The timely ingestion and absorption of colostral immunoglobulin is a critical
determinant of neonatal calf health. Calves are born without appreciable concentrations
of the serum immunoglobulins needed to protect against pathogenic
bacteria, viruses and protozoa (Tyler & Parish, 1995). The beneficial effect of passive
transfer of colostral immunoglobulin also extends beyond the neonatal period and
persists into juvenile and adult life (Robison et al. 1988; Tyler et al. 1998; DeNise et al.
1989). Calves with failure of passive transfer, defined as serum protein < 50 g/l
or serum IgG < 10 g/l, have increased mortality risks that persist until 10 weeks
of age (Tyler et al. 1998).
Several diseases are potentially spread by the ingestion of colostrum, including
bovine leukosis and Johne's disease (Perrin & Polack, 1988; Streeter et al. 1995). In
one study 22% of latently infected cows were demonstrated to shed Mycobacterium
paratuberculosis in their colostrum (Streeter et al. 1995). Optimal programmes to
prevent and eradicate these diseases generally include the provision that calves are
given colostrum derived from cows of known negative disease status. Pasteurization
or heat treatment of colostrum may provide a mechanism whereby calves are
provided with protection against neonatal disease without creating undue potential
for infection by chronic, economically relevant diseases.
Attempts to heat disinfect colostrum are common in goat herds (MacKenzie et al.
1987). Pasteurization has been demonstrated to be effective against the caprine
arthritis–encephalomyelitis virus (Adams et al. 1983; MacKenzie et al. 1987).
Although Myco. paratuberculosis appears to resist pasteurization, this form of
processing has been demonstrated to decrease the likelihood of positive colostral
cultures for Myco. paratuberculosis under experimental conditions (Meylan et al.
1996). Sterilizing the milk and colostrum given to calves is a logical and reasonable
strategy to prevent transmission of infectious microorganisms. The potential
disadvantage of heat treating colostrum is that the immunoglobulins in colostrum
may become denatured (Smith & Sherman, 1994). Pasteurization causes only a slight
decrease in the colostral concentration of IgG in cattle (Meylan et al. 1996); however,
the biological behaviour of these pasteurized immunoglobulins has not been critically
examined. Therefore, we cannot be completely confident that immunoglobulin
absorption, persistence in serum and biological activity are unchanged by this
The goal of this study was to determine the effect of pasteurization at 76 and
63 °C on the absorption of IgG from colostrum. Should these procedures decrease
immunoglobulin absorption, the use of pasteurization in disease eradication
programmes would require increased efforts to optimize the passive transfer of