There is never a time in broiler production where there aren’t challenges facing producers in some form or fashion. Many challenges – whether they are nutritional, health, or management related – tend to be seasonal. Fall is typically a favorite season for many producers, lending optimized weather conditions for broiler growth. But hot summer temperatures bring on a new set of obstacles.
Heat stress, for example, is a concern in the summer – especially when hot temperatures are combined with high humidity. The optimal temperature for raising broilers is between 65°F and 75°F. In this temperature range, birds remain in their thermoneutral zone. In the thermoneutral zone, broilers can maintain their core body temperature without altering feed intake, behavior or metabolism. Body heat production is also at its lowest in this zone. When the temperature reaches beyond the upper range of the thermoneutral zone, birds are unable to dissipate heat without expending extra energy. Instead, heat loss occurs through panting or evaporative cooling. Additionally, birds may exhibit signs of heat stress such as lifting wings away from the body to reduce insulation, increasing water intake and reducing activity – including eating. There are also other physiological changes such as increased blood corticosterone, reduction in thyroid hormones, increased oxidative stress, increased inflammatory cytokines, increased blood pH (respiratory alkalosis), alterations in intestinal microflora, reduction in blood flow to the intestines and other internal organs and loss of intestinal integrity. Ultimately, in addition to being a welfare issue, heat stress leads to economic loss from decreased performance, reduction in meat quality and increased mortality.
In addition to heat stress, there are also health management considerations in the summer. Producers usually switch to a different coccidiosis control program, for example. It is important to know which coccidiostats are best for summer. Coccidiosis vaccines are also quite common, but require attention to management and can be associated with secondary disease conditions.
As with health, there are also nutritional considerations. Summer weather presents optimal conditions for mold growth providing exposure to adequate moisture and heat. If not controlled, mold growth can lead to a decline in feed quality through loss of nutrients and vitamins. Additionally, molds can produce mycotoxins which lend their own detrimental effects, including loss of intestinal integrity and impaired immunity. There is also the risk of feed rancidity which can reduce the fat energy levels in the feed, as well as the availability of fat-soluble vitamins.
Although we face many of the same issues year to year and summer to summer, here are a few reminders on how to combat summertime challenges through management, nutritional and health interventions.
