WHILE colder temperatures mean that livestock producers need to be aware of increased livestock energy requirements, those animals that may be thinner because of the drought over the summer could need extra energy supplements sooner, Ohio State University Extension educator Rory Lewandowski said.
Cold temperatures, cold rains and muddy conditions can significantly increase the energy required by livestock metabolism to provide enough heat for the animal to maintain its body temperature, said Lewandowski, an agricultural and natural resources educator.
However, those animals that have poorer body condition and less body fat as a result of grazing on drought-affected pastures may need to have that additional supplement sooner in order to produce the energy needed to weather the cold period, he said.
Animals in good body condition can call on fat reserves, but if they are in colder temperatures for longer periods, they need the increased energy content in rations to help them alleviate cold stress, Lewandowski said.
"Every year, going into the winter means that producers have to take into account weather conditions," he said. However, "in a drought year like this, we have to look at what kind of body conditions livestock" are in before the cold hits.
"If the herd is pasture based, those animals may be coming into winter in thinner body condition because earlier drought conditions caused pastures to dry up and didn't offer as much forage for livestock. Producers have to evaluate their herds' body conditions and whether those animals can go through adverse weather," he added.
Animals have a thermoneutral zone -- a temperature range in which the animal is most comfortable and not under any temperature stress and that is considered optimum for body maintenance, health and animal performance. When livestock experience cold stress below the lower boundary of that zone, they reach lower critical temperature (LCT), and their metabolism must increase in order for the animals to keep warm, Lewandowski said.
"That means the animal must increase its energy intake to maintain body temperature and basic body maintenance functions," he said. "Generally, energy intake must increase by 1% for each degree of cold below the LCT."
Animals that are fed average- to good-quality hay are more likely to be able to increase intake enough to meet the additional energy demands, but those being fed low-quality forage are unlikely to be able to increase their intake enough, Lewandowski said.
"If poor-quality forage is the only forage option or if there is an extended period of extremely cold weather, then some additional energy supplementation is necessary for the animals," he said.
Producers should keep in mind that LCT is influenced by an animal's size, age, breed, nutrition, housing conditions and hair coat or wool thickness.
The thicker the hair coat or wool, the more LCT decreases, he said.
"With a wet hair coat, regardless of how heavy it is, the LCT increases to 59 degrees F as hair coats lose their insulation ability when wet," Lewandowski said, referring to cattle, horses and goats.
Wool is able to shed water.
"For most livestock, it really is a matter of adapting to the weather," he said. "Cattle will adapt to cold with a thicker coat if they have the feed source, and ensuring that livestock are blocked from the direct force of the wind will help protect them from wind chill."
Breeding livestock that are subjected to prolonged periods below their LCT may experience reproductive issues, while other livestock classes will have reduced gains or even will lose weight, Lewandowski said.