The Rural Voice, 2002-05, Page 16Seeing
the light
Research shows that giving milking cows
more hours of light will increase their
production up to 10
Ken and Jocelyn deBoer have achieved improved
production by varying the light milking cows get compared to
dry cows. New research explains why.— File Photo
Eight years ago Ken and Jocelyn, deBoer began
leaving the lights on 16 hours a day in their
Lucknow-area dairy barn. They were rewarded with
a 10 per cent increase in milk production from their herd.
"That came from visiting the research station atop
Lennoxville (Quebec)," Ken recalled in an interview an
The Rural Voice in 1998. He had visited the research farm
during his term with the Agriculture Research Institute and
learned of research that had been done 10 years previously
but never published. Talking to the researchers Ken also
learned the importance of providing shorter days for dry
cows to boost milk production when they are given longer -
light days on freshening.
Now more research has been published on the benefits
of long light and short light days for dairy cattle. At a
recent dairy conference in British Columbia, Annette
Buyserie, a graduate student in Animal Sciences and Mike
Gamroth, an Extension Dairy Specialist at Oregon State
University delivered a report that was carried in the British
Columbia farm publication Agri Digest. The following
outlines their findings:
12 THE RURAL VOICE
"Photoperiod control for lactating and dry dairy cows
can be used to increase milk production. Photoperiod is
defined as the duration of light an animal is exposed to
within a 24-hour period. A long day photoperiod (LDPP) is
defined as exposure to 16-18 hours of appropriate
continuous light followed by a 6-8 hour period of
continuous darkness. Experimentally, a short day
photoperiod (SDPP) is defined as continuous exposure to
eight hours of appropriate light followed by a continuous
16 -hour period of darkness. In practical application, a
SDPP is anything less than 12-13 hours of light.
"Lactating cows exposed to a LDPP consistently show a
two -litre milk/cow/day or 8 - 10 per cent increase in milk
production regardless of the cow's original production
level. Photoperiod does not significantly influence milk
protein, lactose, fat, or total solids concentration in the
milk. The increased production becomes fully apparent
three to four weeks after initiation of LDPP. Additionally,
cows exposed to a SDPP during the dry period have
increased milk production over cows exposed to a LDPP
during the dry period when both groups are exposed to
natural photoperiod during the subsequent lactation. The
SDPP during the dry period 'resets' the cow's sensitivity to
longer photoperiods in the subsequent lactation.
"Photoreception occurs in the retina of the eye. The Tight
contacting the eye inhibits the rate -limiting enzyme in
melatonin synthesis in the pineal gland. Therefore,
exposure to light suppresses production of melatonin. The
duration of elevated melatonin influences the hormones in
the blood, for example insulin -like growth factor -1 (IGF -1).
Scientists believe changes in IGF -1 concentrations play a
role in photoperiod response, as IGF -1 has been shown to
increase milk yield. The dark period is required to cue
relative day length and maintain the appropriate
photoperiodic effects. Constant exposure to light will not
cause the desired responses.
"Light intensity is measured in footcandles (FC) and lux
(Ix). One FC=10.8 lx. A minimum of 15 FC at one meter
height from the stall floor for 'light' periods and less than 1
FC during `dark' periods are the recommended light
intensities for production results, however it is good
insurance to have the barn as dark as possible. It is not
necessary to leave a night -light on for cows to see, as cows -
are able to find water and feed in the dark. If cows must be
observed or moved during the dark period, use low
intensity red lights (7.5W bulbs at 7.6 to 10 meter
intervals).