August 15, 2006


Summer heat affecting hogs in US corn belt



Scorching temperatures this summer in much of the western US corn belt and the Plains have hampered hog weight gains and production, and the decline in numbers may be felt even into 2007, according to numerous livestock sources.


While the blistering heat has affected all livestock, it has been particularly hard on hogs, which do not have sweat glands and are more susceptible to overheating.


When temperatures rise into the late spring and summer, hogs eat less, and daily weight gains are reduced. During periods of extreme heat, sows and boars can be affected, resulting in reduced conception rates.


Swine experts and other sources said breeding problems that are likely occurring now would affect slaughter-ready hog supplies late next spring and early summer, potentially raising hog and pork prices at that time. However, it is too early yet to tell how many sows or gilts are being affected.


It appears, however, that most of the breeding problems likely will occur in the western corn belt versus the east. Average mean temperatures in Indiana and Illinois during June and July were below normal, with data collected at central locations in each state down 1.3 and 1.6 degrees, respectively.


Many hog producers keep breeding animals cooler during the heat of the summer by using cool rooms with mist sprays and forced air units to evaporate the water and reduce temperatures.


The physiological makeup of the hog favours breeding during the cooler months, however, so swine producers may breed as many as 20 percent to 25 percent more sows and gilts during the hottest months of the year. This helps to offset the reduced conception rates so they will end up with the number of pigs they need to keep their grower and finishing facilities full.


The actual rates experienced at the farm sites can vary by geographic location, temperature and humidity levels, feed and supplement quality, along with the type and quality of management practices that are used, industry sources said.


David Stender, Iowa State University swine field specialist, said that lactating sows are generally affected more by the heat than are gilts. When it turns hot, the animals don't eat as much, and the lactating sows are not able to maintain body weight. They don't take in enough feed, plus they are producing milk for their pigs. After the pigs are weaned, it takes them longer to regain proper conditioning before being bred again.


Producers maintain a certain number of sows and gilts for summer breeding based on expectations of normal weather conditions. If the weather turns unusually hot, as which occurred this summer, the producers don't have enough time to pull even more females into the breeding group, so the result is fewer litters born and in some cases fewer pigs per litter.


Stender said that while he can remember other hot summers, it has been a while since it has been as hot as it has been this summer. The humidity also has been a problem, he said.