Know the best time to inseminate your cow

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Timely service of a cow on heat determines the success of conception and ensures that a cow’s calving cycle is attained, which is good for the productivity of dairy cows. Most farmers serve their dairy cows too early or even too late, resulting in failed conception.

This can be avoided if the farmers are well informed on the tell-tale signs that a dairy cow shows when she is in need of service.

The fertility of a dairy cow is very important. It affects the number of calves born and the total milk produced during the entire life of a cow. Good fertility improves a dairy farmer’s income. A cow’s fertility is determined by the number of calving intervals - this is the period between two successive calvings (births or calving down). A healthy cow should give birth after every 365 days, or every year.

The calving interval is divided into two periods: The calving-conception period (the period the cow gets pregnant) and the conception– calving. So a dairy farmer should pay much attention to the cow between calving and conception period. The farmer should ensure that he serves the cow at the right time to increase the chances of the cow conceiving. The cow should be properly fed with a balanced diet of carbohydrates, proteins and minerals. It is important to point out that a poorly fed dairy cow cannot come on heat at the expected time because its body may not be in good condition for conception. Diseases associated with the animal’s reproductive system may also interfere with conception. A farmer may also fail to notice heat signs in a dairy cow which results in failure when the cow is served too late or too early. Below we repeat some useful hints that the farmers should observe in order to reduce conception failure.

You can listen or download the audio version of this article here;

Signs of an animal on heat

The time during which a cow is on heat can be divided into three phases: The early heat, the standing heat and after heat. During each of these phases, the cow shows specific signs that the farmers should know.

Early heat

An animal on early heat tends to sniff other animals. It is also sniffed by the other animals. It tends to mount other animals but walks away when mounted. The cow is usually restless and keeps on looking around while making noise. Its vulva (lips of vaginal opening) is slightly swollen, moist and reddish. It is also extra attentive. When the animal shows these first heat signs, the farmer is advised not to inseminate (serve) the cow at this stage.

Standing heat

A cow is said to have standing heat when it shows all the signs already mentioned above. At this stage however, the vulva is swollen and deep red and there is a flow of clear mucus from the vulva (vaginal opening). It forgets to eat and its milk production goes down. The cow’s tail is bent away from the vulva. The animals should be inseminated immediately it shows these signs.

After heat

At this stage the cow continues sniffing the other animals and is also sniffed at. However it refuses to stand when being mounted. Clear mucus is evident from the vulva. All heat symptoms cool down rather suddenly. Very often only a few of the above signs are clearly visible. For instance, when the weather is warm, the cow will not be very active and there may be a secretion of mucus indicating that the animal is still on heat.

At this stage it is too late to serve the animal and this may lead to failed conception. In tropical countries such as Kenya, the period during which the farmer can detect heat in a cow is very short. The visible heat period lasts only for between 11-12 hours for grade cattle. This means that the farmer has to remain alert and observe their cows closely to notice any heat signs. Observing the cows during the morning milking and also in the evening can help the farmer to detect heat. A farmer who keeps good records of their animals can also predict when the animal is about to come on heat- this can help them serve the animal at right time. If the animal bleeds from the vulva two days after the end of the heat period, then it will come on heat in the next 17 – 25 days.

Normally a cow will show the first heat within 3-4 weeks after calving. If the dairy farmer kept proper records, it is always easy to predict when the animal will come on heat again. The best time to serve a cow is between 45 to 90 days after calving. Any insemination done before 45 days after calving gives a lower chance of pregnancy. On the other hand any insemination given in 90 days after calving results in birth intervals of over I year, so it is important that the farmer selects the best time between 45 and 90 days for their dairy cows.

Important tips for farmers and AI service providers

The following tips can help farmers and inseminators avoid conception failure:

• If a cow shows heat signs in the morning, let to be served in the evening, if it starts showing signs of heat in the evening, then it should be served the next morning (this is called the AM-PM rule).

• Always maintain the records of each animal eg date of birth AI records, name of bull used to serve the cow and date at age of service, number of services, calving, calving intervals etc.

• Avoid using village bulls to serve your cows in order stop transmission of venereal diseases, always separate the bull from the cows the cows to avoid inbreeding.

• Do not throw away the empty semen straw after use preserve it for future reference and to avoid inbreeding.

• For AI service providers, always keep your nitrogen cylinder tightly closed to stop the liquid nitrogen from escaping (a dried cylinder will kill the semen or make it unviable)

• Always let the semen to thaw for 15 to 30 seconds before serving the cow.

• Load the insemination gun correctly to avoid losing the semen.

• Use one semen straw per cow, some inseminators have been found to use one straw for two different cows to save on semen- this is illegal and can lead to failure of conception.

• Farmers should insist to be given the straw that has been used to serve their cow. The straw has the name of the bull used and its code- which can help the farmer in record keeping.


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