Nutritional Quality of Corn Silage on Dairy Farms in the Republic of Croatia

Abstract

For the purpose of corn silage quality evaluation, 270 samples on dairy farms in twelve (12) counties were analyzed in this study. The prepared samples were subjected to the FT-NIR device using the AgriQuant-B1 spectrometer (Model: QIA 1020), which analyzed the values of nine (9) nutritional, two (2) indicators of rumen fermentation, and three (3) indicators of corn silage fermentation. One physical indicator, the silage particle size distribution, was determined by sieving through a three-sieve system (Penn State Separator). The average values of most of the monitored nutritional indicators were satisfactory: DM = 349 g kg-1, crude protein = 65 g kg-1 DM, crude ash = 38 g kg-1 DM, crude fiber = 180 g kg-1 DM, acid detergent fiber = 210 g kg-1 DM, neutral detergent fiber = 387 g kg-1 DM, acid detergent lignin = 17 g kg-1 DM, starch = 336.59 g kg-1 DM, net energy of milk = 6.76 MJ g kg-1 DM. Significant deviations in Max. and Min. were found for the DM values (156 non-compliant samples), as many as 231 non-compliant samples were found for crude protein, 90 noncompliant samples were detected for the acidic detergent fibers, and 233 for starch. The rumen fermentation indicators, expressed as average digestible organic matter (dOM), amounted to 75.6%, and those of digestible neutral detergent fiber (dNDF) amounted to 52.8%. The average pH value reached a desirable value of 3.85, with an average concentration of lactic acid (54.9 g kg-1 DM) and acetic acid (21.1 g kg-1 DM). The average values of silage particle size distribution, measured through four fractions, resulted in the following values: sieve 1 – 5.7%; sieve 2 – 55.7%; sieve 3 – 26.1% and bottom vessel – 12.6%. The strongest positive correlation was found between the crude fiber in relation to the ADF (r = 0.870), NDF (r = 0.959), and ADL (r = 0.790) and between the NDF and ADF (r = 0.845). Negative correlation was strongest between the ADL and dOM (r = -0.844), between the starch compared to the CF (r = -0.835) and NDF (r = -0.809), and between thepH and lactic acid (r = -0.804). These correlations between the indicators were also statistically highly significant (p<0.001).