Catching Cows in Heat
As we made our switch to seasonal dairying, one of our major concerns was catching cows in heat. That's nothing new to most dairymen, but it is essential if we intend to maintain our seasonal status. In 1993 we used K-Mar patches and watched for heats out in the paddocks. The time we spent was long and monotonous and we still only achieved 50% first service conception. After two services we turned three bulls in to clean up and only had 120 cows bred for our freshening window.
Our plan for 1994 was to use lutalyse with a set up shot 16 days before we were to begin breeding and then the second shot 14 days later to short cycle these cows and have them all in heat within three days. We hoped that this would cut down on heat watching and get more cows bred with less labor. We split the herd into 3 groups and the new heifers into 2 groups. We gave the set-up shots and the breeding shots on Saturdays and Mondays thus expecting to breed all cows on Monday through Friday. We purchased the lutelyse and were prepared to begin with the first set-up shots on Saturday, May 7.
On Friday, May 6, John Coleman, our ABS rep, stopped by to show us some new technology, which they were just introducing. It is called Heat Watch and it consists of a transmitter, which is mounted on the tail head of each cow you intend to breed. The transmitter is placed in a large burlap and canvas patch, and is glued on with sale barn glue. When a cow is mounted it sends a signal to a buffer at a computer, which identifies the cow, the time and duration of the mount and stores the information. The buffer stores the data until the computer program is started and then it is loaded into the program and displays the mounts to identify cows standing. The whole idea sounded like a dairyman's dream. The one concern John had was that the range of the transmitters might not be large enough for our grazing system. John had a system set up at his farm to use for custom breeding heifers for some of his customers. He agreed to bring it over and we walked our paddocks pressing transmitters to see if it would receive from our furthest paddocks. The range was somewhere between 1/4 and 1/2 mile, which was exciting, but not the range we needed for all our paddocks. I told John if the range could be extended we would sure be interested. He called back the next day to say they could install a buffer and receiver in a second location out in the paddocks and we could transport the buffer back to the computer to receive the data. He also said that a repeater would be available by next spring and that would solve our range problem.
I told John to order the system if it could be delivered before our first day of heats. The system arrived on the 20 th of May and we were breeding cows on the 23rd. In the next 25 days we bred over 130 head, and we didn't spend any time watching for heats. The lutalyse might not have been necessary now that we have the Heat Watch, but it did let us breed most of the cows on weekdays and allow us to have some freedom on weekends. Don't think this system is labor free, but the time it took to glue patches on 150 cows, no way compares to the time we spent last year just watching for standing heats. We must check the patches each day to be sure they haven't been rubbed off. We inspect each patch as the cows are milked in the milking parlor and we run the heifers through the corral on their way to a new paddock, so we can examine each of their patches. None of this is new as we did the same things in the past using K-Mar patches. But the time spent is minimal compared to heat watching. We have had a few patches rubbed off from mounting but because we know which paddock the cows were in, most of them have been located. Our most serious losses occurred during the extreme humidity. We feel the glue softened and allowed them to be rubbed off. I also felt that if the patches were a very bright florescent color it would help relocate them.
Since 1994 many improvements have been made to the system. Patches are now made from a material similar to football jerseys. They are also now bright orange thanks to our suggestion. A strap is now attached to the patches so that they can also be attached to the cows through the use of plastic tywraps inserted through the loose skin in the rectal area. This causes little discomfort to the cows and now patches, which come loose from the tail head, will still be suspended at the cow rump at milking time. They have also developed a repeater system, which allows us to have cows more than a mile from the receiver and still pick up all mounts. Line of sight is the most important issue for repeaters so we keep a portable repeater close to the herd with additional repeaters at strategic locations around the farm.
A recent research project by Dr. Ray Nebel at Virginia Tech showed that heat detection rates at that University had dropped 30% over the last 15 years. While milk production rose 25% and herd size increased by 15%.
Some research that he did showed that many heats are missed because cows are not detected when in fact they do stand to be mounted. He related that falling for some of the old breeding myths is part of the problem. Myth 1 Cows stay in heat an average of 12 to 18 hours. His research showed that in a large group of Holstein cows, over 30% stood for less than 4 hours; 27% stood for 4 to 8 hours; 16% stood for 8 to 10 hours and only about 24% stood for more than 10 hours.
The second myth. Myth 2 Cows in estrus stand to be mounted 20 to 55 times. His research showed that in the same group of cows. 15% stood less than 3 times to be mounted 36% stood 3 to 5 times 34% stood 6 to 12 times and only 10% stood to be mounted more than 12 times.
The Heat Watch system is a 24-hour detection system and we have found similar results as Dr. Nebel. One thing that has stood out in our pasture-based herd is that most cows come into heat during the late evening and early morning hours when detection is not as easy due to darkness. Using the Nebel approach and breeding at the next milking after cows show signs of heat has dramatically improved our conception rate.
There are many less costly approaches to heat detection but we feel the Heat Watch system more than compensates the extra cost by giving us 24-hour detection. Having that type of detection provides us with more data to time our breeding at the proper time in estrus. We feel it is worth the extra cost.