ENSILING FORAGE SORGHUM AT 2 STAGES OF MATURITY WITH THE ADDITION OF LACTIC-ACID BACTERIAL INOCULANTS

Whole crop forage sorghum cultivar FS2 was harvested at the late bloom (20.7% dry matter (DM)) and soft dough (28.9% DM) stages of maturity. The sorghum was chopped to approximately 10 mm pieces and ensiled und er laboratory conditions in 1.5 1 Weck glass jars. At ensiling, it was treated with two commercial silage inoculants: H/M F and Sil-All. The inoculants were applied at 10(6) colony-forming units g-1 DM. Silage with no additives served as a control. Three jars per treatment were o pened on Days 1, 2, 5, 10 and 31 post-ensiling to study fermentation d ynamics. After 31 days of ensiling the silages were analysed and subje cted to an aerobic stability test lasting 5 days. The yield of the sor ghum harvested at the late bloom and the soft dough stages was 11.8 to n DM ha-1 and 16.4 ton DM ha-1, respectively. The in vitro organic mat ter digestibility was 61.4% and 67.6%, respectively. At both stages of maturity the inoculants caused a more rapid rate of pH decline and a higher amount of lactic acid production. All the silages were well pre served. Silages of the sorghum ensiled at the late bloom stage with al l treatments were stable after 5 days of aerobic exposure, whereas sor ghum ensiled at the soft dough stage with the addition of the inoculan ts deteriorated upon aerobic exposure. This was evident from a signifi cantly (P < 0.05) higher production of CO2 as compared with the contro l, and increase in pH. It is concluded that addition of lactic acid ba cterial inoculants to mature sorghum at ensiling might impair the aero bic stability of the silage.