Fats are a concentrated form of energy. Per unit of weight, they contain over 2 times as much energy as either carbohydrates or proteins. They also supply a source of essential fatty acids to aid in metabolic processes. Normally 1 to 2% fat will supply the necessary amount of essential fatty acids, with the remainder of dietary fat used as an energy source. Since fat is a concentrated source of energy, it is a convenient ingredient to increase the dietary energy. Fat tends to make feeds and some food more palatable to animals and people. Other nutrients must be properly adjusted in high-fat diets to ensure that the animal still gets the proper balance of essential nutrients as they consume less feed.
Most purified diets are made with a base amount of soy oil or corn oil as a constant source of essential fatty acids (EFA). Typically when additional fat above the minimally-required level is required, porcine lard is used as the source. Other sources of fat can be used in addition to or in place of lard, such as soy oil, corn oil, coconut oil, and hydrogenated vegetable fat (“Crisco”).
Considerable research attention has been given to omega-3 fatty acids in recent years. In grain-based diets, omega-3 fatty acids are derived primarily from the use of fish meal and soy oil. “High-fat” diets (generally considered those in excess of 30-40 kcal% fat) are commonly used in research to study atherosclerosis, obesity, diabetes, hyperlipidemia, and other diseases/conditions.
There are many fat sources to consider when designing a diet for a specific research study. Below, several of the fat sources are provided along with some pertinent nutrient information that may help with the design of a diet and help meet the objectives of an experiment.
|
|
Fatty Acids, %* | |||||||
| FAT SOURCE | Saturated Fat | Mono- unsaturated Fat | Poly- unsaturated Fat | Linoleic Acid (18:2) | Linolenic Acid (18:3) | Cholesterol, mg | Omega 6 | Omega 3 |
| Plant Sources | ||||||||
| Coconut Oil | 86.1 | 6.2 | 1.9 | 2.1 | 0.0 | 0.0 | 2.31 | 0.0 |
| Corn Oil | 13.3 | 24.2 | 58.0 | 57.2 | 0.9 | 0.0 | 57.2 | 0.9 |
| Cottonseed Oil | 25.8 | 19.0 | 51.3 | 51.8 | 0.3 | 0.0 | 51.5 | 0.2 |
| Crisco Vegetable Shortening | 25.0 | 33.0 | 25.0 | - | - | 0.0 | ||
| Olive Oil | 14.3 | 70.9 | 10.4 | 9.3 | 0.7 | 0.0 | 9.8 | 0.8 |
| Palm Oil | 47.2 | 40.2 | 9.9 | 10.6 | 0.2 | 0.0 | 11.0 | 0.4 |
| Peanut Oil | 18.1 | 45.8 | 29.9 | 30.6 | 0.0 | 0.0 | 32.0 | ~ |
| Safflower Oil–High Linoleic | 8.5 | 13.0 | 75.1 | 76.2 | 1.0 | 0.0 | 74.6 | ~ |
| Safflower Oil–High Oleic | 9.1 | 78.5 | 14.0 | 14.5 | 0.5 | 0.0 | 14.4 | ~ |
| Sesame Oil | 14.2 | 38.5 | 42.8 | 41.3 | 0.5 | 0.0 | 41.3 | 0.3 |
| Soy Oil | 14.5 | 22.5 | 57.8 | 51.0 | 7.3 | 0.0 | 51.1 | 7.8 |
| Sunflower Oil–High Linoleic (>60.0%) | 11.1 | 18.6 | 69.0 | 70.0 | 0.7 | 0.0 | 65.7 | ~ |
| Sunflower Oil–High Oleic | 9.7 | 83.6 | 3.8 | 3.6 | 0.3 | 0.0 | 3.6 | 0.2 |
| Animal Sources | ||||||||
| Beef Tallow | 49.8 | 41.8 | 4.0 | 3.1 | 0.6 | 109.0 | 3.1 | 0.6 |
| Butter | 50.9 | 22.2 | 3.0 | 2.7 | 0.3 | 215.0 | 2.7 | 0.3 |
| Cod liver Oil | 20.8 | 46.4 | 28.8 | 1.2 | 0.8 | 570.0 | 0.9 | 19.7 |
| Lard | 40.5 | 43.6 | 10.7 | 9.9 | 0.7 | 95.0 | 9.81 | 0.43 |
| Margarine, 80% Fat | 15.3 | 36.5 | 24.2 | 20.9 | 2.2 | 0.0 | 22.3 | 1.96 |
| Menhaden Fish Oil | 27.1 | 20.4 | 29.9 | 1.2 | 1.4 | 521.0 | 2.81 | 27.2 |
| Pork Animal Fat | 39.7 | 44.2 | 12.1 | 11.0 | 0.6 | 143.0 | 10.0 | 1.2 |
* Values are an estimated average of published values (McCance and Widdowson. 1993. The Composition of Foods (5th Edition). The Royal Society of Chemistry.; NutritionData. 2006. www.nutritiondata.com ) and Land O'Lakes Purina Feed’s formulation system.