Heat detection in dairy cows

The main focus over the next 12 weeks must be on getting cows back in calf. This takes up enormous energy on the part of the farmer, but the rewards are massive. The biggest one is more days in milk for the herd. The next is better fertility in subsequent years and then there are other benefits, such as more streamlining of jobs in the various seasons. Compact calving herds can afford not to milk for most of December and January.

Some people are against compact calving because they say it puts them under pressure in spring. But I don’t think this is enough of a reason not to go hammer and thongs at making sure every cow bulling is seen and served. Getting extra calving pens, using easy calving bulls and getting in extra help for a few weeks, if available are all options for the spring. The challenge for now is to get them in-calf.

Spotting the cows in heat is the first thing. How many signs of heat are there? Two or three?

In fact, there are 10. Of these, there are probably only three sure signs of heat, but a good stockperson will spot the other signs and use these to build up the case as to whether the cow is on or not.

1 The most definite sign is when a cow is standing to be mounted by other cows. One mount will last for only two or three seconds and how many mounts occur depends on how many other cows are on heat in the herd, so the chances of actually seeing a cow on heat being mounted is slim.

2 Tail paint is removed. Cows that have been in standing heat will have their tail paint removed, so this overcomes the fact that it is hard to see a cow being mounted.

3 Heat mount detector (Kamar or scratch card) is triggered. These operate in the same way as tailpaint and are activated when the cow is mounted by other cows. They are probably more sensitive than tailpaint, so some farmers will use these after the first few weeks are over when mounting activity decreases.

4 The cow attempts to mount other cows. Cows that are soliciting other cows are likely to be in heat or coming into heat. Other signs are sniffing the vulva or urine of other cows.

5 Tail paint is rubbed but not removed. This shows that the cow was mounted, but not mounted enough to rub off all of the paint. She could have been mounted by another cow that was in heat, for example in the collecting yard, so it is important to look at the other signs of heat.

6 The cow is restless, bellowing or acting out of character, such as running on the farm roadway.

7 The cow has poor milk let-down. Some cows in heat don’t let down milk.

8 You see clear mucus around the vulva. This is a clear sign of heat, but is unlikely to be noticed on its own.

9 You see mud marks on the flanks. The cow was probably mounted by another cow.

10 The heat mount detector is lost. It was probably knocked off during a mount.

The first three signs of heat all require the cow to be mounted by another cow. Because it is not possible to be present every time a cow is mounted, some form of heat detection aid should be used. Tail paint is cheap and very effective when applied correctly.

The number of mounts and the duration of time the cow is on heat decreases when there are fewer cows on heat at the same time. Because of this, it gets harder to spot cows in heat as the breeding season progresses.

Extra observations or introducing a vasectomised bull is a good idea after the first three weeks of breeding are over.

Good records are essential. Knowing when a cow calved or when she was last on heat is a big help when you’re in doubt about a cow. Using all the tools available will help to minimise missed heats and avoid invented heats.

A pocket diary is very useful for recording cows in heat or those showing signs of heat. Some farmers will write down the number of a cow (with a question mark after it) that is showing some signs of heat, but they are not certain of it. They will monitor these cows closely over the coming days.

While heat detection aids are a big help, you should still observe cows for signs of heat. The best times for observation is first thing in the morning before cows leave the paddock and late evening, three or four hours after the cows have gone into the paddock. Most farmers will observe cows at milking times anyway, but will check them again at midday and in late evening.

Tips to a successful breeding season with Jimmy Quinn

Breeding specialist Jimmy Quinn was speaking at an Aurivo farm walk in Mayo recently. He warned farmers of the dangers of using an aged AI flask.

He said that the ideal life span of a flask is about 15 years. Over this age, the risk of them failing and the liquid nitrogen evaporating becomes very high.

He also warned that flasks should be handled carefully – “they are like a thermos flask” – and can break easily at the neck if knocked around. He advised farmers with old flasks to dip them for liquid nitrogen regularly and plot the usage.

The flask should only drop by about four to five inches of nitrogen between each fill.

Older flasks can have micro cracks in the neck, which can result in a loss of vacuum, and the subsequent loss of nitrogen from the tank.

  • Have a good inventory: one thing to avoid is to go searching through the pot for certain straws. Jimmy advised to have a good inventory for the straws so as to avoid having to search for them. He also advised that each goblet should have a freezer tag with the bull code on it, so that the straws do not have to be touched to read them.
  • Avoid handling straws: temperature changes can lead to sperm dying in the straws. Straws should only be brought up into the neck of a flask for about 20 seconds before being submerged into the liquid nitrogen again.
  • Thaw the straw near the animal: where cows or heifers are on an outfarm, he advised that the straws be brought to the farm and thawed when needed.
  • Thaw the straw correctly: Jimmy advised that the straw be thawed in water at 35°C for at least 30 seconds.
  • Dry the straw: before loading the straw into the AI gun, it is essential that the straw is dried, as water will kill the sperm.
  • Warm the gun: in cold weather, the AI gun can be cold. The straws have a large surface areas, so the temperature of the semen can change rapidly. For that reason, the gun should be warmed by rubbing it and placing it next to your skin (down your back) before the straw is loaded.
  • Metricheck cows

    Jimmy said that it is important to check to see if cows have an intrauterine infection (metritis) well in advance of the breeding season. He said that from experience, up to 10% of any herd can have an infection after calving.

    One way of spotting issues is to conduct a pre-breeding scan to identify problem cows.

    A cheaper way to do this is to tail-paint cows in advance of the start of breeding and record what cows are cycling, and then check the cows that are not cycling.

    He said that in New Zealand it is common to use a metricheck device to identify cows with metritis.

    Jimmy said that where there is white puss being emitted from cows, or where there is an obvious rotten-smelling odour, then it is advisable to talk to your vet and place the cow on a course of antibiotics to try to rectify the issue. The earlier it is picked up, then the higher the chances of getting the cow cycling and back in calf.

    Heat expression

    Jimmy said that cows can often be assumed not to be cycling, but may be having silent heats.

    He said that this is down to nutrition, iodine levels and beta carotene in the diet. He said that studies have shown that where cows are supplemented with beta carotene, the expression of heat intensifies.

    Avoid nutrition upsets

    The egg which a cow produces is created about two months prior to ovulating. After fertilisation, the embryo will float around in the uterus for about one month prior to implantation into the wall of the uterus.

    He said that 90% of embryonic losses occur during this period. For that reason, he advocates that stress on cows is avoided and nutritional changes are also avoided.