DINÂMICA DAS PERDAS DE SÓDIO EM SUPLEMENTOS MINERAIS PARA BOVINOS NELORE EM CRESCIMENTO

Abstract

The mineral mixture is subject to leaching and losses when exposed to the environment. In the composition of the mineral supplement, sodium is the element that has the ability to stimulate and limit the consumption of the mineral mixture. Furthermore, it is among the elements most susceptible to losses due to rain, due to its high solubilization capacity. This demonstrates the need to understand the dynamics of sodium in mineral supplements exposed to the environment. 7 experiments were carried out with the purpose of analyzing the dynamics of sodium losses in mineral supplements exposed to the environment. The first experiment aimed to quantify the sodium that is lost to the environment, by measuring the element in the leached part of the trough. Experiments 3 and 4 were carried out with different levels of sodium in the mineral mixture (35, 70, 105 and 140 g of sodium per kg of mineral supplement) with the aim of identifying whether it would affect supplement consumption through the concentration provided. In the other experiments (2, 5, 6 and 7), precipitation data and analysis of the sodium content in the composition of the supplement leftovers were used to create an equation between the sodium losses of the mineral supplement in relation to precipitation (millimeters or rainy days). The sodium requirement of animals was estimated through the NRC feeding system and BR-CORTE. The exclusion trough methodology was adopted to adjust the sodium values in the mineral supplement exposed to the environment by correcting the quantified losses. As a result, a minimum level of sodium content was created, called the critical level of sodium in g per kg of mineral supplement, by estimating the animals' requirements. It was identified that the relationship between precipitation and rainy days due to sodium losses in the mineral mixture is considered weak (R² = 0.1393 and 0.2203 respectively). Sodium was the second element that suffered the most leaching from the mineral mixture exposed to the environment, 28% of the leached mass is made up of sodium chloride. Therefore, after quantifying the portion of sodium lost to the environment, obtained through data from other experiments, a correction coefficient for the loss of mineral supplement when exposed to the environment was created. These losses were estimated at 25.5% according to the exclusion trough methodology. The critical level value adjusted for losses in the environment was estimated at 87.3 g of sodium per kg of mineral supplement, being the minimum limit to meet the requirements of animals supplemented on pasture. Thus, in experiments 3 and 4 it was observed that in treatments 35 and 70 g of sodium per kg of mineral supplement did not meet the animals' requirements, but there was no statistical difference for performance, but there was a difference for sodium consumption, where had the highest consumption in the treatment with the lowest sodium level per kg of mineral supplement. A total of 373 observations were analyzed and 27.5% of the observations had a sodium value obtained in the remains of the mineral mixture below the critical level. The sodium content interferes with the consumption of mineral supplements and the exposure of the supplementary mass to the environment is subject to losses through leaching, leading to an imbalance in the concentration of the elements, which may not meet the animals' requirements and causing the ingestion of minerals in unbalanced proportions.