Bloat Free Pastures
Feb 24, 2012
Are your Legume Pastures Cattle Friendly?
Legumes can capture nitrogen from the air and use it for their own growth as well as for the benefit of other plants around them. The bacteria that inhabit root nodules trigger a chemical reaction to convert nitrogen gas into a form that is easily used by the plant and put back into the soil.
"Sunken Crown" Alfalfa varieties are by far the most widely used forage legumes. However, other legumes such as Red & White Clovers can also provide significant benefits. And all of the following legumes can increase soil fertility:
- Alfalfa
- White clover (best legume for Pigs and Lambs)
- Red clover (Frost seed in March)
- Bird's-foot trefoil (non-bloating) hard to establish and short lived
Grazing Legume Pastures
Intensive Rotational grazing (quick in & quick out), is practiced to retain legume leaf area for continued photosynthesis and plant growth. Livestock are rotated into a new section of a field before entire plants are grazed down. This type of grazing management allows for optimum returns as it benefits both the cattle and the pasture.
Legumes must have appropriate rest to recover and re-grow. This rest period will help maintain the health and sustainability of the pasture. For example, once cattle are removed from an alfalfa pasture, the pasture should rest for 28 to 35 days before re-grazing. Of course that rest period may be much longer depending on rainfall and heating degree day’s.
Continuous stocking may be sufficient to maintain a grazing animal, but the practice does not optimize either animal or pasture productivity. This type of management has lower input costs, but it also results in lower rates of gain, since animals spend more time searching for forages. In addition, legumes will not tolerate continuous grazing, and the plants will not survive if they are not given enough time to recover and re-grow. And it is strongly recommended that you select a "Sunken Crown" variety of Alfalfa so that the plant’s are not damaged by cattle hoof impact. In Northern regions the sunken crown varieties will also give the stands a better winter survival rate.
Frothy Bloat
Producers have found that feeding/grazing legumes can sometimes cause frothy bloat in cattle. The condition results from the quick degradation and fermentation of plant material in the rumen especially when first introduced to lush green pastures for the first time in the spring. The fermentation gases produced in the animal accumulate and become trapped in a thick foam. The foam prevents the animal from being able to burp up the gases, and this factor may lead to the animal's death.
High Bloat Risk Factors
Forage maturity is the most significant contributing factor in pasture bloat. Your knowledge of plant growth and maturity stages can go a long way toward preventing bloat.
The highest risk of bloat occurs when legumes are in the pre-bud or vegetative stage. As the plant matures, the risk of bloat declines. Studies have found bloat to be twice as likely to occur when plants are grazed at a height of 8 to 10 inches rather than at a height of 20 to 30 inches. If immature plants are wet from morning dew or rain, there is also an increased risk of bloat since the water tends to speed up the rate of digestion.
In the fall, there is an increased potential for bloat after a frost because plant cells burst and become readily digestible. Soil type also seems to play a role in the incidence of pasture bloat. It is possible to determine when the bloat risk is high. However, a visual evaluation of a pasture containing legumes does not give a concrete prediction of bloat potential. Therefore, producers should also rely on good management practices to reduce the risk of legume bloat such as regulating the amount of time you allow your cattle to graze legume filled pastures in the spring.
We will turn them out for ½ hour a day for the first week while still giving them dry hay to help their rumen transition to all fresh grass/legumes. The second week, allow them one hour in the morning and another hour in the late afternoon. By the 3rd week, they should be good to go out on pasture all day but still allowing them plenty of dry hay so they can regulate their dry matter intake until their manure is of an acceptable consistency and not shooting out of them like a fire hose!!
