Zinc hydroxychloride supplementation improves tibia bone development and intestinal health of broiler chickens

Abstract

<p>This study was conducted to investigate the effects of zinc (<b>Zn</b>), as a combination of oxide (ZnO) and sulfate (ZnSO₄), compared with incremental levels of zinc hydroxychloride (<b>ZH</b>) on tibia traits, intestinal integrity, expression of selected jejunal genes, cecal short chain fatty acids and microbial composition in broilers. Day-old male Ross 308 chicks (n = 784) were randomly allocated to seven dietary treatments, each replicated seven times with 16 chicks per replication. The dietary treatments included a negative control diet (<b>NC</b>) with no supplemental Zn, a positive control (<b>PC</b>) with 100 mg/kg supplemental Zn from an ionic bound source combination (50 mg/kg ZnO + 50 mg/kg ZnSO₄), and the NC diet supplemented with one of 20, 40, 60, 80, or 100 mg/kg Zn as ZH. The diets were fed over starter (1–14 d) and grower (14–35 d) phases, with tissue and digesta samples collected from 3 birds per replicate on days 14 and 35. The results showed that dietary Zn level had a significant effect on tibia breaking strength on d 35 (<i>P</i> < 0.05), and tibia Zn concentration both on d 14 and d 35 (<i>P</i> < 0.01). Dietary Zn levels linearly (<i>P</i> < 0.01) increased cecal lactic acid production, increased <i>Lactobacillus</i>, and decreased <i>Bacillus</i> and total bacteria counts (<i>P</i> < 0.05). Inclusion of 80 and 100 mg/kg Zn as ZH tended to upregulate the expression of claudin-1 (<i>P</i> = 0.088) and tight junction protein-1 (<i>P</i> = 0.086). The results obtained in this study suggest that a non-Zn supplemented diet can negatively influence tibia development and gut microbiota composition in broiler chickens. Higher supplemental Zn in the diet alters cecal microbiota population in favor of <i>Lactobacillus</i> and can decrease the total bacterial load. Supplemental Zn level in the feed have the potential to manipulate the jejunal gut integrity at a molecular level.</p>