Bone growth and metabolism in broilers exposed to dietary PUFA or cyclical heat stress under two levels of dietary vitamins and minerals.

Broilers are highly susceptible to heat stress (HS), which can impair bone growth and metabolism. Supplementation with n-3 polyunsaturated fatty acids (PUFA) may affect the metabolism of mineralized tissues, whereas antioxidants can mitigate these effects. The aim was to investigate the combined effects of HS (thermoneutral conditions vs. cyclic HS) or dietary oxidative stress induced by supranutritional n-3 PUFA (control feed without PUFA vs. feed supplemented with 5% linseed oil) with two levels (lower and higher) of dietary antioxidants and minerals on bone properties. The morphology and geometry of the proximal tibiotarsal growth plate, biomechanical behavior, and mineral composition of 42-day-old male Ross 308 broilers were evaluated. HS and high PUFA levels decreased bone size and mass, whereas supplementation with high antioxidant levels had the opposite effect. High PUFA supplementation induced histopathological changes in the growth plate that resembled tibial dyshondroplasia; these effects were attenuated by supplementation with high levels of antioxidants. Additionally, HS had a negative effect on the biomechanics and reduced the crude ash content. High levels of antioxidants increased the bone ash content, fat content, Ca content and Ca:P ratio. Our results suggest that HS and PUFA impair the growth of bones, hindering the overall growth of fast-growing broilers. The incidence of dyshondroplasia appears to be related to diet rather than to environmental changes. High antioxidant levels mitigate the negative effects of both stressors to some extent, suggesting that antioxidants have positive effects on bone growth and functionality, especially under nonoptimal environmental conditions and dietary stress.