Managing Dairy Calves and Heifers During the Winter Months

 By Maurice L. Eastridge

 Attention to dairy calf and heifer management is important for maintaining growth rates, minimizing health problems, and optimizing current and future profitability of the dairy farm. The presence of pumpkins and frost reminds us that the winter months are just ahead, and with most of the crops for the livestock now in storage, it’s time to prepare for these upcoming winter months.

Pre-weaned Dairy Calves
Dairy heifers account for about 30% of the feed costs on a dairy farm, and the most costly period for raising heifers is during the pre-weaning period. The animal’s susceptibility to disease is greatest during this period, and the cost per unit of dry matter (DM) consumed is the highest. As we know, the energy requirement for calves housed in unheated facilities increases during the winter months due to cold stress (lower critical temperature for newborn calves of 48°F versus 32°F for older calves), and the cold stress can increase the risk for disease. Unfortunately, the death rate sometimes increases in the winter, and/or the growth rate plummets unless we provide additional energy to these calves. In addition, we need to realize that small breed calves (e.g., Jersey) have about a 20% larger surface area per unit of body weight than large breed calves (e.g., Holstein).

Different feeding strategies for optimizing growth of dairy calves during the winter months include:
• If a milk replacer is being used, it should contain at least 20% fat.
• The solids content of the liquid from milk replacer can be increased from 12.5% to 16% (from 17 to 22 oz. per gallon).
• Increase the feedings per day from two to three times while holding the amount per feeding the same.
• Feed more milk per feeding, e.g., increase from 2 to 3 qt two times a day.
• Use a combination of these strategies so that small breed calves consume at least 1.3 lb of DM (milk replacer is approximately 95% DM; whole milk 13% DM) with 0.3 lb of fat and large breed calves consume 2.0 lb DM (0.5 lb fat) per day.

These strategies should be used while also offering a high-quality calf starter free choice and plenty of water. Water can certainly be a limiting nutrient during the winter months due to freezing or the calf feeder not offering adequate amounts.
Hypothermia is a major risk for neonatal calves, and housing, feeding, and hydration are key considerations for minimizing hypothermia. Consider these strategies to reduce the chance of hypothermia:
• Position hutches used for calves in a well-drained area (slope and gravel are important), and make sure the prevailing wind is not blowing into the front of the hutch. A windbreak upwind from the hutches can help reduce the wind chill on calves.
• Bed hutches with dry, organic bedding, preferably straw, so the calves can nestle in the bedding for warmth and reduce heat loss by conduction that would occur with inorganic (e.g., sand) bedding. Wet bedding also greatly increases conductive heat loss.
• If calf coats are going to be used, check the inventory and have all of them cleaned for use.
• Keep an ample supply of electrolytes on hand in the event of scours so the calves can be kept hydrated.

Weaning Dairy Calves
As in other periods of the year, calves should be slowly weaned (e.g., reduce the milk allowance in half and feed once per day for a week) and placed into groups of 6 to 8 calves of similar age and size. Minimize other stressors, such as vaccinations and dehorning, at this time.

Housing for Dairy Heifers
Housing of dairy heifers during the winter is critical. The housing system should allow for adequate air exchange without becoming drafty and yet protect the heifers from the extremes of the environmental elements. Oftentimes, respiratory problems increase in calves and heifers in the winter because the housing allows inadequate or excessive air exchange. Continuously monitor the breathing and coughing of the heifers . Accepting as normal that only a few heifers are coughing is not justification for avoiding facility modifications. If these health problems occurred last winter, facility modifications should be occurring now. Heifers housed outdoors need to have access to either natural or constructed windbreaks. Water sources need to be evaluated now for continuous availability of water and for minimizing a slippery surface around the water supply.

Feeding Programs Postweaning
Farmers need to be careful that the long-term advantage of good growth rates in preweaned calves is not lost by how the weaned heifers are managed. Heifers will usually eat about 2.5% of body weight, so an adequate supply of high-quality forages needs to be in storage at this time. If forage supplies are limited, rations may need to be altered to stretch the forage supply.
Overfeeding corn silage can lead to overconditioned heifers, which results in increased feed costs and increased risk for metabolic disease and dystocia at calving. If diets are fed with a high proportion of corn silage, the amount of the diet fed needs to be restricted to control energy intake.
Heifers need to average about 1.7 lb/day of growth for large breed calves or 1.3 lb/day for small breed calves to reach the desired breeding size at 13 months of age. The goal is for heifers to calve at 22 to 24 months of age at about 90% of their mature weight (1,300 and 900 lb for large and small breeds at calving, including the weight of calf). The management of the heifers during the winter months will be important in  achieving these goals.

Evaluate Numbers of Heifers Raised
Now is the time to evaluate the number of heifers on the farm. With improved management and use of sexed semen, many farms are holding large inventories of heifers on the farm, sometimes 125% or greater of the number of cows. At a 30% to 35% cull rate, only about 85 heifers per 100 cows should be held on the farm. With high feed costs and limited forage in many situations, now is the time to sell excess heifers.

Summary
Management and housing strategies need to be in place to reduce the maintenance energy requirement of calves during the winter by providing ample clean, dry bedding; windbreaks; and other improvements to the housing to lessen the cold stress without going overboard to increase the risk of respiratory problems. Feeding of the calves and heifers during winter needs to be changed to provide adequate energy for continued growth rates achieved during other times of the year.