The future of your dairy herd is highly dependent on the success of your calf and heifer replacement program. The goal of almost any dairy farmer is to improve genetics and to increase milk production, no matter how good it already is. Dairy farmers are responsible for the next generation of milking cows and it is important to consider various topics when running a successful dairy farm. These topics can include the following:

 
- The importance of feeding colostrum to new born calves
- Proper timing of weaning
- Calf housing and weather management
 
Importance of feeding colostrum to new born calves
Colostrum is the milk taken from the newly freshened cow immediately after the calf is born. This milk contains high levels of antibodies that the calf needs to prevent diseases caused by existing bacteria and harmful microbes found on almost any dairy farm. New born calves are born with few antibodies and an immature immune system that is not able to produce key antibodies for a few weeks. This colostrum provides the needed disease-fighting antibodies to maintain the calf’s health.
Ideally colostrum should be fed within one hour of the calf being born. If this is not possible, the colostrum should be then fed within 24 hours of birth. The effectiveness of the colostrum decreases every hour after the calf is born because the ability of the calf to absorb the antibodies decreases. Typically, the calf is not overly aggressive enough to feed with a bottle when it is first born. In this case, an esophageal tube feeder is used. Two liters are fed at first feeding, and a second feeding is unnecessary as the calf may suckle on the dam after the initial feeding, if they are kept together. It is extremely important that the fresh cow is tested negative for Johne’s disease, bovine viral diarrhea (BVD) and bovine leucosis virus (BLV) as all of these deathly diseases could pass on to the new born calf and further infect your herd. In some cases the dam may produce more than enough for the new born calf. This may be frozen to feed to future calves when first or second lactation cows may not produce enough. Again, make sure this colostrum is tested negative for the above diseases. In the instance that the colostrum is unusable, powdered colostrum can be purchased from most farm supply stores and is as effective as the original. Below are some tips to consider when looking to feed high quality colostrum.
·         Observation of dams that are springing up is key to maintaining high quality colostrum. If noticeable amount of leaking is noticed before calving, the dam is highly unlikely to have high quality colostrum. Feed stored colostrum or powdered colostrum replacer as an alternative.
·         The sooner the fresh cow is milked after calving, the better quality the colostrum will be. This milk will contain a higher level of antibodies and will be a prime product for the new born calf.
·         Sort colostrum as it is produced and feed the highest quality to the calves you intend to raise for herd replacement. Typically cows that are in their second or third lactation have higher quality colostrum than those of first calf heifers.
·         Do whatever possible to limit stress levels among prefresh dams. High levels of stress may cause low quality colostrum and lower amounts as well. These high levels of stress can be too little resting space, not enough space to eat or drink, conditions that are too hot or too cold, and also too many other cows within the same freshening pens. Try to keep the environment as quiet, well bedded, and comfortable as possible.
 
Proper time of weaning
A calf should not be weaned until the rumen is functional and able to support the calf’s nutritional needs. Some farmers feel it is necessary to look at only age when weaning calves, however, weight and overall health should be considered first. In order to even start considering weaning calves, it is important to monitor calf starter and milk intake as it leads to rumen development.
The source of milk, whether it be milk replacer or dump milk, it is important to monitor the calf’s intake at every feeding. This will provide insight if the rumen of the calf is supplying proper amount of energy and microbial protein sufficient for maintenance and growth. Proper handling of milk and sanitation of feeding supplies/equipment are an essential step to avoid bacterial contamination that can potentially lead to health issues.
Proper consumption of calf starter is also an essential step to raising a healthy replacement calf. Rumen development takes place at a fast rate between 4 and 8 weeks of age because of the large sources of fermentable carbohydrates found in the starter. Ideally, starter should be a texturized feed because it is made of essential ingredients that are highly palatable. These ingredients could include cracked corn, rolled oats, soybean meal, molasses, limestone, and dicalcium phosphate, all of which are found in varying levels. Grain starter should be available to the calf as early as four days after birth and should continue until about four months of age.
A general rule of thumb is to wean the calf is at eight weeks of age, depending on weight and health condition. The calf should weigh around 150 to 200 pounds. Also interestingly enough, another general rule is to wean a calf when they start to consume 800 to 1000 grams of starter for two consecutive days, but not less than 500 g. If these general rules are followed, weaning should be an ultimate success.
 
Calf Housing and Weather Management
When it comes to proper housing and weather management for cattle, it is pretty clear cut. It needs to be comfortable. Cow comfort is a popular topic in any dairy operation, as it leads to higher milk production, increased reproductivity, and decreased health issues. In calf operations in particular, one popular housing system is the portable outside hutches. These hutches should be placed in a well-drained and protected area with the front facing the south. Also, only one calf should be allotted per hutch to avoid spread of disease. In order to provide optimum comfort, plentiful bedding should be used which could be straw or wood shavings. A mixture of the two is a great start as the shavings absorb urine and the straw provides a soft bedding pack and added warmth in the cold winter months. As the calves are moved, the hutch should be cleaned thoroughly and disinfected.
As the calf reaches time for weaning, it may be moved to calf-grow out facilities such as outside pens with overhead shelter. It is important to consider age in these particular settings to avoid younger calves being bullied by older heifers/bulls. The age spread should be no more than 2 months and weights should be relatively the same. It is also very important to monitor proper ventilation systems in the summer heat and adequate warmth in the winter.
Depending on the location of your dairy, this may be a tough time of year. It is always a challenging process to maintain milk production or daily gains in hot, humid conditions. It is extremely important to provide opportunities for calves to find shelter from direct sun. Shelter from the sun allows for cattle to radiate heat away. Providing fresh, clean water is also a key to success as water intake doubles as temperatures go from 70° F to 100° F. With this drastic change in weather it is important to keep water in front of the calves all the time. Another option to maintain dry matter intake would be to utilize night time feedings as this will promote dry matter intake and optimize gains in cooler conditions.
 
From the moment that a heifer calf is born, it should be considered just as important as a milking cow. Every heifer calf born on a dairy farm represents an opportunity to maintain or increase herd size, improve genetics, or to better the economic returns of the farm. Providing that initial colostrum feeding, monitoring feed intake as a young calf, and providing adequate housing as the calf matures will only help your farm generate a successful replacement heifer program. Today’s healthy calf is tomorrow’s high producing cow.