6 October 2009

6 minute read

What is canola?

Canola is a rapeseed crop, traditionally grown for the use of canola oil with a low level of saturated fat. Pods are harvested and crushed to obtain 40 per cent oil, the rest of the seed is used as a high protein livestock feed.

Although the use of canola meal has been used widely and is well documented, little is known about the use of the whole crop for feed. Livestock should be adjusted to canola forage by mixing the feed rations during a seven to 10-day period by blending with other forages to help prevent bloating, suggests Mr Schroeder, North Dakota dairy extension service.

Grazed

Hay

According to Greg Lardy, North Dakota beef extension specialist, haying of canola should be done before it flowers. Being harvested before the crop goes into full pod stage will make good feed for the winter.

Research in Victoria, suggested mowing with a roller mower conditioner to smash the stems as much as possible. This aggressive conditioning will help the stems dry enough, without this feed may go mouldy due to the crops high moisture content. If the crop has to be left for a long period to dry, leaf material (which is better quality than the stalk and has higher palatability) will be lost when raking. Ken Ziegler, beef and forage specialist with Alberta Agriculture and Rural Development, recommends avoiding raking if possible.

Typically, the plants take four to six days to dry to proper moisture levels (16 per cent to 18 per cent moisture content) for baling, explains Mr Schroeder. Experiments in Idaho and Montana have recorded wide variations in yield (2-13 tons per acre), which could be due to difference in varieties, growing conditions and rainfall.

As the crop cures, it will darken, which does not seem to affect palatability. “Given the high cost of fuel, evaluate the field closest to you before spending money to bale and haul what might have limited use,” suggests Mr Schroeder. Silage might be a cheaper option.

Silage

Canola has a high moisture content, typically 75-80 per cent. Consequently, seepage and effluent losses from the silage can be large. Wilting the crop to moisture levels of 60-65 per cent (40 per cent dry matter) will take time but crimping will hasten the drying process. Ensiling the crop will reduce nitrate content by 30 per cent to 70 per cent, making the feed safe. The addition of bacterial silage inoculants may be beneficial when ensiling these crops, which are low in soluble carbohydrates.

When it comes to harvesting canola as a forage or silage crop, treat it similar to cereal crops when cutting, chopping and packing. The one difference is that canola, with its hollow stems (full of moisture), takes about an extra day to dry down to the 60 to 65 per cent moisture content level, says Mr Zielger.

If baling silage, baling at drier than 45 per cent dry matter may lead to poor packing and dry stalk ends. Dry stalk ends not only pierce the silage wrap but have also been known to pierce rumen's. Baling too wet will result in poor foul smelling and low palatability silage due to the high protein contents say Dale Grey and Frank Mickan, Department of Primary Industries, Australia.

Some producers have had good results by filling the silage pit with alternating layers of canola and cereal crops cut for silage. This helps reduce seepage problems and offers the opportunity to mix the layers when feeding the silage suggests Mr Schroeder and Mr Lardy.

Nutritional values

When harvested in the late flowering to early pod stage, canola can often provide average feed values of up to 14 per cent protein and up to 60 per cent total digestible nutrients (TDN). However Mr Schroeder, suggests producers have the forage analysed to determine actual nutrient values.

The feed value is in the top 30cm of flower, small pods and leaves. Studies in Victoria, by Mr Grey and Mr Mickan, showed that canola cut due to drought and frost contained 66-67 per cent digestible dry matter. Crude protein ranged for silage and hay between 16-17 per cent. Silage and hay canola sample in 2007 contained 10 ME MJ/ kg and 41 per cent neutral digestive fibre. The dry matter content of hay averaged 85 per cent, and for silage it averaged 47 per cent. Mr Grey and Mr Mickan believe this data shows the potential of canola to produce good quality fodder high protein and energy value. This data did contain large variabilities between different crops.

To maximize total Dry Matter yield and maintain good protein and energy levels, the crops should be cut any time from the early podded stage just after the flowers have dropped, up to the stage where the lower leaves are starting to drop. Crude protein and energy levels will be higher if the crop is cut in the early podded stage rather than after the lower leaves begin to drop.

Associated Problems

Murray Feist, a ruminant nutrition specialist at the Agriculture Knowledge Centre, Canada, warns that producers considering canola should be aware of the following issues:

High sulphur content: Long term ingestion of brassica forages such as canola may lead to a health condition called polioencephalomalacia (PEM). Some canola forages will contain 0.5 - 1.3 per cent sulphur, which is much higher than the recommended requirement for cattle. For more information read last weeks feature, Sulphur Contents in Cattle Feed.

Scouring: Long-term feeding of canola at greater than 60 per cent of the diet may cause scouring.

Haemolytic Anemia: Canola may contain S-methyl-L-cysteine sulphoxide at levels high enough to be implicated in haemolytic anemia in cattle says Mr Feist. Symptoms include feed intake depression, weight loss, weakness and haemoglobinurea. Long term feeding of high levels of brassica forage puts animals at risk of anaemia.

Goiter: The crop may contain elevated levels of isothiocyanates, a compound that can induce goiter in livestock. Symptoms include growth depression, thyroid enlargement, hypothermia and tendon contractions in neonates.

To avoid the above problems, canola greenfeed or silage are typically fed at no more than 50 - 60 per cent of total dry matter on a daily basis, with the remainder of the ration being other feeds such as straw, hay and grains. According to Australian research, canola hay and silage from failed or frosted canola crops has been fed to livestock for more than 15 years. Mr Schroeder says farmers should watch stock for any signs of illnesses.

It is also important to note that when canola was not originally intended as for cattle feed, check what pesticides were applied to the crop as grazing and feeding restrictions may apply to crops treated or sprayed with pesticides or herbicides.

Is canola suitable for you?

Canola can be planted in Spring, Autumn or late Summer. Winter canola is quick to establish and can be ready to harvest for forage between roughly 60-80 days for first cut, however opinions vary determining the length of establishment.. It has been possible to gain multiple forage harvests when left to recover for 30-days suggests Kansas State University. Ohio State University suggest that canola planted by June can achieve forage yields of up to 8,000lbs of dry forage per acre. Data suggests that cutting later increases the oil content which could reduce dry matter intake.

Canola hay and wrapped silage can be a valuable feed source if producers follow some common-sense precautions when introducing these feeds to their stock, concludes Mr Schroeder.