T.S. Vafa, A.A. Naserian, A.R. Heravi Moussavi, R. Valizadeh, M. Danesh Mesgaran, Effects of Different Levels of Fish Oil and Canola Oil on in vitro Dry Matter and Organic Matter Digestibility, Research Journal of Biological Sciences, Volume 4,Issue 11, 2009, Pages 1171-1174, ISSN 1815-8846, rjbsci.2009.1171.1174, (https://makhillpublications.co/view-article.php?doi=rjbsci.2009.1171.1174) Abstract: This experiment was designated to examine the effects of different levels of fish oil and canola oil on in vitro dry matter and organic matter digestibility of two forages including alfalfa hay and corn silage. Using a completely randomized design with 3x3 factorial arrangement of treatments, the effects of three levels (2, 4 and 6% of DM) of three oil sources (Fish Oil (FO), Canola Oil (CO) and combination of Fish Oil and Canola Oil (FOCO) in 50:50 ratios) in an in vitro batch fermentation on Dry Matter (IVDMD) and Organic Matter (IVOMD) digestibility of alfalfa hay and corn silage were studied. In this experiment, in contrast with control, all oil sources decreased IVDMD (71.4, 69.1, 66.2 and 70 for control, FO, CO and FOCO, respectively) and IVOMD (69.98, 66.4, 63.2 and 68.4 for control, FO, CO and FOCO, respectively) of alfalfa hay significantly (p<0.01). For corn silage, IVDMD (64.3, 63.5, 59.1 and 63% for control, FO, CO and FOCO, respectively) and IVOMD (65.4, 61.9, 58.4 and 62.5% for control, FO, CO and FOCO, respectively) decreased significantly, when oil was added. Among oil sources, canola oil significantly (p<0.05) decreases IVDMD and IVOMD of both forages in comparison with two other oil sources. Increasing oil levels significantly (p<0.05) decreased IVDMD and IVOMD of both forages but alfalfa hay was more susceptible to increasing oil levels than corn silage. Keywords: Fish oil;canola oil;in vitro;digestibility;alfalfa;corn silage;Iran