Effects of neutral detergent fiber digestibility estimation method on calculated energy concentration of canola meals from 12 Canadian processing plants

Jose A Arce-Cordero; Eduardo M Paula; Joao L P Daniel; Lorrayny G Silva; Glen A Broderick; Antonio P Faciola

doi:10.1093/jas/skab309

. 2021 Oct 25;99(11):skab309. doi: 10.1093/jas/skab309

Effects of neutral detergent fiber digestibility estimation method on calculated energy concentration of canola meals from 12 Canadian processing plants

Jose A Arce-Cordero ^1,², Eduardo M Paula ^3,^✉, Joao L P Daniel ⁴, Lorrayny G Silva ¹, Glen A Broderick ^5,^✉, Antonio P Faciola ^1,^✉

PMCID: PMC8763229 PMID: 34694410

Abstract

Our aim was to determine whether the method used to estimate truly digestible neutral detergent fiber (tdNDF) affects calculated concentrations of total digestible nutrients (TDN_1x) and net energy of lactation (NE_L3x) of canola meal (CM). Samples were collected from 12 CM processing plants in Canada over 4 yr (2011 to 2014, n = 47) and analyzed for dry matter (DM), crude protein (CP), ether extract (EE), ash, neutral detergent fiber (NDF), acid detergent fiber (ADF), lignin (ADL), and neutral detergent insoluble CP (NDICP). Ruminal in situ incubation of CM samples was performed at 0, 24, 48, 96, and 288 h to determine NDF fractions (A, B, and C), effective ruminal NDF digestibility (ERNDFD), and indigestible NDF (iNDF) of CM. Three tdNDF-estimation methods were evaluated: 1) National Research Council (NRC) = 0.75 × (NDF − NDICP − ADL) × {1− [ADL/ (NDF − NDICP)]^0.667}; 2) iNDF = 0.75 × (NDF − NDICP − NDF remaining after 288 h in situ); and 3) ERNDFD estimated from in situ NDF digestion kinetics. Resulting tdNDF values were used for calculation of TDN_1x and NE_L3x according to NRC (2001) equations. Data were analyzed with MIXED procedure of SAS 9.4 to determine the effect of processing plant on chemical composition, NDF degradation kinetics and NE_L3x of CM. Effect of tdNDF estimation method on calculated TDN_1x and NE_L3x of CM was also evaluated. Model for analysis of processing plant included the fixed effect of plant and the random effect of year (plant) as replication, while analysis of tdNDF methods included the fixed effect of tdNDF estimation method and the random effects of processing plant and of year(plant) as replication. There was an effect of processing plant on DM (P = 0.03), CP (P < 0.01), EE (P < 0.01), and NDF (P < 0.01) of CM. Processing plant also had an effect on NDF fractions A (P < 0.01) and B (P = 0.02) but did not affect fraction C and ERNDFD. The tdNDF estimation method had an effect on tdNDF (P < 0.01), TDN_1x (P < 0.01), and NE_L3x (P < 0.01) of CM, yielding average NE_L3x values of 1.72, 1.87, and 2.07 Mcal/kg for NRC, iNDF, and ERNDFD, respectively. Our results indicate that calculated energy concentration of CM according to NRC (2001) equations varies depending on the method used for estimation of tdNDF. Further research will be needed to determine the most accurate estimation method.

Keywords: acid detergent lignin, indigestible NDF, in situ, net energy of lactation

Introduction

Neutral detergent fiber (NDF) concentration in canola meal (CM) is approximately 3-fold greater than that in soybean meal (SBM), 28.0 vs. 8.8% of dry matter (DM), respectively (Paula et al., 2018, 2020). A greater proportion of hull in the seed, plus the fact that some of that hull stays in the meal after oil extraction and meal processing, results in a greater NDF concentration in CM compared to other plant-origin protein meals (Newkirk, 2011). According to Weiss and Tebbe (2019), NDF is a chemically and nutritionally heterogeneous fraction, which makes it challenging to accurately estimate its digestibility. Greater NDF concentration may make inaccurate the estimation of the truly digestible NDF (tdNDF) fraction and the subsequent prediction of energy concentration in CM compared to other protein sources such as SBM.

Different models use equations to predict tdNDF as a fraction of the potentially digestible NDF (pdNDF), the latter being estimated based on the concentration of lignin and N associated with NDF. The NRC (2001) suggests a factorial approach (Weiss et al., 1992) to calculate pdNDF based on NDF, neutral detergent insoluble crude protein (NDICP), and acid detergent lignin (ADL).

Studies conducted mainly with forages have reported that using lignin to estimate iNDF and tdNDF is not effective for all feedstuffs (Huhtanen et al., 2006; Krizsan and Huhtanen, 2013; Raffrenato, 2017, 2018). Although this issue is not exclusive to CM, its greater NDF concentration in comparison to other protein sources may impose a greater challenge to estimate its energy concentration. Using CM chemical composition data from our group (unpublished data) to estimate tdNDF with NRC (2001) equation, we estimated that approximately 77% of total NDF in CM is unavailable for digestion. However, in vitro work indicates that iNDF in CM accounts for only 32% of NDF (Cotanch et al., 2014). In addition, low estimates of tdNDF in CM are not consistent with the increases in milk production observed in dairy cows fed CM in substitution of SBM (Huhtanen et al., 2011; Martineau et al., 2013; Broderick et al., 2015; Paula et al., 2020). Greater milk production is explained in part by improved N utilization when cows are fed CM; however, underestimation of CM’s tdNDF may also explain some of that response, as suggested by an increase on DM intake resulting from CM supplementation found in some studies (Huhtanen et al., 2011; Martineau et al., 2013; Broderick et al., 2015). Determining if accuracy of tdNDF estimation in CM needs to be improved will be crucial for a more efficient utilization of CM in diets for dairy cows.

To our knowledge, only one study has evaluated in situ digestibility of NDF in three samples of CM (Mustafa et al., 1996). Hence, the importance of our work consists of generating such data and also demonstrating whether or not the method used for estimation of ruminal digestibility of NDF can significantly impact the estimated energy concentration of CM, so it can be considered for future research work aiming to improve accuracy in diet formulation for dairy cows fed CM as a source of protein.

We hypothesized that calculated energy concentration of CM samples would depend on tdNDF estimation method used to calculate total digestible nutrients (TDN_1x). Our objective was to determine whether the method used for tdNDF estimation affects calculated TDN_1x and net energy for lactation (NE_L3x).

Materials and Methods

Procedures for animal care and handling required for this experiment were approved by the Institutional Animal Care and Use Committee at the University of Nevada, Reno. Canola meal samples were obtained from 12 major Canadian CM processing plants, samples were collected from canola harvested over 4 yr (2011, 2012, 2013, and 2014); 3 samples from each processing plant were collected each year, totaling 144 samples. Currently, there are 14 processing plants distributed in five provinces in Canada; therefore, our samples are a good representation of Canadian CM. Each processing plant represents a series of factors, such as canola genetics, type of soil, harvesting, and processing conditions, which define CM chemical composition and quality.

To accommodate the in situ incubations, samples within year and processing plant were combined, totaling 48 samples. The CM from processing plants 1 to 11 was processed via solvent-extract, whereas CM obtained from processing plant 12 was processed via expeller extraction without solvent. Samples from processing plant 12 in year 2014 were missing; therefore, a total of 47 samples were available for analyses in the present trial. Further details about the samples and processing plants can be found in Broderick et al. (2016) who evaluated in vitro ruminal degradability of protein in CM across processing plants in Canada.

Laboratory analyses and in situ incubations

Canola meal samples were analyzed for DM (method 934.01), ash (method 938.08) and ether extract (EE; method 920.85) according to AOAC (1990), and total nitrogen using a combustion assay (Leco FP-2000 N Analyzer, Leco Instruments Inc., St. Joseph, MI), according to Association of Official Analytical Chemists (AOAC) (2005; method 990.13). For NDF analysis, samples were treated with thermo-stable α-amylase and sodium sulfite according to Mertens (2002) and adapted for the Ankom²⁰⁰ Fiber Analyzer (Ankom Technology, Macedon, NY). For acid detergent fiber (ADF) and acid detergent-insoluble CP (ADICP), samples were sequentially analyzed according to Van Soest and McQueen (1973) and adapted for the Ankom²⁰⁰ Fiber Analyzer. Nitrogen analysis in the ADF residue was performed using a modification of the aluminum block digestion procedure of Gallaher et al. (1975). Nitrogen in digesta was determined by semi-automated colorimetric assay (Hambleton, 1977). Neutral detergent-insoluble CP (NDICP) was isolated by gravimetric determination using thermo-stable α-amylase and sodium sulfite followed by CP analysis (method 990.13; AOAC, 2005) and used to calculate NDF corrected for CP (NDFc). Acid detergent lignin was analyzed according to Van Soest (1973) adapted for Ankom Daisy^II Incubator. Non-fiber carbohydrate concentration was calculated according to NRC (2001): NFC = 100 − (%NDF + %CP + %ether extract + %ash) + NDICP.

Three cannulated steers (average BW = 550 kg) were used for in situ evaluations and were fed (DM basis) at the maintenance level, a diet consisting of 80% alfalfa hay, 17.5% cracked corn, and 2.5% mineral premix; with an adaptation period of 14 d before the incubations started. Approximately 1.25 g of sample was weighted into Dracon bags (R510, 50 µm porosity, 5 cm × 10 cm, ANKOM Technology), allowing 20 mg/cm² of bag surface. Bags were incubated in triplicate in each animal at the following incubation times: 0, 24, 48, 96, and 288 h.

Bags in the 0 h timepoint were only mechanically washed. For the other timepoints, bags were incubated sequentially and retrieved from the rumen at the same time. Afterwards, bags were soaked in ice water for 15 min, then, washed in a commercial washing machine using three cycles of 7 min each, and dried in a forced-air oven at 60 °C for 48 h. Dried samples were analyzed for NDF concentration as previously described and corrected for NDICP.

Fractions and rate of digestion of NDF were estimated for effective ruminal NDF digestibility (ERNDFD). Fraction A was defined as NDF escaping the pores during washing of the 0 h time point bags. Fraction C was defined as the remaining NDF residue after 288 h of incubation in the rumen and washing. Fraction B was calculated as: fraction B = 100 – (fraction A + fraction C). Fractional disappearance rate of fraction B (kd) was calculated using the linear slope over time of the natural logarithm of the residue at each time point as a percentage of that in the incubated material. Effective ruminal NDF digestibility was calculated according to the first-order approach, assuming a fractional passage rate (kp) of 0.07/h (Zanton and Heinrichs, 2009). The ERNDFD method also assumes that all particles escaping the bag are digestible. Additionally, iNDF was estimated as the NDF residue after 288 h in situ incubation of samples.

Estimation of tdNDF and energy concentration of CM samples

Three different methods for estimation of tdNDF in CM were compared and used for calculation of total digestible nutrients (TDN_1x) and net energy for lactation (NEL_3x) using NRC (2001) equations. Two of those methods are based on the Weiss et al. (1992) equation assuming that tdNDF accounts for 75% of pdNDF (tdNDF = 0.75 × pdNDF) and differ only in the way pdNDF is estimated: based on NRC equation, or 288 h in situ iNDF. The third method consisted of directly estimating tdNDF (ERNDFD) based on the kinetics of in situ NDF digestion and passage. Equations for each method of tdNDF estimation were:

NRC = 0.75 × pdNDF; where pdNDF is estimated as (NDF – NDICP – ADL) × {1– [ADL/(NDF – NDICP)]^0.667} according to NRC (2001),

iNDF = 0.75 × pdNDF; where pdNDF is estimated as (NDF - NDICP – iNDF₂₈₈) and iNDF₂₈₈ corresponds to NDF remaining after 288-h in situ incubations,

ERNDFD = fraction A + fraction B × [kd/ (kd + kp)], based on NDF digestion kinetics estimated from in situ evaluation.

The TDN_1x of CM samples was calculated as the summation of the individual truly digestible nutrient fractions (CP, NFC, fatty acids, NDF) according to Weiss (1992). Each fraction was estimated as shown below:

Truly digestible CP = CP × {1 – [0.4 – (ADICP/CP)},

Truly digestible NFC = 0.98 × [100 – (NDF – NDICP – CP – EE – Ash)],

Truly digestible fatty acids = EE – 1,

Truly digestible NDF: estimated by three different methods (NRC, iNDF, or ERNDFD).

The TDN_1x of each sample was calculated based on the three tdNDF estimation methods evaluated. Finally, NE_L3x was calculated according to NRC (2001) equations assuming a diet with 74% of TDN_1x.

Statistical analysis

Canola meal processing plant was defined as the experimental unit of our study. Data were analyzed using the MIXED procedure of SAS (version 9.4). First, we evaluated the chemical composition, in situ kinetics of NDF degradation and NE_L3x concentration of CM to determine how those response variables were influenced by processing plant. Then, we evaluated the effect of tdNDF estimation method on calculated concentrations of TDN_1x and NE_L3x in CM.

Effect of processing plant

A total of 47 observations corresponding to 12 plants and 4 yr were used for this analysis (observation for last year of plant 12 was missing). The statistical model included the fixed effect of plant and the random effect of year (plant) as replication. Repeated measures analysis was performed using year as the repeated statement. Based on lowest AIC, compound symmetry matrix was used for variables of chemical composition and energy concentration (TDN_1x and NE_L3x), and first order auto regressive matrix was selected for variables of NDF in situ degradation kinetics. Effect of processing plant was evaluated with Tukey’s multiple comparisons test and significant differences were declared at P ≤ 0.05 while trends were considered when 0.05 < P ≤ 0.10.

Effect of tdNDF estimation method

It was analyzed using data from 12 plants, 4 yr, and 3 tdNDF estimation methods, discounting for the missing sample (plant 12, year 4), n = 188 observations. The model included the fixed effect of tdNDF estimation method and the random effects of processing plant and of year(plant) as replication. Data were analyzed as repeated measures with year as the repeated statement. Compound symmetry matrix structure was chosen based on lowest AIC for both response variables analyzed (TDN_1x and NE_L3x). Multiple comparisons between tdNDF estimation methods were evaluated with Tukey’s test where P ≤ 0.05 was defined as threshold of significance and trends were considered when 0.05 < P ≤ 0.10.

Results and Discussion

Chemical composition of the CM used in the present study is shown in Table 1. Concentrations of DM, CP, EE, NDF, ADF, and NFC were similar to those reported in previous CM studies (Broderick et al., 2015, 2016). There was an effect of processing plant on concentrations of DM (P = 0.03), CP (P < 0.01), EE (P < 0.01), NDF (P < 0.01), and NDFc (P = 0.03). Most of these differences were observed between plant 12, where CM was mechanically processed, and some of the other 11 plants where oil extraction process was performed using solvents. As expected, EE concentration in CM of plant 12 was greater than EE in CM of plants 1–11. Given its greater EE concentration, CM of plant 12 also had greater DM than CM of plants 1, 3, 4, 5, and 10; and lower CP than CM of plants 4, 6, and 10. Lower CP concentration in mechanically extracted protein meals in comparison to solvent-extracted meals has been previously reported for CM (CCC, 2019), representing a dilution effect of the CP which results from a greater EE concentration in mechanically extracted meal.

Table 1.

Comparison of chemical composition of canola meal from 12 crushing plants

Plant	%¹
	DM	CP	EE	NDF	NDFc	ADF	Lignin	NFC
1	92.2^cd	41.2^bc	3.03^b	31.2^cd	23.4^cd	21.1	8.90	24.4
2	92.3^bc	40.4^bc	3.32^b	32.8^bc	23.8^bc	21.5	9.10	24.4
3	91.8^cd	40.8^bc	3.31^b	30.7^cd	23.7^bc	21.1	8.78	24.6
4	92.1^cd	42.2^ab	3.27^b	31.8^bc	23.7^bc	20.8	9.16	23.8
5	91.9^cd	41.1^bc	3.33^b	30.3^cd	22.9^cd	19.8	8.14	25.2
6	92.5^bc	41.9^ab	2.24^b	31.1^cd	23.8^bc	20.2	8.53	24.3
7	92.6^bc	39.8^bc	3.37^b	32.8^bc	25.6^bc	21.8	10.1	23.9
8	93.1^bc	40.6^bc	3.04^b	32.9^bc	24.0^bc	22.6	9.96	25.1
9	92.5^bc	41.1^bc	2.68^b	36.2^ab	28.2^ab	21.9	9.20	20.5
10	92.2^cd	41.9^ab	2.08^b	30.4^cd	23.4^cd	20.8	9.08	25.4
11	92.7^bc	40.6^bc	3.61^b	33.8^bc	24.9^bc	22.0	9.99	24.5
12	95.2^ab	37.7^cd	9.09^a	33.6^bc	24.6^bc	20.7	9.15	20.4
Mean	92.6	40.8	3.53	32.3	24.3	21.2	9.17	23.9
SEM	0.59	0.70	0.40	0.95	0.96	0.95	0.92	1.11
P-value²	0.03	<0.01	<0.01	<0.01	0.03	0.72	0.94	0.06

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¹DM, dry matter; CP, crude protein; NDF, neutral detergent fiber; NDFc, NDF corrected by neutral detergent fiber insoluble crude protein; ADF, acid detergent fiber; NFC, non-fiber carbohydrates; EE, ether extract. All values are expressed as percentage of DM, except for DM which is expressed on as fed basis. Means with different superscripts within the same column are statistically different according to Tukey’s test (P ≤ 0.05).

²Statistical significance of the effect of processing plant.

Concentrations of NDF and NDFc averaged 32.3% and 24.4% of DM, respectively; which are consistent with NDF values previously reported for CM (Mustafa et al., 1996; Swanepoel et al., 2014; Sánchez-Duarte et al., 2019). The difference between NDF and NDFc values found in this study (approximately 8% units of DM) supports the recommendation of correcting NDF for residual CP in CM samples. The effect of processing plant on NDF indicated that NDF concentration in CM of plant 9 was greater than NDF in CM of plants 1, 3, 5, 6, and 10. However, after correcting for NDICP, we observed that NDFc of plant 9 was only greater than NDFc of plants 1, 5, and 10. Such differences in NDFc concentration may be a consequence of canola genetic variation, differences in processing, or a combination of both. The 12 processing plants evaluated in this study were distributed across five different provinces of Canada, representing a wide range of environmental conditions and probably multiple canola cultivars, which could be determinant factors influencing chemical composition of both canola seed and CM (Pritchard et al., 2000; McCartney et al., 2004; CCC, 2019). Furthermore, ADF and lignin in CM were similar across plants, which indicates that CM from all the processing plants evaluated in this study had comparable concentrations of cell wall components that are negatively correlated with digestibility.

Information on in situ degradation kinetics of NDF is summarized in Table 2 were all the values have been corrected by NDICP and therefore expressed as percentage units of NDFc. Processing plant had an effect on NDF fractions A (P < 0.01) and B (P = 0.02) of CM. Fraction A ranged from 12.2 to 38.7% of NDF, averaging 25.3% across the 12 processing plants. Plant 12 had a greater NDF fraction A than plants 5 and 6. Moreover, fraction B averaged 54.8% of NDF across processing plants, and was greater in plant 5 compared to plants 1, 7, and 12.

Table 2.

In situ NDF degradation kinetics and effective ruminal NDF digestibility of canola meal from 12 crushing plants

Plant	NDF fraction¹			kd, %/h²	ERNDFD³
	A	B	C
1	28.2^cde	46.6^cd	25.2	1.15	71.5
2	23.4^cde	55.9^bc	20.7	1.38	76.3
3	24.9^cde	54.40^bc	20.6	1.21	76.1
4	21.9^cde	61.0^bc	17.1	1.13	79.1
5	12.2^efg	70.2^ab	17.6	1.24	78.4
6	19.4^def	61.1^bc	19.5	1.12	76.8
7	33.4^bcd	45.8^cd	20.7	1.08	76.4
8	29.1^cde	51.0^bc	19.9	1.19	77.2
9	25.7^cde	54.1^bc	20.3	1.44	77.1
10	21.8^cde	58.6^bc	19.6	1.07	76.9
11	24.3^cde	52.9^bc	22.8	1.27	74.0
12	38.7^abc	46.1^cd	15.2	1.33	82.4
Mean	25.3	54.8	19.9	1.22	76.9
SEM	3.48	4.53	3.29	0.16	2.98
P-value⁴	< 0.01	0.02	0.80	0.86	0.66

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¹A = Soluble fraction, B = Slowly degraded fraction, C = undegraded fraction. All values are expressed as percentage of NDF corrected by neutral detergent insoluble crude protein. Means with different superscripts within the same column are statistically different according to Tukey’s test (P ≤ 0.05).

²Rate of ruminal NDF degradation.

³Effective ruminal NDF digestibility, assuming a fractional passage rate of 7%/h.

⁴Statistical significance of the effect of processing plant.

Despite the effect of processing plant found for NDF fractions A and B, no effect of processing plant was observed on fraction C and ERNDFD in the CM of this sample set. Average values found in the present study for fraction C and ERNDFD were 19.9% and 76.6%, respectively. To our knowledge, there are few studies reporting NDF digestibility of CM in the literature. Mustafa et al. (1996) evaluated three types of CM, regular (26.7% NDF), low fiber (24.6% NDF), and high fiber CM (34.7% NDF), and they observed 45.5, 49.3, and 41.1% ERNDFD, respectively, which are lower compared with the values found in the present study (76.9% ERNDFD, on average); however, their samples were incubated in the rumen for 24 h, which may partially explain why they got lower ERNDFD estimates. More recently, Cotanch et al. (2014) evaluated in vitro NDF digestibility of eight non-forage fiber/byproducts feeds, they reported an average NDF digestibility of 58% for CM that was reached at 96 h and maintained up to 120 and 240 h of in vitro fermentation.

At least part of variation of NDF digestibility observed across studies may be attributed to genetic progress made over time through breeding programs in Canada for improvement of canola nutritive value. However, the lack of differences among processing plants for concentrations of ADF and lignin (Table 1) and ERNDFD (Table 2) in our study, despite finding some differences in NDF fractions A and B across plants, reflects the challenges of describing or predicting dynamics of ruminal NDF digestion from chemical composition. In this regard, other studies have shown that the relationship between lignin and digestibility is dynamic and variations in agronomic conditions such as amounts of water, heat and light have greater effects on cross-linking between lignin and hemicellulose than on lignin concentration itself (Huhtanen et al., 2006; Krizsan and Huhtanen, 2013; Raffrenato, 2017, 2018).

The effect of processing plant on calculated net energy for lactation (NE_L3x) is presented in Table 3 for the three methods of tdNDF analysis. There was no effect of processing plant on calculated NE_L3x when NRC, iNDF, or ERNDFD methods were used for estimation of tdNDF. Our data suggest that, although some differences in chemical composition and NDF fractions were found among plants, such differences did not have a significant impact on estimated energy concentration of CM samples regardless of method used for tdNDF estimation.

Table 3.

Effect of processing plant on calculated net energy for lactation (NE_L3x) of canola meal using different approaches for estimation of truly digestible NDF (tdNDF)

Plant	Calculated NE_L3x by method of tdNDF estimation¹
	NRC	iNDF	ERNDFD
1	1.71	1.83	2.02
2	1.71	1.86	2.06
3	1.71	1.85	2.06
4	1.71	1.87	2.08
5	1.72	1.86	2.05
6	1.72	1.85	2.06
7	1.72	1.90	2.10
8	1.70	1.89	2.07
9	1.77	1.93	2.16
10	1.71	1.85	2.06
11	1.70	1.85	2.07
12	1.72	1.91	2.12
Mean	1.72	1.87	2.07
SEM	0.02	0.02	0.03
P-value²	0.60	0.29	0.12

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¹Canola meal tdNDF was estimated according to: NRC equation (NRC), indigestible NDF after 288 h in situ incubation (iNDF), and in situ effective ruminal NDF digestibility (ERNDFD).

²Statistical significance of the effect of processing plant.

The effect of tdNDF estimation method was also analyzed and is presented in Figure 1. Our data indicate that estimated tdNDF of CM samples differs between the three methods evaluated (P < 0.01), showing a large difference between NRC estimate, which indicates that 22.8% of NDF is digested in the rumen, and the two other methods evaluated which estimate that 46 and 76.8% of NDF is digested based on iNDF and ERNDFD, respectively. As shown in Table 1, NDF represents a considerable proportion of total DM in CM samples (32.3% when expressed as total NDF, and 24.3% when corrected by NDICP); therefore, differences observed between tdNDF estimation methods would be expected to yield differences in estimated TDN_1x and NE_L3x contents.

As anticipated, a trend similar to the one observed for tdNDF was found for TDN_1x and NE_L3x when the three tdNDF estimation methods were compared. Calculated values of TDN_1x (Figure 2) averaged 70.0, 72.6, and 80.1% for NRC, iNDF, and ERNDFD methods, respectively, and all three values differed from each other (P < 0.01). Similarly, average NE_L3x values of 1.72, 1.87, and 2.07 Mcal/kg were calculated respectively for NRC, iNDF, and ERNDFD (Figure 3), which resulted in differences between all the methods (P < 0.01) for this parameter as well.

Figure 2. — Effect of truly digestible neutral detergent fiber (tdNDF) estimation method on calculated total digestible nutrients (TDN_1X) of canola meal. The tdNDF was estimated according to: NRC equation, indigestible NDF after 288 h in situ incubation (iNDF), and in situ effective ruminal NDF digestibility (ERNDFD). Least squares means with different superscripts within the same panel are statistically different according to Tukey’s test (P < 0.01).

Figure 3. — Effect of truly digestible neutral detergent fiber (tdNDF) estimation method on calculated net energy for lactation (NE_L3X) of canola meal. The tdNDF was estimated according to: NRC equation, indigestible NDF after 288 h in situ incubation (iNDF), and in situ effective ruminal NDF digestibility (ERNDFD). Least squares means with different superscripts within the same panel are statistically different according to Tukey’s test (P < 0.01).

The differences found among tdNDF estimation methods for calculated NE_L3x in our study could be biologically relevant as well. These differences could potentially impact productivity of dairy cows fed CM as the main protein source of their diet. Considering a hypothetical scenario where cows were fed a complete diet with an average daily intake of 2.3 kg of CM (based on Martineau et al. [2013] meta-analysis), a difference of 0.35 Mcal/kg of CM between the lowest (NRC) and highest (ERNDFD) calculated NE_L3x values, would be equivalent to 0.80 Mcal of NE_L3x. Based on NRC (2001) estimated requirements for lactation, such amount of NE_L3x would allow for the synthesis of approximately 1.1 kg/d of milk with 3.5% fat.

Feeding trials evaluating the substitution of SBM with CM, have reported greater efficiency of nitrogen utilization in cows fed CM, which could partially explain the increase in milk production reported in such studies (Martineau et al., 2013). However, other factors such as underestimated energy concentration of CM may also play a role in the observed animal response and should not be discarded. Our results indicate that calculated energy concentration of CM according to NRC (2001) equations varies depending on the method used for estimation of tdNDF. Such differences highlight the importance of further research to improve accuracy of estimates of tdNDF and NE_L3x values of CM when fed as a source of protein to lactating dairy cows. Moreover, our work consisted of a comparison of estimates, which limits its ability to determine the best approach for estimation of NE_L3x. Therefore, future research evaluations will be needed in order to determine the most accurate tdNDF method for estimation of NE_L3x in CM samples.

Acknowledgments

The authors thank the Canola Council of Canada (Winnipeg, MB, Canada) for partial funding support for this research, Diane Ivey (University of Nevada, Reno) and Hélio Costa (Universidade Estadual Vale do Acarau) for helping with laboratory analyses and for assisting with sample collection.

Glossary

Abbreviations

ADICP: acid detergent insoluble crude protein
ADF: acid detergent fiber
ADL: acid detergent lignin
AOAC: Association of Official Analytical Chemists
CM: canola meal
CP: crude protein
DM: dry matter
ERNDFD: effective ruminal NDF digestibility
iNDF: indigestible NDF
NDF: neutral detergent fiber
NDFc: neutral detergent fiber corrected by CP
NDICP: neutral detergent insoluble CP
NE_L3x: net energy for lactation at 3 times maintenance
NFC: non-fiber carbohydrates
NRC: National Research Council
pdNDF: potentially digestible NDF
SBM: soybean meal
TDN_1x: total digestible nutrients at one time maintenance
tdNDF: truly digestible NDF

Conflict of interest statement

The authors declare no conflicts of interest.

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[CIT0002] AOAC (Association of Official Analytical Chemists) . 2005. Official Methods of Analysis. 18th ed. Gaithersburg (MD): AOAC International. [Google Scholar]

[CIT0003] Broderick, G. A., Colombini S., Costa S., Karsli M. A., and Faciola A. P.. . 2016. Chemical and ruminal in vitro evaluation of Canadian canola meals produced over 4 years. J. Dairy Sci. 99:7956–7970. doi: 10.3168/jds.2016-11000 [DOI] [PubMed] [Google Scholar]

[CIT0004] Broderick, G. A., Faciola A. P., and Armentano L. E.. . 2015. Replacing dietary soybean meal with canola meal improves production and efficiency of lactating dairy cows. J. Dairy Sci. 98:5672–5687. doi: 10.3168/jds.2015-9563 [DOI] [PubMed] [Google Scholar]

[CIT0005] Canola Council of Canada (CCC) . 2019. Canola Meal Dairy Feed Guide. 6th ed. Winnipeg, MB, Canada: Canola Council of Canada. [Google Scholar]

[CIT0007] Cotanch, K. W., Grant, R. J., Van Amburgh, M. E., Zontini, A., Fustini, M., Palmonari, A., and Formigoni, A. 2014. Applications of uNDF in ration modeling and formulation. Proceedings Cornell Nutrition Conference. pp. 114–131. [Google Scholar]

[CIT0008] Gallaher, R. N., Weldon C. O., and Futral J. G.. . 1975. An aluminum block digester for plant and soil analysis. Soil Sci Soc Am J. 39: 803–806. doi: 10.2136/sssaj1975.03615995003900040052x [DOI] [Google Scholar]

[CIT0009] Hambleton, L. G. 1977. Semiautomated method for simultaneous determination of phosphorus, calcium and crude protein in animal feeds. J.A.O.A.C. 60:845–852. doi: 10.1093/jaoac/60.4845 [DOI] [PubMed] [Google Scholar]

[CIT0010] Huhtanen, P., Hetta M., and Swensson C.. . 2011. Evaluation of canola meal as a protein supplement for dairy cows: a review and a meta-analysis. Can. J. Anim. Sci. 91: 529–543. doi: 10.4141/cjas2011-029 [DOI] [Google Scholar]

[CIT0011] Huhtanen, P., Nousiainen J., and Rinne M.. . 2006. Recent developments in forage evaluation with special reference to practical applications. Agric. Food Sci. 15:293–323. doi: 10.2137/145960606779216317 [DOI] [Google Scholar]

[CIT0012] Krizsan, S. J., and Huhtanen P.. . 2013. Effect of diet composition and incubation time on feed indigestible neutral detergent fiber concentration in dairy cows. J. Dairy Sci. 96:1715–1726. doi: 10.3168/jds.2012-5752 [DOI] [PubMed] [Google Scholar]

[CIT0013] Martineau, R., Ouellet D. R., and Lapierre H.. . 2013. Feeding canola meal to dairy cows: a meta-analysis on lactational responses. J. Dairy Sci. 96:1701–1714. doi: 10.3168/jds.2012-5740 [DOI] [PubMed] [Google Scholar]

[CIT0014] McCartney, C. A., Scarth R., McVetty P. B. E., and Daun J. K.. . 2004. Genotypic and environmental effects on saturated fatty acid concentration of canola grown in Manitoba. Can. J. Plant Sci. 84:749–756. [Google Scholar]

[CIT0015] Mertens, D. R. 2002. Gravimetric determination of amylase-treated neutral detergent fiber in feeds with refluxing in beakers or crucibles: collaborative study. J. AOAC Int. 85:1217–1240. [PubMed] [Google Scholar]

[CIT0016] Mustafa, A. F., Christensen D. A., and McKinnon J. J.. . 1996. Chemical characterization and nutrient availability of high and low fiber canola meal. Can. J. Anim. Sci. 76:579–586. doi: 10.4141/cjas96-086 [DOI] [Google Scholar]

[CIT0017] Newkirk, R. 2011. Meal nutrient composition. In: J. K. Daun, N. A. M. Neskin, D. Hickling, editors. Canola: chemistry, production, processing and utilization. AOCS Press, Urbana, IL; p. 229–244. [Google Scholar]

[CIT0018] National Research Council (NRC) . 2001. Nutrient Requirements of Dairy Cattle: 7th Revised Edition, 2001. Washington (DC): The National Academies Press. [Google Scholar]

[CIT0019] Paula, E. M., Broderick G. A., Danes M. A. C., Lobos N. E., Zanton G. I., and Faciola A. P.. . 2018. Effects of replacing soybean meal with canola meal or treated canola meal on ruminal digestion, omasal nutrient flow, and performance in lactating dairy cows. J. Dairy Sci. 101:328–339. doi: 10.3168/jds.2017-13392 [DOI] [PubMed] [Google Scholar]

[CIT0020] Paula, E. M., Broderick G. A., and Faciola A. P.. . 2020. Effects of replacing soybean meal with canola meal for lactating dairy cows fed 3 different ratios of alfalfa to corn silage. J. Dairy Sci. 103:1463–1471. doi: 10.3168/jds.2019-16947 [DOI] [PubMed] [Google Scholar]

[CIT0021] Pritchard, F. M., Eagles H. A., Norton R. M., Salisbury P. A., and Nicolas M.. . 2000. Environmental effects on seed composition of Victorian canola. Aust. J. Exp. Agric. 40:679–685. [Google Scholar]

[CIT0022] Raffrenato, E., Fievisohn R., Cotanch K. W., Grant R. J., Chase L. E., and Van Amburgh M. E.. . 2017. Effect of lignin linkages with other plant cell wall components on in vitro and in vivo neutral detergent fiber digestibility and rate of digestion of grass forages. J. Dairy Sci. 100:8119–8131. doi: 10.3168/jds.2016-12364 [DOI] [PubMed] [Google Scholar]

[CIT0023] Raffrenato, E., Ross D. A., and Van Amburgh M. E.. . 2018. Development of an in vitro method to determine rumen undigested aNDFom for use in feed evaluation. J. Dairy Sci. 101:9888–9900. doi: 10.3168/jds.2018-15101 [DOI] [PubMed] [Google Scholar]

[CIT0024] Sánchez-Duarte, J. I., Kalscheur K. F., Casper D. P., and García A. D.. . 2019. Performance of dairy cows fed diets formulated at 2 starch concentrations with either canola meal or soybean meal as the protein supplement. J. Dairy Sci. 102:7970–7979. doi: 10.3168/jds.2018-15760 [DOI] [PubMed] [Google Scholar]

[CIT0025] Swanepoel, N., Robinson P. H., and Erasmus L. J.. . 2014. Determining the optimal ratio of canola meal and high protein dried distillers grain protein in diets of high producing Holstein dairy cows. Anim. Feed Sci. Technol. 189:41–53. doi: 10.1016/j.anifeedsci.2013.12.007 [DOI] [Google Scholar]

[CIT0027] Van Soest, P. 1973. Collaborative study of acid detergent fibre and lignin. J. Assoc. Off. Anal. Chem. 56: 781–784. [Google Scholar]

[CIT0028] Van Soest, P. J., and McQueen R. W.. . 1973. The chemistry and estimation of fibre. Proc. Nutr. Soc. 32:123–130. doi: 10.1079/pns19730029 [DOI] [PubMed] [Google Scholar]

[CIT0029] Weiss, W. P., Conrad H. R., and St. Pierre N. R.. . 1992. A theoretically-based model for predicting total digestible nutrient values of forages and concentrates. Anim. Feed Sci. Technol. 39:95–110. doi: 10.1016/0377-8401(92)90034-4 [DOI] [Google Scholar]

[CIT0030] Weiss, W. P., and Tebbe A. W.. . 2019. Estimating digestible energy values of feeds and diets and integrating those values into net energy systems. Transl. Anim. Sci. 3:953–961. doi: 10.1093/tas/txy119 [DOI] [PMC free article] [PubMed] [Google Scholar]

[CIT0031] Zanton, G. I., and Heinrichs A. J.. . 2009. Evaluation of modeling procedure for fitting in situ feed degradation profiles. J. Anim. Sci. 87:2080–2088. doi: 10.2527/jas.2008-1180 [DOI] [PubMed] [Google Scholar]

PERMALINK

Effects of neutral detergent fiber digestibility estimation method on calculated energy concentration of canola meals from 12 Canadian processing plants

Jose A Arce-Cordero

Eduardo M Paula

Joao L P Daniel

Lorrayny G Silva

Glen A Broderick

Antonio P Faciola

Abstract

Introduction

Materials and Methods

Laboratory analyses and in situ incubations