Biosekuriteit reeks – Deel 6

Dr Chris van Dijk

If a milk producer was asked where he/she 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 these 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 form 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 result in these animals becoming economic liabilities.

Calf health management

The bottom line regarding calf health is that management factors do influence the illness and death rates of calves. Too many producers have come to accept these high rates as routine or acceptable, not fully realizing the economic cost may be much more than just the value of a dead calf or increased veterinary and drug costs – especially in those animals that survive this risky development period.

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 components in this manner:

  1. Raise the level of resistance in the current dairy population.
  2. Reduce the exposure of the herd to on-site diseases and pathogens.
  3. 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.Rise the level of resistance in the dairy calf (animal, environment).
  • Colostrum and colostrum management
  • Dry cow management and cow vaccination
  • Nutrition
  • Reduce environmental stressors/increase calf comfort

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 form their mother’s bloodstream, and instead they rely on colostrums to provide the antibodies that are critical for disease resistance and protection. This process of getting antibodies from the colostrums is known as passive transfer. If adequate amounts (2-4 litres per calf) of colostrums are not received within a certain time frame (in the first 6 hours after birth), or if the quality of the colostrums is poor, then the calf will not receive adequate antibodies. This low or absent antibody transfer from the colostrum to the calf is know as failure of passive transfer (FPT). A calf which receives no colostrums 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 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 colostrums administered, and colostral quality. For Holstein calves the recommended colostrum program is to hand administer (via bottle or stomach tube) 2-4 litres of colostrum within six (6) hours of birth, followed by another 1-2 litres of colostrum around eight to ten hours post-calving. The initial first 2-4 litres colostrum is most important and becomes even more critical if the quality of the colostrum is not known.

Timing of colostrums 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 an/or death.

Disclaimer: Zoetis takes no responsibility for any claims that may arise from information contained in this information sheet. Individual situations may vary from location to lo px;"cation and it is recommended that you consult your veterinarian before any management or treatment decisions are implemented.

Vrywaring: Zoetis neem geen verantwoordelikheid vir enige eise wat mag voortspruit uit inligting vervat in hierdie inligtingsdokument. Individuele situasies varieer van plek tot plek en dit word voorgestel dat u eers u veearts kontak alvorens enige bestuurs- of behandelingsbesluite geïmplementeer word.