Vet Call: Cold-weather concerns

By Dr. Bob Larson, DVM, professor of production medicine
Reprinted with permission from the Angus Journal.

A high percentage of the U.S. beef herd resides in areas of the country where moderately to extremely cold winter temperatures are common. By planning for winter weather, ranchers can avoid being caught off-guard by extreme events and can manage the typical winter conditions so cattle do not have to continually utilize body fat as an energy source to keep warm, leading to excessive loss of body condition.

Situations that are most likely to cause cold stress are: Cattle with thin fat cover and short hair coats (due to movement from a warmer environment to a colder environment, or extremely cold temperatures early in the fall/winter season); cattle with wet hides, or high wind speed accompanying cold temperatures. Wind chill is a better predictor of cold stress than temperature alone because cold wind draws heat away more quickly than still air at the same temperature. Wet or mud-caked hair losses its ability to insulate the animal and a wet winter hair coat only provides as much protection from the cold as a typical summer hair coat. If cold wind is combined with a wet hair coat (as can occur during a winter storm), the effects can be very profound.

Adult cattle with a dry hair coat, adequate body condition, and abundant, adequate-quality forage can withstand most winter situations, especially if they have the ability to find protection from wind and have been exposed to moderately cold conditions for several weeks which allows them to acclimate by growing a thick winter hair coat and increasing feed intake. As temperatures drop, cattle increase heat production which means the number of calories they need for maintenance increases. This increase is met by consuming more feed and moving it through the digestive tract faster, but the cost of this faster movement is that feed is not digested as fully. The effect of needing increased calories for maintenance at the same time that feed digestibility is decreasing means that if cows do not have access to plenty of digestible feed, they will have to “burn” body fat as a calorie source.

Another factor that can limit feed intake in winter conditions is if water sources are frozen or unavailable. If feed intake cannot keep up with energy demands, and body fat is mobilized to meet energy demands, then the cows will have less fat insulation and will be more susceptible to cold temperatures, causing a viscous cycle that can lead to cold stress and even more weight loss.

Cold weather brings a special concern with bulls because of the potential to have frostbite damage to the scrotum and testicles. It is very important that bulls have protection from the wind and adequate bedding if they are housed on concrete or dirt.

Cold temperatures have the greatest potential to cause serious problems in young calves, particularly calves in the first day of life. Because calves are born wet, have thin skin and very little body fat, they lose body heat very rapidly and if they are not able to become dry, can quickly become severely cold stressed. Contact with snow or wet ground will increase the amount of time that a calf stays wet and in danger. Body temperature of newborn calves can drop to dangerously low levels in 3 hours or less.
Calves are born with a body temperature of about 100˚F. When exposed to a cold environment, calves are able to produce heat in two ways: shivering and the heat production of brown fat (fat that surrounds the kidneys of a new-born), and they can conserve heat by reducing blood flow to the body surface and extremities (feet, ears, etc.). In early stages of cold exposure, calves will shiver vigorously and have a fast heart rate and breathing rate. If that does not keep the body temperature up, the calf’s body sends less blood to feet, ears and nose in an effort to minimize heat loss. Severe cold stress occurs when the body temperature drops below 94˚F. At this temperature, the brain and other organs are affected and the calf becomes depressed, unable to rise, unwilling to suckle, and will temporarily lose the ability to shiver. The good news is that if the calf can be warmed up and its body temperature can begin to rise, the shivering response will return and the core body temperature will slowly increase.

During periods of cold or wet weather, newborn calves (less than 1 to 2 days of age) should be checked every few hours with a thermometer and any calf with a below-normal temperature, even if it appears OK, should be warmed. Calves suffering from cold stress must be warmed so that body temperature can rise above 100˚F. If body temperature has not dropped too far, putting the calf in the cab of a pickup out of the wind and rain or snow will warm the calf. In more severe cases the calves can be placed in warm water, specially designed warming boxes, or near a heat source such as an electric blanket, heat lamp, or hot water bottles. To avoid skin burns, the heat source should not exceed 108˚F. In addition to an external heat source, cold-stressed calves should be fed warm colostrum, milk, or electrolyte fluid with an energy source using an esophageal feeder.

Prevention of cold stress involves management to ensure that calves can be born in a short period of time and both the calf and dam can stand shortly after calving so that they can bond and the calf can begin suckling. Anything that prolongs calving or reduces the chance that a calf will suckle soon after birth should be addressed by management changes. Calving difficulties are minimized by proper heifer development, proper bull selection for calving ease, and proper nutrition so that heifers and cows calve in a body condition score of 5 to 6 on a 9-point scale. Cows with large teats or that are not attentive mothers should be culled.

Use of pasture as the primary forage source during calving encourages cows to keep spread apart and minimizes development of muddy areas. If the herd forage plan includes feeding hay, consider feeding hay in early to mid-gestation and saving stockpiled pasture for the calving season. If supplemental hay and grain are fed during calving, these should be provided at locations that are separate and distant from water sources and windbreaks. I discourage the use of bale rings in calving and nursery pastures and suggest that if using large round bales, they be unrolled and the feeding area changed with each feeding. Unrolled bales will have greater hay waste, but reduced chance for mud caused by concentrating the herd into small feeding areas, and unrolled hay provides bedding for newborn calves so that they are not in direct contact with the ground.

In addition to monitoring the weather forecast for severe winter weather events and to be alerted to times when additional feed is needed, minimizing the effects of cold temperatures on newborn calves involves planning ahead and considering calf comfort and protection when making heifer development, bull selection, nutrition and pasture-management decisions. Making sure that cows will have adequate access to forage and water even in situations with significant snow cover is necessary to provide sufficient calories to maintain body fat and heat production. Protecting the cow herd (and bulls) from winter wind and providing bedding if on concrete or mud/dirt will minimize the effects of severe weather.

Dr. Bob Larson is a professor of production medicine with the College of Veterinary Medicine at Kansas State University, Edgar E. and Elizabeth Coleman Chair of Food Animal Production Medicine, executive director of Veterinary Medical Continuing Education, and faculty member with the Beef Cattle Institute. He specializes in the integration of animal health, production efficiency and economic considerations in beef cattle production. This column is reprinted and redistributed with permission from the Angus Journal.

Vet Call: The role of the veterinarian in your business

By Dr. Bob Larson, DVM, professor of production medicine
Reprinted with permission from the Angus Journal.

Many people impact the success of your ranching business, including your customers, your lenders and your suppliers. One of the important suppliers for cow-calf producers is the local veterinarian. Veterinarians can provide important advice and service to improve ranch income, decrease costs, provide protection from losses due to disease, and offer options for marketing high-health cattle.

Ranch income is primarily derived from the sale of calves either at weaning for commercial operations or as breeding bulls or heifers for seedstock producers. Commercial ranchers can increase their income by increasing the pounds of calves at weaning and seedstock operations the number of marketable breeding animals from the same land and cow resources by increasing the reproductive efficiency of the herd. Veterinarians can provide advice and services to monitor and evaluate heifers, cows, and bulls so that a high percentage of the herd is able to successfully mate at the start of each breeding season.

Nutrition has an important impact on whether or not growing bulls and heifers reach puberty at an appropriate age and your veterinarian may be able to provide you with appropriate diets to meet targeted weight gain goals. Genetics also strongly influences whether developing bulls and heifers reach puberty by target ages, and your veterinarian is a valuable resource when considering selection and culling decisions. By doing breeding soundness examinations of bulls and heifers near yearling age, your veterinarian can help you identify the individuals that reach puberty at the time and with the amount of feed resources that you have identified to meet your ranch goals.

Doing breeding soundness examinations of mature bulls prior to the start of each breeding season allows your veterinarian to remove bulls that may fail during the breeding season due to foot or leg problems, other health problems, or reproductive tract problems. Although the reproductive tracts of mature cows are not routinely evaluated before the start of each breeding season, managing and monitoring the cows to confirm that a high percentage of the cows calve early enough in the calving season and in good enough body condition to resume fertile cycles by the start of the breeding season helps to ensure that herd reproductive efficiency will be high.

Monitoring body condition scores of the cow herd and rainfall amounts as predictors of future forage production potential allows your veterinarian to provide advice on a changing year-by-year basis to alter stocking density, timing of weaning, and supplementation strategies to ensure that cows enter the calving and breeding seasons in good body condition. The land base and herd size dictate much of the cost-side of cow-calf production and making sure that a high percentage of the cow herd becomes pregnant early in the breeding season allows those costs to be spread over a large number of marketable calves. By using body condition scores collected at several key points in the production cycle, your veterinarian can help you fine-tune the management of your herd based on the ranch forage-base, and the availability of cost-effective supplements or grazing alternatives, and the optimum cow size and milking ability for your herd.

While every production year is expected to generate income from the sale of calves and to incur expenses associated with pasture and supplementation costs as well as cow depreciation and bull costs, significant losses due to disease are expected to be a rare event for cattle operations. Losses that are expected to occur rarely if at all but that could have a devastating impact on the financial status of a ranch if they did occur must be managed with cost-effective risk management strategies. Because disease losses do not occur every year, providing no defense may appear to be a sufficient and very low-cost management strategy in the short-run. However, over a longer time-frame, it would be very unusual for a herd with minimal disease protection to avoid devastating financial losses due to disease at some point in the future. Your veterinarian can provide valuable information about the likelihood that your herd could suffer losses from various diseases and the expected magnitude of those losses should your herd be exposed. By considering the likelihood of a disease, the magnitude of losses associated with that disease, and the effectiveness of available control strategies, your veterinarian can work with you to optimize the disease risk management of your ranching business.

Marketing of cattle, whether feeder calves or breeding animals, increasingly includes information about health status. When considering the optimum herd health program from a marketing standpoint, the risks that down-stream buyers face and their willingness to purchase from suppliers who can reduce that risk must be considered. For example, your herd may have very low risk for a disease and incurring expenses through diagnostic testing or herd certification may not reduce your herd’s already minimal risk, but the costs could easily be offset by customers willing to pay for that low disease risk. Increasingly, you must think of your down-stream customers as you work with your veterinarian to plan a health program that not only meets the needs of your herd but also provides a cost-effective marketing advantage.

A successful cattle business requires a combination of cattle and business expertise. Many successful ranchers count on a trusted team of advisors and suppliers to help them improve the profitability and sustainability of their ranching businesses. Finding and working with a local veterinarian who can provide assistance to increase income, control costs and manage risks should be a goal of every cattle producer.

Dr. Bob Larson is a professor of production medicine with the College of Veterinary Medicine at Kansas State University, Edgar E. and Elizabeth Coleman Chair of Food Animal Production Medicine, executive director of Veterinary Medical Continuing Education, and faculty member with the Beef Cattle Institute. He specializes in the integration of animal health, production efficiency and economic considerations in beef cattle production. This column is reprinted and redistributed with permission from the Angus Journal.