THE EFFECT OF LIGHT INTENSITY DURING BROODING ON THE PRODUCTIVITY AND HEALTH OF PARACOX-5 VACCINATED BROILERS
Luciano Gobbi and Raffaele Pezzotti
Schering-Plough Animal Health, Milan, Italy.
luciano.gobbi@spcorp.com
Producers often try to increase
bird activity during brooding to stimulate water and feed intake, increase
growth, reduce early mortality, and improve subsequent flock uniformity.
Some experimental studies show that in young chickens, high intensity light
(>70 lux sqm.) significantly increases activity as compared to low lux
regimens (<20 lux sqm). To further assess the effects of lighting, a trial
was performed in Paracox-5 vaccinated chickens.
Broiler chicks (Ross 508, 20,000 males and 20,000 females) were placed in one of
two experimental houses. From placement until 4 days of age, both houses
received 23 light hours and 1 dark hour. Lighting in one house was 75 lux and,
in the other, 20 lux. After 4 days of age and until slaughter, light intensity
for both groups was maintained at 20 lux.
Birds were evaluated at 0, 4, and 7 days of life, and then weekly, until 49 days
of life. Statistical analysis was conducted as a one-way ANOVA and, when
significant, (p<0.05) means were compared by Duncan’s Multiple Range Test.
Crop palpation to evaluate food and water intake showed that 8 hours after most
birds were placed, 98.5% of those on 75 lux were filled compared to 83.0% on 20
lux. Early growth rate, liveability and flock uniformity were increased by
higher light intensity, while overall mortality and the incidence of intestine
bacterial overgrowth were significantly reduced. There were fewer deaths due to
necrotic enteritis in the 75 lux group during the first 4 days of life. Both
groups demonstrated standard oocyst shedding, but peaked on day 19 in the 75 lux
group as compared to day 27 in the 20 lux group. No coccidiosis outbreaks
occurred in either group.
This study provides compelling evidence that high intensity light regimens
enhance activity in chicks, which in turn increases feed intake and early growth.
Early complete feed consumption appears to enhance endogenous trypsin release,
protein digestion, and vaccinal oocyst excystation, which may explain their
earlier multiplication and peak shedding. Light manipulation during brooding
also appears to minimize factors such as litter eating and dehydration that
predispose to intestinal bacteria overgrowth, possibly necrotic enteritis and
mortality. These results should be confirmed in additional trials before
advising producers to manipulate light intensity.