Studies on grass silage from predominantly Paspalum dilatatum pastures in south-eastern Queensland. 2. Influence of length of cut on silages with and without molasses

Abstract

Five experimental small-scale tower silos, each of approximately 0·75-ton capacity, were used to compare silages produced from predominantly Paspalum dilatatum pasture. The pasture was at a fairly mature stage of growth with a dry-matter content of approximately 35 per cent. and a protein level of 6 · 9 per cent. The total sugar content was low, approximately 2 · 5 per cent. on dry matter.
The. treatments compared were as follows:
(1) Pasture harvested with a flail type of commercial harvester and ensiled without molasses.
(2) Pasture harvested with a flail type of commercial harvester and ensiled with the addition of molasses at the rate of 40 lb per ton of green matter.
(3) Pasture mown, chaffed and ensiled without molasses.
(4) Pasture harvested with a cutter-bar type of commercial harvester and ensiled without molasses.
(5) Pasture harvested with a cutter-bar type of commercial harvester and ensiled with the addition of molasses at the rate of 40 lb per ton of green matter.
The experimental procedure of rapid filling and maximum compaction resulted in low-temperature silages for all treatments. Fermentation losses were low, ranging from 5 to 8 per cent. There was no effluent. Excessive mould formation occurred only in the flail-harvested
product ensiled without molasses.
Optimum silage quality was not obtained in any treatment, but quality, as evidenced by decreased pH and increased lactic acid production, was influenced both by the method of harvesting and by the addition of molasses. The best product resulted from material harvested by the cutter-bar type of harvester and ensiled with molasses.
The ensiling process resulted in a significant decrease in dry-matter digestibility, due largely to a reduction in the digestibility of the nitrogen-free-extract. Silages made from pasture harvested by the cutter-bar showed digestibility coefficients for dry matter, organic matter, protein, fibre and nitrogen-free-extract, which were significantly greater than those for products from either flailed or chaffed material. No improvement in digestibility due to molasses was evident.
Limited comparative palatability studies suggested that the most palatable silage resulted from material harvested by the cutter-bar type of harvester and ensiled with molasses.