ANALISE EXPLORATORIA DE METODO ALTERNATIVO PARA MENSURACÃO DE EMISSAO DE METANO ENTERICO EM TEMPO REAL EM BOVINOS

Abstract

Methane (CH₄) emissions from enteric fermentation in cattle represent one of the main sources of greenhouse gases from livestock farming, especially in tropical countries like Brazil. In this context, the development of practical, accessible, and accurate methodologies for measuring CH₄ becomes essential to improve national estimates, validate mitigation strategies, and promote more sustainable production systems. This study aimed to evaluate the efficiency of an alternative method for real-time measurement of enteric methane in Nellore steers, using a portable gas analyzer coupled to automated feed troughs. The experiment was conducted at the Experimental Farm of the Institute of Animal Science, in Sertãozinho – SP, between August and October 2025, using 55 male cattle fed a diet containing a forage:concentrate ratio of 60:40. The concentrations of CH₄ and CO₂ in the feed trough were recorded every second by the equipment (LI-COR LI-7810, LI-COR Biosciences, USA) installed in the most frequently visited trough, allowing for extensive data collection without interfering with the animals' feeding behavior. The average concentration recorded was 762.05 ± 219.52 ppm for CO₂ and 12.4 ± 4.94 ppm for CH₄. It was possible to observe peak methane concentration patterns during animal visits consistent with the expected eructation physiology observed in other measurement methods. The repeatability of the measurements was low (less than 0.06), indicating that most of the observed variation occurred due to other environmental factors. Principal component analysis showed the first dimension related to the intensity of gas concentrations and the second associated with feeding behavior during visits to the trough. It is concluded that the evaluated method is capable of generating a large volume of data in real time, continuously and without interfering with animal behavior, demonstrating practical viability for use in feedlots. However, the high variability and low repeatability indicate that multiple measurements per animal are necessary to obtain more consistent estimates of emissions, especially when the objective is individual comparison or application in genetic improvement programs.