Cold Stress in Sheep and Goats
As I write this in mid-January, we have just had a cold snap the last several days without temperatures climbing above freezing. Most all of the ag news and coffee talk revolves around the weather and what actions are being taken to keep animals healthy and productive.
My perspective of cold weather is slightly different from most Texans, as I completed my PhD in Montana and worked as an Extension Sheep Specialist in North Dakota for 5 years. The lessons that I learned from living and working in these environments has really shaped how I look cold weather and management of livestock during these weather events.
There are several factors that I consider when making management decisions for sheep and goats during harsh weather events. The class, age, production stage, and condition of the animals are important to consider.
More importantly, the type of weather event and environment that the animals have access to alters how it will affect them. Temperatures are important to consider but wind and moisture can drastically change how cold weather will affect the animals. Wet animals that are exposed to wind are much more susceptible to acute and chronic cold stress. Natural or man-made shelters from the wind and rain are very beneficial to protecting animals from harsh weather. Lucky for us, much of the rangelands in West and Central Texas have plenty of brush and trees that animals will use for protection.
Mature animals that are in good body condition with a healthy hair or wool coat can withstand temperatures well below freezing without any acute health conditions. They will start to use use body resources to maintain body temperature. As long as quality feed resources are available to them, most ranchers will not see any negative effects on animal health or performance.
Mature animals that are under conditioned, recently shorn, or have high demands for nutrients to support a growing fetus or lactation are at a higher risk of cold stress. It is important to provide adequate protection from weather events and supplemental feed to keep these animals healthy.
Newborns are at higher risk to cold weather. First of all, they are born wet from birthing fluids which causes rapid heat loss. They are born with a different type of fat, called brown fat, that can rapidly be mobilized to maintain body temperature. But these energy resources can be depleted within a few hours. Therefore, it is important that they are up and receive colostrum from their mother before they run out of this body reserve. Colostrum is rich in fat and energy to fuel their ability to stay warm. If they are unable to do this, they’ll become lethargic from low body temperature and lose the ability or desire to stand or nurse. In this case immediate action is needed to bring up their body temperature and supply milk or milk replacer, in that order.
Water is the most important nutrient for livestock. As such, ranchers spend a lot of time during these weather events breaking ice from water troughs. But is this necessary? One of the unique aspect of sheep and goats is their ability to survive and thrive with fairly low amounts of water during the winter. In Texas we are blessed to have green forage year-round, as long as their has been come rain events to support this. Sheep and goats that are grazing winter weeds, annual grasses or perineal cool season grasses during the winter may not need additional water or only consume water every couple days.
This may explain why ranchers get frustrated with sheep and goats, as they won’t drink water after we brave the cold weather to bust ice out of the troughs. However, if ranchers are supplementing dry feed such as hay or pellets, these animals may need supplemental water to support normal digestion and hydration. In these cases, they animals should voluntarily consume water.
In my experience, weather events that are below freezing are not near as detrimental to sheep and goats as many people perceive. I worry about cold rainy events with temperatures at or slightly above freezing than I do about sub-zero weather events. Good management prior to these events are more important than the actions that are taken during the event itself. Keeping animals in the proper body condition, providing access to shelter, access to water (if needed), planning shearing events to avoid exposing freshly shorn animals to cold, wet, and windy conditions, protecting newborns from harsh weather, and adequate nutrition during harsh weather are factors that can allow Texas ranchers to weather most any storm mother nature throws at us.
To provide feedback on this article or request topics for future articles, contact me at reid.redden@ag.tamu.edu or 325-657-7324. For general questions about sheep and goats, contact your local Texas A&M AgriLife Extension Service county office. If they can’t answer your question, they have access to someone who can.