MOLECULAR STRUCTURAL AND NUTRITIONAL EVALUATION OF FABA BEAN PLANTS AS HAY AND SILAGE FOR RUMINANTS: EFFECT OF TANNIN CONCENTRATION, CUTTING STAGE, AND FROST-DAMAGE
Guevara Oquendo, Victor
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As new faba bean varieties are available in western Canada and the production is increasing, there is a possible use of this legume as a fodder. The overall objective of this research was to systematically evaluate whole plant faba bean as hay and silage for dairy cows. The effect of the tannin concentration (high vs. low) and the effect of cutting stages (flower, mid pod, and late pod) were determined. In the first study (Chapter 3), the high tannin SSNS-1 and the low tannin Snowdrop variety were harvested at 77, 88, and 97 days from planting (flower, mid pod, and late pod stages, respectively). The results showed that dry matter (DM) yield and the Feed Milk Value (FMV) of whole plant faba bean hay (artificially air dried) was lower (P< 0.05) at flower stage than at late pod stage (7.68 vs. 12.74 t/ha; 1.35 vs. 1.57 kg milk/kg DM hay, respectively). This study indicates that late pod stage may be the alternative to harvest the whole plant faba bean as the yield and production performance are superior. In the second study (Chapter 4) whole plant faba bean silage was evaluated. The results indicated that the whole plant faba bean silage had a similar protein concentration of 22 %DM in all the cutting stages. Additionally, the DVE and the FMVDVE were lower (P< 0.05) at mid pod stage than at late pod stage (59 vs. 68 g/kg DM and 1.20 vs. 1.37 kg milk/kg DM silage, respectively). This study suggests that at late pod stage the predicted production performance is higher. The third study (Chapter 5) determined the nutritive value of frost damaged whole plant faba bean hay. The results showed that the low tannin frost damaged hay had lower metabolizable protein (MP) (-4 g/kg DM) and lower FMVNRC (-0.09 kg milk/kg DM Hay) than the high tannin frost damaged hay. This study suggests that the nutritive value of frost damaged whole plant faba bean hay is lower than the normal whole plant faba bean hay. The objectives of the third study (Chapter 6) were to carry out dairy production performance and metabolic trials with whole plant faba bean silage from Chapter 4. The inclusion of whole plant faba bean silage in high producing milking cows increased significantly (P< 0.05) the fat corrected milk (3.5% FCM), fat yield and efficiency (FCM/DMI) (56.39 vs. 51.98; 2.11 vs. 1.89 kg/cow/d; and 2.15 vs. 1.91, respectively). This study indicates that the inclusion of whole plant faba bean silage at late pod stage significantly improve the performance of dairy cows. In the fourth study (Chapter 7) an intrinsic molecular structure analysis was performed on whole plant faba bean silage from Chapter 4. The results indicated that the total carbohydrates (TC) area was higher (P< 0.05) in low tannin silage at late pod stage than at mid pod stage (+3.45 AU) than the other silages. Amide II area was higher in the high tannin silage at late pod stage than the high tannin silage at mid pod stage (+2.50 AU). Principle component analysis (PCA) detected differences between whole plant faba bean silage, while carbohydrate and protein related structures can be used to predict nutrient utilization and availability with good estimation power (R2 > 0.74). In conclusion, whole plant faba bean should be harvested at late pod stage to obtain a higher yield, and superior predicted production performance as hay and silage. The inclusion of whole plant faba bean silage at late pod stage in high producing milking cows rations improved the performance. On the other hand, molecular structures of the whole plant faba bean silage were affected by the tannin concentration and by the cutting stage, also some of those structures are correlated to nutrient profiles and metabolic characteristics of the silage and can be used to predict them with good accuracy.
DegreeDoctor of Philosophy (Ph.D.)
DepartmentAgricultural and Resource Economics
CommitteeChristensen, David; McKinnon, John; Taran, Bunyamin; Buchanan, Fiona
Copyright DateJuly 2020