406 Impacts of drought on long term cow-calf productivity and potential management strategies for producers to overcome these challenges

Abstract Our climate in North America has shifted to what appears to be a dry cycle reminiscent of the 1930s and 1950s. There are predictions of extended periods of drought and other climate perturbations interspersed with short periods of respite. Drought conditions in the High Plains and Southeastern U. S. in 2011 and 2012 resulted in destocking of cow-calf operations leading to shortages in feeder cattle supplies and record prices in 2015 and 2016, but these high prices were short lived with rapid rebuilding of the cowherd and return to stable cattle numbers. The drought that started in areas of the High Plains in 2021 and intensified throughout the region in 2022 and 2023, has again resulted in massive culling and destocking of the cowherd. Today the U.S. beef cowherd, estimated at just over 28 million cows, is the lowest since 1961. Relief from the low cattle numbers is not in sight because heifer retention numbers are also the lowest since 1950. The reduced cow numbers limit the potential calf crop and available feeder cattle supplies, but the issues can be more intrusive and have long term implications. Data from multiple cowherds in Northwestern Oklahoma (R. Prather, DVM; Ellis County Hospital, Shattuck, OK) shows reductions in AI and overall pregnancy rates as body condition decreases after timed artificial insemination and during natural service breeding in range cows. There are also indications of reduced fertility of replacement heifers retained from these cows in the subsequent year following nutritional and heat stress during pregnancy. Decreasing body condition of cows during late pregnancy decreases the volume and concentration of immunoglobulins in the colostrum, leading to long term health consequences on the offspring. With limited forage resources, calves tend to skip the stocker phase of production and enter feedlots for finishing at younger ages and lighter bodyweights. Research has shown that feeding younger calves decreases performance and body weight at slaughter and produces lighter fatter carcasses. Cows maintained on western rangelands with limited hay feeding are much more susceptible to changing forage conditions than cows maintained in more intensive operations in the eastern U. S., but mature weight of cows is increasing in all regions of the U. S., effectively increasing stocking rates and reducing resilience. Research in Arkansas showed that smaller cows weaned heavier calves and produced more weaning weight per hectare than larger cows during dry years with limited forage availability. Pasture and livestock management plans and nutritional intervention need to be in place in a timely manner to prevent swings in cattle numbers and negative impacts on long-term productivity of feeder calves in response to drought and other climate stressors.