Last month’s article covered some key aspects of the ensiling process. This month will consider some tools to assist in ensuring the best possible preservation. Two of the key principles mentioned last month were, achieving the fastest fermentation to preserve as much forage as possible, and achieving anaerobic conditions by preventing oxygen leaking into the silage.
Crops naturally contain a variety of bacteria species that can convert sugars to acids, thus ensiling a crop. However, the bacteria numbers will vary, and they will produce a variety of acids (acetic, butyric, lactic). This has led to the widespread use of silage inoculants that supply large numbers of specific strains of bacteria that only produce lactic acid, which is the strongest of these acids, resulting in very fast fermentations.
These inoculants tend to have several strains of bacteria that are active over differing pH ranges, so they act as a relay team, speeding up the ensiling process. The faster the fermentation, the less sugars are consumed by the bacteria, so the more nutrients (dry matter) retained.
Sugar levels are highly variable in many crops, so the best inoculants also contain enzymes that break down some of the fibre to its component sugars, to provide a readily available feed source for the bacteria, resulting in faster fermentations, particularly important in hard to ensile crops, e.g. lucerne and high protein pastures. These crops are more difficult to ensile well, as their high protein levels tend to buffer (resist) changes in pH, so more sugars are used to produce sufficient acids to achieve a stable pH.
Plastic covers are slightly porous to air, so some oxygen can leak into stacks or bales using standard silage covers. This has led to the introduction of oxygen barrier covers, that can be used in conjunction with standard silage covers or wrap, which may also have an ultraviolet light (UV) filter. The oxygen barrier provides an effective seal against air leakage, resulting in less waste around the edges of silage bales or stacks, which can be considerable in some cases. Next month’s article will discuss returns on investment from using these tools.
As featured in NZ Dairy Farmer