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Unusual Feeds for 2021 – Kochia and Canola Regrowth

By Travis Peardon, PAg, Livestock and Feed Extension Specialist, Outlook

During times of feed shortages alternative forages are often used. This past summer many of our forage crops left a lot to be desired due to extreme dry conditions. Many producers found themselves baling kochia and canola regrowth. While these feeds do have a place in winter rations, it is important to understand the risks.

Kochia

If baled early and harvested before becoming mature, the feed quality of kochia is excellent, rivaling alfalfa in protein and energy levels. However, what sets kochia apart from common forages is that it contains a compound called oxalate.

Oxalates bind to calcium in the bloodstream, making it unavailable, ;leading to hypocalcemia or low calcium levels. Calcium availability to body systems is severely reduced and calcium crystals can also cause blockages in the kidneys resulting in death. Short-term problems from oxalates occur when unconditioned animals are allowed unlimited access to kochia. Symptoms of short-term poisoning include labored breathing, depression, weakness, coma and possibly death. Some animals show convulsions and tetany within two to four hours of eating a feed containing high levels of oxalates. Short-term effects are more typical of hungry animals as compared to animals that were fed prior to ingesting oxalate laden feeds. If an animal is showing obvious symptoms of having consumed oxalate laden feeds, it generally means serum calcium levels have been reduced significantly and death often results.

With proper management, kochia may be used successfully as a feed. Mature kochia may be fed in cattle diets up to 40 per cent of total dry matter intake while kochia baled at an earlier maturity stage should be limited to 30 per cent of total dry matter intake. As an insurance measure when feeding kochia, feed additional calcium supplements to negate any effect of kochia on calcium use. Prepared minerals containing calcium can be used or limestone can be added to the diet.

Canola Regrowth

Canola regrowth this past summer proved to be a blessing for many producers looking for additional feed. On a dry matter basis, crude protein in canola forage that is in the late flower/early pod stage of maturity generally averages 12 to 14 per cent and can be as high as 18 per cent. Total Digestible Nutrients TDN (energy) typically ranges from 55 to 60 per cent. As the crop matures the levels of protein and energy decrease significantly. A feed analysis is recommended to determine actual nutrient values. Canola tends to accumulate nitrate and sulphur; it is recommended that both parameters be included in the feed analysis.

Cattle may develop scours when fed canola hay or silage as the predominant source of roughage. It is recommended that canola hay or silage comprise no more than 50 per cent of the total feed intake, depending on nutritional analysis. Canola contains high levels of sulfur (0.5 to 1.3 per cent). It is recommended that total dietary sulfur not exceed 0.4 per cent on a dry matter basis. If cattle diets exceed this level of sulfur intake, several implications may result.

Cattle fed long-term diets of these roughages may develop a condition called Haemolytic Anaemia. Feeding at levels of 50 per cent or less should prevent this condition from occurring.

Feeding canola forage to cattle for long periods may inhibit the use of trace minerals, particularly copper and selenium. Ensure that recommended levels of copper and selenium are fed daily.

In some situations, high levels of dietary sulfur create hydrogen sulfide gas in the rumen. This can lead to sulfur-induced polioencephalomalacia (PEM), a dietary disease that can cause lesions to form in the brain. Clinical signs include a lack of muscle coordination, facial muscle tremors, teeth clenching, circling, stupor and blindness. These conditions are soon followed by recumbency, convulsions and death. Fatal cases of PEM have been confirmed in Saskatchewan; it was determined that these were caused by the consumption of large amounts of canola forage with high sulfur levels.

Sulfur is present in groundwater as well as in feed. It is vital to check the sulfur level of both the feed and the water to avoid the cumulative build up of sulfur in the rumen.

When using non-typical feeds such as kochia and canola regrowth feed testing and working with a nutritionist can make all the difference for your cattle. While both feeds present challenges they can be used safely and result in healthy animals coming through the winter.

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