Forages Key to Dairy Nutrition

Good-quality forages are the foundation of the dairy feeding programme, says this North Dakota State University report.
calendar icon 13 July 2009
clock icon 3 minute read

Forages form the base of the dairy nutrition food pyramid, and poor forage quality quickly erodes that foundation and contributes to a host of feeding challenges on dairies, according to North Dakota State University Extension Service dairy specialist J.W. Schroeder.

Forage quality impacts cow performance and health. With spring forage harvest in full swing, here are some timely reminders:

  • Not all silage inoculants are alike. Two main types of inoculant are available: traditional homofermentative types, such as Lactobacillus plantarum, and heterofermenter types, such as Lactobacillus buchneri. Each works differently and should be used in different situations. The rules-of-thumb are if you want to make good silage better, use a homofermenter. If you need to improve aerobic stability, use a heterofermenter.
  • Chop and pack forages the same day. Do not let chopped forages sit in the wagons overnight. You will lose valuable sugar if the forage is not packed right away. The plant still is respiring and aerobic organisms can grow and use the sugars.
  • Pack the forage. Attaining a high silage density when you pack your bunkers this season is important for a couple of reasons. Most importantly, density and dry-matter content determine the porosity of the silage. Porosity is a measure of the voids between the solid particles. Porosity, in turn, sets the rate at which air moves into the silo, which influences the amount of spoilage during storage and feed-out.

“Don’t let warm weather spoil your silage,” Schroeder says. “Warm temperatures can create challenges for producers managing silage feed quality. They can increase heat and spoilage to the bunker face, potentially causing up to 40 percent of the total dry-matter and energy losses that occur in silage. Depending on compaction, air can penetrate up to a foot into the silo face.”

Once silage is exposed to oxygen, the clock has started ticking on the nutritional value of the silage. To minimize these losses, producers need to feed at least 6 inches or more off the face daily.

Throughout the summer months, microbial activity will double with every 10 degrees above 50 degrees. Producers will begin to see a breakdown of the acids that aid in preservation. This breakdown is initiated by yeast. Yeast will start to consume the lactic acid under aerobic conditions and the pH will continue to increase, eventually allowing spoilage organisms (molds) to grow. With the current economics, management is vital in reducing feed-out loss.

Bunker silo covering systems also are an important consideration. A University of Delaware study shows that lining the sidewalls of a bunker with an oxygen-barrier plastic prevented rain from infiltrating the silage at the sidewalls. This technique, in addition to covering the bunker with oxygen-barrier plastic and gravel bags, helped prevent dry-matter loss. Corn silage covered in this manner also had lower neutral detergent fiber than corn silage covered with regular (polyethylene) plastic and split tires.

“More research is needed to evaluate the cost of covering a bunker with oxygen-barrier plastic versus regular plastic,” Schroder says. “However, it probably doesn’t matter what type of plastic you use to line the sidewalls just so long as it doesn’t tear.”

Proper samples are the key to accurate test results. If you want to know how good your forage really is, you have to send in proper samples. Your goal should be to obtain a representative and randomly selected sample. Therefore, following a defined protocol is important when pulling samples. Here are the steps:

  • Identify a single lot of hay.
  • Choose a good, sharp coring device.
  • Sample at random.
  • Take enough cores.
  • Use good technique.
  • Handle samples correctly.
  • The sample should be the right size.
  • Split samples correctly.

“Forage is the key to cost-effective dairy lactation rations,” Schroeder says. “Feeding good-quality forage starts now, in the field and at the feed yard. Don’t let quality escape your feed inventory.”

July 2009

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