ARTICLE FEED & ADDITIVE MAGAZINE March 2022 67 DURABILITY Durability is the ability of an encapsulated nutrient to maintain integrity during handling, storage, and mixing. Abrasion of the protective coating, cracking, fracturing or particle size reduction can all reduce the amount of nutrient delivered to the animal. Another often overlooked factor that can affect coating integrity is temperature. Lipid encapsulates are not robust enough to withstand the temperatures and pressures associated with pelleting. High temperatures designed to gelatinize starch and deliver a harder pellet will melt lipid encapsulates, adversely affecting nutrient payload protection. In addition, the pressure associated with pelleting can crack or fracture encapsulates, further degrading nutrient protection. A less obvious and often overlooked issue is freezethaw stability of lipid encapsulates. When lipid encapsulates are frozen and then thawed the coating can expand and contract. The micrograph in Figure 3 demonstrates the damage that occurs to an encapsulated product’s coating during a freeze/thaw cycle if the product is not designed to be stable under freezing and thawing conditions. Notice cracks that develop in the coating’s surface which allows moisture and rumen microbes to enter the coating and degrade the encapsulate, thus greatly reducing the product’s efficacy. This allows water to penetrate during storage or in the rumen resulting in a loss of nutrient protection. Figure 4 shows a diagram demonstrating the damage that can occur and the resultant loss in rumen protection if an encapsulated product is not designed to be freeze/thaw stable. The first two bars signify a product that is freeze/thaw stable and the last two bars signify a product that is not freeze/ thaw stable. Some of the more established encapsulation companies have solved this issue. RUMEN PROTECTION Rumen protection refers to the encapsulation system’s ability to protect a nutrient from degradation in the rumen so that it can pass into the small intestine. Degradation rate is determined using time-release studies in either rumen fluid or water (both are highly correlated). Water tests simplify the analytical process since there is no interference from nutrients in the rumen fluid. Figure 1. Illustration showing the differences between a matrix encapsulation and a true encapsulation. Figure 2. Micrograph of a true encapsulated nutrient demonstrating the layers of lipid coating surrounding the outside of the active compound to create a protective barrier. Figure 3. Freeze/thaw damage to encapsulated product.
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