Free-range table-birds being reared from slower
growing breeds need a different vaccination regime from that of faster-growing
broilers, when being immunised against Gumboro
disease.
This previously-unknown fact has emerged from laboratory and field trials,
involving several hundred thousand birds on farms throughout the UK, carried out
by Lohmann Animal Health in conjunction with poultry vets.
“When using a 'hot' vaccine conventional broilers in the UK are normally
vaccinated at around 14-16 days when their maternal immunity is waning,â€
said Adam Goddard, Lohmann's UK sales consult. “However, we've found this
maternal immunity lasts longer in the slow-growing breeds which are reared both
indoors and out.â€
Realistically, the correct day of vaccination for free-range table-birds is
more likely to be achieved by using the vaccine date predictions for
broiler-breeders, rather than that of the broiler, under the Deventer formula,
which gives calculations for different types of bird.
He therefore advises producers to consult their vets who can take blood
samples to get an accurate prediction regarding optimum timing of vaccination
with their own particular flocks.
“Our trials have shown that, in general, and depending upon the breed used,
the decline in maternal immunity is delayed - perhaps for 4-5 days. So, in order
to get a better 'take', we recommend vaccinating these birds later or using an
IBD vaccine that 'takes' in the presence of high maternal immunity,†said
Goddard.
Earlier this year Lohmann Animal Health launched a new 'hot' vaccine,
classified as an 'intermediate plus' against the very virulent form of Gumboro
disease. Because of its ability to break through high levels of maternal
antibodies, it allows vaccination to take place earlier than with other existing
vaccines.
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