Managing the Feedlot in the Cold
By John M. Kelly, Ph.D.
The writer is Manager of Technical Services with Land O’Lakes Farmland Ontario
Winters in Ontario over the past few years have been variable. Last year, we went through temperatures that were higher than normal and indications are that this years average temperatures will be on average above normal, however there were periods when temperatures were very low, particularly during the month of January. Temperature fluctuations that are seen under Ontario conditions can be very stressful to feedlot cattle. While we cannot change the weather, we can implement some management and production techniques that increase cattle comfort and keep cost of gain figures from increasing.
Watch out for cold stress
Cattle, like other mammals, must maintain their core body temperature (about 38o C). Thermoregulation is the means by which an animal maintains its body temperature by either heat gain or heat loss. When cattle are stressed by the cold, their metabolic rate increases in an effort to maintain body temperature. Many environmental factors influence nutrient requirements and the subsequent performance of cattle. The most important variable is temperature, however wind, snow, rain and mud also cause winter cold stress. Cold is an obvious stress factor that increases an animal’s demand for energy. Cattle not acclimated to the cold environment can become acutely cold stressed and those that are will have a higher resting heat production. As this demand for energy (maintenance) increases more feed is used for heat and less is available for gain.
Cattle have a comfort zone of approximately 15o to 24o C where they are content and consume feed at a normal intake. Above this temperature range or the upper critical temperature, intake starts to decrease and below this temperature range or lower critical temperature (LCT), intake starts to increase. Below the LCT, the amount of energy required by the animal to maintain core body temperature increases. The LCT depends on age and size of the animal, environmental temperature, wind and moisture conditions and hair coat. When cattle reach their LCT, they will shiver, increase their metabolism and release energy from fat. It was once thought that, as cold increases the energy requirement, cattle would just consume more feed. This is true to a point, cold weather will increase intakes, however extreme conditions will lower intake, especially over prolonged periods. During hypothermia, the body core temperature drops below normal. Performance suffers because energy used for maintenance increases at a rate greater than feed intake. Records from Canada and the United States indicate that in the winter feedlot average daily gain is 10 to 26% lower than during the summer months, even though intakes were the same or slightly greater than in the summer. These reduced gains associated with decreased efficiency are likely due to increased maintenance energy requirements.
The impact of the cold on the
cattle is affected by the thickness of the hair coat, provision of wind blocks
and intake. Hair coat thickness is very important factor in cold weather. The
length as well as the quality of the hair coat will determine the critical
temperature that we need to be concerned with. When cattle become wet, the
insulation value of the hair coat can be lost such that the insulation
properties become similar to those of a summer hair coat. Lower critical
temperatures for beef cattle in relation to hair coat are shown in Table 1. As
the hair coat thickens, the LCT becomes lower.
Table 1. Impact of hair coat
type on lower critical temperatures (LCT) for beef cattle*
|
Coat Description |
LCT ( ◦C) |
|
Summer or wet |
15 |
|
Fall |
7 |
|
Winter |
0 |
|
Heavy winter |
-7 |
|
Wet |
14 |
*
The values are for cattle in average body condition.Photoperiod also works against intakes in the wintertime. Research has documented that cattle subject to 16 hours of light and then 8 hours of dark consumed substantially more feed than cattle subject to 8 hours of light and 16 hours of dark.
Here are a couple of facility ideas
For existing facilities site selection is already determined, however it is an important consideration for expansion or new construction. Two structures that can me modified or improved on existing facilities are windbreaks and resting mounds.
Properly placed and constructed windbreaks can reduce wind velocity up to 70%; this greatly decreases the chilling effect of the wind. In most cases, proper placement of windbreaks can and provision of adequate feed can eliminate hypothermia. Windbreaks should be placed where they protect cattle in their natural laying, eating and drinking areas. Prevailing winds in Ontario come from the northwest, so windbreaks, either constructed or natural (trees) can also be utilized on the northwest sides of feedyards. Windbreaks should be a minimum of 10 feet high and should be 80% solid and 20% open; this makes them easier to keep upright in strong winds and provides a wider area of calm air in front of the break.
Mounds should be high and dry and in normal traffic patterns. Mounds should be tied into concrete aprons and waterers, and provide cattle the opportunity to eat, sleep and drink without walking through mud. While mounds do provide some protection from the wind in the winter, their payoff is in the late winter/early spring when mud is the profit robber. Remember that cold stress can occur at any time depending on conditions. A feedlot animal can have a higher energy requirement in April, than they do in January, if it is raining and the wind is blowing.
Cattle comfort is key to profitability
Cattle in the feedlot must be protected from conditions which impair growth. Improving cattle comfort by enhancing the environment that they are in can make the difference between profit and loss. The ability of an animal to cope in cold environments is impacted by its ability to thermoregulate. The feedlot animal’s body condition, degree of insulation, health status and housing area are therefore very important in maintaining body temperature.
Hair provides insulation by trapping air close to the hide and creating a "dead air space". This decreases heat loss from the body. Good health and proper nutrition (i.e. copper and zinc) lend themselves to a good natural hair coat. Moisture, mud and fecal material cause matting of the hair coat and destroys the insulation value. This causes the requirement of the animal for energy to increase.
During cold weather it is increasingly important to watch feet and legs. Walking on frozen surfaces is difficult and if it is too much of a struggle, cattle will skip a trip to the feedbunk or water trough. Cattle with sore feet will be less inclined to consume as much feed or water, impacting average daily gain (ADG). Keep cattle movement patterns cleared of snow, ice and frozen mud. Animals with footrot, toe abscesses and injuries should be aggressively pulled and treated.
Bedding cattle during periods of cold stress has shown profitable results, even with some labour drawbacks. The key to bedding cattle is doing it often and in small amounts. It must be remembered that any organic matter will hold moisture in the spring, which will increase the mud depth of the pen and may cause holes in mounds. Furthermore, the bedding will eventually have to be hauled out in the form of manure. Despite these two drawbacks, research conducted at Colorado State University showed that bedding an area of the pen did have a positive net return per head. Cattle fed in pens with a light coating of bedding, by means of a mechanized chopper, incurred significantly higher ADG and dressing percents as well as improved feed efficiencies and feed cost of gain.
Timely snow removal is a practice that also increases cattle comfort and decreases the amount of moisture (and therefore mud) during the spring thaw. Along with snow removal the rough areas of the yard should be scraped smooth. This ensures ease of cattle movement, helps with foot health, improves cattle comfort and allows the yards to drain properly. Concrete, such as aprons should be frequently scraped and free of snow, mud and spent bedding. You don’t want anything to deter the cattle from approaching the bunk to eat.
If the winter is exceptionally hard, pregnant animals may use a lot of their energy to generate heat, and consequently not the calf. Additionally, when nutrients are moved to produce heat, cattle begin to lose body condition. This can lead to cows, and more commonly heifers, in poor body condition having increased risk of calving problems and subsequent post-partum troubles. Because of energy redistribution, the quality of the colostrum for the calf can suffer, and neonatal mortality may increase. Further reproduction risks include these animals not cycling and delayed breeding in the spring and summer.
Monitor body condition scores throughout the winter and be prepared to supplement the ration with increased energy, protein, vitamins, and minerals when the cattle are exposed to cold temperatures for extended periods. Sick animals should be removed from adverse environmental conditions with access to 18 to 24 inches of bunk space. Healthy adult functioning ruminants will survive long periods of cold, but may pay the price at calving or rebreeding.
Energy, the bunk and ration management
The biggest challenge of having cattle on feed during periods of cold stress is determining what ration should be offered and how much of that ration should be delivered. The common practice of increasing the roughage level of the diet (storm rations) has pros and cons. The rate of passage and ruminal motility are both increased during periods of cold weather, this further dilutes the energy level of the ration, by allowing less time for digestion. However, adding the extra fiber to the ration makes bunk management much easier and helps maintain cattle on feed.
Another option for cold weather feeding of cattle on high-energy rations is to drop back one ration step (i.e. from a 61 Mcal to a 58 Mcal). This increases the level of fiber slightly while maintaining an energy level.
From a management standpoint the best practice is to keep intakes as consistent as possible. Utilize past intake information you have to determine the amount of the next delivery (a 5-7 day average is a good start). Be disciplined not to get ahead of the cattle on intake, they may act hungry but offering more feed than required will cause a crash in intakes and start the roller coaster pattern. If the weather is still bad (especially extreme wind chills) at feeding it may be necessary to "stir" the cattle. Physically getting them up from the mounds or loafing area to encourage them to walk to the bunk may be necessary. Conversely, if the storm front has passed, and the cattle are very aggressively charging the bunk, it may be wise to split the feed delivery to prevent "tanking" and digestive upsets (feed 50% of the feeding and return about an hour later to feed the remainder). Another option is to feed a few kilograms of hay per head first to take the edge off and then return within a couple hours and feed the regular ration.
Provide water
Provision of adequate water at all times is an absolute must in cattle production and it is just as important during the cold months of the year. During the winter months, waterers are usually cursed because of their tendency to freeze up, leading to decreased water consumption. Decreased water intake results in reduced feed consumption and average daily gain. Water consumption is typically lower in winter months, but is still the most important nutrient in any weather. Be sure that tank and pipe heaters are working in a safe and efficient manner. However, be sure to watch for hidden problems such as stray voltage. Nebraska research has indicated that stray voltage above 3-4 volts will decrease water intake. Ensure that all waterers are checked for stray voltage on a timely manner, especially when the heaters are running.
The Bottom Line
Steps to minimize stress in the feedlot can only be done once the signs and symptoms of stress in both the individual animal and as a herd have been identified. Observations on appropriate or abnormal behavior, degree of sickness, decreased weight gains and subsequent growth can all be used to indicate stressed animal conditions. Cattle not protected from the harsh effects of cold stress will not perform as well as those which have some protection from the elements. Hair coat thickness and condition, wind, moisture, mud and environmental temperature all impact the animals energy requirements. The bottom line is that if cattle are kept in cold conditions below their lower critical temperature, your money is being directed to keeping them warm, rather than gaining weight.