The increased concern of modern societies on the emergence of antibiotic-resistant bacteria has led regulatory institutions to minimize the number of antibiotics that can be used in food-producing animals for therapeutic and preventive treatment of infectious diseases.

The sometimes unreasonable use of antimicrobials in beef and dairy operations could result in potential adverse effects on human health as the risk of transmission of resistant micro-organisms to the human population could potentially increase.

Prophylactic and methaphylactic administration of antibiotics to prevent disease in calves early after arrival to feedlots and dairy calf ranches is not uncommon.

At the same time, as overuse of antibiotics is evident in some situations, the discovery and development of new antimicrobials to treat old and novel infections in human and veterinary medicine has decreased in the last years. It is estimated that the antibiotic shortage increased around 283 percent during 2006 through 2010.

To overcome the limited availability of antibiotics to treat food-producing animals, and at the same time the high morbidity and mortality rates observed in some cattle operations such as feedlots and dairy calf-rearing farms, the development of alternatives to antibiotics such as antibacterial vaccines, immunomodulatory agents and antimicrobial peptides (AMPs) have been proposed.

Maternal colostrum provides specific immunity to the newborn calf through Immunoglobulin G (IgG) that effectively protects against infectious micro-organisms during the first weeks of life.

In addition to IgG, maternal colostrum provides high concentrations of immunomodulatory factors (cytokines), antibacterial peptides (lactoferrin), growth factors (EGF, IGF-1) and vitamins that enhance immune responses and exert antimicrobial functions in the young calf.

Colostrum intake in newborn calves should occur immediately after birth because the ability of the calf’s intestine to absorb IgG decreases progressively after six hours of life.

Calves with adequate passive transfer of IgG during the first 24 hours of life demonstrate lower morbidity and mortality rates compared with calves with failure of passive transfer of IgG (FPT); however, the benefits of maternal colostrum components, including immunoglobulins (IgG, IgA, IgM), immunomodulatory factors, vitamins, growth factors and antimicrobial molecules, could be prolonged during the pre-weaning period through continuous administration of maternal colostrum in the calf’s ration.

Studies have demonstrated that although absorption of IgG after 24 hours of life does not occur in the calf, the effects of immunoglobulins and other immune factors present in colostrum provide local immunity in the gastrointestinal tract and might prevent infection caused by enteric viruses and bacteria.

One study demonstrated that when 70 grams of a dried colostrum/colostrum replacer product containing 10 grams of IgG mixed in the milk replacer ration was administered twice daily from 1 to 14 days old to dairy calves with partial or complete FPT, the number of days with diarrhea and the number of antibiotic treatments was significantly decreased when compared with a control group of calves with FPT that did not receive colostrum replacer supplement.

In a more recent trial at SCCL, we administered 150 grams of a dried-colostrum/colostrum replacer mixed into the milk replacer twice daily from days 1 to 14 to Holstein calves in a calf ranch and compared the incidence of disease (diarrhea and pneumonia) and total number of antibiotic treatments with a control group of calves that did not receive colostrum replacer supplement in their ration.

All calves used in this trial had adequate passive transfer of IgG at the start of the trial (IgG in serum greater than 10 g per L).

The overall incidence of disease in calves supplemented with colostrum replacer was reduced by 40 percent; additionally, the number of antibiotic treatments in the group of calves that received colostrum replacer was reduced four times.

It is possible that components present in the dried colostrum/colostrum replacer such as IgG, immune factors, vitamins and other antimicrobial peptides such as lactoferrin could have played a role in increasing local and systemic immunity in calves receiving supplemental colostrum.

The results of these studies suggest that colostrum supplementation of dairy calves during the first two weeks of life independently of passive transfer status reduces presentation of disease and minimizes prophylactic and therapeutic use of antibiotics before weaning.  PD

References omitted due to space but are available upon request. Click here to email an editor.

• Manuel F. Chamorro

• Director of Technical Services and Clinical Research
• Saskatoon Colostrum Company Ltd.
• Email Manuel F. Chamorro