Take another look at the food pyramid from elementary school and you will see that it has changed multiple times over the years. The last update was as recent as 2011. This is due to not only our growing knowledge of nutrition, but also to the changing availability of nutrients over the years. This sparks a question as we relate this concept to animal nutrition. Have swine diets kept pace with nutrition and nutrient availability? Recent research shows that mineral levels in hog diets might just be the next leap in nutritional evolution.
How does the feed industry determine appropriate trace-mineral concentrations when formulating swine diets? A reference commonly relied upon is the report from the National Research Council (NRC), “Nutrient Requirements of Swine,” which was most recently updated in 2012. The problem with the NRC requirements, is that they are based on information that is over a decade and half old. Those that are involved in the swine industry know that a lot has changed and advancements in swine production have been made since the 1990s.
Dr. Donald Mahan, professor emeritus, The Ohio State University, recently asserted that NRC recommended mineral requirements do not accurately reflect pig nutritional needs. “Very little new information has been published on the mineral requirements of modern pigs and the most recent NRC document (2012) relies on data more than 15 years old. Since that time, significant changes have occurred in the feed industry,” Mahan said.
Mahan, who recently presented at the Midwest Swine Nutrition Conference, gave a few examples of why NRC requirements should be reevaluated:
- Processing of feeds leads to improved digestibility of innate minerals- In 2013, Jolliff and Mahan showed that the digestibility of innate minerals should not be ignored in feed formulation because they influence overall mineral nutrition.
- Supplementing with exogenous enzymes that improve trace mineral digestibility – NRC documents were developed based on studies that did not utilize exogenous enzymes. This means that typically dietary trace mineral inclusion rates have not been adjusted to reflect the effects exogenous enzymes have on minerals such as zinc (Zn) and iron (Fe) (Adeola and Cowieson, 2011).
- Utilizing organic trace mineral sources, which are more bioavailable than inorganic sources - Trace minerals are classified as either organic or inorganic. These classifications refer to the form of the mineral source and are not to be confused with strict chemical definitions. Organic sources of trace minerals mimic the forms that are naturally present in feedstuffs and, as such, may provide a metabolic advantage that can improve performance. In the 2013 study by Jolliff and Mahan, they confirmed that organic minerals are more bioavailable than inorganic minerals in young pigs. In contrast, inorganic mineral salts, such as sulphates, carbonates, chlorides and oxides, are broken down in the digestive tract to release free ions, which can react to form indigestible mineral complexes. These complexes are then excreted to the environment without conferring nutritional benefits to the animal.
In two recent experiments on trace mineral requirements (Gowanlock et al., 2013; Mahan et al., submitted), levels of trace mineral (copper (Cu), manganese (Mn), Fe and Zn) were evaluated in swine. In both studies, diets were composed of conventional feed ingredients for the Midwestern United States and supplemented similarly with iodine and organic selenium. Phytase was added to diets in line with modern industry practice. Micromineral premixes were prepared and added as percentages of the NRC (1998) recommendations, such that the inclusions of all the trace minerals were adjusted simultaneously, which, unlike past studies, did not allow independent mineral evaluations.
In the experiments newly weaned pigs were fed diets that contained 0, 25, 50 or 100 percent of NRC (1998) trace mineral levels as inorganic mineral salts or as organic minerals, and finisher pigs were fed corn and soybean meal diets that were supplemented with organic trace minerals at 0, 50 or 100 percent of NRC (1998) recommendations. Results showed that both nursery pig and finishing pig trace mineral requirements did not appear to need dietary trace-mineral supplementation at the magnitudes recommended by the NRC. This indicates that the NRC recommendations for the addition of dietary trace minerals may result in levels above those needed to support health and wellbeing and to maximize growth and development of swine. Advancements in feed processing techniques, exogenous enzyme technology and the use of organic minerals appear to have exhibited effects on the recommendations for dietary trace mineral additions which were previously accepted without questioning within the feed industry.
Find out more about this and other critical topics at the pig symposium May 17- 20 during Alltech’s REBELation, a week of innovation, inspiration and revolution. Join the conversation as we examine the next frontier in swine nutrition.