Factors influencing the development of mucosal immunity in hand-reared calves

Summary

The potential for rearing bull calves from dairy cows in order to supply the bull beef market is hampered by high rates of death and disease.  In the first three weeks of life mortality rates for hand-reared calves ranges between 2 and 15% of calves reared and the prevalence of disease averages about four to five times the mortality rate. The high costs of rearing calves (especially when coupled with costs incurred for treatments of diseases and losses through deaths) makes calf rearing an economically risky enterprise.  The majority of diseases in calves in Australia are enteric diseases affecting the gut and causing severe diarrhoea or scours.  The development of the gut-associated immune system of calves in the first three weeks of life was investigated through the influence on the health and immune responses of calves of two different forms of additives to calf milk replacer.  In particular, observations and analyses were made on the Peyer's patches of the small intestine. These specific and important immune structures are critical for the calf against pathogens.