If this is exceeded, rumen fermentation can be affected and milk fat depression, reduced feed intake and off-feed problems may occur. There are three sources of supplemental fat. The most common oilseeds grown in Manitoba are canola and sunflowers . The seed coat protects the rumen from rapid exposure to the fat and prevents rumen fermentation from being adversely affected. Some of the benefit from the seed coat will be lost if seeds are processed prior to feeding.
Sunflower seeds are a popular fat source.
Whole canola seeds are less digestible because of their small size and hard seed coat. The digestibility can be increased by processing but the small size and high oil content of the seed makes on-farm processing difficult. Some form of commercial processing may be necessary to maximize fat utilization. The University of Manitoba has fed up to 2kg of whole canola seed with no detrimental effects. Vegetable oils are unsaturated fats and will likely cause changes in rumen fermentation.