Structural carbohydrate and lignin content of perennial cereal forage grasses depending on the growth phase and digital innovations in forage composition analysis

Abstract

The article is devoted to the study of the content of cell wall carbohydrates – neutral detergent fiber (NDF), acid detergent fiber (ADF), acid detergent lignin (ADL) – in cereal forage grasses depending on the growth phases. An increase in all cell wall fractions was revealed as the growth phases changed. The content of acid detergent fiber, neutral-detergent fiber and acid detergent lignin (% in dry matter) in cereal forage grasses (awnless brome, meadow fescue, meadow timothy) is 31‑32, 50‑55, 4‑6 before earing; in the earing phase – 32‑37, 55‑65, and 5‑6; in the flowering phase – 40‑45, 70‑72, 7‑9, respectively. As grasses grow, their composition changes with the accumulation of cell walls. The increase in the proportion of neutral detergent fiber occurs mainly due to an increase in the proportion of cellulose and a decrease in the proportion of hemicellulose, which is consistent with a higher digestibility of grasses in the early growth stages. According to the results of the study, the relationship between crude fiber and acid detergent fiber was closer (n = 64, s = 2.4%, r = 0.93) than between crude fiber and neutral detergent fiber (n = 64, s = 4.4%, r = 0.87). As the composition of grass changes daily during the growing season, it is advisable to determine its composition as soon as possible. As chemical methods are time-consuming, an express method based on an infrared analyzer can be used to solve this problem. The express method involves, after the grinding of the sample, sequential operations such as calibrating the analyzer, placing the sample in the analyzer and analyzing the samples with the analyzer. This means that this method is also quite time-consuming. To obtain information more quickly (two hours), digital technologies are now increasingly being used. The method based on digital technologies involves the sequential execution of the following operations: UAV launch, crop survey, transmission of multispectral data to the server, information processing and calculation of crude fiber content.