1143
Ruminal degradability and intestinal digestibility of protein and amino acids in canola meal
Ruminal degradability and intestinal digestibility of protein in canola meal
N. K. Jayasinghe, K. F. Kalscheur, J. L. Anderson, D. P. Casper, Dairy Science Department, South Dakota State University, Brookings, 57006.
Differences in processing by different plants may result in canola meal (CM) with varying nutritional composition. The Dairy NRC (2001) estimated CM to be 35.7% rumen undegradable protein (RUP) with an intestinal digestibility of 75% when DMI was set at 4% of BW. Seven CM samples were obtained from different processing plants and 1 soybean meal (SBM) to evaluate the variability in ruminal degradability and intestinal digestibility of CP. Dacron bags containing 5 g of each feed were incubated in the rumen in duplicate for 0, 2, 4, 8, 12, 16, 24 and 48 h using three ruminally cannulated lactating cows. The rate of passage was calculated at 6.6%/h. The A fraction (rapidly degradable CP) varied from 26.6% to 17.8%, respectively, for CM10 and CM5 (P<0.05). The B fraction (slowly degradable CP) was highest for CM5 (79.9%) and lowest for CM12 (62.4%), whereas the C fraction (undegradable CP) was highest for CM12 (14.6%) and lowest for SBM (0.6%). The rate of degradation of B fraction, Kd (%/h) was highest for SBM (11.1%/h) and lowest for CM12 (4.0%/h). The RUP (% of CP) was highest for CM12 (53.8%), whereas lowest for SBM (31.0%), while the IDP (measured by pepsin-pancreatin digestion) ranged from 94.5% for SBM to 71.6% for CM10. The total digestible protein (TDP) was highest for SBM (98.2%) and CM ranged from 85.1% to 90.8% for CM12 and CM10 (P<0.01), respectively. The mean ruminal and intestinal digestibilities of CM are in agreement with NRC, however considerable variation exists between CM processing plants.
Item2 |
Feeds1 |
||||||||
SBM |
CM5 |
CM6 |
CM7 |
CM9 |
CM10 |
CM11 |
CM12 |
SEM |
|
A, % |
23.0c |
17.8b |
21.7bc |
26.4c |
24.8c |
26.6a |
25.1a |
23.1ab |
1.18 |
B, % |
76.5ab |
79.9a |
76.8ab |
66.3cd |
69.8bcd |
69.6bcd |
72.6abc |
62.4d |
1.84 |
C, % |
0.6b |
2.3b |
1.5b |
7.4b |
5.4b |
3.8b |
2.3b |
14.6a |
1.42 |
Kd, % h |
11.1a |
5.6bc |
5.2c |
9.1ab |
4.6c |
9.7ab |
6.2bc |
4.0c |
1.32 |
RUP, % of CP |
31.0d |
46.1b |
44.8b |
35.4cd |
46.6b |
32.3d |
40.8bc |
53.8a |
2.05 |
IDP, % |
94.5a |
76.8bc |
75.8bcd |
72.0de |
77.4b |
71.6e |
75.3bcde |
73.0cde |
2.50 |
TDP, % |
98.2a |
89.3bc |
89.1c |
90.1bc |
89.4bc |
90.8b |
89.3bc |
85.1d |
0.73 |
a-e Means in rows with different superscripts differ significantly ( P < 0.05)
Keywords: Canola meal, rumen degradability, intestinal digestibility