Contamination of Colostrum

Colostrum management is the key aspect to any successful calf rearing system. We know the importance of feeding our calves colostrum quickly (within 2 hours of birth), quality (>50mg/l) and quantity (10% of birth weight) but do we know the detrimental effect of the contamination within colostrum if we were to leave it standing after harvesting.

Bacterial contamination of colostrum often occurs on farms, with two associated concerns:

1. The risk of transfer of infection to calves.

2. Decreased absorption of IgG in the intestines.

Calves fed colostrum with extremely high levels of bacteria (>1,000,000 cfu/ml) have decreased serum IgG concentrations at 24 hours, whereas calves fed colostrum with bacteria levels of 100,000 cfu/ml achieves adequate passive transfer.

When bacteria are introduced into colostrum they do not begin to grow immediately. A short period of time, the "lag phase," is needed for the bacteria to modify to their new environment in order to reproduce. This means that bacteria in freshly milked colostrum, almost the same body temperature as cow 38 degrees Celsius, double in 20 minutes. At 15 degrees Celsius this doubling time is about 2.5 hours. When in refrigeration at 4.5 degrees Celsius generation time is over 24 hours.

Desirable bacterial counts can be achieved through hygienic colostrum collection, avoiding bacterial contamination, immediately refrigerating or freezing surplus colostrum or implementing heat treatments of colostrum.

Heat treatment (pasteurisation) of colostrum at 60°C for 30 or 60 minutes reduces the bacterial count, preserves IgG concentration and increases the apparent efficiency of absorption of IgG compared to calves fed raw colostrum. In addition, calves fed heat-treated colostrum are at lower risk of illness.

A protocol system is essential to ensure standards are achieved -