Effect of Different Stocking Densities as an Environmental Stressing Factor on Broiler Behavior and Performance

Six hundreds of unsexed Arbor Acres chicks were used and housed in symmetrical 9 pens with
three levels of stocking12 bird/m², 15 bird/m² and 20 bird/m². Productive performance parameters
were measured including, average daily Feed intake, average body weight, average weekly weight
gain, feed conversion rate (FCR), mortality rate, dressing yield and visceral organs weight.
Behavioral observations including feeding, drinking, leg scratching, leg -wing stretching, preening,
litter eating and dust bathing were done by scan sampling, birds were observed 3 days /week.
Results revealed that the growth performance within the first and second weeks, the high stocking
density group (20 bird/m2) showed a high feed intake, body weight and body weight gain, followed
by medium stocking density group (15 bird / m2) and the lowest performance parameters through
the first two weeks were recorded in the control group. From the fourth to the fifth weeks, medium
density group (15 bird / m2) showed a higher feed intake body weight and body weight gain. The
moderate stocking density achieved a higher final body weight was 1954 ±1.73 g, body weight gain
1911.75 ±1.73 g, also feed intake passed in the same direction MSD consumed 3117.19 ±11.4 g/
bird. Finally, all group showing the same feed conversion ratio as all different stocking densities
showing no significant differences in FCR. The results carcass characteristics showed that the
moderate stocking density group (15 bird/ m2) achieve the highest dressing weight and higher
dressing percentage compared with other two groups. Regarding to internal organ weight the
control group showed the highest gizzard, liver, and heart weights followed by moderate and high
stocking density group respectively. the results clearly showed that increasing SD significantly
reduced the weights of the lymphoid organs. Behavioral Indicators showed that within the first two
weeks, the feeding and drinking behavior was significantly differ, as the moderate and high density
groups showing the higher feeding than control group. The final feeding and drinking behavior
within the whole experimental period, there was no statistical significant difference between the
different groups. The welfare behavior indicators, including leg and wing stretch, leg scratch,
preening and resting behavior were recorded within five weeks and also from total means for all
group it was clear that from the first week till the end of experiment the stocking density negatively correlated to the welfare behavior indicators. Regarding to resting behavior within weeks and in allover means in the different groups although there was no significant difference between different groups as p > 0.05 there was a decrease in the resting behavior percentage with increased stocking density.