Iodine Values: Pigs are what they Eat
Posted: December 1, 2015
While pork carcasses are not typically classified by quality like beef carcasses, there is one measure of carcass quality which is very closely monitored by meat packers: iodine value (IV). This name is a bit misleading as it has nothing to do with the iodine in a pig’s diet but rather it describes a chemical reaction used to determine the saturation of carcass fat. A lower IV means the carcass fat is composed of a greater proportion of saturated fatty acids while a higher IV indicates a higher proportion of unsaturated fatty acids. A simple way to distinguish saturated and unsaturated fats is their state at room temperature: saturated are solid (i.e. tallow) while unsaturated are liquid (i.e. vegetable oil).
So what does IV have to do with carcass quality and why do meat packers discount for high values? It all comes down to bacon! Bacon is derived from pork bellies, one of the most valuable pork cuts. Fat constitutes about 50% of the belly, therefore the composition of the fatty acids from which it is composed is critically important. Firm bellies (composed of more saturated fats, low IV) slice very easily and uniformly while yielding a high percent of saleable product. On the other hand, soft bellies (more unsaturated fats, high IV) are very difficult to slice and will have a low product yield. Additionally, the cook loss on high IV bellies is extremely high. Shriveled up slices of bacon do not make for happy end customers or repeat pork consumers!
If IV is so important to packers and consumers, how can pork producers manage it to ensure a high quality product in the marketplace? It is very simple: pigs are what they eat. The more unsaturated fats (vegetable derived fats) a pig consumes, especially in the last 45-60 days, the higher its carcass IV will be. On the other hand, pigs which are fed predominately saturated fats (animal derived fats) in the latter part of the finishing phase will have lower IV carcasses. If a diet without added fat is fed, the IV will fall in between these other two scenarios and will likely be deemed acceptable. Another ingredient which producers must be mindful of is distiller’s grains (DDGS). DDGS typically contains 7-9% fat and as this fat is derived from corn, it is highly unsaturated and can cause carcass quality challenges if fed at high rates. A sound practice to follow is to reduce the inclusion of DDGS to no more than 10% for the last 45 days on feed to mitigate most quality issues.
Contact your Form-A-Feed swine representative for more in-depth information on feeding strategies to manage your carcass iodine values. 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.