Determination of nutritive value and analysis of the CNCPS contents in barley grass cultivated using a hydroponic system

The nutritive value of green barley grass (Hordeum vulgare) was investigated by sprouting barley grain in a still, hydroponic growing chamber for the 4^th, 5^th, 6^th, and 7^th days and then sampling it to determine the dry matter (DM), crude protein (CP), crude ash (Ash), crude fat (EE), neutral detergent fiber (NDF), acid detergent fiber (ADF), starch, neutral detergent insoluble protein (NDIP), acidic detergent insoluble protein (ADIP), acidic detergent lignin (ADL), soluble protein (SOLP), and the non-protein nitrogen (NPN) contents. A simultaneous determination of minerals and the contents of 18 kinds of amino acids was also undertaken along with an analysis of the grain components using the Cornell net carbohydrate-protein system (CNCPS). The results showed that 1) the CP, NDF, ADF, NDIP, ADIP, SOLP, and NPN contents in the grain on the 7^th day were significantly higher than on the 4^th, 5^th, and 6^th days (P < 0.05); 2) the calcium (Ca), manganese (Mn), and iron (Fe) contents of the grain on the 7^th day were significantly higher than on the 4^th, 5^th, and 6^th days (P < 0.05); 3) the lysine (Lys), total amino acid (TAA), and essential amino acid (EAA) levels in the grain on the 7^th day were significantly higher than on the 4^th, 5^th, and 6^th days (P < 0.05); and 4) the medium speed degradation protein (PB₂) contents in the grain on the 7^th day were significantly higher than on the 5^th, and 6^th days (P < 0.05). The slow degradation protein (PB₃) and non-degradable crude protein (PC) contents were significantly higher on the 7^th day than on the 4^th day (P < 0.05). The non-structural carbohydrate (CNSC) contents on the 7^th day were significantly lower than on the 4^th, 5^th, and 6^th days (P < 0.05). Finally, the available fiber (CB₂) contents on the 7^th day were significantly higher than on the 4^th, 5^th, and 6^th days (P < 0.05). In summary, on the 7^th day, barley grass had higher nutritional value than the other days and could be a high quality forage grass resource that can be used for herbivore development and nutrition.