SDecialists. Researchers

The negative effects that high environ-mental temperatures have on hen per-formance are well documented. These temperature increases have been linked to decreased egg production [l, 21, decreased egg weights [3,4] and reduced egg shell quality [5, 61, with older hens being particularly susceptible to the effects of heat stress [7J. Several studies have shown that, under normal environmental conditions, increasing dietary protein increases egg weight [8, 91. It is also known that a calcium deficiency results in reduced egg shell quality and increasing dietary calcium correspondingly increases shell quality [lo, 111. Because heat stress depresses feed consumption [12] and concurrently nutrient intake, nutritionists commonly recommend compensating for this reduction by increasing dietary calcium and protein levels [13, 141. This technique has met with varying degrees of success. Reid and Weber [15] reported that increasing dietary protein under heat stress did not improve egg production. There was a significant increase in egg weight as protein level was increased at 32.2"C, but not at 35°C. Valencia et al. (161, using a wider range of protein levels, also observed a significan