Submitted to: Transactions of the ASAE
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 6/18/2003
Publication Date: 9/1/2003
Citation: MUCK, R.E., HINTZ, R.W. EFFECTS OF BREEDING FOR QUALITY ON ALFALFA ENSILABILITY. TRANSACTIONS OF THE AMERICAN SOCIETY OF AGRICULTURAL ENGINEERS. 2003. v. 46(5). p. 1305-1309 Interpretive Summary: Alfalfa is a difficult crop to ensile because of its limited sugar content and high resistance to pH decline in the silo. Forage breeders are making great strides at improving alfalfa quality, but no one has looked to see if changes in quality are having any effect on how alfalfa ensiles. We ensiled eight alfalfa varieties (two standard, two improved and four high quality), ,grown at one location and cut at four different times (first cutting, earl and late maturities; regrowth, early and late maturities). Some varieties ensiled somewhat more easily than the others, and those differences were consistent across the four trials. However, the differences were small, and the high quality varieties included one which ensiled the best of all eight varieties and several that were slightly worse than the standard varieties. Consequently, breeding for high quality in alfalfa is not having a major effect on ensilability. Farmers who ensile alfalfa do not have to be concerned about one variety being substantially more difficult to ensile than another one. In fact, the variation in ensilability due to growing and harvesting conditions from one cutting to the next is much greater than the variation between varieties.
Technical Abstract: Eight alfalfa genotypes were cut at early and late maturities in primary growth and in regrowth, wilted to 350 g DM/kg, and ensiled to determine if breeding for high quality affects the ensilability of the alfalfa. Two genotypes were of standard quality, two of improved quality and four of high quality. The high quality lines were approximately 30 g/kg dry matter (DM) higher in crude protein and 35 g/kg DM lower in neutral detergent fiber than the standard lines at ensiling. In contrast, there were no significant differences among genotypes regarding ensiling characteristics [water soluble carbohydrate (WSC) concentration, buffering capacity (BC), WSC/BC ratio] in the unensiled forage. However, the three highest BC values were in three of the four high quality lines, but the other high quality line had the highest WSC/BC ratio of the eight lines. Silage pH and lactic and acetic acid concentrations did vary significantly by genotype. The genotype with the best fermentation (lowest pH and acetic acid, highest lactic acid) was a high quality line. The other three high quality lines were numerically worse (0.03 to 0.09) than the standard lines in pH although only one was statistically significant. Overall, the magnitudes of these differences were small practically and not necessarily in an adverse direction for all high quality genotypes. These results suggest that present efforts in breeding for high quality are not having a substantial negative effect on ensiling.