RESUMEN
This experiment quantified the effect of decorticated and toasted oat (Avena sativa L.) on fatty acid (FA) supply, ruminal biohydrogenation (BH) of FA, and intestinal digestibility of FA in 4 ruminal and intestinal cannulated Danish Holstein cows. Experimental diets containing untreated oat, decorticated oat, toasted oat, and decorticated and toasted oat were fed ad libitum to the cows in a 2 × 2 factorial arrangement in a Latin square design throughout 4 periods. Unless otherwise mentioned, the results of this study indicate the main effect of decortication and toasting. Decortication increased the intake of FA by 40.3 g/d and increased feed-ileum digested FA, whereas toasting decreased the intake of FA by 69.3 g/d. Toasting increased both feed-ileum and total-tract digestibility of FA by 59.8 and 67.4 g/kg of FA intake, respectively. The proportion of C18:2n-6 in FA intake increased, and the C18:3n-3 proportion in FA intake decreased due to decortication. Toasting resulted in a dramatic reduction of the C18:2n-6 proportion in FA intake, and it increased the proportions of C18:0 and C18:3n-3 in FA intake. Toasting reduced ruminal BH of C18:1n-9 and C18:2n-6 by 134 and 11.7 g/kg of FA intake, respectively, and toasting increased the proportion of unsaturated FA to saturated FA in the duodenal FA flow. Decortication decreased the ruminal BH of C18:3n-3 by 38.0 g/kg of FA intake. Decortication increased small intestinal digestibility of C12:0, C15:0, C20:0, and C22:0. Toasting increased the small intestinal digestibility of C15:0, C18:0, trans-C18:1, C20:0, and C24:0. Toasting reduced the small intestinal digestibility of C18:1n-9, C18:2n-6, and C20:1n-9. This study showed that decortication successfully increased the intake of FA and flow of FA at the duodenum and feed-ileum digested FA. However, toasting oat at 121°C caused a remarkable decline in FA concentration in oat, and thereby FA intake; therefore, toasting cannot be recommended.