EFFECTS OF MOLASSED SUGAR-BEET PULP AND FORMIC-ACID ON SILAGE FERMENTATION, INTAKE AND DIGESTION, AND RUMEN FERMENTATION OF SHEEP

A cyclic changeover experiment, involving six sheep, was undertaken to evaluate the effects of molassed sugar-beet pulp (MSBP) and formic ac id (FA), as silage additives, on silage fermentation, intake and rumen fermentation patterns. Herbage from the primary growth of a perennial ryegrass sward, which had dry matter (DM), water-soluble carbohydrate and crude protein contents (g/kg) of 205, 38 and 124 g/kg DM, respect ively, was ensiled either untreated or treated with formic acid (Add-F , 2.5 I/t) or MSBP (50 kg/t). The pH values were 4.10, 3.97 and 3.98 ( s.e. 0.039) and concentrations of ammonia nitrogen were 149, 147 and 9 5 (8.6) g/kg N and of butyrate were 1.0, 3.2 and 1.6 (s.e. 0.36) g/kg DM were recorded for the untreated, FA and MSBP treatments, respective ly. Relative to the untreated silage, treatment with MSBP increased DM and gross energy (GE) and reduced acid detergent fibre (ADF) (414 v. 392 g/kg DM, s.e. 8.0) and hemicellulose (216 v. 202 g/kg DM, s.e. 4.9 ). Additive treatment did not alter DM intake or the DM, organic matte r, ADF, nitrogen or GE digestibility coefficients of the silages. The pH of rumen fluid was lowered and the concentrations of total VFA's we re increased due to the MSBP treatment. The molar proportions of aceta te, propionate and the non-glucogenic ratio were 660, 639 and 660 (s.e . 7.3), 231, 253 and 236 (s.e. 5.0; P < 0.05) mmol/mol total VFA and 3 .41, 3.10 and 3.43 (s.e 0.10) for the untreated, FA and MSBP treatment s, respectively. It is concluded that additive treatment did not alter silage intake or silage digestibility. However, MSBP decreased rumen pH and increased the total VFA concentrations of rumen fluid.