Effects of Environmental Temperature and Dietary Ascorbic Acid on the Diurnal Feeding Pattern of Broilers*

Abstract: The present study was carried out to determine the diurnal feeding patterns of broiler chickens given a choice between ascorbic acid (AA) supplemented and unsupplemented feeds under heated or unheated conditions. Broiler chickens were offered supplemented (with 200 mg AA/kg feed) and unsupplemented feeds, and the feeding behaviour for each feed was monitored by continuous recording of the weight of the feed container for 4 days under unheated (UH) and the next 4 days under heated (H) conditions. The weight and timing of each meal was used to calculate cumulative feed intake, AA intake, number of meals, mean meal size and length, intermeal interval, interval length, eating time and consumption rate. The results showed that heating had a significant (P<0.05) effect on feed selection and AA intake; under UH, birds consumed 8.75 mg AA by selecting 70% unsupplemented and 30 % supplemented feed of 152 g total intake, while under H they consumed 17.92 mg AA by eating 38% unsupplemented and 62 % supplemented feed of 148 g total intake. Although under both temperature regimes the number of meals eaten from both feeds per bird per day was 55, 0.73 of those being meals from 1 food only. Under UH, 0.78 of single meals were from unsupplemented feed, and of all mixed meals 0.14 were started with unsupplemented feed. However, under H, 0.62 of single meals were taken from supplemented feed, and 0.60 of all mixed meals were initiated with supplemented feed. As a result, the eating time for unsupplemented feed was longer throughout a day under UH whereas birds spent longer consuming supplemented feed during a day under H. It is concluded that birds can regulate their AA intake according to environmental temperature, and that the regulation occurs no