Abstract The use of additives in the diet of ruminants consists of a management protocol that makes the livestock system more productive, sustainable and profitable. In practice, additives promote the balance of the microbial population, and improve the energy balance from food. The use of these compounds becomes advantageous as they reduce energy losses by methanogenic metabolic pathways, and the emission of enteric gases from ruminal fermentation. The short-chain fatty acids which are compounds resulting from rumen fermentation, constitute the main source of energy in the rumen, and therefore, the entire metabolic process can directly reflect the productivity performance of the cattle. Fator P is a natural additive composed of amino acids, minerals, probiotics, prebiotics and fatty acids, which was developed to meet current market needs. The aim of this study was to evaluate the synthesis of short-chain fatty acids from ruminal fluid collected from grazing animals treated with the Fator P additive over a period of 365 consecutive days. The ruminal metabolism work was conducted at Research Center of Premix (Patrocínio Paulista-SP, Brazil), using 3 cattle per treatment, which received a daily dose of 6 g of Fator P additive in the treated group, and 6 g of placebo in the control group. Ruminal fluid samples were collected weekly, and the analysis of short-chain fatty acids were carried out by the method of gas chromatography coupled to mass spectrometry. The results of the difference between means showed an increase of 15.2% (P < 0.0001) in the production of total fatty acids in the group treated with the natural additive Fator P compared with the control group. Notably, there was also an increase in the production of the three main AGCC: 13.3% for acetate (P < 0.0001); 14.7% for propionate (P = 0.0003); and 18.4% for butyrate (P = 0.0001; Table 1). Statistical analyzes were performed using the ANOVA test followed by the Tukey mean test (P < 0.05) in GraphPad PRISM Program 7.00 version. Therefore, the results indicate that the natural additive Fator P improves energy levels through the increase of short-chain fatty acids and directly reflects on the productivity indexes of the cattle. Furthermore, the product reduces the use of growth promoting antibiotics, improve intestine health, immune response of animals, carcass finishing, increase herd weight gain and milk production in a profitable and sustainable way for the cattle breeder.