DairyNZ senior farm systems specialist Ron Pellow.
Dairy farmers’ pickled pasture – silage – depends on good inputs, DairyNZ says.
The industry-good body said that, to produce high-quality grass silage, both the quality of the original pasture and the fermentation process were crucial.
DairyNZ senior farm systems specialist Ron Pellow said that good-quality pasture silage could be a valuable source of energy and protein for milking cows; however, poor-quality pasture may only be suitable for dry cows or non-pregnant cattle.
“It’s impossible to produce high-quality silage from low-quality feed, no matter how good the fermentation is,” he said.
“Ensuring optimal dry matter content, rapid wilting, proper compaction, and effective sealing will help retain the nutrients and feeding value of the silage.”
“To prevent spoilage, especially in warm weather, it’s also essential to feed out silage quickly once exposed to air.
“Both the quality of the ensiled (stored) pasture and the quality of the fermentation must be considered, whether buying silage or choosing when to feed it.”
Pellow said that when pasture was ensiled, its sugars were converted into lactic acid by bacteria.
“It is the lactic acid which prevents further respiration of the plant material, allowing it to potentially be preserved for months, or even years.
“With well-preserved and sealed silage, losses in feeding value during fermentation and storage will be small, and the final silage will be only slightly lower in feeding value than the original pasture.”
Pellow said losses occurred as sugars and proteins in the grass were broken down by enzymes and bacteria.
“This process starts as soon as the grass is cut.”
He said losses decreased quality as well as quantity, because it was the highly digestible components that were most rapidly broken down.
Pellow said losses depended on the dry matter (DM) of the pasture.
“The optimum DM for silage is 30-35% because total DM loss is minimised.”
Pellow said that once the silage was sealed, nothing could be done to further enhance the fermentation process.
Poor fermentation, however, (such as air in the stack) leads to major losses of protein quality.
“Silage begins to break down once exposed to air and will begin to heat up as micro-organisms turn the remaining sugars and protein into heat and energy.
“Therefore, when feeding out, aim for as little time as possible between exposing the silage to air and the cow eating it.”
There are several ways to limit losses from silage while feeding out:
Pellow said that to make the best use of well-preserved silage, made from high-quality grass, it was also important to know how much there was and how much is being fed each day.
While many contractors now offer estimates of harvested yields, farmers can also estimate the yield of their own silage crop: