Enteric methane emissions and thermal comfort indexes of Nellore steers in a livestock-forestry system in the Amazon biome.

Abstract

Livestock-forestry (LF) systems enhance the delivery of ecosystem services and sustainability by providing shade, increasing diversity, and improving carbon sequestration. Despite these benefits, more evidence is needed to establish LF systems as a viable alternative for reducing enteric CH₄ emissions and improving thermal comfort in beef cattle production. We aimed to evaluate the impact of the forestry component into a forage-based livestock system on animal performance, thermal comfort, and its consequences on enteric CH₄ emissions. The experimental design was a randomized complete block with two systems: livestock (L) and LF, each with four replicates. During both seasons, microclimate variables such as relative humidity, photosynthetically active radiation, black globe temperature, and black globe temperature-humidity index were greater in the L system. Plant-part and chemical compositions did not differ between the systems, except for a 10% greater leaf proportion in LF during the rainy season. During the dry season, the LF system showed a 47% greater total gain per ha and 33% greater stocking rate. There was no system effect on CH₄ production (g/day). However, in the dry season, LF presented greater CH₄ emissions per area. These results indicate that integrating trees into forage-based livestock systems can improve thermal comfort and animal productivity without increasing individual CH₄ emission, enhancing long-term productivity and sustainability.