Not All Fat Sources Are Created Equally
Adding fat to swine diets has the benefit of improving feed conversion rates, average daily gain, and group uniformity, however, not all dietary fat sources are created equally. Fat sources have different energy values, usage level limitations, palatability, and possible negative effects. As a whole, the quality of a fat source depends upon two overarching factors: the raw ingredient source from which the fat is derived and the condition of the fat source.
The raw ingredient(s) from which a fat source is derived is the most common way fats are classified and determine its primary characteristics. Tallow (beef), choice white grease (pork), vegetable oils (corn, soybean, canola, etc.), and animal/vegetable blends are the most common fat sources used in U.S. swine diets. The degree of fatty acid saturation and fatty acid chain length determine most of the physical and nutritional properties of a fat. Saturation determines physical characteristics such as whether a fat is liquid or solid at room temperature with more saturated fats being solid (lard) and more unsaturated fats being liquid (vegetable oils). The saturation of a fat also has some nutritional ramifications as more unsaturated fats are more readily absorbed by the pig and thus provide a greater amount of energy. While shorter chain fatty acids do provide less gross energy on a per unit basis, they are also more readily absorbed by the pig and provide more digestible energy. These absorption differences are even greater in the young pig as its developing gut cannot easily absorb saturated or long chain fatty acids. It is due to these two characteristics that vegetable fats such as corn and soybean oil provide more available energy to a pig than animal based fats such as tallow and choice white grease.
While assuming all fat sources are the same regardless of source may result in lower energy diets than intended, the condition of a fat source can cause even greater problems. The condition of a fat source is largely determined by how it was handled by the manufacturer. While all fats are exposed to some heat during normal processing, extended or intense exposure to heat will cause lipid oxidation (damage). This is why fat sources such as restaurant grease are less desirable as they have undergone many cycles of intense heat. Additionally, the more unsaturated a fat is, the more susceptible it is to oxidation. Adding an antioxidant and ensuring rapid turnover of unsaturated fats like corn oil are best practices to prevent post-delivery damage at your mill or farm. Oxidation will result in less energy available to the pig, but the bigger concern is the rancidity and subsequent decreased palatability. This can lead to reduced intakes, pigs going off feed entirely, and bins full of unusable feed. Another factor to take a look at is the level of impurities and free fatty acids. These are undesirable components which reduce energy value and should be extracted in a purified fat source.
When selecting a fat source, be sure to look at more than just price. It is always a smart choice to request a certificate of analysis or product specification sheet from your supplier. When a supplier says they have great deal on a fat ingredient, it is buyer beware. There are often reasons why it is such a bargain and you may be left with a sub-standard or unusable ingredient.
As this was only a brief summary and does not cover all factors to consider when selecting a fat source, contact your Form-A-Feed swine representative for more in-depth information on feeding fat and fat sources. Don’t have or know a Form-A-Feed representative? Submit your request through our “Talk with a Species Specialist” form and one of our swine specialists will respond promptly.