If a milk producer was asked where s/he experienced the most illness and death on the dairy, the most common answer would have to be 'in the calves', especially those less than four weeks of age. With this in mind, several other questions need to be asked: 

• Why the higher level of illness and death among calves?
• Are those losses expected or considered a routine part of the dairy business?
• Does calf care and management have a lower priority than other management areas on the dairy?

While the answers to the above questions will vary between producers, the facts suggest that calf mortality (death) in the average dairy runs anywhere for 5.1% -20.2%. Most of these deaths will occur during the first month of life. If these numbers seem high, then the number of calves that become ill (morbidity) during this period must be even higher.

Calf Growth Rate
While many producers judge the success of their calf raising by the percentage of those that survive to weaning, a better measure of success might be to consider the growth rates of the calves. In the case of replacement heifers, growth rate ultimately affects the timing of puberty, which affects the age of first lactation (24 months vs.28 months), and even first lactation milk production.

When the age of first lactation and milk production come into the picture, the economic impact of calfhood diseases takes on a new meaning. While no uniform data is available, it is generally recognized that calf diseases ultimately set the calf back in regard to growth rate and often create chronic conditions that will never allow the animal to reach its full genetic potential. These previously sick (but recovered) calves may lag behind healthy herdmates by weeks or even months. In addition, if their illness was severe enough or long standing, permanent damage and/or chronic pain may be present which will ultimately results in these animals becoming economic liabilities. 

Biosecurity Program Principles
A more obvious situation for the implementation of a biosecurity program would be hard to find. Let's review the principles of a biosecurity program as previously covered in this series, and apply these principles to the dairy calf.

Disease comes about from the interaction of three primary components: the animal, the pathogen (disease-causing organism), and the environment. The basic concept of a biosecurity program for the dairy addressed these three components in this manner:

• Raise the level of resistance in the current dairy population.
• Reduce the exposure of the herd to on-site diseases and pathogens.
• Control and monitor all cattle, livestock, equipment and people entering the dairy.

Success in maintaining herd health requires that all three components be addressed simultaneously. Ignoring any one area is all that is required to allow disease to gain the upper hand and create economic losses.

Calf Biosecurity
Our biosecurity program adjusted to the unique situation and needs of the calf would include the following recommendations:

1. Raise the Level of Resistance in the Dairy Calf (Animal, Environment)

• Colostrum and colostrum management
• Dry cow management and cow vaccinations
• Nutrition
• Reduce environmental stressors/increase calf comfort

2. Reduce Exposure of the Calves to On-site Disease and Pathogens
Calves are born with essentially no antibodies and an immature, non-fully functional immune system. Human babies born into this situation would undoubtedly be placed into a special sterile environment to reduce the chances for contracting disease. Calves however, are thrown into the sea of infectious agents found in and around the mud, urine, feces, flies, and sick animals that reside in their surroundings. 

The following list contains some common sense suggestions that, if followed, will greatly decrease the exposure of the calves to disease organisms and improve their health, survivability and growth rates.

• Clean teats before the calf nurses or before milking out colostrum.
• Filter colostrum to remove any fecal matter (pasteurization of colostrum is often beneficial). 
• Utilize individual hutches and thoroughly disinfect between occupants.
• Keep maternity pen clean and freshly bedded. 
• Separate calves from dams as soon as possible, and move the calf to an individual hutch.
•   Keep calves away from other members of the herd, avoiding calf-to-calf contact.
• Add more bedding or move hutches to decrease exposure to infectious agents.
• Pay strict attention to sanitation measures. Thoroughly clean and disinfect all equipment that comes in contact with calves. When applicable, each calf should have her own dedicated feeding utensils. Feeding buckets should not have scratches (plastic) or other rough surfaces that allow bacteria to reside in them. 
• Isolate sick and diseased calves, feeding them last.
• Keep water sources, feeds, etc. free from manure contamination.

3. Control and Monitor all Cattle, Livestock, Equipment, and People Entering the Dairy
Part of the strategy of a biosecurity program is to keep infectious agents from entering the dairy in the first place. As previously discussed and supported by NAHMS data, most dairies fall short in this regard and leave themselves open to receiving someone else's problems. While a truly closed dairy may seem undesirable or impractical, the health benefits are undeniable. Just attempt to walk onto most major swine rearing facilities. The swine industry has recognized the benefits of biosecurity measure and has aggressively implemented them.

Pictured here, Dr. Gregory Quakenbush, D.V.M,.Technical Services, Pfizer Animal Health

Colostrum Management
Unlike human babies, calves are born with essentially no antibodies against disease-causing organisms. Human babies will receive antibodies while still in the womb via the mother's bloodstream. Calves do not receive antibodies from their mother's bloodstream, and instead they rely on colostrum to provide the antibodies that are critical for disease resistance and protection. This process of getting antibodies from the colostrum is known as passive transfer. If adequate amounts of colostrum are not received within a certain time frame, or if the quality of the colostrum is poor, then the calf will not receive adequate antibodies. This low or absent antibody transfer from the colostrum to the calf is known as failure of passive transfer (FPT). As an example of the critical nature of this passive transfer, the University of California-Davis Veterinary Medical Extension states that a calf which receives no colostrum is 74 times more likely to die than calves receiving colostrum by the recommended method.

Most dairy producers realize the importance of colostrum, but surveys continue to show that colostrum management often falls short of what is necessary for maximal transfer of antibodies. Good colostrum management depends primarily upon three factors: timing of administration, volume of colostrum administered, and colostral quality. For Holstein calves the recommended colostrum program is to hand administer (via bottle or stomach tube) four quarts of colostrum within two hours of birth, followed by another two quarts of colostrum around eight hours post-calving. The initial four-quart colostrum feeding is most important and becomes even more critical if the quality of the colostrum is not known.

Timing of colostrum administration is critical because the small intestine can only absorb the large antibody protein molecules for a matter of hours. For the first nine hours following birth, the ability of the intestine to absorb antibodies into the bloodstream has decreased by 50%. By 24 hours, the small intestine is essentially closed to large molecules and no antibody transfer can take place.

Hand administration of colostrum is important to ensure that an adequate volume of colostrum is administered within the critical time frame. Surveys reveal that 30% of dairies allow the calf to remain with the dam for up to 12 hours and nurse colostrum on their own. Studies in these situations have shown that only 25% of calves receive an adequate volume of colostrum to provide passive transfer. This leaves 75% of calves at risk of failure of passive transfer and are therefore more susceptible to disease and/or death.

Dry Cow Management and Cow Vaccinations
Antibody content and colostrum quality can be greatly affected by management of the cow during the dry period. Colostrum quality is going to be directly proportional to the immune status of the cow. Anything that affects immunity of the cow will be reflected in the quality of the colostrum. If the cow is under stress, or if forage quality is low, then colostrum quality will suffer. However, vaccinations of the cow three to four weeks before freshening will often result in increased antibodies in the colostrum and may be considered a way to vaccinate the calf (i.e.. through the colostrum).

Vaccinating the dry cow for E. coli, Rotavirus, Coronavirus and Clostridium perfringens may help in the management of calf diarrhea. Respiratory viral vaccines administered to the dam containing IBR, P13, BRSV and BVD can reduce the incidence and/or severity of these diseases in the young calf. Keep in mind that vaccination of the dam during the dry period does not guarantee calf health, but it will help to provide the calf with high antibody colostrum.

Pictured here, Dr. Victor Cortese, D.V.M,.Technical Services, Pfizer Animal Health

Calf Nutrition
It goes without saying that the calf's resistance and disease incidence levels will be greatly affected by nutritional management of the calf. Quality of milk replacer, introduction of calf starter rations, maintenance of caloric intake during cold weather and/or illness, and availability of fresh water are just some of the nutritional issues that need attention. Keep in mind that we want to obtain an overall growth rate of at least one or more pounds per day during the pre-weaning period. By the time calves are weaned they should be gaining 1.5 pounds/day. Consider utilizing growth rates in addition to survivability as a measure of your calf raising success. Calf and young heifer growth rates ultimately relate to the first lactation milk production.

Reduce Stress and Improve Calf Comfort
Stress plays a large role in reducing resistance levels of individual animals and therefore makes them more susceptible to disease and even death. For example, calves that undergo a difficult birth requiring assistance (pulling) are 4.2 times more at risk of becoming ill and/or dying than a calf undergoing a normal unassisted birth. Every effort should be made to look for stressful situations, eliminate them and supply tender loving care. Common types of stress experienced by many calves include uncomfortable, cramped housing; poor ventilation; drafty environments; inconsistent feeding practices; and heat or cold.

Treatment vs. Prevention
The whole purpose of a biosecurity program is to reduce the incidence of illness and disease, protect the resident herd, and increase profitability. The goals of such a program ultimately rely upon preventive measures rather than treatment to reduce the incidence of illness and the spread of disease.

In no other part of the dairy operation can the results of a biosecurity management program be more readily appreciated and the positive results more rapidly observed than with calves. Dramatic reductions in calf death and illness rates are available to producers who are willing to increase the level of attention that successful calf-raising requires. Producers who rely on treatment alone in their battle against calf disease are always going to be greatly disappointed. An ounce of prevention, in this case, is truly worth a ton of cure.

This article reproduced with permission from Midwest Dairy Business.