Ensiling quality of columbus grass ( Sorghum almum) grown in northern Nigeria

Abstract

A study was conducted with field grown Columbus grass ( Sorghum almum) to examine its ensiling characteristics, and the influence of stage of maturity and forage components at ensiling on the nutritive value of resultant silages. Forage was harvested at 50, 60, 70, 80 and 90 d post-planting and ensiled for 21 d in model silos. The forage at ensiling declined in moisture contents (85.0 to 56.0%) and leafiness (46.0 to 26.0%) with advancing stage of maturity. Bloom content increased from 10.3 to 95.1% while DM yield increased from 1.30 to 8.40 t/ha. Satisfactory silages were made as evaluated by acceptable colour, aroma and pH. The HCN content was low in general and declined from 244.0 to 183.0 mg/kg DM with increasing maturity. Plant components favouring digestibility (i.e., CP, EE, and carotene) declined while some cell wall structural constituents (i.e., NDF and ADF) showed positive relationships. The variations in nutrient constituents were: 6.4–14.7% CP, 5.3–7.7% FE, 5.3–8.5% ash, 25.2–390.4 mg carotene/kg DM, 72.6–78.8% NDF, 38.8–49.5% ADF, 0.23–0.58% Ca, 0.12–0.21% P, 0.15–0.26% Mg, 1.85–3.75% K, 0.08–0.13% Na, 26.7–49.6 ppm Mn, 360.7–1625.2 ppm Fe and 9.6–13.2 ppm Cu. Significant linear relationships were described between forage components at ensiling and nutrient components of the resultant silage. The silages at all stages of stand growth compacted well and the fermentation was complete at 21 d. As a compromise between yield and quality the soft dough stage (i.e., 80 d post-planting) is indicated as the optimum for harvesting the stand for ensiling. Such silages would be sufficient in supplying ruminant requirements of Ca, Mg, Mn, Fe, Cu and carotene but deficient in N and P and borderline for Na.