By Greg Goodell, DVM, The Dairy Authority, LLC
For calf managers, bloat is a constant threat that can be downright heartbreaking. Nearly every long-term calf raiser has experienced the highly frustrating scenario of “fine at one feeding, dead the next” at least once.
Bloat is most commonly caused by an overgrowth of clostridial bacteria — usually Clostridium perfringens type A. These bacteria are naturally present in the calf’s gastrointestinal tract. But under the right conditions they can rapidly multiply and produce large amounts of gas and toxins.
Whenever I see or hear about a case of early-life bloat, the cause can almost always be traced back to a violation of one of the “4 Ts” of consistent calf feeding:
- Time
Just like cows, calves crave consistency. Calves should be fed on a regular schedule with consistent intervals each day. If feeding times are 5 a.m. and 5 p.m., the calves need to be feed at that time each and every day. When the time between feedings is longer than usual, calves may become overly hungry and swallow excess air as they feed aggressively.
Irregular feeding times can also disrupt normal digestion and proper milk clot formation in the abomasum. This instability creates an environment that allows clostridial bacteria to proliferate.
- Temperature
Strive to feed milk or milk replacer at a temperature near the calf’s body temperature, approximately 102°F. Again, consistency is key because if the temperature of the milk or milk replacer fed varies by more than 1 or 2 degrees from what the calf is used to it can hinder proper abomasum function. When milk sits in the abomasum for an extended time, fermentation occurs which allows clostridia to multiply and produce excessive gas and that leads to bloat. Wide swings in feeding temperature from one feeding to the next can also interfere with proper milk clotting in the abomasum.
That rule is only a starting point, because the right feeding temperature for pre-weaned calves depends on several factors, including air temperature, housing conditions (outdoor hutches versus an indoor calf barn), and feeding method — such as bottles kept warm in a milk house or buckets placed outside at the hutch. For example, winter checks on a few farms have showed that when the air temperature drops below 20°F, milk replacer mixed at 108°F cooled by 10 degrees within 30 seconds after being poured into a cold bucket at the hutch. That temperature loss did not occur when calves were fed with warm bottles stored indoors. When evaluating feeding protocols always check the temperature of the milk or milk replacer when the batch goes out the door and the temperature of the milk fed to the last calf. It’s the only way to ensure that every calf receives milk at the proper temperature.
- Total Solids
When feeding milk replacer, changes in total solids from one feeding to the next can disrupt digestion and lead to bloat. Most nutritionists recommend a consistent solids level of 12-13%, with 14% being a maximum upper limit on solids concentration.
When milk replacer solids are too concentrated, digestion slows and delays abomasal emptying which creates an environment favorable for fermentation and gas production. High osmolality from overly concentrated milk replacer can also contribute to scours, as water is drawn from the bloodstream into the gut to dilute the excess solids.
Milk solids that are too low can cause calves to consume their milk too quickly and gulp excess air. Low solids also result in inadequate nutrient intake and poor calf performance.
Use a digital refractometer to monitor every batch of milk replacer to help ensure consistency of total solids. If you feed hospital milk, total milk solids are generally lower (about 11 to 11.5%), so always check with a refractometer before feeding. When using refractometers the truest measurement is total solids, however a Brix refractometer has slightly different ranges. Most experts suggest adding 2 points to a Brix reading to get a more accurate approximation of total solids.
- Transport Feeding
Young calves transported to calf ranches have a higher risk of clostridial bloat. But you can cut that risk by feeding calves within 1-3 hours of transport. Calves fed right before they get on the truck have a full belly, will lay down for the trip, and are good for about 12 hours. Upon arrival calves are fed again. Also, ensuring that milk solids fed at both locations are the same is extremely helpful. Typically, calf ranches mix milk replacer to deliver 13 to 13.5% of total milk solids — that’s 1 % higher than cows’ milk and 2% higher than hospital milk. That big of a change in total solids from one feeding to the next is too much for the calf and bloat often occurs.
To minimize that risk ask the calf ranch what level of total milk solids they feed calves and try to match it. For calves transported on day one or two of life feeding colostrum for all meals is a big help. Or you can adjust the mix of milk replacer to increase solids a little to help narrow the difference in total solids.
Develop a plan
When bloat does occur in young calves, it can develop so fast that lung capacity is compromised, essentially suffocating the calf. Toxins produced by clostridial bacteria can also lead to shock and sudden death. Even if a bloated calf is detected and successfully treated, bacterial toxins may damage the intestinal lining, resulting in long-term digestive issues and performance setbacks.
Clostridial vaccines are commercially available, but young calves typically do not respond well to them unless the correct toxoid is used. Clostridia perfringens C and D toxoid should be used in young calves. The most effective protection against clostridia in pre-weaned calves comes from strong maternal antibodies provided through a well-designed dry cow vaccination program and excellent colostrum management
Like their adult dams, calves thrive on consistency. Establishing and maintaining well-trained feeding protocols — and consistently observing all of the “4Ts” — is critical to calf health, welfare, and long-term performance. Ask your veterinarian, or one of The Dairy Authority veterinarians, to develop a calf-feeding program that minimizes the risk for bloat in pre-weaned calves.
