Putting up high-quality forage is essential to a profitable dairy operation. The high protein potential, and savings, you can gain from producing high-quality alfalfa forages make it well worth the extra effort to do it right.

Ensiling a wet forage starts with a crop at an acceptable moisture level for the method of ensiling. Chop the crop to a suitable length. Pack it as densely as possible to exclude oxygen, then quickly seal it to prevent oxygen and moisture from entering back in. This starts an anaerobic fermentation phase where sugars in the crop are converted to lactic acid. The pH of the ensiled material drops to a level that eventually inhibits all microbial activity and thus “pickles” and stabilizes the silage.

Alfalfa and grass haylages are by far the most problematic forages to ensile successfully. Their low sugar and high soluble protein levels can work against a rapid drop in pH. There may not be enough substrate, in the form of sugars, to produce the necessary lactic acid. And the soluble protein has a tendency to convert to ammonia which can neutralize acidity.

Pre-season decisions

All forage planning begins with a sound fertilizer policy. Most cropland destined for dairy forages will see some manure applied during the fall and winter months. This is a valuable source of both nutrients and organic matter, but don’t over do it on your alfalfa fields. Alfalfa can become excessively high in potassium, and its nitrogen requirements are minimal compared to a corn crop. Always bring in an agronomist to spot-sample soils for adequate N, P and K. There’s no point spending money on expensive fertilizer if it is not needed. Also, check the soil pH and test for trace element deficiencies such as sulfur, zinc, copper, manganese, molybdenum and boron to maximize the impact of your fertilizers on both yield and feedout quality.

Decide next which forage variety you’ll plant. Be it alfalfa, corn or small grain forage, always choose a seed company that provides good data on crop yields. Ask for feedout values in terms of milk produced per acre or per ton of the forage, with trials from a variety of areas so you can see the repeatability of their performance. Recently, alfalfa varieties have shown improvements in disease resistance and yield potential. Pick the varieties that have performed well in your geographical area.

Making the cut

Digestibility and feedout performance of your preserved alfalfa crop still depends mainly on when you cut it, and the efficiency of ensiling or baling – both of which are very dependent on prevailing weather conditions. With alfalfa, the timing of your first cutting is critical because it pre-determines the sequence of cuttings for the rest of the season. The first cutting of alfalfa will always provide the most bulk. Windrow your first cutting at the early budding stage to maximize quality, without compromising quantity. Cutting this first crop a little earlier will also set you up for a possible bonus cutting at the end of the season, if the weather co-operates. For subsequent cuttings, it’s easiest to cut at mid- to late-bud stage.

An accurate way to assess nutrient value is to clip representative plants with scissors at a normal cutting height, grind them up in a food processor and send them for analysis. Aim for your ready-to-feed haylage to average 30% ADF and 40% NDF (which will be around 150 RFV.) Remember that after first bud a plant will lose 4 RFV points a day. Inevitable harvest and ensiling losses will mean that, in order to get an ideal end product, you should harvest when the alfalfa tests at least 3 points of both ADF and NDF lower or the equivalent of around 170 RFV.

Alfalfa, hay or haylage, often contributes the majority of the feed material cows use to make the fiber mat in their rumen. It’s essential to ensure that haylage is cut at a length that will add to the fiber mat and encourage cud chewing. This should be a theoretical length of cut (TLC) around 0.5” when the ensiled crop is at an ideal moisture for the type of storage facility you have. If your crop becomes too dry, shorten the TLC so you’ll still get a good packing density but don’t cut shorter than a TLC of 0.25 inch. Anything less than that compromises the crop’s ability to make an effective fiber mat.

When windrowing alfalfa or grass it is always preferable to do so in the afternoon as the plant will have built up a higher level of sugars from the morning sunlight. It is best to lay it out in a wide swath as this will lead to quicker, more even drying and will lay lighter on the stubble beneath allowing air to circulate and won’t retain moisture from rain as much as a narrower heavier swath. A narrower swath will dry on the outside, stay wet on the inside and press against the ground picking up unwanted soil contamination, increasing the ash content in the crop and the chances of soil borne clostridia and mold contamination. These last problems will also occur if you are not dumping the chopped crop onto a concrete apron at the bunker. This makes it inevitable that dirt will be bladed into the chopped material which is highly undesirable. Gopher mounds are also a source of soil contamination so make some plans to eliminate these pesky critters as well.

Packing the bunker

Bunkers require the highest moisture levels of between 60 and 70 percent. Any drier and you won’t be able to achieve a good packing density. Air will infiltrate and a prolonged fermentation will occur; burning up valuable carbohydrates making the protein unavailable. Ensiling it too wet may lead to a clostridial fermentation in haylage, producing high levels of butyric acid. Upright storage structures and bags require less moisture. For stave silos, aim for 60 to 65 percent, sealed uprights 55 to 60 percent, bags 55-65 percent and wrapped or bagged bales 60 to 65 percent.

Filling bunkers should be done as quickly as possible, using a ‘progressive wedge’ technique which minimizes exposure of the ensiled crop to the air. Haylage piles should be built up in layers no more than 6 inches deep and compacted thoroughly. Good compaction is absolutely essential for profitable haylage production. Kansas State research has shown an inverse, linear relationship between dry matter losses and compaction density after 180 days from ensiling. Their results show that if you only achieve 10 pounds per cubic foot of dry matter density, you will lose 20 percent of the dry matter. Doubling the dry matter density to 20 pounds per cubic foot will cut your dry matter loss to only 10 percent.

Adding up the additives

When putting up alfalfa forages, consider using inoculants or additives to enhance the preservation process. There are plenty to choose from: Organic acids literally pickle the wet forage as it is chopped, and they preserve dry hay. Oxygen scavenging chemicals help accelerate the haylage into its anaerobic phase of fermentation. There are enzymes that help break down starch and fiber in the crop to simple sugars so bacteria have a much larger supply of substrate for producing lactic acid.

Of all these additives, bacterial inoculants are the most popular. Most bacterial products should supply 100,000 colony forming units (CFUs) of lactic acid producing bacteria (LABs) per gram of ensiled material. Combining fiber and starch digestive enzymes with LAB’s will make more sugar available for lactic acid production and more rapid fermentation.

Under the sheets

Before you sheet down your haylage crop with a regular, .6mm gauge, white plastic sheet, decide if you’re also going to use an under-sheet oxygen barrier. These extra sheets are very effective in eliminating waste at the top of the pile or bunker and are definitely worth considering. There’s also a heavy plastic netting for weighing down these sheets that’s an alternative to tires. However, you choose to weigh down the covers, make sure you minimize the chance of air infiltrating back into the crop and you will complete the task of making excellent haylage.

Put your dry hay under cover, either in a barn or under tarp. If you don’t, you could lose up to a third of the feed value of your crop from its exposure to the elements. And the molds that proliferate on weathered hay can cause severe harm to your animals.

Take care of your forages because they are the core of sound and profitable ration building and at the end of the day, healthy and profitable cows. PD

Mike Bettle is a field nutritionist at the Form-A-Feed and TechMix companies, headquartered in Stewart, Minnesota. For more information, call Mike at (800) 422-3649 or send an email to articleinfo@formafeed.com