Silage:

Silage for Goats

By John Hibma

Goats are natural browsers in the wild, being very selective of what they eat. If the seasonal nutritive values of browse and other feedstuffs decline or fluctuate, silage can be a good alternative, especially in production situations that require consistent nutrition on a daily basis. Feeding silage to goats is generally safe but does come with some risks and challenges. There is nothing inherently wrong with feeding silage to goats. Like all ruminants, goats can digest fermented feeds quite well. However, as with all forages, quality and nutritional value, as well as price, should be the deciding factors when considering feeding silage to dairy goats. While silages are an excellent way to preserve forages, improperly processing, ensiling and possible mishandling after ensiling can result in a dangerous product that will have an ill effect on goats. As with any forage, maturity and preparation at the time of harvest is critical to its quality and nutritional value.
Len Woodis mixes his TMR outside and transfers it to a push cart and feeds it out by hand in the barn. He’s milking about 85 does now and likes the economical and high nutritive value of silage for his goats. Photos by John Hibma

Silage is the product formed when a forage crop such as grass, alfalfa or corn is fermented so as to preserve it in a state of high moisture while at the same time preventing it from decay. In theory, any organic material containing sugar or starch can be ensiled provided there's enough of it to justify the effort. Ensiling grass is a good alternative to baling when the weather doesn't cooperate.

The key to making good silage is to use the weight of the crop to squeeze out all of the air, arresting the natural process of oxidation and decay after the crop has been harvested. There are essentially three ways of ensiling crops: in a vertical silo (the kind visible on many dairy farms throughout the country), in horizontal bunkers (usually constructed of cement floors and walls), and in the long, plastic, tubular bags that are generically referred to as "ag bags" by those in the know. Each method, when done correctly, will yield high quality silage for animal feed.

In Riverdale, California, Tony Brady milks about 1,800 goats—mostly Saanens—and has been feeding them silage as part of their diet for over 10 years. He feeds both corn silage and oat silage and ensiles them in ag bags. Brady said that when he first put up silage, he tried the pit style bunker and his herd developed major health issues. Two hundred goats died. He said there was never a positive conclusion reached as to what caused the deaths, but the silage was heavily implicated. His suspicion was that something went awry with fermentation in a poorly packed bunker. He's been using ag bags ever since with no problems. Brady feels the ag bags give him much better control of the ensiling process.

The ensiling process is one of fermentation and acidification, where naturally occurring bacteria consume the starches and sugars present in the forage, eventually consuming all of the oxygen and shutting off the decaying process. Once the proper level of acidity has been reached in the pile, the organic matter will then stabilize and cool, leaving a sweet smelling, "pickled" product that will keep for many months, sometimes years, so long as it isn't disturbed and more oxygen is introduced, which will begin the decaying process all over again.

The single most important factor to consider when ensiling any forage is the moisture content at the time of harvest. The bacteria need a certain amount moisture to synthesize the fermentation acids. There are a number of fermentation acids that develop in a pile of silage. The good ones are lactic acid and acetic acid. The bad ones are propionic acid and butyric acid. Secondary by-products such as ammonia and alcohol are also formed during fermentation.

Lactic acid should be the predominant acid present in any silage. It is odorless so there is no way to tell how much is present without a laboratory test. The presence of lactic acid from 8% to 10% indicates a good fermentation and the fermentation process progressed rapidly with a minimum of total spoilage in the pile. Acetic acid will also be present in silages and should be about 1/3 the level of lactic acid. The smell of acetic acid is similar to that of vinegar. If there's a lot of acetic acid present, it indicates the pile went through a slower fermentation with a greater loss of organic matter usually due to slow packing of the bunk or the forage was too dry when harvested. There's no real danger of high acetic acid levels in a silage pile; it only indicates that the pile took longer to stabilize and more organic matter vanished into thin air before the oxidation process came to an end. The longer a pile takes to stabilize, the greater the chance of undesirable bacteria getting into the silage such as clostridiums.

Extended fermentation and heat will also degrade protein so that it will vanish as ammonia. If butyric acid is present in significant amounts, it quite often means the forage crop was much too wet when chopped. The silage will have an extremely putrid smell, making it very unpleasant to handle. Aside from the fact that goats will probably turn their noses up at this foul smelling forage, silage with high levels of butyric acid should never be offered to goats. It will do bad things in the rumen.

Corn silage, by far the most ensiled forage in United States agriculture, ideally needs to have a dry matter level of around 28% to 32%. The high level of starch present in corn grain is a natural food-source for the bacteria and, when properly chopped and packed, corn silage makes an excellent feed. The best corn silage is made when the grain is in mild dent and still doughy and the leaves are still plenty green. When examining a pile of corn silage to dairy goat feed, the grain kernels should be soft and easily broken apart with a finger nail and the chop length of the crop should be around 3/8 inch long. Whether it's put in upright silos, horizontal bunks, or bags, corn silage needs to be packed very tightly with heavy equipment to squeeze out all the air in order to accomplish a good fermentation.

Grass and/or alfalfa crops pose a bit more of a challenge when making silage—commonly called "haylage." Hay crops are often cut longer when harvested, making the packing process more difficult which causes more degradation of organic matter. Hay crops are lower in starch, tending to be higher in sugar and protein, making them more susceptible to poor fermentation. Butyric acid can be much more of a problem in haylage than in corn silage due to high moisture levels at the time of harvest. Haylage should be drier than corn silage when put up in a silo or bunker—the dry matter being around 35% to 40%. Often a hay crop needs to be left in a windrow for a number of hours to allow time for some of the moisture to evaporate before ensiling.

When examining haylage, pay particular attention to the color of the forage. It should be a dark, olive green. If haylage is black, it means it has been subjected to a very high temperature while fermenting, and much of the feed value will be unavailable, regardless of what a laboratory analysis says. Often, very dark or blackened haylage will have a strong ammonia smell indicating the breakdown of protein. Again, the presence of butyric acid should be very small—less than 1%. If, after handling any haylage, a smell remains on hands and continues to smell (i.e. stink), even after multiple washings, pass up the pile of haylage as a possible feed source for goats.

High-moisture wrapped bales—the kind that look like a big marshmallow—are also a good way to put up hay crops. Again, the key is to pack it tightly, keeping the air out. There has been instances of listeria, a highly toxic organism, being found in some haylages.

When ensiling a pile of forage, the heat production of fermentation must come to an end in a few days. Someone who attempts to ensile a few hundred pounds of grass or corn, will most likely end up with a spoiled product since there isn't enough mass to weigh itself down—air will continue to seep into the pile and the pile will continue to cook. Attempting to ensile grass in garbage bags is most likely going to result in failure. The ag bag will work well for moderate amounts of tonnage. If attempting to put up a horizontal type bunk, consider at least 100 tons in order to ensile properly. For many goat owners, this kind of tonnage might be out of reach and the next best alternative is to purchase silage from a neighboring cow dairy or feedlot that has put it up properly. Be aware of the fact that once silage is disturbed when it's taken from the silo or bunk, it will begin a secondary fermentation, so it should never be left lying around for more than two days before it's fed. Once the feed begins to ferment again, it takes on characteristics that make it unpalatable and goats will not be very inclined to eat it.

Extended exposure to air and the elements quickly spoils silage. Often this spoilage will contain molds that will be found at the outer edges of a pile. If any noticeable, musty traces of mold are detected the silage should be discarded.

The presence of mycotoxins is a significant problem in corn silages. Mycotoxins are toxins produced by molds and can be found in varying degrees in nearly any corn silage. There are a multitude of different strains such as aflatoxin, vomitoxin, zearalenone, T-2 and fumonisins. At high enough levels, mycotoxins will affect the immune systems, milk production and reproduction in goats. For those who choose to feed corn silage to goats, it's always good insurance to include a mycotoxin binder in any purchased grain mix—there are a number of different types on the market. If there's one strong argument for avoiding silage as a feed for goats, it's probably the uncertainty of mycotoxins and other molds.

Because goats are selective eaters, they, better than us, can tell if there's something amiss with the feed offered to them. Incorporating silages into a feeding program probably works best in a confinement operation where close attention can be paid to daily consumption and the possibility of spoiled feed.

High quality corn silage will provide a good deal of energy to the diet—a good thing when your does are milking in early lactation. Four or five pounds of corn silage in a lactating diet (remember, it's about ¾ water) should be properly balanced with an adequate protein and vitamin/mineral source. Corn silage tends to be low in calcium compared to a legume forage such as alfalfa. Extra calcium must be supplemented in the diet. Haylage can be high in protein so levels of protein in the grain should be adjusted accordingly.

Len Woodis, New Braintree, Massachusetts, has been milking about 80 Saanens for several years. To trim feed costs he began purchasing a TMR (total mixed ration) ration which included corn silage from a dairy farm neighbor during the 2007 season. His goats quickly adapted to it and milked very well for the season. This past fall he ensiled both a couple hundred tons of corn silage and haylage in horizontal bunks at his farm. This year he's been feeding the silages together in a 50/50 ratio along with two pounds of an 18% protein pellet and a pound of corn meal for added energy—all mixed as a TMR. The goats get another one and a half pounds of the pellet each time they're milked in the parlor. The daily silage consumption works out to about seven and a half pounds on an as-fed basis. Dry matter of the ration tested about 54% and the percentage of forage in the ration was just under 40% (40:60 forage to concentrate ratio). In mid March the herd was averaging just over seven pounds milk, including first year does, with a butterfat test of over 4%.

Care must be taken to not over-feed corn silage to late lactation and dry goats. They'll get over-conditioned very quickly which may lead to metabolic problems at kidding. However, the goat owner need not be afraid to feed silage to goats. Each situation needs to be evaluated individually and the economics and availability must be considered. Those who make goat milk cheeses may find that the fermented feed will impart a different taste to the cheese. Yet, when silages are managed correctly they provide goats with an economical and high source of nutrition.

Silage for goats should:

Always be tested for nutritional levels and mycotoxins.

Be balanced with the rest of the ration.

Be fed in a closely managed environment to avoid spoilage.

Not be fed if molds or mycotoxins are present.

Not be fed if fermentation profiles are suspect.