Effects of climate change on livestock/ja: Difference between revisions

A follow-up paper considered the impact of several adaptation measures. Installing a [[ground-coupled heat exchanger]] was the most effective intervention at addressing heat stress, reducing it by 90 to 100%. Two other cooling systems also showed substantial effectiveness: [[evaporative cooler]] pads made of wet [[cellulose]] reduced heat stress by 74 to 92%, although they also risked increasing [[wet bulb temperature]] stress as they necessarily moistened the air. Combining such pads with [[regenerative heat exchanger]]s eliminated this issue, but also increased costs and reduced the effectiveness of the system to between 61% and 86%. All three interventions were considered capable of completely buffering the future impact of climate change on heat stress over at least the next three decades, but installing them requires substantial start-up investments, and their impact on commercial viability of the facilities is unclear. Other interventions were considered unable to fully buffer the impact of warming, but they were also cheaper and simpler by comparison. They include doubling the ventilation capacity, and having the pigs rest during the day while feeding them at night when it is cooler: such a 10-hour shift would require that the facility only uses [[artificial light]] and switch to predominantly [[Night working|night shift]] work. Similarly, stocking fewer pigs per facility is the absolute simplest intervention, yet it has the lowest effectiveness, and necessarily reduces profitability.

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=== Poultry ===

[[File:DSC00187_(4018480068).jpg|thumb|left|Photo of an egg farm in [[New England]], taken around 2009]]

It is believed that the thermal comfort zone for poultry is in the {{convert|18-25|C}} range. Some papers describe {{convert|26-35|C}} as the "critical zone" for [[heat stress]], but others report that due to [[acclimatization]], birds in the tropical countries do not begin to experience heat stress until {{convert|32|C}}. There is wider agreement that temperatures greater than {{convert|35|C}} and {{convert|47|C}} form "upper critical" and lethal zones, respectively. Average daily temperatures of around {{convert|33|C}} are known to interfere with feeding in both [[broiler]]s and egg hens, as well as lower their [[immune response]], with outcomes such as reduced weight gain/egg production or greater incidence of [[salmonella]] infections, [[footpad]] [[dermatitis]] or [[meningitis]]. Persistent heat stress leads to [[oxidative stress]] in tissues, and harvested [[white meat]] ends up with a lower proportion of essential compounds like [[vitamin E]], [[lutein]] and [[zeaxanthin]], yet an increase in [[glucose]] and [[cholesterol]]. Multiple studies show that dietary supplementation with [[chromium]] can help to relieve these issues due to its [[antioxidative]] properties, particularly in combination with [[zinc]] or herbs like [[wood sorrel]]. [[Resveratrol]] is another popular antioxidant administered to poultry for these reasons. Though the effect of supplementation is limited, it is much cheaper than interventions to improve cooling or simply stock fewer birds, and so remains popular. While the majority of literature on poultry heat stress and dietary supplementation focuses on chickens, similar findings were seen in [[Japanese quail]]s, which eat less and gain less weight, suffer reduced [[fertility]] and hatch [[egg]]s of worse quality under heat stress, and also seem to benefit from mineral supplementation.

Around 2003, it was estimated that the poultry industry in the United States already lost up to $165&nbsp;million annually due to heat stress at the time. One paper estimated that if global warming reaches {{convert|2.5|C-change|F-change}}, then the cost of rearing broilers in Brazil increases by 35.8% at the least modernized farms and by 42.3% at farms with the medium level of technology used in livestock housing, while they increase the least at farms with the most advanced cooling technologies. On the contrary, if the warming is kept to {{convert|1.5|C-change|F-change}}, costs at moderately modernized farms increase the least, by 12.5%, followed by the most modernized farms with a 19.9% increase, and the least technological farms seeing the greatest increase.

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=== Reindeer ===

By mid-2010s, indigenous people of the Arctic have already observed [[reindeer]] breeding less and surviving winters less often, as warmer temperatures benefit biting insects and result in more intense and persistent swarm attacks. They also become more susceptible to parasites spread by such insects, and as the Arctic becomes warmer and more accessible to [[invasive species]], it is anticipated that they will come in contact with pests and pathogens they have not encountered historically.

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