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

Abstract

Six hundreds of unsexed Arbor Acres chicks were used and housed in symmetrical 9 pens withthree levels of stocking12 bird/m2, 15 bird/m2 and 20 bird/m2. Productive performance parameterswere measured including, average daily Feed intake, average body weight, average weekly weightgain, 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 stockingdensity group (20 bird/m2) showed a high feed intake, body weight and body weight gain, followedby medium stocking density group (15 bird / m2) and the lowest performance parameters throughthe first two weeks were recorded in the control group. From the fourth to the fifth weeks, mediumdensity group (15 bird / m2) showed a higher feed intake body weight and body weight gain. Themoderate stocking density achieved a higher final body weight was 1954 ±1.73 g, body weight gain1911.75 ±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 densitiesshowing no significant differences in FCR. The results carcass characteristics showed that themoderate stocking density group (15 bird/ m2) achieve the highest dressing weight and higherdressing percentage compared with other two groups. Regarding to internal organ weight thecontrol group showed the highest gizzard, liver, and heart weights followed by moderate and highstocking density group respectively. the results clearly showed that increasing SD significantlyreduced the weights of the lymphoid organs. Behavioral Indicators showed that within the first twoweeks, the feeding and drinking behavior was significantly differ, as the moderate and high densitygroups showing the higher feeding than control group. The final feeding and drinking behaviorwithin the whole experimental period, there was no statistical significant difference between thedifferent 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 allgroup 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.