Researchers at Teagasc Moorepark have estimated 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 has indicated that inadequate absorption of antibodies from colostrum is a major factor in approximately 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 colostrum with inadequate antibodies, in rare cases.
Colostrum is very high in energy, protein and vitamins, and most importantly, high levels of antibodies which enable calves to fight infection.
Researchers emphasise that only the first milk the cow produces is suitable to feed to calves for their first feed.
The interval from calving to milking also has an effect on colostrum.
The quality is reduced by 86% in milk collected between nine and 12 hours after calving, compared with milk in the first three hours after calving.
Farmers should be aware of this very important aspect of calf rearing.
The quality of colostrum generally improves in second and subsequent lactations, but researchers have 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.
As a result of their findings, the 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 of colostrum that is required for maximum immunity.
It is recommended that dairy calves are 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 will 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.
However, results of a Teagasc trial indicated that milk replacer or ordinary milk can be introduced after the first few feeds of colostrum.
Traditionally, dairy calves were fed about 4-4.5 litres of milk (or milk replacer) per day, or about 10% of birth weight, until weaning.
Worldwide research results has shown that feeding greater amounts of milk before weaning resulted in better growth rates, and lower disease and mortality, in addition to higher milk production and fertility in cows later on.
Moorepark trials with Holstein calves receiving 10% and 15% of birth weight (four and six litres) indicated that the calves getting the higher levels of milk reached weaning weight earlier.
There was no evidence of more scouring from the extra milk.
US research findings
Research in the US indicated that the performance of calves from birth to weaning is very important for the performance of heifers in their first two lactations.
Feeding high levels of milk replacer were compared with more traditional levels in trials at Cornell University over a long period, in high-performing Holstein herds (milk recording results from 1,200 animals were analysed).
It was found that calves receiving up to 50 kg of milk replacer, and gaining over 0.9 kg of live weight per day, produced an extra 850 litres of milk in each of their first two lactations. The effect might not be as striking in Irish herds, due to lower yields, but is still very interesting.
It is likely that achieving higher weight gains before weaning will have a long term effect. To test for this, long term trials regarding this aspect of calf rearing would be very useful. It is often noticeable that calves reared very well, they go on to become very good milk producers.
Based on Moorepark and US research findings, it is advisable to feed higher than the traditional levels of milk or milk replacer up to weaning.
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