They stated that heat-stressed laying hens had a depressed egg production due to imponderables in calciume strogen relationship. This implies that thermal stress decreases albumin consistency, yolk size and calcium deposit in the egg
shell. The depression in the ovarian blood flow is a possible mechanism for the reduction of the ovarian function; a differential ovarian blood flow pattern was detected in laying hens subjected to elevated ambient temperatures (Mashaly etal.,2004).