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♦ High-Quality Heat Detection is Vital to Success
♦ High-Quality Heat Detection is Vital to Success

High-Quality Heat Detection is Vital to Success

Steve Sheppard, Dairy Area Sales Manager, Genex

When it comes to being a successful dairy, one of the most important things is to be able to get cows pregnant. Remember, the longer it takes for a cow to successfully breed back, the longer the calving interval. A longer calving interval means more days in milk, which lowers the percentage of cows at peak milk. This lowers average milk production and likely leads to a higher cull rate. Therefore, it is safe to conclude achieving pregnant cows efficiently equates to more milk.

Pregnancy rate is commonly used to measure reproduction program success. As the pregnancy rate goes up, the dairy becomes more profitable due to the previously stated reasons. Also, the more pregnant cows you have, the more options you have at cull time. If you can only sell open cows and have to keep every pregnancy, you have limited options. If you have a high pregnancy rate, you could sell lower quality or the least profitable cows. This improves your herd's genetic level at a faster rate and improves milk production.

There are two factors in calculating pregnancy rate: conception and heat detection. Let's look at heat detection. The definitive sign of a cow in heat is standing to be mounted. Secondary signs may include: restlessness, bellowing, sniffing or licking, attempting to mount other cows, scuff marks on tails/flanks, a drop in milk yield, red or swollen vulva and clear discharge from the vulva.

The length of time a cow is in heat can vary greatly as shown in Graph 1.


The time and amount of heat shown can be affected by several factors. These include, but are not limited to: temperature, increased milk production, slippery surfaces, number of other cows in heat, nutrition, health, body condition score and other general stress inducers. A modern, high-production, fully confined milking facility with 3x milking is not the ideal place for a cow to show heat, so heat detection should be a priority.

We can detect heat in a number of ways. The first is visual heat detection. This takes time. If the average cow is in heat for 12 hours and you heat detect once a day, the most you can detect is half of the cows. The best way is to observe for heats multiple times throughout the day and night. A higher percentage of cows show heat at the quietest, coolest time of the day, meaning the early morning hours.

Tail paint or chalk can be a helpful heat detection tool, when done correctly. Tail paint helps identify which cows were ridden when nobody was watching. Paint a line on the tail head of a cow or heifer, and when mounted, it should rub off. This is an economical and quite labor efficient method, but takes some skill. Reading tail paint is often considered an art. Kamar® Heatmount® Detectors have a similar effect as tail pain. They can be easily read when activated but can be more expensive.

Activity systems detect cows in heat by monitoring movement. They can be expensive to install but can save labor and time. They also record baseline and activity spikes, providing a record of when a cow was previously in heat to assist in deciding whether she truly is at the current time. note that 5-30% of all A.I. services to observed estrus are conducted at the wrong stage of the estrous cycle (Appleyard & Cook, 1976; Senger et al., 1988; Smith, 1982). These systems watch cows 24 hours per day and seven days per week. With activity systems, inaccuracies stem from cows showing too much activity when not in heat, possibly due to a management change such as a group move. Training and practice are required to understand activity reports.

Time A.I. synchronizes cows to be bred on a pre-determined time and day. This reduces need to detect heat. It can be expensive for the shots and there has to be absolute compliance. Record keeping has to be accurate, and everyone involved needs to be trained on the importance of compliance.

Heat detection is an important part of any reproduction program, and it takes training and good record keeping. it is a skilled job, demanding time and patience. The best heat detection programs utilize combinations of two or more methods, such as tail paint, visual heat detection and timed A.I. to catch all cows in heat.

April 2014