Feed and biological value of the alfalfa green mass carbohydrate-lignin complex

Abstract

Purpose. To study how the content of the main nutrients, the amount and ratio of structural and nonstructural carbohydrates in the green mass of alfalfa changes during the process of growth and development. To establish a phase in which the produced feed will have high feed and biological value. Methods. Sampling was carried out in accordance with the State Standard of Ukraine (SSU) ISO 6497:2005, determination of the content of moisture and other volatile substances – SSU ISO 6496:2005, nitrogen and crude protein – SSU 7169:2010, crude fat – SSU ISO 6492:2003, fiber – SSU 8844: 2019, raw ash – SSU ISO 5984:2004, carbohydrate-lignin complex (sugars, hemicellulose, cellulose) – SSU 7982:2015, neutral detergent fiber – SSU ISO 16472, acid detergent fiber and lignin – SSU ISO 13906:2013, starch – SSU ISO 6493:2008. Results. During alfalfa green mass growth and development, the content of dry matter increases gradually from 15% to 25%, the content of crude protein in it decreases from 26% to 13%, and crude fiber increases from 15% to 38%, the content and composition of nitrogen-free extractives change. In the phase of branching, the cellulose content is 12%, in the phase of full flowering – 24.6%, during beans development – 30.6%. The lignin content increases from 2.3% to 14.4%, that is, more than six times. The feeding value, expressed in the feed unit indicator, decreases from 0.9 to 0.79, and the exchangeable energy in the phase of budding and the beginning of flowering is at the level of 9.5 MJ. Conclusions. The green mass of alfalfa in the phase of budding-beginning of flowering is a valuable raw material for the production of feeds (hay, silage, granulated feed, grass flour, etc.), since the yield of the crop in this phase is still high, the crude protein content is at the 20% level, the amount of easily hydrolyzed carbohydrates is 14%, the amount of structural carbohydrates is still at the 30.0% level. The calculated feeding value of green mass is higher than the feeding value of the produced hay in terms of feed units by only 3.5%, digestible protein by 11%, and exchangeable energy by 2.6%.