THE EFFECT OF ADDITIVES ON THE ENSILAGE OF FORAGE OF DIFFERING PERENNIAL RYEGRASS AND WHITE CLOVER CONTENT

Pure perennial ryegrass or perennial ryegrass / white clover mixtures (70:30 and 40:60 on a fresh-matter basis) were ensiled in laboratory s ilos either untreated or after treatment with freshly cultured Lactoba cillus (Lb.) plantarum or freshly cultured Lb. planatarum plus Lactoco ccus (Lc.) lactis, freeze-dried Lb. plantarum or freeze-dried Lb. plan tarum plus sodium formate, sodium formate or formic acid. The effect o f these additives on silage fermentation characteristics and quality o f the resultant silages was examined. There were significant interacti ons between treatments and herbages for all silage quality parameters measured, except for acetic acid concentration. The influence of addit ives on the final pH of all silages was small but statistically signif icant. Lactic acid concentration was not directly related to herbage m ixture, overall mean values ranging from 118 to 120 +/- 1.5 g kg(-1) d ry matter (DM), but wider variation was seen between treatments for in dividual herbage mixtures. Acetic acid concentrations were significant ly (P<0.001) affected by herbage mixture ensiled, increasing linearly as clover content increased from zero to 60%. Untreated control and fo rmic acid-treated silages contained significantly (P<0.001) higher ace tic acid concentrations than those treated with other additives. Silag e ammonia N concentrations were significantly (P<0.001) influenced by herbage mixture. Lowest ammonia N concentrations (< 50 g kg(-1) DM) we re observed in silages that had been treated with formic acid, freshly cultured Lb. plantarum or Lb. plantarum plus Lc. lactis. The fraction 1 leaf protein (F1LP) contents of silages were significantly (P<0.001 ) affected by both treatment and herbage mixture, with consistently an d significantly higher values found in freshly cultured inoculant-trea ted silages. A poor correlation (r(2) = 0.12) existed between ammonia N and F1LP in all silages. The inclusion of up to 60% white clover in the ensiled herbage did not adversely affect final silage quality. How ever, additive treatment markedly influenced the residual F1LP content of silages, those treated with freshly cultured inoculants having the highest values.