Summary
Six experiments indicated minimum amounts of dry feedstuffs needed for storage of wet distillers grains plus solubles (WDGS) in a silo bag, with a constant pressure of 300 psi, were 15% grass hay, 12.5% wheat straw, 22.5% alfalfa hay, 50% dry distillers grains and 60% wet corn gluten feed (WCGF) with the remaining percentage as WDGS (DM basis). For storage in bunker silos, the recommended levels are 40% grass hay, 30% wheat straw and 30% cornstalks.
Introduction
Because WDGS are delivered in semi-load quantities and are perishable in 7 to 10 days, smaller operations may not be able to use WDGS. Similarly, most cow-calf operators do not purchase WDGS because of low feeding rates which can lead to spoilage. Cow-calf operations demand for WDGS is often in the winter. The demand for WDGS in the winter is much higher compared to summer due to a greater number of cattle-onfeed in Nebraska feedlots.
WDGS will keep when oxygen is excluded; however the DM of the traditional WDGS is relatively low (30%-35%). As a result, WDGS by itself is challenging to store in a bunker silo or a silo bag under pressure.
Two other types of byproducts are modified WDGS (DM 45%-50%) and WCGF (DM 45%-60%). These byproducts can be packed into silo bags under pressure but cannot be packed into a bunker silo without additions.
The objective for the first three experiments was to maximize the amount of WDGS stored with adding minimal forages. In the next three experiments, the objective was to mix in larger amounts of low quality forage with the byproducts to obtain greater use of the low quality forages, while storing the wet byproducts.
Procedure
Traditional WDGS were mixed using a truck mounted feed mixer with weighing capability. During all of the bagging experiments, the bagger was held at a constant pressure of 00 psi. All of the grass hay, wheat straw, and cornstalks were ground through a tub grinder with a 5-in screen; alfalfa hay was ground with a 7-in screen. Feed products used in the experiments contained different DM (Table 1), therefore all percentages are presented on a DM basis.
Experiment 1
WDGS were mixed with one of five different feedstuffs including grass hay, alfalfa hay, wheat straw, dry distillers grains (DDGS) and wet corn gluten feed. During the experiment, adjustments were made based on how the different products bagged.
Grass hay was tested at 17.5%, 15%, 12.5%, 10%, and 7.5% with the remaining percentage being WDGS on a DM basis. Alfalfa hay was tested at 25%, 22.5%, 20%, 17.5% and 15% on a DM basis. Wheat straw was mixed with WDGS at 15% and 12.5% DM basis. Ratios of DDGS:WDGS evaluated were 50:50 and 60:40 (DM basis). Wet corn gluten feed was mixed with WDGS at ratios of 40:60 and 50:50, respectively (DM basis).
Experiment 2
Two semi-loads of WDGS were mixed with 30% grass hay and two loads were mixed with 40% grass hay for storage in silo bunkers. A skid loader with rubber tracks was used for packing mixtures in the bunker silos. To test how well the mixture of grass hay and WDGS packed, a pay loader was driven onto the pile to determine if the mixture would maintain the weight of the pay loader.
Experiment 3
Cornstalks (29% of DM) were mixed with WDGS to be packed into a bunker silo. This mixture was packed into the bunker silo using a skid loader with tracks.
Experiment 4
WDGS were mixed with wheat straw at two different levels and stored in silo bags to be used in a feeding study (2008 Nebraska Beef Cattle Report, pp 33-34). One mixture was 67% wheat straw and 33% WDGS (DM basis). The other mixture was 33% wheat straw and 67% WDGS (DM basis).
Experiment 5
WDGS were mixed with cornstalks and stored in a silo bag. Cornstalks: WDGS were mixed at a ratio of 50:50 (DM basis).
Experiment 6
In the last experiment, WDGS was mixed with grass hay. Grass hay was mixed with WDGS at a ratio of 56:44 grass hay to WDGS (DM basis). The mixture was stored to be fed over the course of the summer to grazing cattle.
Results
Calculations of minimal levels of WDGS and feedstuffs needed to prevent splitting of the bag from Experiment 1 are shown in Table 2. During Experiment 1, the silo bag split open during the bagging process at the 7.5% and 10% grass hay levels. It also split open at the 40% and 50% levels of WCGF. Based on Experiment 2, the minimal level of grass hay with WDGS in a bunker silo was 30% grass hay; however, we recommend the 40% level of grass hay because a skid loader with tracts was used to pack the product into the bunker silo. The skid loader with tracts has a lower lb/in2 for compaction compared to a pay loader. The 30% grass hay pile was not able to support the weight of the pay loader when compacting the pile.
In all of the experiments, quality of the stored material was good because spoilage did not occur. Exclusion of oxygen is necessary for good storage. Mixtures of 12.5% to 67% (DM basis) wheat straw with WDGS in silo bags were successfully stored. Based on Experiment 1 and Experiment 5, it appears that wheat straw and cornstalks have similar characteristics for storage in a silo bag.
The range of roughage levels that can be used for storing in bunker silos is likely narrower than for bagging, although fewer levels were evaluated. Likely, 30% to 40% roughage with WDGS is appropriate for bunker storage with grass hay or equivalent, and lower levels when using wheat straw or cornstalks.
Producers may need to make adjustments as they store WDGS to make it work within their operations.
1Daniel R. Adams, graduate student; Mallorie F. Wilken, graduate student; Brandon L. Nuttleman, graduate student; Luke M. Kavorik, graduate student; Josh R. Benton, research technician; Matt A. Greenquist, research technician; Galen E. Erickson, associate professor; Terry J. Klopfenstein, professor; and Rick J. Rasby, professor, Animal Science, Lincoln.
