Antibiotics and the Performance of White Leghorn Chicks during Hot Weather

Abstract

Heywang (1951) found that the average increase in body weight resulting from feeding antibiotics to White Leghorn female chicks seemed rather small during both cool and hot weather and was variable, ranging from none to about eight percent. The parent stock had not been fed any antibiotic.In later experiments (Heywang, 1959a) the egg production of White Leghorns was improved during hot weather by the feeding of antibiotics and arsanilic acid. It seemed of interest to determine whether stimulation of growth much greater than that previously observed would occur if the progeny of those White Leghorns were also fed during hot weather the same antibiotic, or arsanilic acid, at the same dietary level as their dams.Accordingly, six experiments were conducted during two summers with chicks of both sexes. The number of day-old chicks in each group at the start of the separate experiments varied from 63 to 100, and …