Three Simple Steps to Weaning Healthy Calves

Lowell T. Midla V.M.D., M.S.

Midla Lowell
Lowell T. Midla V.M.D., M.S.

Editor’s note:  Dr. Midla is veterinary technical services manager, Merck Animal Health

As an industry, we’re learning how to prevent morbidity and mortality due to neonatal diarrhea. However, knowing how to implement what we’ve learned on individual farms — within their individual management and facility constraints — is more difficult.  Below you will find the “what to do.” It will be up to producers, working with a veterinarian, to decide “how to do it” on a specific operation. If producers embrace the challenge to not shortcut anything in the implementation of the recommendations, then operations can achieve the goal of not only weaning every calf, but also weaning calves that are healthier and destined to produce more milk when they enter the lactating herd.

Step 1: Decrease the magnitude of the disease challenge.

Tactic 1: Decrease the amount of pathogens (ideally to zero) left behind by the former residents of the facility where the calf will be housed. I am often asked: “What disinfectant should I use?” My answer is this: Don’t worry about the choice of disinfectant until you have removed all the organic matter from the surface to be cleaned. Power wash floors and walls, power wash hutches, place fresh gravel beneath hutches, etc. After all organic matter is removed, then apply a disinfectant. You can’t disinfect manure.

 Tactic 2: Decrease pathogen ingestion by the calf in the period immediately after birth. Maintain a clean environment into which calves are born. This is obviously also important for metritis prevention. Bottom line: Regardless of any other preventive intervention, the likelihood of illness is directly related to the magnitude of the challenge.

Tactic 3: Decrease the amount of pathogens to which the calf is exposed via equipment. Bottles, nipples, and buckets, and anything with milk residue, is difficult to clean. Plastic with bite marks, chips or dents, is especially difficult to clean efficiently. Biofilms, in general, are difficult to remove. Make sure that your idea of clean is exactly that – clean. Clean means that all organic matter has been removed. Following cleaning, ensure that all surfaces of the feeding equipment are allowed ample time to dry.

Tactic 4: Utilize individual housing in early life to limit the spread of pathogens. Individual hutches that are too closely spaced or allow nose-to-nose contact no longer achieve the goal of limiting the spread of pathogens.

Tactic 5: Do not exceed suitable number of calves per pen. There is a number of calves per pen on every dairy where the likelihood of disease in those calves rises sharply. Do not exceed this number. This means that you must have a plan for how to deal with slugs in the number of cows calving. It is also likely that there is some absolute limit to the number of pre-weaned dairy calves that can be housed in a single pen without increasing the likelihood of disease. While we do not yet know that number, it is likely a lower number than many existing pens were designed to contain. Finally, keep in mind that the calves in a given pen should be close in age. Bottom line: If you put 100 calves in a 30-by-30-foot pen, then you are going to have lots of problems. If you put two calves in a pen the same size, then you are less likely to have problems. Somewhere in the middle is the “sweet spot” for the optimum number of calves per pen.

Step 2: Ensure that the calf has basic/fundamental/essential resistance to the challenge.

Tactic 1: Make sure calves get colostrum. I know that you’ve probably heard the colostrum lecture about a thousand times. Still, there is a reason that you have heard it a thousand times – it is important. Remember that calves are born with very little to no antibodies with which to fight disease. Without colostrum, calves are immunologically naked. The more antibody absorbed from colostrum the better. The reason that the recommendation is to feed four quarts of colostrum is that we can’t give more. Also critically important is timing, since timing determines the amount of antibodies that are absorbed. Forget the recommendations to feed colostrum within six hours or four hours or two hours after birth. Efficiency of absorption begins to decline and steadily declines immediately after birth. Volume and timing are the “big two” for colostrum. Other factors to consider include: 1. Quality – there is variation between cows.  2. Timing of harvest – quality begins to decline following calving.  3. Contamination – colostrum sitting in a bucket in the parlor at room temperature prior to feeding or freezing leads to growth of bad bugs to unacceptable levels. You are actually giving them the bugs that will cause the diarrhea.

Tactic 2: Provide better energy and protein levels. The immune system requires energy to function. Think about the days when we vaccinated the entire lactating herd on the same day and the bulk tank would be down 10 percent or more the following day. This is due to several reasons, but it is largely a demonstration of the idea that the immune system requires energy to function. Therefore, it is imperative that we provide not just adequate, but better stated appropriate levels of energy and protein to calves to achieve optimum immune function. Also remember that energy required for maintenance rises as the ambient temperature drops, so if we do not provide additional energy during cold weather then most or all dietary energy will be devoted to maintenance with none left over for immune function (or growth). Bottom line: appropriate levels of energy and protein are not only necessary, but critical to achieving optimum immune function.

Tactic 3: Remember the basics. Provide clean water. Mix milk replacers and balance whole milk to an appropriate level of solids concentration. Do not create non-infectious “nutritional” diarrhea by feeding errors.

 Step 3: Increase/Augment/Complement the calf’s ability to resist the challenge.

Tactic 1: Vaccinate the dam to increase the level of antibody directed against specific pathogens in the colostrum. There are several commercially available vaccines designed for this purpose. Typically, they are directed against E. coli, bovine rotavirus, bovine coronavirus, and Clostridium perfringens. This tactic does indeed enhance the ability of the calf to resist disease. However, remember that this fails if the calf does not get the antibody generated in the dam via the colostrum. Also, remember that dams being vaccinated for the first time (e.g. heifers, purchased cows) need both a dose and a booster for the tactic to be effective.

Tactic 2: Vaccinate the calf directly against the pathogen. You might choose this method if it is difficult to give vaccine to cows during the dry period (due to facilities or other considerations). However, there is evidence that some of these vaccines can enhance protection even in calves that received colostrum from vaccinated dams. For example, there is a vaccine available against bovine coronavirus that is labeled to be given intranasally. Intranasal vaccination stimulates production of IgA-type antibodies that may be more important than IgG (the type that results from IM/SC vaccination and the types that are passed to the calf via colostrum) in preventing neonatal diarrhea. Even if IgA is not “more important” than IgG, it may still be the case that having both types of antibodies (and not just one or the other) is still important toward preventing clinical disease.

Tactic 3: Give antibodies directly to the calf. There are products available that provide antibodies directly to the calf. It is critical that these products be given very soon after birth for them to be absorbed.

Tactic 4: Spike the milk/milk replacer with a colostrum replacement product for the first several days after birth. (Note: I am not aware of any research to support this tactic, but I am aware of anecdotal reports that it helps and it does make sense that it could help.)  The effect is not due to the calf absorbing the antibody – since the calf no longer can – but instead due to the local effect of the antibody from the product within the gut. Care must be taken to monitor the total dissolved solids concentration in the final diet delivered to the calf to prevent the addition of the colostrum replacement product from making the milk hyperosmotic. It’s also important to recognize that colostrum replacement products are expensive. Thus there will be a balance between health effect and economics when deciding how much of the product to add. It may be that the level necessary to benefit health is cost prohibitive.

Tactic 5: Eliminate/Minimize other stressors. Examples of stressors include: Navel ill, ventilation/ammonia problems, pneumonia, stressor storms (vaccinating, dehorning, changing diet all on the same day), BVD PI calves, etc.

In conclusion, there are several tactics producers may take to prevent neonatal diarrhea. Knowing what to do to prevent neonatal diarrhea is easy, but actually doing it is difficult. The degree to which you do it will greatly determine the degree of success that you achieve on your operation.