Studies on grass silage from predominantly Paspalum dilatatum pastures in south-eastern Queensland. 1. A comparison and evaluation of the additives metabisulphite and molasses

Abstract

In one experiment, the silage treatments compared were untreated, metabisulphite at 8 lb/ton green matter and molasses at 40 lb/ton. In a second experiment, two additional treatments, metabisulphite at 12 lb/ton and molasses at 80 lb/ton, were included.
The experimental procedure of fine chopping, rapid filling and maximum compaction resulted in low-temperature silages. Fermentation losses were of the order of 10 per cent. in all treatments. Appreciable effluent resulted only in treatments involving the addition of sodium metabisulphite.
In both experiments the use of additives improved silage quality. The best quality, as indicated by lower pH and increased lactic acid concentration, resulted from the use of molasses. There was little further improvement in quality from the higher content of 80 lb molasses/ton.
In comparison with the control silage, both metabisulphite and molasses treatments showed a significantly greater digestibility of the nitrogen-free-extract, organic matter and dry matter, this effect being most marked with the greater concentration of additives used in the second experiment. In the first experiment there were no significant differences in digestibility between the products made with additives. In the second experiment some differences between additives attained significance, metabisulphite giving greater digestibility of dry matter, organic matter and fibre, and molasses giving greater digestibility of the nitrogen-free-extract.
Some loss of digestibility was apparent from the ensiling process, the digestibility of the nitrogen-free-extract, organic matter and dry matter being markedly greater in the pasture prior to ensiling than in any of the resultant silages.
The order of palatability of the silages in relation to additives used was molasses at 80 lb/ton, metabisulphite at 8 lb/ton, molasses at 40 lb/ton, metabisulphite at 12 lb/ton, untreated.