Moorepark researchers estimate that calf mortality ranges from 3% to 15% on Irish dairy farms. They say that the target for good calf rearing should be less than 3% mortality.
Calves are born without a developed immune system, and depend entirely on antibodies from colostrum to gain adequate immunity, until they develop their own immune system at three or four weeks of age.
Colostrum key to health
Data from veterinary laboratories indicates that inadequate absorption of antibodies from colostrum is a major factor in about two thirds of calf deaths and diseases in Ireland.
This can be due to a calf not receiving sufficient colostrum, or not getting colostrum soon enough after being born, or in rare cases, colostrum with inadequate antibodies.
Colostrum is very high in energy, protein and vitamins and — most importantly — high levels of antibodies which enable calves to fight infection.
The researchers emphasise that only the first milk the cow produces is suitable for calves’ first feed.
The interval from calving to milking also has an effect on colostrum.
The quality is reduced by at least 86% in milk collected more than nine hours after calving, compared with milk in the first three hours after calving.
The quality of colostrum generally improves in second and subsequent lactations, but the researchers found that even the quality of colostrum from first calvers was adequate in the vast majority of cases.
Cows that are too fat at calving may have poorer quality colostrum.
Researchers recommend that calves should not be left with their mothers for their first feed of colostrum, because it is unlikely that they will drink the required amount that is required for maximum immunity.
Recent studies recommended that dairy calves be fed three litres of colostrum within two hours of birth.
A stomach tube is the method of choice, if the operator is trained properly.
As calves vary in weight, these quantities can be varied a little to suit different calves.
About 8.5% to 10% of birth weight is the optimum amount of colostrum to be fed.
Despite the drop-off in absorption, calves are generally fed colostrum for at least three days after birth.
A Teagasc trial indicated that milk replacer or ordinary milk can be introduced after the first feeds of colostrum.
More milk, earlier weaning
Traditionally dairy calves were fed about 4-4.5 litres of milk (or milk replacer) per day until weaning.
Recent research worldwide has shown that feeding greater amounts of milk before weaning resulted in better growth rates and lower disease and mortality, and higher milk production and fertility in later life.
Moorepark trials with Holstein calves receiving 10% and 15% of birth weight (four litres and six litres) showed that calves getting the higher levels of milk reached weaning weight earlier.
There was no evidence of more scouring from the extra milk.
Research from the US has indicated that calf performance from birth to weaning is very importance for heifer performance in their first two lactations.
Feeding high levels of milk replacer was compared with more traditional levels in trials at Cornell University over a long period in high-performing Holstein herds.
It was found that calves receiving up to 50 kg of milk replacer, and gaining more than 0.9 kg of live weight per day produced around an extra 850 litres of milk in each of their first two lactations.
The results are based on milk recording results from 1,200 animals.
The results may not be as striking in Irish herds, due to lower yields, but they are very interesting.
It is likely that achieving higher weight gains before weaning will have a long term effect, and long term trials regarding this aspect of calf rearing would be very useful.
Based on the Moorepark and US research, it is advisable to feed higher than the traditional levels of milk or milk replacer before weaning.
Give your calves a good start in life by ensuring that they get adequate colostrum within two hours of birth from cows which are milked within a few hours of calving.
If there is a risk of Johnes disease in the herd, don’t pool colostrum, and remove calf immediately after birth.
Make sure calf houses and calving houses are well cleaned and disinfected.
All housing should have adequate ventilation without droughts.
As cows come near calving, give careful attention to cubicles; cows that are uncomfortable lying on cubicles should be removed to a loose straw-bedded house
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