Fat contains over two times the amount of energy found in grain. This makes it a very good energy supplement for early lactation cows.
The intake of supplemental fat should not exceed 5% of the ration. This corresponds to approximately 0.7 to 0.9 kg fat/day (1.5 – 2 lbs). 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. Both contain approximately 40% fat and 20% protein. Soybeans contain 20% oil and about 40% protein. 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 2 kg of whole canola seed with no detrimental effects.
Commodity fats include animal fats (tallow, lard) and vegetable oils. Vegetable oils are unsaturated fats and will likely cause changes in rumen fermentation. Animal fats are saturated fats and are less likely to cause milkfat depression. Special equipment is necessary to keep tallow in a liquid state. Feed intake will be reduced if rancid tallow is fed.
A number of commercial products are available (eg. Booster Fat, Golden Flake, Megalac). These fats are “protected” so they have the advantage of being inactive in the rumen. They are easy to handle but are a more expensive form of fat.
Animal Nutritionist, Animal Industry Branch
Manitoba Agriculture & Food
204-545 University Crescent
Winnipeg, Manitoba, Canada R3T 5S6