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‘New Forage’ Challenges

May 25, 2013
 
 

Non-traditional forages will be finding their way into summer and fall feeding programs. Here’s help in managing them.

Linn blueBy Jim Linn

Forage inventories on many dairy farms in the Midwest are about depleted, especially hay crop forages. A high-yielding first cutting of quality alfalfa is needed for feeding this summer.

However, many producers were hit hard with winter kill in their alfalfa. They have had to scramble to figure out what to replant and then find seed for planting.

For many producers in this situation, non-traditional forages will be finding their way into the summer and fall feeding program. For those whose alfalfa did survive the winter, the cool wet spring has slowed plant growth and delayed 1st cutting.

Whichever the situation, feeding newly harvested forages or feeding a new forage species, the forage and fiber needs of the cow remain the same. Quantity, quality and effective fiber are the three things to keep in mind as forages are harvested this summer.

Forage quality is certainly important, but quantity supersedes quality this year. High quality legumes and grasses yield less per acre than good quality. As quality increases, cows eat more forage and it takes more forage in the diet to meet fiber requirements.

A 140 to 150 relative feed value (RFV) alfalfa haylage (40% Neutral Detergent Fiber--NDF) will yield more and be better at meeting the forage and fiber requirements of the cow than 170 and higher RFV alfalfa. From cutting to feeding, RFV will drop about 20 units so harvesting at about 26" in the very late bud or early flower stage should result in good yield and quality of alfalfa.

Some producers will be harvesting the newer grass varieties for forage this year. The goal for harvest in a pure grass stand is 55 to 60% NDF or a late boot stage. However, don’t be fooled into thinking cows will eat less of this high NDF forage.

Research studies on the newer grass varieties have shown DM intakes don’t decrease with higher NDF. Grass will not replace straw in diets unless the grass is very mature. For producers who have interseeded grass into a poor alfalfa stand, target the mixed alfalfa-grass crop for harvest at about 50% NDF for quality and quantity.

Small grain silages will likely be a major forage source in many dairy diets this summer. Oatlage-alfalfa as the first cut of new seeded alfalfa is likely to be forage in lactation diets and not just heifer diets by midsummer.

The traditional problem with this and most small grain silage is harvesting and ensiling them at the correct moisture. Target should be 60% moisture (40% dry matter--DM) in small grain silage for best ensiling and feedability.

High or all corn silage diets will likely be the norm this fall and winter. With lots of winter kill acres available with good nitrogen credits, expect to see more replanting into corn or possibly BMR sorghum-sudangrass if dry conditions and/or above average temperatures are expected.

Harvesting corn silage should be as normal. But kernel processing and the option of shredlage for good fiber digestion and physically effective fiber will be essential for healthy cows and good milk production.

Feed Out Rules

When feeding the newly ensiled crop, a good inoculant should be added to the forage at ensiling. The forage mass should remain undisturbed for at least two weeks before feeding. When ensiled at the right moisture and packed well, forage fermentation will be complete within 7 to 10 days.

Fermentation will be a little longer in legume silage than cereal grain or corn silage. That’s because the high protein and calcium content of legume plants buffer fermentation more than cereal grain or corn silage.

Waiting a month or longer to feed is best, but when having to feed ensiled forage sooner the number one problem will be aerobic instability and heating. As feed is removed from storage, the mass is disrupted and oxygen is allowed back in for bacteria and yeast growth.

Mature, dry and long particle size forages are more prone to heating on feedout than good quality correctly ensiled forages. A rapid feedout with excellent face management of the ensiled forage will be the best retardant to aerobic instability.

Hot silage also shortens feed bunk life of the TMR. Adding a propionic acid or other mold inhibitor designed for the TMR will help reduce bunk life problems. Treating the last several feet of the silage that will be fed first and the top foot of the pile or bunker with propionic will also help minimize heating of the silage during the early feeding period. 

Jim Linn is a dairy nutrition consultant and retired Extension nutrition specialist at the University of Minnesota–St. Paul. Contact him at linnx002@umn.edu.

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