Canola meals from different plants over two production years differ in rumen-undegraded protein

Abstract Text:

Lactation trials showed improved production and N efficiency when dietary soybean meal was replaced with equal CP from canola meal. Three canola meal samples were collected from each of 12 Canadian production plants over 2 years (total = 72) and analyzed for chemical composition and ruminal protein degradability. The Michaelis-Menten inhibitor in vitro method was used to quantify protein degradation rates and rumen-undegraded protein (RUP), assuming passage rates of 0.16/h and 0.06/h for soluble and insoluble proteins. Differences among plants were assessed using the SAS Mixed model; LS-means for plants over both years, and for each year, are reported in the table. Although CP concentration and NDIN and RUP proportions were unaffected by year (P ≥ 0.21), NDF and soluble N were lower (P ≤ 0.01) in canola meal produced in 2011 than 2012. Proportions of NDIN ranged from 18 to 28% of total N but were unaffected by plant (P = 0.15). However, differences were detected among plants in CP and NDF concentrations (P ≤ 0.03) and proportions of soluble N and RUP in total N (P < 0.01). Plant x year interactions (P ≤ 0.04) also were found for concentrations of CP and NDF and proportions of NDIN and RUP, but not for soluble N (P = 0.19). Results indicated that differences in canola meal RUP concentration were consistent over 2 production years and, depending on plant of origin, ranged from 38 to 50% of CP, a difference of 30%.

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Table 1.  Mean composition of canola meals from 2 production years

Plant	CP, % of DM	NDF, % of DM	NDIN, % TN	Sol-N, % TN	RUP, % TN
1	42.8ab	25.7cd	17.7	37.1a	40.1ef
2	41.2e	27.1bcd	24.8	21.3de	42.9de
3	41.7de	26.7bcd	22.9	22.1de	45.4cd
4	43.2a	25.3d	21.2	25.5cd	43.1de
5	42.0cd	27.7abc	20.2	19.5e	49.7a
6	42.7abc	27.0bcd	22.8	28.0bc	47.8abc
7	40.2f	26.0bcd	18.4	30.2bc	40.4ef
8	42.2bcd	27.5abcd	23.2	27.8bc	41.1ef
9	41.3e	29.3a	27.7	32.5ab	46.3bc
10	43.3a	26.3bcd	19.9	32.7ab	38.2f
11	41.5de	25.8bcd	18.3	28.7bc	42.2e
12	37.8g	27.8ab	23.1	21.2de	49.3a
Prob-Plant	< 0.01	0.03	0.15	< 0.01	< 0.01
2011	41.7	25.8	20.9	25.6	43.5
2012	41.7	27.8	22.5	28.8	44.3
Prob-Year	0.84	< 0.01	0.27	0.01	0.21
Plant*Year	< 0.01	< 0.01	0.04	0.19	< 0.01

^a-f Means within columns with different superscripts differ (P < 0.05).

Canola meal

Inhibitor in vitro

Rumen-undegraded protein