Most producers have heard the saying, "Once late, always late." And while there are females in any given herd that tend to calve at the tail end of the calving season year after year, records on my wife's ranch show them to be very few. Universities have, perhaps falsely, taught generations of producers that late-calving cows will continue to calve late and should always be culled. But, should producers routinely cull all late calvers?
My wife, Nancy, operates the Bath Ranch near Tie Siding, WY, in partnership with her sister, Bonnie. An average-sized Wyoming ranch, they have about 250 Angus-Gelbvieh cows.
Like many western ranchers, they summer their cows on federal lands which prevents a defined breeding season. They co-mingle their herd with another lessee who has a later breeding season, so bulls are present for at least 100 days. Although we'd like to limit our breeding season to about 60 days, this is not possible.
Overall pregnancy rates have averaged in the 96-97% range for the last several years. Even so, with an extended breeding season we're constantly faced with the decision of what to do with several late calving, but highly productive, younger cows.
Open cows and late calving, less productive cows are culled. However, younger cows with good production records are routinely kept if pregnancy examination shows they should calve within about 90 days of the start of the calving season.
Check Calving Records Records for all cows calving after 60 days from the start of calving were examined. About 10-15 cows per year were kept that fall into this category. Surprisingly, these cows averaged a gain of 36 days at the time of calving in the subsequent year (see Table 1). Two cows gained 72 days! Only five of the 92 cows represented calved later the following year (average loss of 18 days) and only six failed to get pregnant.
Bath Ranch's calves typically gain about 2.5 lbs./day on the cow. So, a calf born 30 days later than the main herd would be about 75 lbs. lighter and would bring about $65 less at current prices.
Costs For Developing Heifers Compare this with the cost of developing or purchasing a replacement heifer of unknown production history and with an equal or even higher probability of not getting pregnant. The later-calving but high-producing cow has about an 80% chance she'll gain at least two weeks and, on average, she will gain about five weeks. The chance that these animals will not get pregnant is certainly no greater than that of a virgin heifer.
Whether you could expect to have similar results in your own herd would depend on the condition of the cows at the time of calving and whether they're on an increasing plane of nutrition to provide for lactation and estrus.
On average, if you have good records, check the subsequent parturition dates on any late calvers that are retained. Depending on your level of nutrition, it will probably be cost effective to retain some of your tail-enders if they have been productive mothers in the past and are physically sound.