Location: Livestock and Range Research LaboratoryTitle: Early calving benefits livestock production under winter and spring warming
|Rinella, Matthew - Matt|
|Bellows, Susan - Bartlett|
|VAN EMON, MEGAN - Montana State University|
Submitted to: Rangeland Ecology and Management
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 1/18/2022
Publication Date: 2/15/2022
Citation: Rinella, M.J., Bellows, S.E., Geary, T.W., Waterman, R.C., Vermeire, L.T., Van Emon, M.L., Cook, L.A., Reinhart, K.O. 2022. Early calving benefits livestock production under winter and spring warming. Rangeland Ecology and Management. 81:63-68. https://doi.org/10.1016/j.rama.2022.01.003.
Interpretive Summary: Grasslands supply critical forage for livestock, and livestock are essential to food security. Whereas nutritional needs of growing livestock steadily increase, forage quality of grasslands steadily declines after the early growing season. This implies timing birth before the growing season could benefit livestock production by ensuring forage quality is elevated when young are heavier and need more nutrition, but this risks mortality from cold exposure. We found calving before instead of during the growing season increased calf production (survival probability × calf weight), with the benefits increasing over our 82-year study period as climate change reducing lethal cold. Managing birth timing to increase meat produced from grasslands reduces reliance on more economically and environmentally costly means of meat production.
Technical Abstract: Nutrient demand of young livestock increases steadily as they grow, while nutrient supply of grasslands increases then declines as plant tissues grow then mature and senesce over the growing season. For most livestock in the temperate zone, breeding is managed so that young are born late winter to mid-spring, roughly 60 d before to 60 d after the growing season begins. In many grasslands, timing birth early in this interval may benefit livestock production by ensuring plant nutrients are elevated when young are heavier and require more nutrition, but early birth risks exposing newborns to lethal late winter cold. We estimated effects of calving date on growth and exposure risk of beef calves using long-term data from the western U.S. Averaged over 82 years, our analysis indicated 180-d old calves weighed 0.4 ± 0.1 kg (mean, 95% CI) less for each day later they were born. This translated into calves born before (early March) instead of during (early May) the growing season weighing 11 ± 3% more when 180 d of age. Early March calving also benefited calf production (survival probability × survivor weight at 180 d of age), with benefits increasing as climate change reduced lethal cold. Compared to early May calving, calf production from early March calving was 7 ± 4% greater in the 1940s and 9 ± 4% greater in the 2010s (p<0.001). If warming continues as predicted, early calving will continue becoming more beneficial to calf production.