Effect of Pelleting on Digestibility of Encapsulated Nutrients Embedded in a Fat Matrix

Abstract Text: Pelleting of livestock feed is routinely performed because it may offer advantages related to animal health and performance. However, the additional handling as well as the temperature and pressure related to pelleting may alter the properties of additives within the pellets, which could lead to reduced animal performance. In order to determine the effects of pelleting on digestibility of nutrients embedded in a fat matrix, a concentrate feed was mixed with the following: 1) DL-Methionine (MetiPEARL™; Kemin Industries Inc., Des Moines, IA); 2) Lysine HCl (LysiPEARL™; Kemin Industries, Inc.); or 3) Choline Cl (CholiPEARL™; Kemin Industries, Inc.). In addition, a complete feed was mixed with a source of butyric acid (ButiPEARL™; Kemin Industries, Inc.). Each embedded product was mixed at 1.0% of the as fed weight of either the concentrate or complete feed and these treatments were referred to as fortified. Half of the mixture was used as the meal form of each treatment, while the remaining was pelleted. Pelleting was done under commercial conditions. A modified three-step in vitro digestion technique (Sapienza Analytica, LLC; Slater, IA) was used to estimate the 16 hour ruminal and intestinal digestive properties. Digestibility estimates were determined for dry matter, crude protein, and the respective nutrient of interest of each treatment. Data were analyzed using the Fit Model of JMP with digestibility estimates included as Role Variables. Contrasts were used to compare the effects of pelleting and nutrient fortification. The addition of the embedded nutrients increased (P < 0.001) rumen digestibility of each of the respective nutrients for both the meal and pelleted forms. Pelleting did not affect (P > 0.01) ruminal digestibility of lysine (35.84 vs. 33.33%), choline (81.48 vs. 81.52%), or butyric acid (45.00 vs. 44.58%) for the fortified meal and pellet forms respectively. However, ruminal methionine digestibility was greater (P < 0.001) for the fortified meal (51.01%) compared with the fortified pellet (27.32%). Additionally, intestinal methionine digestibility was lesser (P < 0.01) for the fortified meal (61.55%) compared with the fortified pellet (72.56%). Intestinal digestibility estimates for the fortified lysine treatments (76.27 vs. 74.01%) tended (P= 0.07) to be greater for the meal compared with the pellet. These results demonstrate that the embedded nutrients evaluated in this study can be added to a feed and then pelleted and still have similar or better digestibility characteristics than when fed in a meal form.

Keywords: pelleting, embedded, amino acids