On a blue-sky day at the foot of the LaPlata Mountains, Douglas Zalesky, superintendent of the San Juan Basin Research Center walks among one of his two herds of cattle. The calves are small for late August, but they're supposed to be. The calves are part of a five-year experiment to test the efficacy of late-season calving at the San Juan Basin Research Center near Hesperus. The study is an example of how the research center is conducting management research to mimic a commercial ranch. "We are doing more systems-type research to study how resources intertwine," says Zalesky.
Traditionally, cows are bred to calve during March and April to get steers ready for market as early in the year as possible. "March and April is about as early in the spring as ranchers can get away with," according to Zalesky. However, calving so early in the spring may come with a price of increased feed, labor, machinery, and health costs.
Zalesky theorizes a later calving season in May and June will offer ranchers some economic gains. A cow's nutrient requirements are highest right after calving. Little forage is available during the traditional March and April calving season, so ranchers must feed their herd hay and alfalfa. By May and June, natural forage availability and its nutrient content are much better. The herd's feed may need to be augmented in the fall, but the herd's nutrient demands are lower at that stage of development than in the spring. The later calving season may be a better match between cow nutrient requirements and forage nutrient production. This should reduce the costs of feed and the labor of getting the feed to the herd.
In addition, similar studies done in Nebraska have indicated a lower incidence of calf illness and fewer deaths associated with a later calving season. The ultimate market price for steers may be better with late-season calving as well. "By selling later, there can be an advantage as prices rebound after the flood in the market in October and November," says Zalesky.
To test the theory, Zalesky randomly divided in two a herd of cattle at the San Juan Basin Research Center in May 2001. One herd was bred to calve in the traditional March/ April season and the other in May/June. Over five years, the herds will stay separated and repeatedly bred for their corresponding calving season. The calves from both groups will be weaned at seven months. Heifers born to each herd will remain as replacements.
Zalesky will record and analyze statistics on breeding, calving, weaning, and health. He will track nutrient content of the forage and the amount of hay produced at the research center and its nutrient content. Economic variables including the amount of hay fed, and its cost, labor costs, health costs, and net values of calves will be evaluated. So far in 2002, Zalesky has had to feed approximately one-third less hay to the late calving group as compared to the traditional herd.
The drought is setting back the study because of the lack of natural forage. At the research center's 7,500-foot elevation, there are only about 100 days to grow feed. Zalesky thinks the later calving season will optimize this short growing season typical of the Four Corners region. Since the San Juan Basin Research Center's study is similar to a commercial ranch, the results of the study will be readily applicable to the region's ranches.