# 15th International Silage Conference Highlights – Part 2



## ZB (Apr 1, 2008)

This article continues to summarize the topics discussed at the XVth International Silage Conference held in Madison, Wisconsin July 27-29.

_Session 3: Silage Management _

Dr Brian Holms of University of Wisconsin-Madison and Dr. Keith Bolsen formerly of Kansas State University outlined the recent changes in order to improve the overall management of silage making. He began by describing a "silage triangle" of people involved in silage making, namely the nutritionist, the agronomist, and the silage harvester. In many situations the farmer himself is one or all of these people, but the principle remains the same-many factors influence how silage is managed. If everyone involved in the process is not on the same page, problems are much more likely to happen. It is very important that these individuals and the farmer meet on a regular basis to discuss how their demands affect the silage making process and come to an agreement for how and when the silage will be harvested, treated, stored, and feed to the animals.

Safety in and around bunker silos is an important issue that can have dire consequences if precautions are not taken. Not overfilling bunkers, properly sloping piles, evenly removing silage from the bunker face, operating at a safe distance away from the bunker face, and many other practices can reduce the risk of injury or death when working in and around silage bunkers.

The increasing rate of harvesting forage has dramatically affected the filling and packing of bunker silos. More often than not the hauling/packing crew cannot keep up with the rate of harvest if the number and weight of packing tractors is not sufficient. Selection of right number of packing tractors with the correct weight is critical is ensure that the silage is packed to a density and porosity that excludes air and enhances proper fermentation. Table 1 outlines the details of this issue. AF=as feed silage-about 65% moisture or 35% dry matter (DM).










When packing bunkers, the emphasis is shifting toward the porosity, rather than the DM density of the silage. The porosity is the amount of space between each particle of silage, while the DM density is the number of particles per unit area of silage. Porosity is determined by the bulk density (fresh silage density) not DM density. If drier silage is pack the porosity (space) increases, while the DM density remains the same. This space determines how much gases and liquids can flow throughout the bunker. More space = more silage exposed to oxygen = more silage lost. Limiting this space between silage particles will provide more consistent fermentation. Bottom line-Dr.Holmes recommends a minimum bulk density of 705 kg AF/m3 or 44 lb AF/ ft3 and a maximum porosity of 0.40 as a goal when packing forage in bunker silos and drive-over piles. If silage is being packed at 30-40% DM these parameters should be easily met. Silages above 40% DM will need more weight on the tractors to pack the silage to a porosity below 0.40.

A couple of major barriers exist to achieving a bulk density of 44 lb AF/ ft3 and a maximum porosity of 0.40. One is an increasingly common recommendation by nutritionists to put up drier alfalfa silage in order to balance wet corn silage in the ration. Additionally the fields are sometimes mowed and raked faster than the harvesters can keep up which leads to excessive drying in the field to above 40% DM. These are a couple of examples where the members of the "silage triangle" need to sit down and find a solution to improve the quality of silage making. A final consideration when packing bunkers is the type of vehicle used. Many farmers have experimented with using construction vehicles to pack their bunkers. The use of bulldozers, concrete trucks and dump trucks may seem attractive, but farmers must remember these vehicles are not designed to pack bunkers and may have some safety hazards and problems associated with weight distribution. If these vehicles are used, equipping them with tracks can help stability them on the wet surface of the silage. Collapse of bunker sidewalls may occur if the weight of the vehicle greatly exceeds the needs of packing bunkers as well.

Oxygen barrier films are now available on the market to improve the sealing of bunker silos. A layer of plastic that excludes oxygen is placed on the bunker sidewalls and over the top at filling. This layer "sticks" to silage a lot like a Saran wrap does to a kitchen bowl. Then a layer of regular polyvinyl plastic is placed on top. This system virtually eliminates spoilage of the silage compared to a conventional two-layer plastic system. Table 3 below outlines the economics of the feed quality savings vs the cost of the system compared to a conventional two-layer plastic cover.http://www.silostop.com/


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