The Rural Voice, 1978-10, Page 32Sunny side up future
for older hens
Older hens have a future that is
sunny side up in the egg market. Research,
funded by the Ontario Ministry of
Agriculture and Food and Agriculture
Canada, shows hens older than one and a
half years might be profitable for some
poultry farmers -but payments would have
to be based on yolk content.
Professor G.W. Friars, Department of
Animal and Poultry Science, Ontario
Agricultural College (OAC), University of
Guelph, says the proportion of yolk in an
egg increases with the age of the bird. This
favorable characteristic partially offsetsthe
fact that compared to younger hens, older
hens produce fewer eggs and thinner egg
shells.
"When egg size increases as the bird
gets older, 60 to 70 per cent of that increase
is in the yolk. In contrast, when egg size
has been increased through breeding of
stock, only 5 to 10 per cent of the total
increase is in the yolk," says Professor
Friars.
Because older hens produce more yolk,
researchers wanted the hens to lay eggs for
longer periods. To obtain improvement in
shell quality, the older birds were forced
to molt at 41 weeks. This was acheived by
restricting feed, water and light for a
limited time.
In the OAC study, the hens stopped
laying in two or three weeks, but by eight
weeks ,high levels of production were
regained with very large eggs containing
high yolk content.
These high levels of yolk contain more
food value and are desirable in the
breakout trade. This 10 per cent segment
of the poultry industry uses surplus and
undergrade eggs for convenience foods
and other industries. -
Eggs from older hens could be marketed
profitably if the poultry industry decided to
pay for yolk content. Producers are
currently paid on the basis of grade of shell
eggs.
Is your cab too noisy?
How noisy is it in the cab of the
combine or large tractor you use or are
intending to buy? Do you know that
prolonged exposure to noise levels over 90
decibels measured on the A -scale (Db -A)
can cause hearing impairment?
The School of Engineering at the
University of Guelph conducted a
decibel -level sampling on the late model
combines and large tractors produced by
major reputable manufacturers. In the cabs
of these machines, which cost in the range
of $30,000 to $50,000, decibel readings
ranged from 77dB-A to 97dB-A. This is a
significant difference, since every increase
of 3dB-A doubles input to the ear.
Moreover, the price of the combine
registering the 77 dB -A reading in its cab is
no greater than that of machines with the
higher decibel readings.
Workers in the U.S. are protected by
Federal law (the Walsh -Healey Public
Contracts Act) from being exposed to noise
levels in excess of 90 dB -A for more than
eight hours per day; over 95 dB -A for more
than four hours per day; over 100 dB -A for
more than two hours per day; over 105
dB -A for more than one hour per day; over
115 dB -A for more than 15 minutes per
day. Where exposure for longer periods
cannot be avoided, ear protection must be
used. (For many people, the decibel range
of 115 to 120 dB -A is the threshold of
discomfort. Consequently, hearing damage
can occur although the individual is never
aware that sound level is excessive.)
It has been established that repetitive
exposure to the above decibel levels for
longer daily periods than the maximum
recommendations will cause hearing
impairment. This impairment involves loss
of the ability to discern the higher sound
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1.1 'run min * l amIrL inrTnuc: R 1978