Dairy farmers know the value of colostrum for the young calf and the need to achieve adequate intakes early in life. Yet local research has shown that in many instances, calves have received inadequate levels of colostrum and that calf mortality, and health problems in general, represent a significant economic and welfare cost to the Northern Ireland cattle industry.

Insufficient intake of colostral antibodies in the first six hours of birth is the main cause of calf health problems in the pre-weaning period.  Calves that do not receive adequate antibodies through colostrum are twice as likely to die as those calves receiving adequate colostrum.  Recent research has found that calves fed 4 litres of colostrum compared with 2 litres within one hour of birth had reduced veterinary costs and increased milk output during their first and second lactations.

Calves that are fed colostrum either by stomach tube or by bottle within the first hours of life, compared with calves that are left to suckle the mother, are almost 3 times more likely to have adequate immunity to fight off neonatal diseases.  Primarily this is a result of variation in the time taken by calves to suckle successfully.  Slowness to suckle successfully can be pronounced in dairy calves, with the average calf from a dairy cow taking over 4 hours to suckle.

Particular types of antibodies in colostrum attach to the lining of the intestine in the calf preventing pathogens from causing disease.  Consequently, it is recommended that, wherever possible, colostrum should be fed for the first 3-4 days of the calf’s life making full use of this protective function of colostrum as well as its high nutritive value.

Using the Zinc Sulphate Turbidity test (ZST), carried out on a blood sample taken within 1 week of birth, AFBI Hillsborough investigated the immune status of 150 bull calves, sourced from 12 commercial dairy farms.  Overall, 19% of calves (Figure 1) had inadequate immune status (ZST levels less than 20 grams per litre), although there was very significant variation between farms.  Over 70% of the calves purchased from one farm had ZST levels less than 20 grams per litre whereas at the other extreme some farms had no calves with ZST levels less than 20 grams per litre.  The importance of immune status has been highlighted by data produced by AFBI Veterinary Sciences Division, where 37% of calves submitted for post mortem had no detectable colostrum immunity and 60% of the dead calves had inadequate cover, with ZST values less than 10 grams per litre.

The immune status of calves can have long-term effects on growth.  Data from AFBI Hillsborough has shown that calves with ZST levels less than 20 grams per litre had 7% lower liveweight gains from birth to 9 months relative to those with ZST levels greater than 20 grams per litre.  Thus at 9 months of age, cattle which had ZST levels less than 20 grams per litre were 23 kg lighter than those with adequate ZST levels.

Figure 1.  Immune status of spring-born Holstein and beef x Holstein bull calves sourced from dairy farms in Northern Ireland (AFBI Hillsborough)

Main messages

Emphasis on colostrum management during the first 6-hours of life is crucial. Wherever possible, stomach tube or bottle feed calves with colostrum (10% of calf weight) within 6 hours of birth and continue feeding colostrum for 3-4 days.