Abstract
Background:
Sheep are a main source for meat, and animal housing is to protect them from harsh environmental conditions and to provide an environment suitable for animal comfort and in an economical manner as possible.

Aim:
The aim of this experiment was to compare the effect of two types of housing systems (semi-closed barn and closed barn) on some productive and carcass traits of Awassi male lambs.

Methods:
Two groups of Awassi lambs totaling forty weaned male lambs ranging in age from 4 to 6 months were divided into two types of barns: the first was housed in a semi-open barn, and the second in a closed barn with 20 lambs for each group. In order to find an effect between the two groups and to find out the significance of these differences, the obtained data were analyzed using the t-test.

Results:
No significant differences were observed between the two groups in productive traits and carcass, such as final weight, weight gain, feed conversion efficiency, feed intake, carcass weight, dressing percentage, and carcass residues from the head, feet, and skin. There were also no big differences in the viscera of the carcass, such as the lungs, heart, liver, spleen, kidneys, intestines, the weight of the full and empty rumen, or the weights of different fats, such as buttocks, abdomen, kidney, and heart fat. There were also no big differences in the area of the eye muscle or the thickness of the subcutaneous fat, or in the major and minor cuts. Moreover, the proportions of muscle, fat, and bone remained consistent. The net second transaction exhibits an arithmetic advantage.

Conclusion:
There was an arithmetic increase in favor of the first treatment, and this may be due to the increase in feed intake in the lambs of the semi-open pens compared to the closed ones. In addition to the availability of ideal conditions for the lambs, including fresh air and better oxygen availability, air movement inside the barn, and lower temperatures compared to a closed barn, thermal stress reduces weight gain.

Key words: Awassi lambs; Housing system; Growth performance; Carcass traits; Animal welfare.