Projected heat stress challenges and abatement opportunities for U.S. milk production

Abstract

Cost-effective heat mitigation strategies are imperative for maintaining milk production and dairy farm profitability in the U.S. with projected climate change. This study investigated the cost-effectiveness of four heat abatement strategies, including Minimal (open barn or shading), Moderate (forced ventilation), High (fans and misting), and Intense (air conditioning). Heat stress and subsequent impacts on milk production per cow were predicted across nine climatic regions in the U.S. for early (2015 to 2034), mid (2045 to 2064) and late (2081 to 2100) 21 st century, using downscaled climate projections. Heat abatements were used to adjust predicted milk production losses and illustrate the potential to reduce milk production losses due to heat stress. Economic analysis included a cost-benefit ratio calculation associated with the implementation of each heat abatement. Results showed that milk production losses were expected to accelerate across the U.S. at a mean rate of 174±7 kg/cow/decade, with the fastest rate in the Southeast region. Relative to Minimal heat abatement, Moderate, High, and Intense heat abatements increased annual milk production per cow by 3%, 4%, and 6% during early-21 st century, 3%, 6%, and 11% during mid-21 st century, and 3%, 8%, and 21% during late-21 st century, respectively. The cost effectiveness of different heat abatement strategies generally increased with subsequently stronger heat abatements. In mid- and late-21 st century, mean annual net values of High and Intense heat stress abatement implementation approached -$30 to $190 /cow and -$20 to $590 /cow, respectively, with the largest net annual benefit in late-21 st century under Intense abatement. Findings from the study demonstrate the value of using downscaled climate projections to shed light on local and regional strategies to abate heat stress on cattle and mitigate potential milk production losses due to climate change.

Heat Stress Impacts Immune Status in Cows Across the Life Cycle

“…Because genetically altering the thermal tolerance of high producing animals is difficult (120), and there are many reviews that cover nutritional and metabolic responses and nutritional management for heat-stressed dairy cattle [i.e., (119,121)], this section will briefly review heat abatement by physical modification of the environment. A recent analysis predicts that the milk production loss due to heat stress increases at a rate of 174 ± 7 kg/cow/decade in the 21st century, but implementation of intensive cooling using fans, water or air conditioning minimizes the loss of milk yield and is associated with significant economic return for dairy producers (122). Therefore, heat abatement is an efficient and profitable approach to alleviate the negative impacts of heat stress and is the essential component of heat stress management on dairy farms.…”

Effect of heat stress on udder health of dairy cows

“…However, in extreme heat, providing shade alone is insufficient, since it has no impact on environmental temperature or relative humidity. In these circumstances, active cooling is required (St-Pierre et al, 2003;Tucker et al, 2008;Gunn et al, 2019). St-Pierre et al (2003) identified three different models of cooling system using fans and/or forced ventilation, combination of fans and sprinklers, and high-pressure evaporative cooling to abate moderate, high and intense heat respectively in the dairy farm.…”

Will dairy cattle production in West Africa be challenged by heat stress in the future?

“…Later, different equations were developed for different livestock species that could be used in heat stress impact studies. During the past decade, several studies tried to use different THI indices to assess heat stress conditions on dairy cattle under future conditions across global and regional scales (e.g., Hernández et al 2011;McCabe et al 2016;Gunn et al 2019). For example, Lallo et al (2018) investigated heat stress conditions for different livestock in the Caribbean and concluded that ruminants will experience higher heat stress under a future climate as compared with present-day conditions, and that this will threaten their productivity.…”