DiLorenzo is a professor and extension beef specialist with the University of Florida and based in Marianna. Tarnonsky and Podversich are graduate research assistants.
The development of forage harvesting equipment and silage bags has improved and facilitated the preservation of forages as silage. This technique allows us to preserve the excess forage production of the summer to bridge the gap during forage shortages. Additionally, ensiling forages offers a reduced weather risk and allows for greater quality feed compared to dry hay. However, labor and equipment costs can mount as larger volumes of silage are preserved and fed.
Farm labor availability has been on a long-term decline while wages and other input costs continue to rise. This situation pressures ranchers to come up with alternative solutions to keep up with production and profitability. Therefore, cattle producers continue to implement strategies that require less workforce while maintaining productivity.
One option being explored at the North Florida Research and Education Center (NFREC) is the use of “self-feeding” silage bags. The use of self-fed ensiled forages is a suitable alternative for producers who want to reduce input costs such as equipment use and labor. This is a low-cost approach in which cattle are allowed to eat silage free choice from a silage bag.
The bag is opened on one end with electrified wires running across the opened face of the silage bag. The sides of the bag are also fenced off. This approach can be implemented on a small or large scale and can be used for both growing and mature cattle. While there is no individual control of the silage intake, this free-choice approach system reduces the need for tractors, feed wagons, or diesel fuel. In today’s economy, such savings can be appealing. Nonetheless, there are different aspects to consider when deciding to use a self-feeding silage bag, as farm situations differ and the feeding operation must be tailored to fit.
Pick a dry site
Silage bags should be located in a well-drained location to avoid excessive mud accumulation. Normally, the location of the silage bag would be dictated by the layout of existing facilities such as feeding yards, but if no infrastructure exists, the preferred area would be an elevated terrain to take advantage of the natural water drainage. In such cases, we recommend to position the silage bag on the slope. Feed animals downslope from the bag so that urine, rainwater, and feces run off away from the face of the silage.
Ideally, the bag should be opened facing south, as this will provide maximal sunlight exposure and keep the ensiled material and the soil surface dry. It is advisable not to place the silage bag under trees. It is also important to fence off the sides to prevent cattle access to the bag. This can be done with an electric fence, taking advantage, whenever possible, of existing perimeter fences to reduce costs.
Maintain adequate feedout
Once the bag is opened, oxygen penetrates the ensiled forage, and this allows yeasts to grow and cause spoilage. Therefore, allow cattle to consume enough material every day so it does not spoil and waste. This is called the face removal rate or daily frontal advance. As a rule of thumb, it is recommended to remove at least 1 foot off the silage face per day in the winter and 1.5 feet during summer so that fresh silage is always being fed.
This rule of thumb may be flexible depending on location and climate. The face removal rate goes hand-in-hand with the number of animals stocked with the self-feeding silage bag. Additionally, the use of heterofermentative inoculants during the ensiling process can delay the growth of yeast once the feed is exposed to oxygen, extending the aerobic stability of the silage.
The easiest way to control cattle’s frontal advance into the bag is with the use of electric fence. Cattle learn quickly how to eat silage from the front of the bag while respecting the hot wire. There are also other more sophisticated options to restrict access to cattle such as hurdles or feeding gates, but those require a greater investment and are harder to manage. However, these options could reduce waste. The gates should be easy to move (many farmers use wheels attached to the structure to push the gates), keeping in mind that cattle should be allowed a fresh portion of silage every day as it is being consumed.
Each day, remove a “slice” of the plastic bag and move the hot wire closer to the face, allowing cattle access to new feed. This can quickly be done by one person, and the tools needed for the daily care are a pocketknife and a pitchfork (to pile up any loose silage in the bottom and push it behind the wire). The savings in time, diesel fuel, and tractor use can compensate for any feed waste generated with this feeding strategy.
The ideal stocking rate will depend on the size of the bag, moisture content, packing density, and face removal rate. Roughly, stocking rate can vary from 50 to 100 head per bag, depending on the animal category being fed. Our experience with the 12-foot bagger used at the NFREC has shown a packing density of around 2 to 2.1 tons per linear foot of bag for corn and sorghum. With that packing density, we have been able to feed at least 45 mature cows. We can remove the previously mentioned 1 foot off the frontal face of the bag to minimize spoilage due to oxygen exposure and continuously offer fresh silage to the animals.
If a greater “slice” is offered, for example 2 linear feet per day, more animals can be fed. However, if we exceed this number of animals accessing the silo, some animals will become competitive and keep others from maintaining adequate feed consumption. To ensure that all animals have access to the silage bag, and that competition is minimized, it is recommended to have homogeneous groups of animals eating from the same bag. Therefore, avoid mixing, for example, weaned calves with mature cattle. A good, practical indicator of a correct stocking density is to see all cattle in the paddock resting at the same time with no anxious feeding behavior. Weighing the animals every few weeks or monthly can help determine if the target gains are being achieved.
Ensure nutritional needs
If intending to utilize silages for growing cattle, remember that most ensiled forages (with the exception perhaps of winter annuals or legumes) are typically deficient in protein; therefore, protein supplementation is required. Without enough protein in the diet, cattle will waste some of the fibrous portion of the feed because the rumen bacteria cannot fully degrade it. The exception can be ensiled winter annuals or legumes; these forages can have adequate levels of protein, but this needs to be confirmed with a feed nutrient analysis. In a study conducted recently at the NFREC, a reduction of 40% in body weight gain was observed in growing heifers self-fed corn silage without protein supplementation compared with heifers fed corn silage plus 10% cottonseed meal on a dry matter basis (2.5 pounds per day).
The most common forages ensiled in our area are corn and sorghum (forage or grain hybrids). These silages provide high energy due to their starch content when harvested at the right maturity. Perennial warm-season grasses and winter annuals can also be ensiled but require wilting to reduce moisture.
In the case of cow-calf operations, self-feeding silage bags of warm-season perennials like limpograss or bermudagrass can be utilized to feed mature cows during periods of grass shortage, avoiding the need to feed round bales. Another interesting strategy is to allow cattle some hours of grazing of winter grasses during the day and placing them at night in a pasture with a self-feeding silage (corn or sorghum) bag. With this management, the winter grass provides high levels of protein that helps utilize the energy from the silage.
In summary, self-feeding ensiled forages can be a useful strategy for cattle operations, mainly due to reduced costs in labor and equipment. Different forages can be utilized, and nutrient deficiencies should be corrected depending on the requirements of the animals to be fed. If managed properly, minimal losses can be expected from this feeding system.
This article appeared in the March 2023 issue of Hay & Forage Grower on page 15.
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