SIOUX FALLS, S.D. – Scours and sick calves are an unfortunately common ailment on dairy farms. This is a problem that can be easily remedied through management of feeding practices.
    Dr. R. M. Thornsberry, DVM presented research on ensuring cows get off to a healthy start March 28 at the Central Plains Dairy Expo in Sioux Falls, S.D.
    Thornsberry spoke about calf nutrition, energy, the calf’s unique anatomy and the affects of poor versus proper nutrition during his seminar, “Importance of Energy and Osmolality For Reducing Scores and Sick Calves”.
    “Nutritionists look at energy in a pretty complicated manner,” Thornsberry said. “Today, I want you to remember fat has 2.25 times more energy per given weight than sugar does.”
    Sugar is quick energy, but not sustaining. If a calf needs quick energy, glucose and lactose are a good solution, but to sustain energy in a young calf, fat is necessary. While protein has some energy value, it should not be used it for that.
    The amount of energy in a calf depends on what they eat. Of what they eat, not everything gets digested, and of what is digested, not everything is metabolized. An accurate analysis of feed energy is the net energy of metabolized feed.
    This is similar to how a lactating cow’s diet is analyzed. Nutritionists often look at the amount of feed consumed, and how much of the feed can be used as energy to make milk. The model translates to calves, but in the sense of putting on weight rather than making milk.
    Carbohydrates serve as a quick source of energy, fats are a sustaining energy and protein should never be used for energy.
    “We want to balance out protein in these diets for good growth and good gain, but not for energy,” Thornsberry said. “Excess protein in the diet is seen a lot today. We tend to think, ‘If 18% protein is good, 24% must be better.’”
    This is not the case, and excess protein in a calf’s diet will cause diarrhea, which is why the fat in the diet is so important for sustenance.  
    “A Holstein calf is born with enough fat in his body to live for 48 hours,” Thornsberry said. “This is why it’s so significant for the calf to get colostrum immediately; for not only the transference of antibodies, but also for the high fat content the calf needs to stay alive.”
    In a newborn calf, the rumen is the size of a clenched fist. For a weaned calf eating starter feed, the maximum their rumen will be is the size of a soccer ball, which is why it is important not to feed hay to these young animals.
    The calf is not yet a ruminant animal and cannot use the hay in their diet.
    “A calf may munch on their bedding to add fiber to their diet, but he cannot live off hay,” Thornsberry said. “Even nice, dairy hay like alfalfa will go straight through them. The protein concentration is too high at 24%.”  
    Understanding the esophageal or reticular groove is key to understanding the function of the calf’s stomachs. After feed is swallowed, it moves down the esophagus toward the stomach. Since the esophagus joins the stomach in the area of the rumen and reticulum, ingested feed first enters this section of the stomach.
    However, prior to weaning, milk and milk replacer take a different route to the stomach. A combination of factors such as suckling, the presence of milk proteins and anticipation result in neural responses that cause muscular folds in the reticulorumen to form a groove that extends from the esophagus to the abomasum.
    The esophageal groove allows milk and milk replacer to bypass the rumen, reticulum and omasum and to flow directly into the abomasum.
    “If we tube feed a calf, we bypass all those nerves and everything we feed the calf goes straight into the rumen,” Thornsberry said. “If we bucket feed a calf, the calf will drink the milk faster than she can swallow it and when it gets to the U tube, it’ll try to get through in great volume and push it open a little bit, resulting in overflow in the rumen.”
    According to Thornsberry, this is why most veterinarians suggest bottle-feeding for a few weeks until the calf’s physiology is mature enough to regulate the intake of milk. Milk should never sit in the rumen, he said.
    If milk gets into the rumen, rumen bacteria try to break down the sugars and turn it into D-lactic acid. This acid is absorbed in the blood stream and signals the brain to shut off of the suckling reflex.
    “The farmer will think the calf won’t drink and will tube feed the calf, which just causes more spillage into the rumen, producing more acid and we’re stuck in a cycle,” Thornsberry said.
    Tubing colostrum is different; because when it is administered, the calf is a newborn with a sterile rumen. A short time later, the rumen is full of bacteria from licking themselves, their mother and the ground, making it unsafe to tube feed.
    Another aspect of a calf’s anatomy is a valve in the back of the neck, to prevent inhaling food or drink.
    “The natural suckling of a calf is with its head down, below the level of its eyes,” Thornsberry said. “Calves that are forced to drink from too high can get milk into their lungs and develop pneumonia.”
    Understanding the proper functions of a calf’s anatomy can help farmers produce a healthier herd and, in turn, healthier productions down the road. Better analysis of energy and how the calf can use said energy; farmers can grow a healthy population into the future. The future of the industry begins with calves.