The Effect of Two Levels of Methionine on the Biological Performance of Laying Pullets in Controlled Environments

AN EARLIER paper (Mueller, 1961) dealt with the performance of pullets at constant temperatures of 32°C. (90°F.), 13°C. (55°F.) and in an environment where temperature cycled from 32°C. to 13°C. and back to 32°C. every 24 hours. Using performance at a constant temperature of 13°C. as a base, continuous exposure to 32°C. reduced egg production of survivors 28%, average egg weight 15% and feed intake 32%. Little is known about the mechanisms which cause these adverse effects of high temperature. One possibility, suggested by further analysis of the data reported in 1961, was environmentally induced nutritional deficiencies. Hill and Dansky (1950) reported that, while daily nutrient requirements appeared to be relatively constant absolute quantities, requirements expressed as percentage of the ration were related to feed intake. Since the rations used from 1958 to 1960 (Mueller, 1961) were formulated in terms of required nutrient levels per unit weight of feed, the …