## 1 Introduction  
The feeding of dairy ruminants, including buffalo, has become increasingly complex as it requires the precise incorporation of a wide variety of dietary components. This approach is aimed at meeting the metabolic demands of high-yielding animals while supporting optimal rumen function [1]. Buffaloes require a fibre-rich diet that varies with plant maturity stages and cultivation practices [2,3]. Carefully formulated nations are essential to prevent nutrient oversupply, reducing feed costs and minimising environmental waste [4]. To achieve nutritionally balanced diets, Total Mixed Rations (TMRs) are commonly used. These rations combine on-farm forages with concentrates and fatty compounds as well as vitamin and mineral supplements. The use of TMR facilitates the integration of critical nutrients, thereby supporting productivity, animal health, and sustainable production [3,5]. The rising demand for buffalo-derived products, such as mozzarella, has led to the increased mechanisation on buffalo farms, boosting farmer incomes and making TMRs the preferred feeding method. In this context, the effective management of dairy buffaloes now requires careful monitoring of rations and timely adjustments. Achieving optimal TMR composition not only requires a high-quality mixer-wagon but also continuous assessments of feed quality. This is particularly important in silage-based diets, where significant silage variability can impact the overall diet composition [6, 7, 8]. The evaluation of the chemical composition of ruminant diets, beyond merely providing balanced nutrition, is essential for enhancing the quality of animal-derived products. Among dietary components, starch and fibre fractions play a crucial role in modifying the nutritional and chemical quality of these products [9,10]. The fatty acid (FA) profile of TMR can also contribute to product quality [11]. Thus, despite the complexity in analysing the profile, there is a strong relationship between the quality of animal products and their diet. Nowadays, it is common practice to manipulate and enrich animal diets with particular FAs, aiming to deliver specific nutritional substances through the consumption of these products [12]. In this context, near-infrared spectroscopy (NIRS) emerges as an effective and versatile tool for modern feed analysis, providing rapid, non-destructive, and cost-effective evaluations [7,13]. The NIRS device enables the quick assessment of chemical composition in samples using the near-infrared spectrum, specifically at wavelengths from 900 nm to 2500 nm. It is commonly used to analyse chemical components in raw materials such as corn, soybean meals, and forages [14,15], as well as to evaluate blended raw materials in TMRs [16, 17, 18]. NIRS is also a valuable tool for studying the digestion process in livestock through the analysis of both feed and faecal samples [19, 20, 21]. Several NIR instruments with different features and performance levels have been employed to develop robust predictive models and to provide accessible and affordable options for on-site analysis [15,22]. Benchtop NIRS devices have long been fundamental in analytical contexts due to their high precision, stability, and ability to analyse a wide variety of samples with minimal interference [14]. Over the years, these instruments have undergone significant advancements in spectral resolution, data processing capabilities, and the development of sophisticated calibration models, establishing themselves as the benchmark for in-depth, highly detailed, and accurate analyses [16]. In NIR spectrometry, spectral bands correspond to specific molecular vibrations of chemical bonds (e.g., C-H, N-H, and O-H), allowing for the identification and quantification of various components [23]. The NIR spectrum comprises fundamental, overtone (first, second, and third harmonics), and combination bands.