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Cold weather conditions can create a challenge for cattle. Balanced feed formulations developed for cows in mild or warm conditions will be unsuitable when those animals experience cold weather or cold stress; weight loss and reduced performance can result. Animals undergoing cold stress require more energy and feed to maintain body condition and body temperature, as well as performance in terms of growth, gestation, and lactation.
What is the lowest temperature threshold a cow can withstand?
The low critical threshold temperature for most beef cattle in Alberta is at -20°C, assuming calm conditions and that animals have a dry winter coat. This threshold is higher when cattle still have the summer coats. Progressively windier conditions push this threshold higher; for example, with a 20 km per hour wind, a cow's lower critical temperature threshold would be more around -6°C. Also, fatter cattle have a lower critical threshold temperature than thin cattle.
During cold weather, does the breed of the animal have any effect on energy requirements?
Breed affects energy requirements for cattle somewhat, primarily with hair coat thickness and metabolic rate. Skin thickness has no effect; Shorthorns and Angus have thinner skin than Herefords, however are as acclimatized and require the same energy requirements as Hereford cattle. Brahman cattle have thick skin, however are not as cold tolerant as the aforementioned breeds because it is adapted as a tropical breed.
Certain breeds do have thicker hair coats than others, such as with Galloway and Scottish Highland cattle, which usually reduces their need for additional energy during cold weather.
Cattle with higher metabolic rates use more energy and require more energy or risk losing weight, than those with lower metabolic rates. Breed type has some influence on metabolic rates, such as with Simmental and dairy-type cattle versus most beef breeds, however it will also differ more or less between individual animals within a breed, than between breeds.
How does body condition affect energy requirements during colder temperatures?
Body condition score also has a great effect on energy requirements. Thinner cows (with less than a body condition score (BCS) of 3 out of the Canadian scoring range of 1 to 5, 1 being most emaciated) require more energy for maintenance and productivity than moderate or fat cows (BCS of 3 or higher). Moderate-conditioned to fatter cattle have more insulation with increased fat cover compared with thin cows, so they can withstand colder weather and have lower energy requirements.
How does the cold weather affect a lactating cow's energy requirements?
Normally, in mild and warm weather conditions, lactating cows require about 25 to 30% more energy than when they are in gestation. In colder weather conditions this differential is greater, with lactating cows requiring 40 to 60% more energy than if they were dry and pregnant. Lactating cows in these cold conditions need the additional energy because they have to maintain their body condition and produce milk for their calf while withstand the cold. They increase more so when cold conditions dip below their lower critical threshold levels and especially when the wind picks up.
What other factors affect a cow's energy requirements in cold weather?
Acclimatization is important, because cattle that are raised primarily indoors where temperature is controlled are more likely to become cold-stressed than cattle that are raised outdoors all year round; this is because they have not been able to grow a thicker hair coat in response to increasingly cooler temperatures.
Metabolic rates tend to increase as well when the weather gets colder; this is a way for the cow to increase heat production to maintain body temperature. When metabolic rates increase, there is a greater need for dietary energy, as well as a rise in daily feed intake.
Hair condition will also affect energy requirements of cattle; Cows that have mud-caked or wet coats will have higher energy requirements because the insulating properties of a winter coat will be greatly reduced, making them more susceptible to cold stress.
How much additional energy should a cow get to meet her increased energy requirements during cold weather?
A general rule of thumb to use is for every 10-degree drop below -20°C at noon, a beef cow will need an additional 3 to 4 Mcals of digestible energy. In other words, because barley contains about 1.5 Mcals of DE per pound, adding 2 pounds of barley to the ration for every 10-degree drop will be sufficient to meet her requirements. Cows will also need additional energy when wind speed increases to more than 5 to 10 km per hour. Grain rations over 10 pounds a day should be split into two different feedings–morning and evening–otherwise rumen-upset may be experienced if cattle are eating over 5 to 6 pounds of grain at one time. Cattle that are being first introduced onto grain will need to be introduced slowly over a period of 5 to 10 days.
Even though cows can also generate energy with rumen activity with digesting roughages like hay or straw, there still is energy lost with this process that needs to be reclaimed in the diet. Often hay and straw does not have enough digestible energy to compensate for this loss, thus grains like barley need to be fed so that cows can maintain their energy requirements.
Energy requirements during cold weather are determined by hair coat condition, and body condition. For example, a cow in moderate condition with a clean, dry winter hair coat will have lower energy requirements during a cold winter storm than if her coat were wet and matted or covered in mud. If this cow were in poorer condition (BCS 2.5 or lower), energy requirements would be higher still, no matter what condition her coat would be in.
It is important that cows have access to higher-quality feed (not straw, as this has a low protein content), or have access to additional feed during cold conditions. Otherwise, if lower quality feed does not allow them to eat enough to meet their energy requirements, body reserves will be used up to produce metabolic heat. Cows lose weight as both feed energy and stored fat are diverted into maintaining core body temperature and vital functions. Cows get into a down-ward spiral; the more weight they lose, the less insulation they have, and the more susceptible to cold they get, then the faster they lose weight.
How does a cow's intake level change during cold weather?
For a cow in normal body condition (BCS 3) with a dry, clean winter coat, dry matter intake levels can increase from 5 to 30% or more. This is because a cow's metabolic rate has increased in response to colder conditions. In increased metabolic rate increases a cow's appetite, which in turn increases rate of passage of feed. This is an adaptive response to colder conditions; cows can increase internal heat production via rumen activity or fermentation, which decreases their risk of cold stress. An increase in a cow's internal heat production reduces her lower critical threshold temperature.
Some cold weather conditions, like severe winter storms with high winds, can suppress intake because cattle are more concerned with trying to stay warm than eating. Wet and matted hair coats, or cattle covered in wet snow or mud can also suppress intake because of the cold stress they are experiencing.
Can cows digest feeds more efficiently in cold weather?
Efficiency of digestion is actually reduced with cold weather and cold stress. This is mainly because rate of intake has increased. When cattle eat more, the feed spends less time in the first two stomach chambers (reticulum and rumen) and passes through more quickly. Nutrients are more likely to escape microbial breakdown, making it more available to the cow. Protein can be reduced during cold events because of this, particularly when more protein is available for absorption in the small intestine.
What are some other management strategies that can be used to combat cold weather and limit the effects of cold stress in cattle?
There are several more strategies you will need to know to help your animals in cold conditions:
- Monitor weather conditions and act accordingly. Monitor temperature changes so you can have more feed available to cattle in colder weather conditions.
- Ensure there is enough shelter from the wind. Effects of cold stress increase when wind speed increases. Any kind of available protection, whether it is natural (bush, valley bottoms or hillsides) or man-made (such as simple windbreak fences or shelters) can be highly valuable in helping cows cope with extreme temperatures and wind-chill effects.
- Provide bedding to help keep cattle clean and dry. Bedding, such as barley straw, will make a significant difference in how cattle can withstand cold stress. Provide enough so that all animals have access, and so that it is about a foot thick, or thick enough animals can lay comfortably. Depending on weather conditions, bedding may need to be added every two to three days; sooner if a significant amount of snow fell soon after bedding was spread out. Cattle will experience a 25 percent energy loss if they are lying on snow.
- Provide additional feed. Increase grain and hay for when temperatures drop below the lower critical threshold level.
- Feed later in the day or evening. Incremental heat production (energy from feed available to produce heat and keep the animal warm) peaks at 6 to 8 hours after cattle eat. Feeding in late afternoon or early evening provides additional warmth from fermentation activity in the early morning (or around 4 to 6 a.m.) when temperatures are at their lowest. This makes for better use of your feed supplies and meet your animals' higher energy requirements at a time when it is most needed.
- Provide water. Make sure animals have ample water available at all times. A limit in water available will limit feed intake and make it more difficult for cattle to meet their energy requirements. Frozen troughs and excessively cold water can severely limit water intake.
- Sort off thin cows for more specialized care. Sorting off thinner cows from the rest of the herd allows you to feed them differently and eliminate competition from bigger and bolder cattle. Thinner cows need more energy to cope with colder conditions, and will also have higher nutrient demands when they get ever closer to calving and into lactation. Separating them from the bigger cows allows them the chance of gaining weight, and even gives the bigger, fatter cows the ability to lose excess or maintain weight. This, overall, will make the best use of existing feed inventories.
Body Condition Scoring Your Cow Herd
Cold Stress in Cows- NutrecoCanada
Winter Management of the Beef Cow Herd - NDSU
Refernces:
Chistopherson, R.J., & B.A. Young. 1986. Effects of Cold Environments on Domestic Animals
In: Gudmundson. O. (ed.) Grazing Research at Northern Latitudes. Plenum Publications, London. P. 247-237
Schwartzkp[f-Genswein, K.S., K.A. Beauchemin, T.A. McAllister, D.J. Gibb, M. Streeter, & A.D. Kennedy. 2004. Effect of feed delivery fluctuations and feeding time on ruminal acidosis, growth performance, and feeding behavior of feedlot cattle. Journal of Animal Science. 82:3357-3365.
Young, B.A. 1981. Cold Stress as it Affects Animal Production. Journal of Animal Science. 53.1:154-163
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