Estimation of relative feed value, relative forage quality and net energy lactation values of some roughage samples by using near infrared reflectance spectroscopy

The aim of this study is to determine the relative feed value (RFV), relative forage quality (RFQ) and net energy lactation (NEL) values of some roughage samples, based on the measurements taken from two different near infrared reflectance (NIR) devices. Corn silage (n = 18), alfalfa (n = 9), oat grass hay (n = 15), wheat straw (n = 10) were used as roughage samples and NIR measurements were taken from these samples in two ways. In the study, two different NIR (NIR1, NIR2) devices were used and nutrient values of roughage samples which were used were determined. The reference chemical analyzes of the roughage samples used in the study were made in the laboratory as dry matter. After the determination of the nutritional values, by adding these nutritional values (Dry matter, ether extract, crude protein, ash, neutral detergent fiber, acid detergent fiber) to the RFV, RFQ, NEL equations, RFV, RFQ and NEL values of each roughage sample were calculated. Meanwhile, the roughage samples used in the study were also analyzed in NIR devices and after the nutritional values were determined, these nutritional values were written in the RFV, RFQ, NEL equations thus RFV, RFQ, NEL values of each roughage samples were calculated separately for each device. Relationships between predictions obtained from NIR1 and NIR2 devices and reference chemical analysis values were determined by statistical tests. It was determined that the type of device and sample used had an important effect on the relationships between the results obtained from the reference analyzes and the predictions based on NIR measurements. Regression coefficients between RVF, RFQ and NEL values obtained from NIR1 and NIR2 devices and RVF, RFQ and NEL values obtained from reference (REF) analysis were determined to be 0.37 and 0.50. Among the roughage types, the highest similarity between NIR results and reference analysis results was found in alfalfa samples. The study results showed that indirect estimation by NIR relating to RVF, RFQ and NEL parameters is possible depending on the sample type and that there is a need for calibration improvement studies to determine these parameters directly with NIR.