Question: I know how to care for the newborn calf or lamb, but what must be done to ensure the cow or ewe gets pregnant again after calving or lambing?
First of all, small-scale farmers have to remember that the number of calves or lambs born is the most important factor in profitable livestock farming.
Cattle are pregnant for about 9 months and if we want to get a calf from each cow every year, the cow must become pregnant again within 3 months of calving. It is, in fact, possible that the cow can be ready to mate again 1 or 2 months after calving.
To ensure this, you need to understand the cow’s heat (oestrus) cycle. This starts on the day the cow shows interest in mating with the bull again, and is called the day of standing heat. On this day the cow will allow the bull to mate with her and conception could take place.
If it doesn’t, the cow will only show standing heat again about 3 weeks – or an average of 21 days – later. This gives rise to the heat cycle which is repeated every 21 days until the cow becomes pregnant.
It’s important for small-scale farmers who know their animals individually to observe their cows in the month or 2 after calving to see if they show standing heat. A sick cow, or one that’s in very bad condition, will not show standing heat and will not become pregnant within 3 months after calving.
Remember that the suckling calf is also 1 to 3 months old at this stage, and this means that the cow’s nutritional needs are at their greatest.
In small stock, the reproductive cycle works differently. The ewe is pregnant for about 5 months so there’s more time for her to get pregnant again in order to produce at least one lamb per year.
Lambs are weaned at 3 to 4 months old, which allows the ewe to boost her condition again and become pregnant within the next 3 to 4 months. The heat cycle in ewes is also shorter than in cows and healthy ewes in moderate to good condition will show standing heat about every two weeks until they have conceived again.
How important is it to know if cows or ewes are pregnant?
It’s crucial to know which animals become pregnant so that you can plan for the time when they will lamb or calve. It’s also important to identify animals that don’t become pregnant and consequently need more attention, such as supplementary feed, or have to be slaughtered because they don’t produce offspring.
In large commercial herds, a veterinarian determines which animals are pregnant and when they will calve or lamb. This is very important in a livestock business, as it enables the farmer to plan ahead, specifically for the availability of grazing or supplementary feed.
Small-scale farmers don’t always have access to a vet to do pregnancy examinations, but they do see all their animals every day. This means pregnancy can be determined with a high degree of accuracy if the farmer understands the heat cycle and observes his animals closely.
All the farmer has to do is record the day, name or number of an individual cow or ewe when it mates. Then he or she observes the animal again; 3 weeks later for a cow to see if she shows signs of heat or mates again, and 2 weeks later for ewes.
If there are no signs of heat, the farmer can assume the animal is pregnant and determine an estimated calving or lambing date. For cattle, the estimated calving time is 9 months after the day the animal was served by the bull; for ewes, add 5 months to calculate an estimated lambing date.
Successful livestock farming depends on planning and knowing the pregnancy status of individual animals.
- This article was written by dr. Danie Odendaal and first appeared in Farming SA.