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

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.