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24/08/07
A survey of more than 400 dairy farms has found that 10% of calves
required antibiotic treatment for pneumonia last winter. Before
accounting for the effect on in-contact calves, Pfizer veterinary
manager Carolyn Hogan calculates that losses arising from this
incidence are more than £700/year for the average 168-cow
herd taking part. [1]
“This would increase substantially if you added the impact
on in-contacts,” she says. “A major concern is that
44% of farmers said the issue of treating close contact calves
at the same time had not been discussed with their vet.”
However, not all farmers are ignoring the in-contacts, although
only 10% of farmers will also treat pen-mates or house-mates in
most* cases, a further 8% in some* cases and 26% in a few* cases.
(* ‘Most’, ‘some’ and ‘few’ were
defined in the survey as ‘75-100%’, about ‘50%’ and ‘about
25%’ of cases respectively).
This “Good Start In Life” calf survey was sponsored
by Rispoval® IntraNasal, Pfizer’s single-dose pneumonia
vaccine for dairy calves. This sponsorship was not disclosed to
farmers at the time the survey was carried out. Among the 443 participating
farms, 57% had made changes in the last three years to improve
calf health and/or growth rates.
The two improvements in joint top spot were better ventilation
and vaccination. Next was allowing more space per calf, which Carolyn
Hogan says is obviously a good move if calves are too crowded.
However, she warns that it is also possible for calf density to
be too low in housing with a large air space, such that convection
currents created by body heat are too weak to drive stale air out
through the roof vents. “When this happens, the air circulates
inside the building, with the result that calves are breathing
stale air rather than fresh,” she says.
During the first three months of life, the survey finds that the
second month is regarded by farmers as marginally higher risk for
pneumonia than the first or third, possibly because this is when
immune protection derived from colostrum is starting to wear off
and before immunity derived from the environment has developed.
This would be consistent with the good colostrum practice evident
from the survey: 91% of farmers have a golden rule for the timing
and quantity of colostrum, the average being 2.98 litres within
5¾ hours of birth. While this is very close to the recommended
three litres within six hours, Carolyn Hogan identifies a concern
about the range of answers, especially where colostral intake is
low.
In the extreme, some farmers said they aimed for nine litres within
two hours of birth, whilst others only two litres within 12 hours.
To make sure enough colostrum is taken within the target time,
32% of farmers maintain close supervision of suckling and a further
16% give a manual feed by bottle or stomach tube as a matter of
routine.
As dairy herds get bigger and the workforce smaller, Carolyn Hogan
says it would be easy, but wrong, to jump to the conclusion that
calves come quite low down a dairy farm’s pecking order.
Among the farmers taking part in the survey, 95% said new-born
heifer calves represented their hopes and expectations of the future.
She urges farmers to take every opportunity to discuss ways of
improving calf health with their veterinary surgeon.
The prevention and treatment of pneumonia will be a feature of
the Pfizer stand at the Dairy Event, where vets and livestock advisers
will be available to discuss the main issues with farmers.
[1] Andrews A.H (2000) Cattle Practice Vol
8 Part 2: 109-114. This paper estimates a case of pneumonia in
a dairy calf to cost £43 per treated animal on average. In
the survey being reported here, the average farm reported 17 cases
of pneumonia in the past year requiring antibiotic treatment. Cost
estimate = 17 cases x £43/case = £731.
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