Sorghum can be one of the most suitable forages to produce silage in regions with problems of rainfall or irrigation restrictions. This crop can also be a good alternative when forages are grown on saline soil and high environmental temperatures. However, the nutrient composition of silage made from conventional sorghum varieties have lower neutral detergent fiber (NDF) digestibility. This reduction is the result of the high lignin content in the plant – particularly in the lower portion of the stems. One management practice available for producers is to cut the plants higher at harvest. This strategy, however, can be controversial because of the reduced forage dry matter (DM) yields, while improving silage quality or vice versa.
Dry matter yield or silage quality
The balance between DM yield losses and sorghum silage nutrient composition must always be considered when leaving more stubble in the field at harvest. This is because very high DM yield losses negatively affect the money invested in the crop. On the contrary, harvesting the least digestible part of the forage reduces the energy content of the silage.
Research on black sorghum demonstrated that increasing the stubble height at harvest from 6 to 18 inches decreased forage lignin by 1.3% and, consequently, increased fiber digestibility, an effect closely associated with a reduction of the lower portion of the stems. However, DM yield losses in sorghum can reach 10% if the cutting height at harvest increases to 8 inches. Therefore, one must consider increasing stubble height at harvest to improve silage quality without losing too much yield.
Continue reading this article published in Progressive Forage.
