The Value of Hay Provided in Different Phases of Alfalfa Development

This article presents the results of research on the study of the chemical composition, digestibility, energy value of hay from alfalfa-rump grass mixture, harvested by the method of active aeration in different phases of alfalfa development, the productive properties of hay of different quality when fattening bulls in the dry steppe zone of the Nakhchivan. The amount of digestible energy decreased as the plants aged. Its highest concentration (12.8 MJ per 1 kg of dry matter) was observed during the budding phase. Then a decrease in this indicator was recorded by 0.8 MJ in the flowering phase and by 1.5 MJ during seed formation. The same pattern was noted for the content of metabolic energy in hay. Thus, the greatest amount was in hay harvested during the budding phase — 8.3 MJ per 1 kg. During the flowering phase, the amount of metabolic energy in 1 kg of hay decreased by 0.4 MJ, and seed formation by 1.2. Thus, the coefficient of digestibility of dry matter was higher than similar indicators during later harvesting by 4.01 and 7.05%, respectively. Crude protein in early harvested hay was digested better than in hay prepared in the phase of flowering and the beginning of alfalfa seed formation, by 11.83 and 18.03%, crude fiber — by 3.0-3.26%. A significant difference was also noted in digestion of raw fat. The digestibility of this substance decreased noticeably as plants aged. A decrease in the digestibility of nitrogen-free extractives was observed in hay during the seed formation phase. Calculations carried out on the basis of actual material obtained in the experiment show that when feeding hay harvested at the beginning of alfalfa budding, the yield of bull calves (increase in live weight) per 1 hectare of harvested area increases by 27.6% compared with harvesting in the flowering phase and 3.1 times in the seed formation phase.