High Environmental Temperatures as Affecting the Reaction of Laying Hens to Iodized Casein

Abstract

SUMMER temperatures in the majority of the United States present a problem for poultrymen. During a five day heat wave in August, 1948 it was reported that close to two million birds died from heat prostration. This estimate was only for the middle Atlantic states where the temperature was close to 105° F. in the shade. However, harmful effects occur below the lethal temperature. Perhaps the most marked effects are the reduction of egg size and shell thickness reported by Bennion and Warren (1933). The objective of the present study was to determine: (1) the effect of high temperature on the various physiological responses of the laying hen as measured by body weight changes, feed and water consumption, body temperatures, heart and respiration rates, egg production, egg weight, egg shell thickness and fertility; and (2) the effect of breed, dubbing (the removal of comb and wattles) and feeding iodized casein . . .