When Should I Calve My Cows?

In Manitoba the most common type of cow/calf operation is what we would consider “Winter Calving”, where calves are born in the January - March period. There are several reasons for this but basically this system is more conducive to mixed farming operations and pure bred operations, where the cow/calf enterprise doesn’t interfere with the cropping enterprise and calves have extra months to put on weight prior to sale. This was probably the norm in Manitoba where the average herd size was 60 to 70 cows. However, with larger herd sizes and producers being more committed to multi-enterprise activities, is this still the best system?

One of the most common questions asked in the last few years is “Should I switch my calving season to spring or summer? Or “Why not fall calving”? It seems like an easy question to answer but there are many factors each producer must consider. Most producers calve at a particular time of the year because that’s how it’s always been done on the farm. Some producers have chosen a particular calving season because it best fits with their other farm commitments (i.e. multi enterprise operations) or to reach certain production targets (i.e. purebred breeders).

Success for each cow/calf producer is related to the ability of the producer to wean one healthy calf per cow each year. For maximum fertility, it is recommended that cattle not be bred earlier than 60 days following parturition, even though they may exhibit heat earlier. A disturbing problem with beef cattle can be the excessively long period before the first postpartum estrus, since it becomes difficult to breed for a yearly calf crop if the breeding interval is longer than 90 days.

The objective of any cow/calf operation is to try to keep the calving interval as short as possible. Most producers would consider an interval of 45-60 days ideal as this insures a relatively uniform calf crop. The calving interval is greatly influenced by nutrition and health which if not managed properly, will spread out the calving interval making less efficient use of resources such as labour and capital. Therefore, choosing a calving season that allows the producer to provide the necessary care to ensure maximum fertility is very important.

Definition of Calving Seasons

For the purposes of discussion in this factsheet let’s define four specific times of the year for potential calving seasons. That being, Winter (January, February, and March), Spring (April and May), Summer (June and July) and Fall (August, September and October). This factsheet will outline the advantages and disadvantages of each of the four calving periods.

For the purpose of this comparison we are assuming that all operations will be feeding in confinement for 180 days and grazing for 185 days. All the cows will be fed with the same quality hay and are assumed to have a mature weight of 1,300 pounds. To determine the cost of feeding the cows hay was valued at $60/ ton and barley $2 per bushel. Supplemental energy is provided where necessary. Feed waste is estimated at approximately 10 - 12% in confinement feeding (round bale feeders) and 3 to 5% when wintering in larger fields (ex: feeding with a bale shredder).

Estimates on infrastructure costs would suggest that they are greatest for winter calving operations. Facilities for spring and fall calving would be similar, about 20% less than those for winter. Summer calving operations would require the least investment in facilities, about 25% less than winter operations.

Total labour requirements for a cow calf operation would be greatest for winter calving operations. Fall operations would require 10% less labour, followed by spring operations with 20% less, and finally summer operations with about 25% less labour.

While this list may not be complete, it will help each operation to evaluate the individual goals, resources and labour requirements necessary to select the most suitable calving season.

Winter Calving

For herds that calve in the winter the traditional time period is usually considered January to March, with an average date of February 15. Depending on the type of operation, the cow herd can be confined as early as October/November through to May/June, a period of approximately 180 days with the pasture period being about 185 days.

During the confinement period which coincides with the animals third trimester and first 3 months of lactation a 1,300 pound cow would consume approximately 3.8 tons of good quality alfalfa/grass hay (42 lbs/cow/day) and 7 bushels of barley. Total feed cost for this period would be $242. This excludes the cost of additional feed supplements.

Calves are normally weaned in the fall and weigh approximately 600 to 650 pounds, depending on the breed of animal. Approximately 10 to 15% of the calves would usually be retained either as replacements or for further development due to quality reasons at time of sale (eg. light weights, off quality etc.). Calves retained for further development are normally sold in the February/March period.

To calve during this period an insulated barn and calving shelters are essential to protect cows and calves from the elements.


  • Calves can be weaned off grass in August/September and are available as 650 lb feedlot replacements.
  • Weaned calves are older/heavier and less stress prone for feedlots.
  • Minimal feeder calves over wintered.
  • Re-breeding can be controlled prior to cows going out to pasture.
  • Winter born calves can be finished before April to take advantage of stronger markets.
  • Labour commitments don’t interfere with other farm operations.
  • Calves garner a higher gross revenue at time of sale.


  • Infrastructure cost higher than other systems due to need for good calving facilities.
  • Labour intensive because calving in winter requires constant vigilance.
  • Manure buildup greatest due to confinement therefore removal costs are higher.
  • Increased feed costs due to cows lactating during winter and having to feed cows during her highest nutritional requirement period.
  • Extended pasture grazing (i.e. November) may not meet the cows nutritional requirements if the cow is in her third trimester.
  • Increased risk of neo-natal diseases due to higher animal density because of confinement.

Spring Calving

Spring calving herds usually calve in the months of April and May. The confinement period is similar to a winter calving operation. The difference between calving seasons is the feed requirements for the third trimester and lactation periods. In a spring calving scenario the nutritional requirements during these critical periods are lower due to warmer weather.

For this period which includes second and third trimester and lactation nutrition requirements for the cow, each animal would consume approximately 3.2 tons of good quality alfalfa/grass hay (35 lbs/cow/day) with no grain required, for a total cost of $192 (cost of minerals/vitamins excluded). Calves are normally weaned in the fall and weigh approximately 450 to 500 lbs, depending on breed type. Producers would expect to keep at least 30% of their calves for back for replacement or further development (light weights). Those not used for replacements can be sold in March.


  • Reduced infrastructure costs.
  • No calves suckling in winter conditions.
  • Moderate temperature improves comfort for both cattle and operator.
  • Least labour intensive system of all four.
  • Decreased feed costs since feeding the cow during lactation is for a shorter period than with winter calving.
  • Bigger calves can be marketed in November when the market is traditionally stronger.
  • Lower quality feeds (i.e. straw and byproducts) and extended grazing meet the cows nutritional requirements in her second trimester.
  • Less bedding required for the calves.


  • Interferes with mixed farming.
  • Finished calves may be marketed during periods of lower prices (i.e. June).
  • May need to background smaller calves which comes at an additional cost.
  • Spring storms can cause high calf mortalities.
  • Breeding season occurs during the hottest summer months which may affect conception.

Summer Calving

Summer calving herds usually calve in the months of June and July, with calves born on pasture. The confinement period is similar to a winter calving operation. For this scenario cows are fed heavier for approximately two of the six winter feeding months, because they are lactating.

Approximately 3.4 tons of good quality alfalfa/grass hay (lactating cow with calf 55 lbs/day; dry cow 30 lbs/day) will be required along with 4 bushels of grain during the lactation period. The total cost of feeding in confinement is $212 (supplements excluded). Calves are normally weaned (December-January) during the winter months weighing approximately 500 to 550 pounds, depending on breed type, at which point they are fed until reaching suitable health and condition to be marketed. This period of retention results in additional cost to the system.


  • Less labour and infrastructure required since cows calve on pasture.
  • Good quality summer pasture meets all the cow’s nutritional requirements.
  • Winter feed costs are reduced.
  • Calves are “hardened” by weather and usually trouble free to wean and start on feed.


  • Time commitments may overlap with other chores such as seeding, spraying and haying.
  • Predation and flies may be a challenge to calves.
  • May have to over winter calves.
  • Handling animals on larger pastures may be difficult.
  • Calves need to be tagged immediately after birth, otherwise may be difficult to locate on expansive pasture.
  • May have increased udder problems due to higher lactation yields.
  • Cows having calving difficulties maybe left too long or overlooked.
  • Suckling of late lactation cows require a higher investment in feed.
  • Difficult to pinpoint a good time to wean as the long cold stretches usually coincide with desired time to wean.

Fall Calving

Fall calving herds usually calve in the months of August, September and October and normally wean the calves in the spring weighing approximately 450 to 550 pounds, depending on breed type. These calves are normally pastured and supply the yearling grass-fed market.

In difficult years with challenging environmental conditions, such as drought or excess moisture, reproductive problems may occur. Conception rates may decline if quantity and/or quality of feed is limited, if elevated insect populations cause animals stress, and if muddy conditions make breeding difficult for herd bulls. Challenging conditions like these may cause cows that are normally fertile to remain open or become repeat breeders. In situations like this, it may be reasonable to consider keeping these open cows and repeat breeders and shifting them into a fall calving program rather than downsizing your herd.

The confinement period of 180 days includes the nutritional requirements to maintain pregnancy and suckle a calf. Therefore, the approximate stored feed requirements of the cow are 4.5 tons of good quality alfalfa/grass hay (50 lbs/day - with calf included) with 7 bushels of barley, for a total of $302 (excluding supplement costs).


  • Calves marketed as grassers in the spring when markets are traditionally stronger.
  • Cows pre-calving nutritional requirements can be met by pasture.
  • Cows may calve in semi-confined areas thus reducing neo-natal diseases and reducing labour requirements.


  • Must use stored feeds during the cows highest nutritional demand period (i.e. lactation) thus increasing feed costs.
  • Cows must re-breed while being fed stored feeds thus proper nutrition is critical.
  • Increased bedding requirements.
  • Interferes with mixed farming.


All management systems can be made to work. No one calving system has all the advantages, there is no one system that is right for everybody. Because the land resources, equity position, labour availability, wants and needs of the operator; are all variable - success is when an operator combines all the parts into a viable operation that meets their needs. Switching your calving season is a major farm decision. Consider the advantages and disadvantages carefully.