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Fall pasture management sets the tone for spring

Mike Lamborn Published on 11 October 2011

With fall approaching, graziers are entering the season of opportunity. While year-round pasture management is essential, fall sets the stage for the quantity and quality of pastures in the spring.

This year fall pasture management will prove especially important, given the lack of rainfall many graziers in the southern U.S., and in Texas in particular, are experiencing.

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Management strategies

As we approach fall, certain management strategies should be implemented to ensure all available dry matter left in dry pasture is consumed by cows or harvested by machine. Remember that, while this feed may appear or look unappetizing, it is equal to good-quality hay, and it is feed that is already paid for.

When the dry spell breaks, rain will begin the rotting process and, for a three-week to four-week period, there will be nothing substantial to graze. Most of the available natural nitrogen left in the soil will be aiding this rotting process and, of course, it takes time for grass to re-grow from the ground up.

It also is important to keep in mind that drought-stressed, nitrate-accumulating or prussic acid-accumulating plants (including corn, small grains, sudangrass, sorghum and some weeds) may be unsafe to graze for weeks after a significant rainfall.

The toxic compounds accumulate in these plants during times of drought or other insult, and may not be converted into amino acids and proteins in the case of nitrate, or dissipate in the case of prussic acid, for one to two weeks after a drought has broken.

Nitrate and prussic acid poisoning result in an inability of blood cells to carry an adequate amount of oxygen. In cases of mild toxicity, this may result in poor performance or abortion. In cases of severe toxicity, respiratory distress and death may occur.

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Your veterinarian can assist in forage sampling, result interpretation and toxic forage management. Unlike prussic acid, nitrate will not dissipate by field curing, so special precautions must be taken when managing high-nitrate hay.

Although rainfall uncertainty often discourages producers from risking fall nitrogen applications or from drilling annuals into some paddocks, think of nitrogen as a cheap source of supplementary feed rather than fertilizer. Even if response rates are low, nitrogen is well worth purchasing and applying.

If you have been fortunate this summer and have pastures that have not been stressed by abnormally high temperatures and lack of adequate rainfall, it is still important to manage pastures with spring production in mind. Final grazing needs to be done correctly to ensure quantity and quality in the spring.

Strict attention to post-grazing residual in pre-winter pasture management (2 inches for perennial ryegrass and 3 inches for tall fescue) will ensure both quantity and quality feed in the spring.

Early fall is a time many dairymen replant perennial pastures, overseed into thinning stands or add a few paddocks of winter annuals for strip grazing.

Most state extension offices have a guide available with recommended seeding rates and dates. Check with your local extension office, seed dealer, input co-op or Natural Resources Conservation Service (NRCS) office for appropriate guides for your area.

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Make sure to plan your grazing round in such a way that cows won’t pull newly established seedlings. Use the “pull test.” Wrap your index finger around a tuft of new forage in the row or drill run and pull it. If the grass or forage comes out by the roots, it is too early to graze.

Plan also to use temporary fence to strip feed high-quality fall grazing for maximum utilization. Every pound grown and grazed saves you potentially 10 to 15 cents worth of TMR. A bit of care in feeding is worth the trouble this year.

The two major physiological aspects of fall plant growth are root regeneration and carbohydrate storage. For perennial grasses, the storage of carbohydrates occurs in the lower part of the stems.

Maintaining an appropriate post-grazing residual according to plant species ensures an adequate carbohydrate source for future growth – this is what will ensure successful spring re-growth. Grazing below the recommended stubble height this fall will sacrifice pasture production next spring.

This year, with corn exceeding $7 per bushel and dairy concentrate running more than 15 cents per pound of dry matter, high-quality fall and spring grazing will quickly repay the investment in new plantings for dairy pasture.

In the southern U.S., where there is a dependence on warm-season perennials that go into a dormant phase in late fall to winter, no-tilling cool-season annuals such as small grain cereals and/or annual ryegrasses into existing pastures is a superb opportunity to capture the cheapest milk you can produce all season.

If there ever was a time to take a risk in planting temporary pastures, this fall is that time.

Fall-calving herds

For fall-calving herds, the majority of grazing managers will be depending on either stockpiled forages, winter annuals or both to drive early lactation.

Early fall is usually the time to fertilize and cease grazing a pasture to be stockpiled. As the growing season winds down, the stockpiled forage lengthens the grazing season into late fall and early winter, decreasing the demand for expensive stored forages.

In the case of stockpiling, tall fescue is by far the best option. This is one instance where even infected endophyte KY31 tall fescue comes into its own.

Stockpiling involves a post-grazing residual and a strategic application of nitrogen (50 units) to boost growth into late fall and winter, where it can be rationed by strip grazing with an electric fence. Grown and fed right, this method of supplementation is equal to very good-quality hay without the associated harvesting cost.

Although stockpiled forages may maintain good nutrient profiles, milk production may be improved by grazing higher-energy winter annuals such as cereal grains and annual ryegrass. These annuals, planted in late summer or early fall, can provide a high-quality forage from late fall through early spring, depending on climate and management.

As a young first-year sharemilker in New Zealand 28 years ago, I hired the services of a well-known farm consultant and, for the next 12 years, this gentleman went on to be my grazing mentor.

He told me that while all seasonal management segments within a season were important, fall pasture management was the most critical.

Why?

Because, he said, how you manage your pastures in the fall, excluding inclement weather conditions, will determine your spring quantity and quality of pasture. And that, in turn, will ultimately help you produce your cheapest seasonal milk. PD

Mike Lamborn is a consultant for Dairy Grazing Services , a program offered as part of DFA’s Farm Services Division.

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