Search for simplicity when planning for calving season

Vet Advice with Dr. Ron Clarke

As Oliver Wendell Holmes said, “The chief work of civilization is making the means of living more complex.” In the cattle industry, striving for optimum production and managing change sparks a counter-impulse toward simplicity.

Preparing for calving season is always a chance to look for simpler ways. A big part of getting to “simple” is planning. Producers calve at a particular time of year because that’s how it’s always been done, or because it works best in a multi-enterprise operation.

The calendar for most cattle operations in Western Canada is tied to the reality of feeding in confinement, or at least under controlled conditions, for 180 days, and grazing for 185 days. Three pivotal events typically appear on all production calendars: breeding, calving season, weaning. Other operational decisions are interspersed among these events.

A common question of producers is: “Should I switch calving seasons?” Initiating change in calving seasons isn’t easy. The to-do list can be extensive, but none more important than keeping the calving interval as short as possible. For a producer to ensure each cow calves every 12 months, they need to rebreed within 83 days after calving. The calving interval is greatly influenced by nutrition and health. If not managed properly, calving intervals backslide. Choosing a calving season that allows the producer to couple change with maximum fertility is essential and should involve discussion with a veterinarian.

Defining the calving period and setting clear objectives for reproductive performance and maximum health using a three-year target is achievable. Disappointment often follows change planned inside three years.

Shifts in calving seasons are riveted on heifer replacement. Success depends on front-loading the breeding season, which calls for the majority of cows and heifers cycling through the first 21 days of breeding season. If first-calf heifers have their second calf in the first 21 days of the subsequent calving season, they probably stay in the herd and become an important part of building positive momentum. Heifers calving in the first 21 days of six successive calving seasons, produces the equivalent of an additional calf over her productive lifetime. It’s imperative producers pay close attention to the genetic selection and management of future “breadwinners,” especially when one considers it takes about three years for a heifer to contribute to the positive side of the ledger.

Front loading the breeding season should result in a front-loaded calving season if health, bull power and nutrition are looked after, but it doesn’t always work that way. Calving two-thirds of bred animals in the first 21 days of the calving season is neither easy, nor quick. It starts by culling deeply for late pregnancies, bad eyes, poor udders and bad feet. Replacement heifers should be selected from the pool of potential replacements born early in the calving season.

Moving calving seasons will not fix systemic problems (disease, poor bulls, inadequate nutrition, and cows with low body condition scores). There are no one-time solutions for an irregular or prolonged calving season without fixing systemic problems. Disease issues, timing of vaccination programs and bull problems require discussion with a veterinarian. Nutrition becomes the major manageable component.

In the opinion of Kansas State University veterinarian Brad White, building reproductive momentum begins at weaning. Fifteen to 20 per cent of breeding females are replaced annually in most cow herds. Replacement heifers represent the future and ultimate profitability of an operation.

Calving seasons fall into four periods on the calendar: Winter (January, February, and March); spring (April and May); summer (June and July); and fall (August, September and October).

Winter calving is associated with the highest infrastructure costs followed by spring and fall calving (about 20 per cent less). Summer calving requires the least investment in facilities, about 25 per cent less than winter operations.

Total labour requirements for a cow-calf operation would be greatest for winter calving, fall calving requires 10 per cent less, followed by spring calving at 20 per cent less, and summer calving the lowest at 25 per cent less labour than wintertime calving.

All management systems can be made to work. No one calving system has all the advantages, and there is no one system that is right for everybody. Switching calving seasons is a major farm decision.

Principles that apply to all calving systems include:

  • Managing feed resources requires feed analysis. You can’t manage what you haven’t measured.
  • Optimal disease control and use of feed resources require separating cows into groups.
  • Do not underestimate the importance of basic biosecurity — start clean, stay clean.
  • Have cows go into calving season with a BCS of 2 to 2.5 and heifers at a BCS of 2.5 to 3. Mineral and energy needs post-calving increase rapidly.
  • Know what things affect future reproductive potential. Work with a veterinarian.
  • Ensure calves receive five per cent of their birth weight of high quality colostrum (1.8 to two litres for a 75 pound calf) before they are 12 hours old.
  • Cull deep! Assume things like early cancer eye, chronic lameness and pendulous udders are only going to get worse on pasture.
  • Ask your veterinarian if vaccination programs need adjustment. Herd expansion involving large numbers of replacement heifers usually requires a rethink on BVD vaccination programs. When buying replacements, question suppliers about vaccination and herd health programs, including biosecurity practices and efforts to prevent or control Johne’s disease.
  • The most common cause of a drop in reproductive performance is the lack of dietary energy and protein. Monitoring body condition is critical.
  • Calving season should not span more than the equivalent of two cow cycles (6 weeks) if bull power was optimal and cows went to the breeding pasture in good condition.

About the author


Dr. Ron Clarke prepares this column on behalf of the Western Canadian Association of Bovine Practitioners. Suggestions for future articles can be sent to Canadian Cattlemen ([email protected]) or WCABP ([email protected]).


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