Integrated Systems Agriculture: 4 Benefits of Grazing Cover Crops to Beef Producers

Intensive, specialized crop production has several widely agreed upon downfalls.  These specialized systems tend to have stationary yields with expensive pesticide and herbicide inputs all while profitability is widely dependent on a global market over which we have little control.  Dependence on these practices  leads to higher resistance among  insects  and weeds, reliance on fertilizers due to nutrient depletion  in the soil,  soil erosion and contamination of waterways due to run off, and improper soil management practices. Soil scientists and agronomists agree that the addition of cover crops to a cropping rotation can improve soil quality and health through decreased erosion, increased microbial activity, increased carbon sequestration, more soil aggregates, and increased conservation of moisture in the soil, all due to a more extensive rooting system and ground residue protecting the soil for more months out of the year.  The addition of livestock, most commonly beef cattle, to this rotational cropping system decreases the need for herbicides and fertilizers, as they help deplete the weed seed bank and their manure contains many nutrients vital to plant nutrition and soil health. Guest author, Emily Shafto, covered the benefits to the soil extensively in her blog Cattle and Crops: Completing the Nutrient Cycle.  Here are four benefits of grazing cover crops to cattle producers:

 

  1. Grazing cover crops extends the grazing season, leading to decreased costs of stored feeds.  Supplementation needs are also lessened due to the animal’s ability to preferentially graze to meet their nutritional needs. According to a study by Practical Farmers of Iowa, grazing cover crops can offset winter feed storage costs by up to $40,000. Of course, it is important to mention that labor costs increase, and grazing cover crops requires more intensive management of the land and cattle.  The cost may be offset by the reduced need to cut and bale excessive amounts of hay or corn silage. Feed should still be stored for emergency use, such as a failed cover crop or a stressed crop that has accumulated too much nitrate to graze.

 

  1. Grazing cover crops can improve cattle’s nutritional plane through preferential grazing.  Animals consuming a cover crop mix can choose plant parts such as leaves over stems which are higher in protein and non-fiber carbohydrates and lower in fiber.  Cattle can also choose less mature plants for the same nutritional reasons.  Therefore, by grazing a mix of annual crops, cattle can consume more protein and carbohydrates for performance than a balanced ration of roughages and grain supplements. Therefore, grazing cover crops can improve nutrition and eliminate the cost of ration balancing and mixing.

 

  1. By improving their nutritional plane, animal performance can increase when grazing cover crops.  Growing steers typically have increased feed intake when consuming cover crops as opposed to a mixed ration, which results in increased weight gains.  Heifers and cows on the higher plane of nutrition provided by cover crops can have increased reproductive performance.

 

  1. Grazing cover crops rotationally can have an added benefit of forage regrowth.  When animals graze a paddock for the first time, they open the top canopy and allow sunlight to reach shorter plants.  When the cattle are removed from that section, plant growth is stimulated and if allowed enough time, may recover sufficiently enough to allow the area to be grazed again.   Grazing regrowth is like bonus forage and can also contribute to decreased feed production and storage costs.

 

Integrating cropping systems with forage production and grazing benefits soil health, grazing livestock, and your pocketbook.  Grazing cover crops specifically benefits beef production by extending the grazing season, thereby saving on winter stored feed costs, improving the animals nutritional plane resulting in improved animal performance through increased intake and gains, and bonus regrowth can also be grazed, again saving on winter feed costs.  Don’t forget to take proper precautions before allowing cattle to graze cover crops. See my blog post: 6 Cautions When Grazing Cover Crops. 

6 Cautions When Grazing Cover Crops

Grazing cover crops can be a cost-effective way to achieve multiple productions goals.  Cover crops can provide ground cover to prevent erosion, improve soil health over time, and provide nutrition to beef cattle.  However, cover crops are not a fool proof feed.  Turning cattle out onto cover crops to graze without proper feed tests can lead to a wreak due to improper management.  Recently, I had a producer lose 12 head of growing cattle to polioencephalomalacia, a neurological disease in cattle consuming too much sulfur.  After the incident, that producer wanted to test his cover crops to ensure he did not experience another tragic loss.  My advice, is to test cover crops before grazing for protein, energy value, minerals, nitrates, and under some circumstances, prussic acid to ensure proper management and prevent undue losses. These are the 6 cautions to consider when grazing cover crops:

  1. Nitrates

Cover crop mixes include several plant species known to accumulate nitrates for example: brassicas, such as turnips and radishes, or small grain plants, such as oats, millet, or grain sorghums. When cattle consume high nitrate feeds, the microbes in the rumen convert that nitrate to nitrite.  The nitrite is then in the gas, which the cattle belch and then inhale.  The nitrite then binds to the blood hemoglobin preventing oxygen from binding.  At levels between 1,400 – 2100 ppm NO3-N this can cause spontaneous abortions with no warning signs or symptoms.  At levels between 2,100 – 4,000 ppm NO3-N sudden death may occur and therefore, animals grazing cover crops should be slowly acclimated to consumption of nitrates and offered a low nitrate roughage to fill up on first.  Never allow hungry cattle onto a high nitrate field.  Nitrate levels above 4,000 ppm NO3-N should not be grazed as sudden death will likely occur.

  1. High sulfur

The toxic level of sulfur in a cattle diet is 0.40 ppm on a dry basis.  Brassicas are sulfur accumulators, that occasionally test above the maximum tolerable level, and are often included in cover crop grazing mixes.  When sulfur intake is above the tolerable level, thiamin metabolism is impaired in a condition known as polioencephalomalacia (PEM). Head pressing, blindness, and muscle tremors are all clinical symptoms of PEM which, untreated, results in death.

  1. Low magnesium

Grass tetany is a condition commonly associated with lush spring pastures.  These pastures are known for having low magnesium due to rapid growth conditions. Cover crops also tend to have low magnesium.   The magnesium requirement for a beef cow is 0.2% of the diet at peak lactation and 0.1% of the diet for growing cattle.  When cover crops contain less magnesium than is required, a magnesium deficiency can develop resulting in grass tetany.  The signs of grass tetany are cattle stop grazing, become overly alert, and appear uncomfortable, they will then begin to stagger until they finally lie down with their head pulled back into a “star gazing position”.  Untreated, this condition will result in death.  To prevent the development of a magnesium deficiency, many producers grazing cover crops feed a mineral between 8-12% magnesium to be consumed at a rate of 2.5-4oz per head per day.

  1. Prussic acid

In cover crop mixes there are species of plants which accumulate hydrogen cyanide, a poisonous gas commonly known as prussic acid, in their leaves under stressful growing conditions.  These plants include sorghum grasses, sudan grasses, and flax.  Stressful growing conditions includes drought or frost.  Plants grown in drought conditions should be tested for prussic acid prior to grazing because consumption of high levels of the gas is sudden death.  Contrarily, frost typically breaks cell walls allowing the release of the gas and therefore should be safe to graze after 4 days.  Regrowth after a frost however, should be tested prior to grazing because the plant is stressed from the previous frost, but the cell walls have not been broken to allow the gas to escape.

  1. Bloat

A frothy bloat is often attributed to legumes or high protein grasses.  Cover crop mixes high in legumes such as clover, beans, or cowpeas may result in some animals over indulging in the legumes resulting in frothy bloat issues.  These legume plants are high in soluble protein and sugars which allows the microbes to ferment and grow at a rapid rate resulting in a high rate of gaseous by-product accumulation.

  1. Choke

Brassicas such as radishes and turnips may be pulled from the ground to be consumed by cattle grazing cover crops.  If they are swallowed without proper mastication the animal may choke on the large root.  This is typically more of a problem for young cattle who are inexperienced in grazing brassicas.

Overall, grazing cover crops can be a great way to provide nutrients to cattle, prevent soil erosion and improve soil health.  However, the producer should be aware of the risks they are assuming feeding these diverse forages.  Testing for nitrates, minerals, and potentially prussic acid is highly recommended to avoid unnecessary losses due to grazing cover crops.