Effects of Using an Emulsifier on Energy Digestibility and Growth Performance of Growing Pigs

Two experiments were conducted to test the hypothesis that 1) dietary inclusion of an emulsifier (LYSOFORTE®; Kemin Industries, Inc. Des Moines, IA) and choice white grease (CWG) independently increase the apparent total tract digestibility (ATTD) of dry matter (DM) and gross energy (GE), and 2) inclusion of the emulsifier in diets for growing pigs increases growth performance. In Exp. 1, four diets containing corn, soybean meal, and distillers dried grains with solubles were arranged in a 2 × 2 factorial with 2 levels of the emulsifier (0 or 0.05%) and 2 levels of CWG [0.5 or 2.5%, representing a difference of 95 kcal of metabolizable energy (ME) per kg]. Thirty-two pigs (initial weight: 25.91 ± 1.89 kg) were housed individually in metabolic crates. After a 7-day adaptation period, feces and urine were collected quantitatively for 4 days to determine the ATTD of DM and GE, and ME in diets. In Exp. 2, three diets were used: 0.5% CWG, 2.5% CWG, and 0.5% CWG with 0.05% emulsifier. A total of 168 pigs (initial weight: 22.43 ± 2.82 kg) were used, with 4 pigs per pen (n = 14/treatment). Feed intake and body weight (BW) were recorded for 6 weeks. Data from Exp. 1 were analyzed using a model including emulsifier, CWG, and the interaction as fixed variables and replicate as random variable. In Exp. 2, diet was fixed variable and replicate and weanling group were random variables. Means were separated using the pdiff option if the model was significant. Results from Exp. 1 demonstrated no interactions between emulsifier and CWG (Table 1). Emulsifier inclusion increased ATTD of DM (P = 0.025) and ME in diets (P = 0.026) and tended to increase (P = 0.077) the ATTD of GE. The ATTD of DM and GE was not affected, but ME was increased (P = 0.005) by adding CWG to diets. In Exp. 2, pigs fed 0.5% CWG diet tended to have reduced (P < 0.10) final BW and average daily gain compared with pigs fed 2.5% CWG diet (Table 2). There was no difference between 2.5% CWG diet and 0.5% CWG diet containing emulsifier. Average daily feed intake was not affected by dietary treatment. Gain-to-feed ratio of pigs fed 2.5% CWG diet was greater (P < 0.05) than of pigs fed 0.5% CWG diet containing emulsifier, but there were no differences between pigs fed 0.5% CWG diet and 2.5% CWG diet or between pigs fed the two 0.5% CWG diets. In conclusion, emulsifier inclusion increased the ME concentration of diets fed to growing pigs. Inclusion of emulsifier in a 0.5% CWG diet resulted in growth performance at a level similar to that achieved with a 2.5% CWG diet.