October 27, 2011
by Allan Nation
While it’s still cold in much of the country, thinking ahead is absolutely crucial in building a beef finishing forage chain. The basic idea behind a forage chain is that the quality of the forage should increase as the animal nears harvest.
Keep in mind that in grass finishing, we want a forage capable of producing an average daily gain of at least 1.7 pounds per day. If gains are less than this, the meat becomes tough and the animals grow frame rather than fatten.
Summer is the most difficult season to produce highly digestible forages in most of the United States. While lowered animal performance is often thought to be the heat’s effect on the animal, a much bigger problem is the heat’s effect on the forages.
Most perennial grasses and legumes lignify - become less digestible - when the daytime ambient temperature is consistently above 86 degrees F (30 C). This period runs from roughly from the Fourth of July until mid-September in most inland USA locations.
Warm-season perennials are of finishing quality from greenup until the Fourth of July but digestibility falls rapidly after that. While cool-season grasses are normally though to be of higher quality than warm-season grasses, they produce similar gains (less than one pound per day) in mid-summer.
The one perennial that does not do this is white clover. This is why white clover should always be your first forage choice in grass finishing and dairying if your climate is humid enough for it to grow. Alfalfa and Red clover both lignify and are not of finishing quality in the mid-summer.
Jan Bonsma said that finishing beeves on perennial grasses in the summer should not be attempted at elevations of less than 4000 feet. Above 4000 feet, nighttime cooling normally helps preserve perennial grass digestibility. This is why the Appalachian region was the USA’s premier grass finishing region in the 1950s.
Transhumance, the herding of animals to cooler higher elevations in the summer, is widely practiced throughout the world. The reason dairy cows go up high in Alps in the summer is that the valley floors are blistering hot in the summer.
However, cooler temperatures at higher elevations are not always the case.
I was in Durango, Colorado - which is above 7,000 feet - in June 2003 and it was above 100 degrees F every day I was there with only a very short period of nighttime cooling. These high temperatures were related to the very dry conditions and were admittedly unusual. I mention this just to show you that rule-of-thumbs are seldom 100 percent in accuracy. There are always exceptions.
Other than going to the mountains, there are two primary ways to beat the heat.
One is to not build a program around not harvesting animals between mid-July and October. This is the New Zealand approach.
The New Zealand manual for beef finishing said the primary way to maintain the eating quality of grassfed beef was to harvest the animal before mid-July (North American equivalent month).
Since New Zealand (and Ireland) primarily produce beef for export, their beef markets can be and are highly seasonal in nature with two big spikes in production in (Northern American equivalent) late May and June and another in the late fall.
On the other hand, Argentina consumes most of its own beef production and therefore must have it on a relatively constant year-around basis. Therefore, it must rely on the second major way to beat the heat which is to plant summer annuals.
(Strip grazing with temporary fence is the recommended way to harvest the annuals mentioned in this story.)
The two primary summer annuals the Argentines use are corn (maize) and soybeans. Both of these plants are capable of producing two pounds a day of gain in mid-summer and both are relatively drought tolerant.
GRAZING CORN (MAIZE)
There is no negative gain period for rumen adjustment when going from cool-season pasture to corn. However, cattle that have grazed corn must be harvested off the corn as there is no higher quality plant they can be shifted to and gains will plummet. Cattle that go from high quality forages to a lower quality forage always have tough meat. Therefore, only those animals that are nearing finish should be grazed on corn.
Keep in mind with grazed corn we are primarily interested in the plant’s leaves as the plant will be grazed off before it has a chance to make grain. Therefore, silage varieties are better than grain varieties. Stay away from genetically modified varieties as their leaves have a bad flavor and will not produce the gains of the older varieties.
The Argentines prefer to use non-hybrid, open-pollinated corn for grazing. These older varieties are much more drought tolerant and can grow plentiful leaves on relatively little soil nitrogen. The frugal Argentines like that they can use their own home-grown seed as well.
(Open pollinated corn seed is available from (name) in Indiana but needs to be ordered well before planting as it is hard to come by.)
Twice as many seed should be planted within the row compared to corn grown for grain but the rows should have the same spacing as corn planted for grain. The corn should be planted in three plantings 15 days apart to stagger the maturity of the crop. The corn should be grazed when it is shoulder-high. Do not force the cattle to graze the pithy part of the stalks as this will dramatically lower their average daily gain.
In the 1950s, Southern graziers always planted their corn for grazing with a climbing legume to increase the protein content of the graze. This is not necessary with finishing weight animals of over 900 pounds but is a very good idea for dairy graziers.
The Argentines do not use supplemental nitrogen on their grazed corn but rely on accumulated soil nitrogen from plowed-down, legume-dominant perennial pastures.
Keep in mind you cannot go directly from a perennial pasture to an annual without a 45 day “digestion” period for the plants to breakdown and release the nitrogen. This is why the Argentines always go from permanent pasture to winter annuals first and then that land is planted to summer annuals.
Rye, wheat and annual ryegrass are always planted in separate paddocks due to their different maturity dates. This naturally produces the staggered planting in the desired summer corn crop.
For graziers with nitrogen deficient soils, grazed soybeans are a good summer option. Soybeans are very drought tolerant and can provide 45 to 60 days of high quality grazing in mid-to-late summer. There are no bloat or off-flavor problems with soybeans but as with corn cattle should be harvested off the crop for the same reasons.
A key point with soybeans is to always plant the longest growing variety that you can find as bean pod production is definitely not wanted as it can cause animal health problems. The ideal variety would be a Brazilian tropical variety. If any forage supplier has these, please let us know and we will pass it the information on to our readers.
As with the corn, the cattle should not be forced to graze the stems of the plant and should be moved to a fresh break when 50 to 60 percent of the plant’s leaves have been consumed. With such lax grazing, gains of two pounds per day can be obtained.
Plowing down green soybeans with this much leaf still on it can add the equivalent of 100 pounds of nitrogen for use by the subsequent winter annual forage.
CORN AND SOYBEANS TOGETHER
A better situation than corn or soybeans would be corn and soybeans.
The corn and soybeans can be planted in separate paddocks or several rows of corn and then several rows of soybeans. The reason for this separate planting is so the animals can balance their protein and carbohydrate needs by moving from soybeans to corn.
If planted in separate paddocks the soybeans should be grazed in the morning and the corn in the afternoon. In this way, the carbohydrate in the corn will help the animal digest its morning fill of legume.
If planted in the same paddock, the animal will do this on his own.
Australia has the same summer heat problems as the USA. Down there brassicas are used to a much greater extent than in the USA or Argentina for a highly digestible summer forage. The primary summer beef finishing brassica used in Australia is forage rape.
Unlike turnips, rape has not been identified with any milk or meat flavor tainting.
Forage rape is the most versatile of the brassicas, being suitable for a wide range of soil fertility and environmental conditions. It has a crude protein percent of 16, a digestibility percent of 85 (compared to 71 for corn grain) and a metabolizable energy ratio of 12 (compared to 10 for corn grain).
Rape may be sown from early spring to late summer and used to 12 to 16 weeks later. It can be grown at lower soil fertility than other brassicas and responds well to irrigation.
Rape can also be mixed with turnips and grazed oats in summer moist areas.
Like all brassicas, animals take some time to attain maximum voluntary intake when changed from a pasture to a brassica diet. This may take several weeks but this time can be minimized by introducing the animals slowly to the crop.
The beeves should be placed on the brassica paddock for only two to three hours a day for the first seven to ten days. This will give the animals sufficient time to develop the new rumen bugs needed to digest the brassicas.
Brassicas are very low in fiber. Allowing animals free-choice access to hay or grass paddocks throughout the grazing period can occasionally increase average daily gains.
Fiber is important in maintaining correct rumen pH and in diluting “anti-quality” factors in the brassicas.
Nitrogen fertilizer should be used in very small amounts on brassicas to prevent the possibility of nitrate poisoning. No more than 20 units of N should be sown with the plants. Another 20 units of N can be applied two to four weeks after plant emergence.
When used as energy supplements to grass pastures, the brassicas should be grazed in the mornings and the animals moved to grass pastures in the afternoons as with legumes.
Many graziers get up to four grazings from rape with approximately 20 to 30 days regrowth between grazings.
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