EFFECT OF A MIXTURE OF SALTS OF CARBOXYLIC-ACIDS ON SILAGE CONSERVATION, VOLUNTARY INTAKE AND GROWTH-RATE OF CATTLE FED GRASS SILAGES

A mixture of carboxylic salts (CS) was used to restrict the extent of fermentation in predominantly grass silages. In trial 1, wilted annual rye grass/red clover [292 g dry matter (DM) kg(-1)] was ensiled witho ut additive or after application of 8 L carboxylic salts t(-1) fresh f orage at ensiling. After 5 mo storage in a plastic silo tube, silages were offered to growing Holstein steers ad libitum, either alone or wi th 2 kg barley d(-1) for 70 d. Use of CS restricted the extent of carb ohydrate fermentation and protein solubilization compared with the unt reated silage. When fed to steers, CS-treated silage resulted in highe r intakes and body weight (BW) gains. Barley supplementation increased total DM intake, but reduced silage intake. Feeding barley increased BW gain. Feed conversion efficiency was improved by CS in unsupplement ed silages but not in supplemented silages. In trial 2, first-cut, wil ted orchardgrass/red clover was ensiled at 283 g DM kg(-1) either with formic acid (FA) at 2 L tl or CS at 3.5 L t(-1) in bunker silos. The regrowth was ensiled at 304 g DM kg(-1) either with FA at 4 L t(-1) or CS at 5.3 L t(-1) in heap silos. Both CS- and FA-treated first-cut si lages underwent butyric acid fermentations. Both second-cut silages we re well preserved. Relative to the FA treatment, CS had little influen ce on fermentation or protein solubilization of the ensiled grass. Whe n fed to growing heifers, intake and BW gains were less for first-cut than second-cut silages. There was no effect of additive on DM intake or BW gain, but feed to gain ratio was better in heifers fed CS-treate d than FA-treated silage for both cuts. Carboxylic salts were effectiv e at restricting fermentation and protein solubilization in silage whi ch was beneficial to animal performance.