While crops could be impacted by climate change, it is likely that farm animals would be even more susceptible to changes in the climate.
It is expected that increased air temperatures will cause more stress on livestock. Both humans and livestock are warm-blooded animals, so both are affected by increased heat and humidity. During stifling heat, livestock reproduction declines as well as their appetite. Decreased appetite will lengthen the time needed for the livestock to reach their target weight (most animals only eat about half of normal quantities when they are heat-stressed). Stress can also increase the incidence of sickness, decrease rates of reproduction, and increase fighting among animals in confinement. In some areas, night-time temperatures are even more above average than daytime temperatures during heat-waves, which has resulted in increased mortality rates. Despite the warmer winter temperatures, global warming could have a negative overall impact upon livestock.
As indicated above, increased carbon dioxide may result in feed and forage that is less nutritious even if there is more of it. It is likely that growers would be forced to use feed additives in order to see the expected growth gains in livestock, and to avoid illnesses. This increased cost to the grower would result in increased food costs to the consumer. Availability could also decrease if there is not enough water and nutrients in stressed soils to keep up with plant growth.
Insect parasites and diseases could also become more prolific as global warming progresses. New diseases may also emerge in the Southeast that were once considered to inhabit only tropical areas. It is expected that in cases of increased heat stress and humidity, most livestock will not be able to fight these diseases without the use of costly medicines.