The effect of a dacitic (rhyolitic) tuff breccia on growth, intestinal health, and inflammatory and antioxidant responses in broilers challenged with a chronic cyclic heat stress

Abstract

SUMMARY: Heat stress (HS) negatively impacts animal production worldwide, being an economic and welfare issue. In poultry, HS was shown to reduce feed intake and increase mineral excretion, suggesting a marginal mineral deficiency. The objective was to assess the response of Azomite, a dacitic (rhyolitic) tuff breccia (DTB), on performance, antioxidant system, gut health, inflammation, and bone characteristics in broilers under a chronic cyclic HS challenge. A total of 1,280 one-day-old male broiler chicks (Cobb 500) were distributed in a randomized complete block design with four dietary treatments, 16 replicates of 20 birds. The treatments consisted of control (0% of DTB), and diets with 0.125, 0.25, and 0.5% of DTB added. Data were analyzed by Mixed procedure (SAS) with linear and quadratic contrasts for dose-response. Using 0.25% DTB tended to improve daily gain from 28 to 42 d (P = 0.06), and improved feed efficiency from 28 to 42 (P = 0.04) and 0 to 42 d (P = 0.02) compared to 0.5% DTB. Crude protein and phosphorus digestibility linearly increased with DTB supplementation (P < 0.01), and calcium digestibility was higher in 0.125 and 0.5% than 0.25% DTB (P < 0.01). Ileal crypt depth was greater in 0.25% than control and 0.125% DTB (P = 0.01), whereas ileal villus:crypt ratio and GSH-Px were higher in control than 0.25% DTB (P < 0.05). Bone mineral content, mineral density, and area were improved when birds were supplied with 0.125 and 0.25% DTB. The results showed the potential of DTB in improving feed efficiency, bone characteristics, and crude protein, Ca, and P digestibility in birds subjected to chronic cyclic HS.

Keywords

• AZOMITE
• broilers
• dacitic tuff breccia
• heat stress
• performance