The date for turning bulls in with the cows is one of the hardest decisions for a cow/calf operator. Before making this decision, every aspect of your management practices should be studied. The two best options for calf delivery are when forage is most abundant and nutritious or when the market is usually at its annual peak. Caution and considerable thought need to be employed in choosing one of these options because calving dates are not easily changed.
Lee Manske of the Dickinson North Dakota Research Extension Center said that nutritional values for grass from early May to the end of the grazing season in October have a defined pattern. Crude protein percentage starts high at more than 17 percent in May and slowly decreases during the grazing season to less than five percent by fall.
“Peak lactation requirements are one month after calving, so it makes sense to have cows with month-old calves on a high-protein pasture in May,” reported Kris Ringwall at North Dakota State University. “Decrease in pasture protein production will coincide with the gradual decline in cow and calf protein requirements. Dates of high protein production in forage are location dependent, so every producer needs to get access to the numbers for his or her geographical area and environment.”
If you have good winter pasture, then calving to coincide with peak market values is a good option. The seasonal price index for 500 to 600 pound Texas feeder steers from 1989 through 1998 show the highest prices occurring in March, April and May. The lowest prices occurred in September through December. Ernest Davis, et al. explained that this pattern is logical because approximately 76 percent of the annual calf crop is born in the first six months of the year. There are short supplies of 500- to 600-pound calves during that period, but larger supplies are available after August when fall weaning and marketing begin.
Whether the goal is to breed cows to take advantage of peak forage protein production or seasonally high market prices, calving has to occur during a relatively short period of time to be successful. Bruce Carpenter, Extension Livestock Specialist at Fort Stockton, Texas said that when the calving season is too long, management is more difficult and many cows will not calve every year. Shorter calving seasons make the bottom line better because both herd management expenses and marketing income are controlled more easily.
“Cows are pregnant for about 285 days of a 365-day year,” Carpenter continued. “There is not much time left for reproductive tract recovery and subsequent rebreeding. If cows are to calve every 12 months, the calving season can be no longer than 80 days per year (365-285=80). Thus, a calving season of 80 days would be followed by an 80-day breeding season.”
Once a calving period has been selected, the next step is to determine what percentage of the herd is calving outside of the desired months. This can be done by recording calving dates for individual cows or by rectal palpation. Most cattle naturally breed at the time of the year when forage nutrition is best. So if this is your target, getting the herd on a controlled schedule is often just a matter of culling a few animals. The culls would be those females calving at the wrong time and those that do not calve consistently. The key is to replace culls with heifers or cows that are bred to calve slightly before, or near the start of, the desired calving period.
“If a large percentage of the herd is calving in undesirable months, there may be two options,” said Carpenter. “One option is to slowly tighten the breeding season over a period of three to four years, replacing culls with heifers or cows bred to calve before or near the start of the desired period. The second option is to split the herd into two herds (typically spring and fall calving cows) and add replacement animals to only one herd. Attrition will eventually take care of the herd that is calving at the undesired time.”