Abstract
The main objective of this research was to study the effect of variety and tannin level on the degradation kinetics and intestinal digestion of primary and bypassed nutrients of faba beans grown in western Canada. 24 samples of faba bean seeds (8 varieties, grown in 3 locations in western Canada per variety) with 2 tannin levels (low vs. normal) were used for study on dry matter (DM), protein (CP), carbohydrates (CHO), and fiber content (NDF) fermentation. Rumen degradation kinetics were determined using the standard in situ animal trial procedure with four cannulated cows according to the ‘gradual addition/all out’ schedule for 0, 2, 4, 8, 12 and 24 hours. Intestinal digestion was determined using the three-step in vitro technique with 12 hours pre-rumen incubation sample. MIXED model procedure of SAS 9.4 was used for statistical analyses of RCBD data with significance declared at P<0.05. Low tannin seeds proved higher content (P<0.05) of rumen bypass starch (BSt) than normal tannin seeds (93 g/kg vs. 84 g/kg); rumen bypass neutral detergent fiber (RUNDF) was significantly higher (P<0.01) on normal tannin seeds compared to low tannin seeds (109 vs. 99 g/kg DM). Intestinal digestibility of rumen bypass protein (dIDP) was significantly higher (P<0.01) in low tannin seeds (83% vs. 75%). Total digested starch (TDST) was higher (P<0.05) in normal tannin seeds (98% vs. 96%) while total digested neutral detergent fiber (TDNDF) was higher (P<0.05) in low tannin seeds (58% vs. 53%). There was no significant difference (P>0.05) in rumen undegraded crude protein (RUP); however, a tendency was observed (P<0.10) with a higher content on normal tannin seeds (67 vs. 62 g/kg DM). Results indicate that both low and high tannin faba bean varieties have desirable metabolic characteristics as for them to be used in cattle diets in terms of protein and energy supply.