Oilseeds Hold Key to Specialized Milk Output

REGINA - May 22/02 - SNS -- Including oilseeds such as flax and sunflower can allow dairy producers to produce specialized milks with fatty acid compositions that benefits the human heart and circulatory system.

Dr. David Christensen, a professor in the university's Department of Animal and Poultry Science, said, "Such milk is produced in some Asian countries at present, so another opportunity revealed by this project is the marketing of Canadian oil seeds and oil-seed products for use in North American and Asian dairy rations."

Christensen says the objective of this project was to determine the fatty acid composition of milk as affected by fatty acid sources and rumen conditions. He explains that some fatty acids found in milk and meat have been associated with "lower-gut" tumour formation and development of heart and circulatory disease. The researchers hoped to change this negative effect on the human body to a positive effect, and this goal was achieved.

"Conjugated linoleic acid (CLA) is a desirable fatty acid that is produced by rumen bacteria and is transferred to milk. Under conditions of high grain feeding with low levels of fat in the ration, there is a very low level of CLA in the milk. But it has been found that supplementing the ration with certain forms of fat may increase the CLA content of milk. In our research we used flax seed in a dairy-production trial and found that it doubled the CLA content of milk fat and depressed the undesirable fatty acid content.

"Flax oil contains a high level of alpha linolenic acid (ALA), which is partially converted to CLA in the rumen. Increased levels of ALA was also found in the milk. ALA, like CLA, has anti-tumour properties and also maintains heart and circulatory system health. In a second trial, whole sunflower seeds were fed to lactating dairy cows, and the CLA content of the milk fat doubled.

"In some feeding conditions, furthermore, it was found that milk yield was substantially increased - milk revenue rose by more than $2 per cow daily - by feeding one kilogram of whole sunflower seed daily with little or no depression in milk fat or protein percentage. The palatability and preference trial indicated that raw and roasted sunflower seeds were equally acceptable and readily eaten by dairy cows when fed separately or mixed with a total mixed ration," says Christensen.

The project Feeding and Management to Maximize Desirable Fatty Acid Content in Milk and Beef, #20000057, was supported by the Agriculture Development Fund (ADF). A copy of the project's final report is available by phoning 306-787-5929 in Regina or by accessing the Saskatchewan Agriculture, Food and Rural Revitalization Web site.

This project was confined to a study of the effect of fat sources on the milk of dairy cows, but further ADF support will allow a related project to start soon: the effect of sunflowers and an extruded flax-pea mix on the fatty acid content of beef. Christensen says department researchers are also measuring the fatty-acid content of colostrum, and looking at the effect of fat sources such as flax, canola and sunflower on a cow's immune system before and after calving.