EFFECTS OF BREEDING FOR QUALITY ON ALFALFA ENSILABILITY

Abstract

Eight alfalfa (Medicago sativa L.) populations were cut at early and late maturities in primary growth and inregrowth, wilted to 350 g dry matter (DM)/kg, and ensiled to determine if breeding for high quality affects the ensilabilityof the alfalfa. Two populations were of standard quality, two were of improved quality, and four were of high quality. Thehighquality lines were approximately 30 g/kg DM higher in crude protein and 35 and 30 g/kg DM lower in neutral and aciddetergent fiber, respectively, than the standard lines at ensiling. In contrast, there were no significant differences amongpopulations regarding ensiling characteristics [watersoluble carbohydrate (WSC) concentration, buffering capacity (BC),and WSC/BC ratio] in the unensiled forage. However, the three highest BC values were in three of the four highquality lines,but the other highquality line had the highest WSC/BC ratio of the eight lines. Silage pH and lactic and acetic acidconcentrations varied significantly by population. The population with the best fermentation (lowest pH and acetic acid,highest lactic acid) was a highquality line. The other three highquality lines were numerically worse (0.03 to 0.09) thanthe standard lines in pH, although only one was significant. Overall, the magnitudes of these differences were small practicallyand not necessarily in an adverse direction for all highquality populations. These results suggest that present efforts inbreeding for high quality are not having a substantial negative effect on ensiling.