Effect of formic acid and a formalin and sulphuric acid mixture on the intake and digestibility of grass silage

Abstract

ABSTRACTIn two experiments of Latin square design the effect of additives on the ad libitum intake of direct-cut perennial ryegrass silage and its digestibility by steers was determined. The diets were offered to British Friesian castrated male cattle, mean initial live weights 386 and 368 kg for Experiments 1 and 2 respectively. In Experiment 1, untreated silage was compared with silage treated with either formic acid (‘Add-F’) or a formalin and sulphuric acid mixture (‘Sylade’) each applied at the rate of 4·5 1/tonne of fresh herbage. The silages were offered either with or without 5 kg of supplement per day. In Experiment 2, silages treated with 4·5 and 9·0 1/tonne of the formalin and sulphuric acid mixture were compared. Silage treated with 4·5 1/tonne was offered either with or without 5 kg supplement/day. In Experiment 1, the application of an additive had no significant effect on silage digestibility. Although differences were not significant, the intake of silage dry matter was higher from additive-treated silage (91·2 and 80·6 g/kg W0·73 for the formalin and sulphuric acid mixture and the formic acid respectively) than from untreated silage (78·0 g/kg W0·73). Supplementation significantly reduced (P<0·05) silage dry-matter intake and crude fibre digestibility and significantly increased (P<0·05) total dry matter and digestible energy intake. Digestible energy intake from the formalin and sulphuric acid treated silage was significantly higher (P<0·05) than that from untreated silage but differences between the additive-treated silages were not significant.In Experiment 2, neither rate of application of the formalin and sulphuric acid mixture nor supplementation had any significant effect on intake.