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Cattle production: Why would cows not calve every year?

Question: My cattle aren’t calving every year. What could be the problem? I have a good bull that’s been tested and proved itself to be productive.

The most important, and most difficult, task is to manage a cow in such a way that she calves once every year. One calf a year means that if she calves in October this year she will also calve next year during October or November.

A cow is pregnant for 9 months, and if she’s going to produce one calf every 12 months she has to be mated within 3 months after calving. During these 3 months, called the critical period, the cow has her highest nutritional needs.

Having enough food available from calving until she is pregnant, again, is by far the most important factor. This means that the cow must be managed to calve at the start of the rainy season, so that she will conceive again when the best grass is available three months later.

After calving the cow has to resume reproductive activity; she must start showing signs of heat. Once this happens, the cow will repeatedly show these signs every 21 days, on average, until she again mates successfully with the bull.

The livestock owner’s job is to record the date of calving for each cow and then to observe if she show signs of heat. By day 60 a normal cow would have shown signs of heat. A cow that takes up to 90 days after calving before showing signs of heat needs further support, and a cow that doesn’t show heat for up to 90 days after calving will not produce one calf a year.

The most important reason for a cow not to show heat by day 60 after calving is a body condition that’s too low. The management action the livestock owner could take to get such cows cycling again would be to provide supplementary feed to each individual cow that doesn’t show heat by day 60 after calving.

This input is needed if you want the cow to produce one calf per year.


  • Heat is the term used for the period when a female animal is ready for breeding/mating with the bull (in the case of cattle).
  • This period only lasts one day in cows.
  • A non-pregnant cow in good condition will show signs of heat on average every 21 days (3 weeks).
  • In practice this means that if a cow in heat is not mated, or if the mating isn’t successful, this cow will be ready to be mated again in 3 weeks’ time.
  • This knowledge can be used in the management of cattle.
  • If all the animals run together in a communal grazing system, and the farmer doesn’t want the cow to be mated, he/she simply has to keep the cow in the kraal for the one day that cow is on heat during every three-week heat cycle.
  • A cow no longer shows signs of being on heat if she is pregnant, and if the farmer has kept a record of the last mating date, he/she can effectively determine if the breeding was successful by observing the cow from day 18 to day 23 after mating. If the cow doesn’t show heat again, it is a good indication that she has become pregnant.

Also read:
Livestock production: Assisted calving

Cattle production: Why is it necessary to wean calves?

  • This article was written by dr. Danie Odendaal and first appeared in Farming SA.

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