Aditivos ionóforos para bovinos: Efeitos no metabolismo e produtividade e implicações de uso

Abstract

The discussion regarding the impacts of anthropogenic activity has gained significant relevance in recent decades, with the worsening of the greenhouse effect correlated with the increasing emissions of pollutant gases being one of the most debated issues. Between 1984 and 2019, atmospheric methane concentrations rose from 1,644.66 parts per billion to 1,866.55 parts per billion. One of the potential aggravating factors is the interaction between methane and ozone gases, as ozone is directly associated with an increase in ardiorespiratory syndromes. Enteric methane production in cattle occurs largely through the activity of archaebacteria, especially methanogenic ones, which degrade organic matter and produce carbon dioxide, methane, and free hydrogen as metabolic byproducts. As an alternative to improving animal performance, and secondarily, to reduce greenhouse gas emissions, ionophores have been used. In addition to ethanogenic microorganisms, the ruminal environment also contains bacteria, fungi, and protozoa, forming a complex ecosystem in which each microorganism plays a crucial role in rumen function. Bacteria are the most abundant, accounting for 70–80% of the microbial population, and are classified into Gram-positive and Gram-negative types. Despite the microbial diversity, archaebacterial populations directly influence the rest of the indigenous ruminal microbiota. One mechanism of controlling methanogenic microorganisms is through the use of ionophore additives. Certain pharmacological bases are authorized by the Ministry of Agriculture and Livestock (MAPA) for use as performance-enhancing additives, including monensin, lasalocid, narasin, and salinomycin. Several studies report the efficacy of ionophores in improving animal performance, either by enhancing digestibility or by altering the proportions of volatile fatty acids produced during microbial metabolism. Nevertheless,ionophore additives must be used rationally, following recommended dosages and avoiding use in species more susceptible to toxicity. Due to the inert metabolic properties of cattle concerning monensin, the use of certain ionophores is considered safe during lactation and in animals close to slaughter. However, animals exposed to high doses may exhibit symptoms of chronic toxicity, such as motor incoordination, diarrhea, dehydration, and ruminal atony.