Late fall and winter weather present some challenges for raising new born and young dairy calves. A newborn calf has a lower boundary thermal neutral zone (TNZ) of 50-60 degrees F, while the lower boundary TNZ of a month old calf is in the 32 to 40 degree range. These figures are important because when temperatures drop below the lower thermal neutral zone boundary the calf needs more energy and calories to stay warm. Regardless of the season, the goal is to keep calves healthy, keep them growing and keep them gaining weight. However, in cold weather if calves don’t get extra energy, they use the energy provided to keep warm instead of growth. If the shortage of energy is too great, the calf’s immune system can weaken and the calf can get sick. If basic body maintenance requirements are not met, the calf’s body temperature can begin to drop, again with health consequences up to and including death.
Cold weather calf care requires attention to several management practices. For the newborn calf, the first priority is to receive a feeding of high quality colostrum within the first few hours after birth. The goal is to feed 4 quarts of high quality colostrum within one-half to one hour after birth. Feed another 2-3 quarts within 6-8 hours after birth. Colostrum is higher in solids and fats than regular milk and provides additional energy for the calf to burn. This is important because a calf is born with only 3-4% body fat so they have very little extra energy reserve to get them through cold weather.
After that first 24-hour period, most calves are fed a milk replacer. The standard milk replacer feeding program with a solids content of 12.5% utilizing a 20:20 crude protein to fat content used in warmer months will not be sufficient for the cold weather calf. Calf managers should switch to a milk replacer with a higher fat content or add an additional fat supplement to the milk replacer feeding program. In addition, increase the solids concentration up to 15 to 16%. When the solid content is increased, provide additional water free choice so that calves stay hydrated. Provide fresh, warm water (102-105 degrees F) to calves within 15-30 minutes of milk replacer feeding and for calves in outdoor hutches, remove the water before it freezes. Another cold weather feeding recommendation is to increase the energy intake of the calf by adding an additional feeding when the temperature drops below the calf’s thermal neutral zone and in below zero weather the recommendation is to add two extra feedings per day.
Make sure calves have access to a calf starter grain mix. In cold weather, calves can be expected to eat more to get the extra energy they need and the starter mix can provide the added fat or energy source the calves need in cold weather. Calves under 2-3 weeks of age will probably not consume enough starter mix in cold weather to meet their extra energy requirement as compared to older calves, so the extra milk replace feedings are a very important management practice.
Some other management practices that help calves cope with cold weather include calf jackets or blankets and bedding depth to allow calves to nestle to conserve body heat. Calf jackets are particularly important during the first 3 weeks of a calf’s life and especially in outdoor calf hutch environments. Fit calf jackets to the calf. The jacket should close securely in the front of the calf and not restrict or interfere with calf movement. Calf jacket straps should not cross the belly of the calf. This has the potential to rub against the calf’s navel, which could result in an infection. With regard to bedding, cold temperatures signal the need for the calf manager to shift to a straw bedding material and evaluate proper bedding depth by the use of a nesting score.
Straw, when provided at an adequate depth, will help the calf maintain its body heat. An adequate amount/depth of straw bedding is determined by assigning a nesting score. A nesting score is essentially a scoring system that makes a visual appraisal of the ability of the calf to snuggle down into or nestle into the bedding material. A 1-3 scale is used. A score of 1 indicates that the calf’s legs are entirely visible when lying down, a 2 indicates legs are partially visible when lying down and a score of 3, which is our goal, indicates legs are not visible when the calf is lying down.
Cold weather requires some additional care and management to keep newborn and young calves healthy, comfortable and growing. Contact the Wayne County Extension office at 330-264-8722 for more information.