|
Influence
of Early Feed and Light Restriction on Compensatory Growth, Stress
Response, and Processing Yields of Commercial Broilers
Kieu
V. Vo
Cooperative
Agricultural Research Program
Seminar Series
Tennessee State University, Nashville, TN
February 17,
1999
Introduction. Commercial broilers have been
selected for fast growth rate for a number of years. Recent research,
however, has shown that fast growth is often associated with abnormal
skeleton development and sudden death syndrome. Feed and light
restriction during early life may be one of the possible ways to
minimize these problems. In addition, feed cost accounts for about 75%
of production costs in broiler production. This high feed cost
emphasizes the need to improve feed utilization.
Objectives. The objective of this study was
to evaluate the effect of early feed and light restriction on
compensatory growth, leg abnormalities, stress response, and processing
yields of commercial broilers.
Methodology. Six hundred thirty one-day-old
T-100 commercial broiler chicks obtained from a poultry breeding farm in
Georgia were used in a completely randomized design. They were
wing-banded, weighed, and randomly assigned to seven treatment groups.
Three replicates of 30 chicks each were used in each treatment. Three
feed and light restricted schemes utilized were 1) 24-hr feed: 24-hr
light which served as the control (C); 2) 16-hr feed: 16-hr light (R1);
and 12-hr feed: 12-hr light (R2). Treatments were applied for either 7,
14 or 21 days from day-3 to day-24. Following restricted period all
birds received 24-hr feed: 24-hr light until 49 days of age. Water was
given for ad libitum consumption.
Results. Results obtained from this study
indicated that feed and light restriction to 12 hr feed: 12 hr light for
14 days or to 16 hr feed: 16 hr light for 21 days significantly reduced
weight gain. The average weight gains during the 21-day restricted
period were 746.5, 714.8 and 680.1 g for groups C, R1 and R2,
respectively. Compensatory growth was observed in both R1 and R2 groups
when returning to 24 hr feed: 24 hr light. Birds in both groups can
compensate for weight reduction by 49 days of age. Eviscerated yields,
dressing percentage, abdominal fat weight, part yields, and composition
of breast, thighs and drumsticks were not significantly affected by the
degree and duration of feed and light restriction used. Feed conversion
was significantly improved in both R1 and R2 groups when restriction was
applied for either 14 or 21 days. The same trend was also observed with
7-day restriction. The difference, however, was not statistically
significant. Continuous lighting of 24 hr per day produced a hemostress
condition as indicated by an increase in the percent of heterophils and
a decrease in the percent of lymphocytes. Early feed and light
restriction slightly reduced the incidence of leg abnormalities and
mortality.
Impact. Based on these results, commercial
broilers could be raised under feed and light restriction up to 21 days
during their early life to reduce cost without adverse effect on growth
performance or processing yields.
Return
to Seminar Series
|
