Substitution of soybean meal by canola meal in dairy rations on fluid-associated and particle-associated bacteria at the duodenum
Citation
Nadeau, F., Charbonneau, E., Hasnaoui, M., Lapierre, H, and D. R. Ouellet. Substitution of soybean meal by canola meal in dairy rations on fluid-associated and particle-associated bacteria at the duodenum. J. Dairy Sci. 106, Suppl. 1.
Résumé en langage clair
Canola meal (CM) has a positive effect on milk production even if NRC (2001) predicts a decrease in supply of metabolizable protein (MP) when CM replaces soybean meal (SBM) in dairy rations (Martineau 2013 JDS 96:1701). The aim of this project was to estimate the effect of substitution of SBM by CM in dairy rations on duodenal proportion and flux of fluid-associated (FAB) and particle-associated bacteria (PAB). Four cows fitted with ruminal and duodenal cannulas were used in a cross-over design (28-d/period). Cows were fed a total mixed ration (65.9% grass silage and 34.1% concentrate, DM basis). The SBM ration was formulated to supply 100% NEL and MP requirements for a cow producing 25 kg/d of milk (NRC, 2001), contained 10.8% of SBM; substitution was made on a CP basis and the CM diet contained 14.7% of CM. After 14 d of adaptation, 18 duodenal samples were collected, covering 3 d. Duodenal digesta flows were determined using 3 markers. The FAB and PAB proportions were assessed by purine analysis and gravimetry (differential centrifugations). Statistical analyses were made using mixed model in SAS. Dry matter intake (18.6 ± 0.27 kg/d), milk production (15.9 ± 0.74 kg/d) and milk composition were not affected (P > 0.33). Results for digesta are detailed in the table. Proportion of FAB was greater for CM then SBM and the opposite was observed for PAB. Duodenal flux of FAB and PAB were similar. Pre-duodenal apparent DM digestibility was numerically greater for CM then for SBM. In conclusion, although proportion of FAB was greater for CM compared with SBM ration, their fluxes were similar, reinforcing the assumption that positive effect of CM could be attributed to the soluble fraction flowing at the duodenum.
Variable SBM CM SEM
Phases, %^^
Fluid 32.3 35.4 1.47
Small Particles 22.5 26.7 1.78
Large Particles 45.2 38.0 3.24
Bacterial source, % (flux, kg/d)^^
FAB 19.9b (2.57) 24.7a (2.64) 0.52 (0.19)
PAB 80.2a (10.58) 75.3b (8.18) 0.52 (0.62)
Apparent DM digestibility,%`` 29.6 40.7 3.77
a,b: values within the same row with a different superscript differ at P = 0.03; ^^Duodenal site; ``Pre-duodenal
Résumé
Canola meal (CM) has a positive effect on milk production even if NRC (2001) predicts a decrease in supply of metabolizable protein (MP) when CM replaces soybean meal (SBM) in dairy rations (Martineau 2013 JDS 96:1701). The aim of this project was to estimate the effect of substitution of SBM by CM in dairy rations on duodenal proportion and flux of fluid-associated (FAB) and particle-associated bacteria (PAB). Four cows fitted with ruminal and duodenal cannulas were used in a cross-over design (28-d/period). Cows were fed a total mixed ration (65.9% grass silage and 34.1% concentrate, DM basis). The SBM ration was formulated to supply 100% NEL and MP requirements for a cow producing 25 kg/d of milk (NRC, 2001), contained 10.8% of SBM; substitution was made on a CP basis and the CM diet contained 14.7% of CM. After 14 d of adaptation, 18 duodenal samples were collected, covering 3 d. Duodenal digesta flows were determined using 3 markers. The FAB and PAB proportions were assessed by purine analysis and gravimetry (differential centrifugations). Statistical analyses were made using mixed model in SAS. Dry matter intake (18.6 ± 0.27 kg/d), milk production (15.9 ± 0.74 kg/d) and milk composition were not affected (P > 0.33). Results for digesta are detailed in the table. Proportion of FAB was greater for CM then SBM and the opposite was observed for PAB. Duodenal flux of FAB and PAB were similar. Pre-duodenal apparent DM digestibility was numerically greater for CM then for SBM. In conclusion, although proportion of FAB was greater for CM compared with SBM ration, their fluxes were similar, reinforcing the assumption that positive effect of CM could be attributed to the soluble fraction flowing at the duodenum.
Variable SBM CM SEM
Phases, %1
Fluid 32.3 35.4 1.47
Small Particles 22.5 26.7 1.78
Large Particles 45.2 38.0 3.24
Bacterial source, % (flux, kg/d)#
FAB 19.9b (2.57) 24.7a (2.64) 0.52 (0.19)
PAB 80.2a (10.58) 75.3b (8.18) 0.52 (0.62)
Apparent DM digestibility,%^^ 29.6 40.7 3.77
a,b: values within the same row with a different superscript differ at P = 0.03; #Duodenal site; ^^Pre-duodenal