[Fontes e níveis variados de zinco em rações para frangos de corte Ross 308: seu efeito no desempenho, na utilização de nutrientes, na morfologia intestinal e na composição microbiana]

Abstract

ABSTRACT Broilers (n=480) were used in an experiment designated for a 3(4 factorial arrangement to investigate the efficacy of three zinc (Zn) sources (organic Zn-Methionine, inorganic Zn sulphate and Zn oxide) and four inclusion rates (zero, 60, 120 and 180mg/kg of feed). Growth performance was not affect by Zn source in the entire of experimental period, however Zn level at 180 mg/kg improved body weight gain and feed conversion ratio compared to other Zn levels (P<0.05). Inclusion of Zn-Methionine in the diet increased the population of Lactobacillus (P<0.05), while E. coli counts decreased in birds which received Zn sulphate compared with Zn oxide group (P<0.05). Inclusion 180 mg/kg of Zn decreased total intestinal aerobic bacteria in comparison to zero level (P<0.05). An improvement of intestinal villus length and width was found in treatments supplemented with organic Zn (P<0.05), Zn oxide increased intestinal crypt depth in birds as well (P<0.05). Ileal digestibility of crude protein increased in broilers received Zn at 120 and 180 mg/kg compared with zero level (P<0.05). Consequently, Zn-methionine supplement had an optimistic effect on the microbial population and intestinal morphometric variables. The level of 180mg/kg of supplemental Zn had beneficial influence on growth performance.