by other animals, the hair on her tail head could be standing up or completely missing), restlessness (the cow may bawl and travel long distances in search of a bull), grouping together (animals coming into heat will usu­ally congregate in small groups of three to five animals), clear mucus discharge (some animals in heat will have a clear, thick mucus discharge from her vagina and the discharge may be smeared on her rump by her tail).  A bloody discharge on the cows tail or smeared on her rump usually indi­cates a missed heat; write down the date and observe this animal in 17–24 days for her next heat.

Five recommendations for heat-detection program success

1. Des­ignate someone to be in charge of the heat-detection program and record information including animal identification and time of observation. Keep good records and update them frequently.

2. Conduct visual observation for heat at least two to three times a day for a minimum of 30 minutes. The best times for observation are early morning, noon, and late evening.

3. Set aside a heat-detection pasture or corral. This makes it easier to focus on the animals that you want bred.

4. Use heat-detection aids such as heat patches or spray painting tail heads. Studies show that 43% of cattle are in standing heat between midnight and 6 am, making it difficult to observe them. Using heat-detection aids will help you know if your animals came into heat during these hours. These aids should be used only as a help aid and should not replace visual observation.

5. Cattle who are nutrient deficient have a hard time cycling. Have a good mineral program in place at least three weeks before the breeding season and don’t let the cattle run out of mineral while they are breeding.