EFEITO DA TEMPERATURA E NÍVEIS DE ZINCO SOBRE O DESEMPENHO DE CODORNAS JAPONESAS NAS FASES INICIAL E CRESCIMENTO

Abstract

This study aimed to determine the best level of zinc supplementation in the diet of Japanese quail in early stages, maintained in thermal comfort conditions and heat stress. The experiment was conducted in environmental chambers at the Federal University of Paraíba, Unity II, Areia-PB, Brazil. Five hundred female quails aged 1 day were used. The animals were distributed in two environmental chambers were adjusted to thermal comfort and heat stress. Each room contained 25 cages with 10 birds; the treatments consisted of zinc supplementation levels (30; 60; 90; 120 and 150 mg of Zn/kg of diet). The level of 30 mg/kg represented the treatment control, since it is the requirement for quails, and the other treatments were the supplemental levels of zinc. The experimental period was 42 days and food intake, weight gain and feed conversion. were assessed weekly a completely randomized design in a 5x2 factorial arrangement (five zinc levels and two climatic environments) was used, with 10 treatments and 5 repetitions per treatment. The data were submitted to analysis of variance (ANOVA), tests with models of polynomial regression and the differences in thermal environments was obtained by the test F. The differences between means with probability lower than 0.05 were considered significant. In the first phase, weight gain decreased linearly with the increase in supplemental zinc level. Zinc levels influenced food conversion of Japanese quails in a linear manner. High environmental temperature improved feed conversion. In the second phase, food intake was higher in birds kept in thermoneutral temperatures (355.69 g) as well as weight gain. There were differences in the responses of animals in the different phases, and zinc affected only the results of animals from 1 to 21 days of age. The level of 30 mg of zinc fulfils quail requirements, independent of the phase and the thermal environment. In both phases, heat stress interfered negatively in the performance of the quails, and the most significant losses were seen in the older quails.