The use of visible/near-infrared spectroscopy to predict fibre fractions, fibre-bound nitrogen and total-tract apparent nutrients digestibility in beef cattle diets and faeces

Figures & data

Table 1. Ingredients and estimated nutrient content of the adaptation diet supplied to beef cattle.

Item^a	Mean	SD^b	Min	Max	CV^c
Diet ingredient, Kg as fed
Feedstuff^d	0.66	0.27	0.40	1.00	40.58
Wheat middlings	1.00	0.00	1.00	1.00	0.00
Distiller	0.75	0.21	0.50	1.00	27.76
Corn gluten meal	0.50	0.28	0.30	0.70	56.57
Alfalfa hay, 15% CP	0.20	0.00	0.20	0.20	0.00
Grass hay	0.80	0.28	0.60	1.00	35.36
Corn meal	1.33	0.51	0.90	1.90	38.49
Cane molasses	0.42	0.08	0.35	0.50	18.33
Wheat straw	1.40	0.27	1.00	1.60	19.34
Earlage^e	1.38	0.88	0.75	2.00	64.28
Dry Beetpulp	0.53	0.46	0.00	1.00	87.11
Corn silage, 36% DM	4.75	1.71	3.00	7.00	35.95
Soybean meal, 46%CP	0.30	0.00	0.30	0.30	0.00
Soybean hulls	0.35	0.00	0.35	0.35	0.00
Diet composition^f, % DM
DM, % as fed	62.41	4.12	56.89	66.74	6.60
CP	12.62	0.16	12.43	12.83	1.30
EE	3.31	0.12	3.19	3.47	3.60
CF	18.71	1.14	17.24	20.02	6.09
Ash	6.49	1.68	4.12	7.84	25.81
NDF	41.20	2.43	39.25	44.34	5.90
Starch	23.95	1.93	21.08	25.32	8.07

^aDM: dry matter; CP: crude protein; EE: ether extract; CF: crude fibre; NDF: neutral detergent fibre.

^bSD: standard deviation.

^cCV: coefficient of variation.

^dFeedstuffs provided are Bull ONE composed of wheat middlings, rapeseeds meal, corn gluten meal, calcium carbonate, sunflower meal, sodium chloride, dry extract of Aspergillus oryzae, Yucca schidigera, hydrolyzed lignocellulose, sodium bicarbonate, cane molasses, magnesium oxide, corn meal, palm oil fatty acids, yeasts; Bull 100 composed by wheat middlings, corn gluten meal, calcium carbonate, wheat meal, sunflower meal, sodium chloride, dry extract of Aspergillus oryzae, Yucca schidigera, hydrolyzed lignocellulose, sodium bicarbonate, cane molasses, magnesium oxide, corn meal, palm oil fatty acids; Bull 1500 composed by rapeseeds meal, soybean meal 46% CP, sunflower meal, corn gluten meal, wheat middlings, wheat meal, calcium carbonate, sodium chloride, cane molasses, dry extract of Aspergillus oryzae, Yucca schidigera, hydrolyzed lignocellulose, sodium bicarbonate, corn meal, magnesium oxide, yeasts.

^eEarlage, 64% DM, 58% starch, 14% NDF.

^fThe nutrient content was estimated using the ration formulation software NDS Professional version 3.9.9.05 (RUM&N Sas, Reggio Emilia, Italy).

Table 2. Average chemical composition of the diets provided to animals of each pen (n = 164).

Trait^a	Mean	SD^b	Min	Max	CV^c
DM, % of pre-essiccated^d	94.91	1.06	91.70	97.00	1.11
aNDF, % DM	40.19	5.46	22.86	61.74	13.58
N-aNDF, % DM	0.85	0.17	0.55	1.33	19.80
ADF, % DM	21.72	2.79	12.79	27.56	12.83
N-ADF, % DM	0.72	0.15	0.45	1.31	21.31
ADLom, % DM	4.06	1.19	1.83	13.54	29.45
N, % DM	2.05	0.17	1.64	2.62	8.33
Ash, % DM	7.19	1.66	2.70	14.10	23.11
uNDF, % DM	10.59	2.81	3.06	19.99	26.57
uNDF, % NDF	26.07	5.74	10.40	44.77	22.02

^aDM: dry matter of the pre-dried samples; aNDF: amylase treated neutral detergent fibre expressed as inclusive of residual ash; N-aNDF: nitrogen bound to neutral detergent fibre; ADF: acid detergent fibre expressed as inclusive of residual ash; N-ADF: nitrogen bound to acid detergent fibre; ADLom: acid detergent lignin expressed as exclusive or residual ash; N: nitrogen; uNDF: undigestible neutral detergent fibre evaluated after 240 h of fermentation.

^bSD: standard deviation.

^cCV: coefficient of variation.

^dSamples were pre-exsiccated at 50 °C for at least 24 h.

Table 3. Fitting statistics of modified partial least squares regression models in leave-one-out cross-validation for chemical parameters in total mixed ration for beef cattle.

Trait^a	Scatter correction^b	Mathematical treatment	LF^c	Outliers	N^d	R^2C^e	SEC^f	R^2CrV^g	SECrV^h	RPD^i
DM, % of pre-exsiccated^j	D	1,8,8,1	12	11	153	0.88	0.35	0.76	0.49	2.05
aNDF, % DM	SNV + D	1,8,8,1	8	14	150	0.87	1.54	0.80	1.77	2.27
N-aNDF, % DM	D	2,10,10,1	7	7	157	0.92	0.05	0.80	0.07	2.27
ADF, % DM	SNV + D	1,4,4,1	8	2	162	0.90	0.90	0.86	1.05	2.67
N-ADF, % DM	D	1,8,8,1	8	8	156	0.78	0.07	0.68	0.08	1.77
ADLom, % DM	None	1,4,4,1	12	13	151	0.79	0.29	0.53	0.42	1.46
N, % DM	SNV	0,0,1,1	8	12	152	0.85	0.06	0.83	0.06	2.43
Ash, % DM	MSC	1,8,8,1	11	9	155	0.89	0.48	0.82	0.61	2.36
uNDF, % DM	SNV	2,10,10,1	8	12	152	0.88	0.79	0.66	1.35	1.72
uNDF, %NDF	SNV	2,10,10,1	6	10	154	0.76	2.47	0.52	3.53	1.44

^aDM: dry matter of pre-dried samples; aNDF: amylase treated neutral detergent fibre expressed as inclusive of residual ash; N-aNDF: nitrogen bound to neutral detergent fibre; ADF: acid detergent fibre expressed as inclusive of residual ash; N-ADF: nitrogen bound to acid detergent fibre; ADLom: acid detergent lignin expressed as exclusive or residual ash; N: nitrogen; uNDF: undigestible neutral detergent fibre evaluated after 240 h of fermentation.

^bD: detrending; SNV: standard normal variate; SNV + D: standard normal variate and detrending; MSC: multiplicative scatter correction.

^cLF: latent factors.

^dnumber of samples of the calibration dataset, excluding the outliers, with which the calibration curve was developed.

^ecoefficient of determination of calibration.

^fstandard error of calibration.

^gcoefficient of determination of cross-validation.

^hstandard error of cross-validation.

ⁱresidual predictive deviation of cross-validation.

^jSamples were pre-exsiccated at 50 °C for at least 24 h.

Table 4. Average chemical composition of the pre-exsiccated faeces collected from the animals of each pen (n = 172).

Trait^a	Mean	SD^b	Min	Max	CV^c
DM, % of pre-exsiccated^d	93.72	2.24	79.37	99.79	2.39
aNDF, % DM	56.40	3.90	44.50	64.15	6.92
N-aNDF, % DM	0.72	0.11	0.40	1.03	15.05
ADF, % DM	35.06	4.83	22.38	55.76	13.78
N-ADF, % DM	0.71	0.18	0.47	1.88	24.96
ADLom, % DM	15.33	6.04	5.63	39.62	39.36
N, % DM	2.63	0.23	1.50	3.24	8.72
Ash, % DM	11.67	1.34	8.43	15.65	11.49
uNDF, % DM	33.68	4.91	20.98	52.58	14.58
uNDF, %NDF	59.75	8.00	42.31	91.44	13.39
N-NDS, % DM	1.90	0.23	0.80	2.60	12.32

^aDM: dry matter of pre-dried samples; aNDF: amylase treated neutral detergent fibre expressed as inclusive of residual ash; N-aNDF: nitrogen bound to neutral detergent fibre; ADF: acid detergent fibre expressed as inclusive of residual ash; N-ADF: nitrogen bound to acid detergent fibre; ADLom: acid detergent lignin expressed as exclusive or residual ash; N: nitrogen; uNDF: undigestible neutral detergent fibre evaluated after 240 h of fermentation; N-NDS: nitrogen solubilised in the neutral detergent.

^bSD: standard deviation.

^cCV: coefficient of variation.

^dSamples were pre-exsiccated at 50 °C for at least 48 h.

Table 5. Fitting statistics of modified partial least squares regression models in leave-one-out cross-validation for chemical composition in beef cattle pre-exsiccated faeces.

Trait^a	Scatter correction^b	Mathematical treatment	LF^c	Outliers	n^d	R^2C^e	SEC^f	R^2CrV^g	SECrV^h	RPD^i
DM, % of pre-exsiccated^j	None	2,10,10,1	11	10	159	0.94	0.35	0.80	0.64	2.22
aNDF, % DM	MSC	1,4,4,1	8	4	165	0.83	1.60	0.75	1.92	2.00
N-aNDF, % DM	D	0,0,1,1	5	4	165	0.40	0.08	0.32	0.09	1.22
ADF, % DM	None	1,8,8,1	10	11	158	0.88	1.11	0.82	1.34	2.39
N-ADF, % DM	MSC	1,8,8,1	7	8	163	0.54	0.06	0.40	0.07	1.29
ADLom, % DM	SNV + D	2,10,10,1	1	10	159	0.09	4.54	0.04	4.67	1.02
N, % DM	D	2,10,10,1	12	4	165	0.94	0.05	0.75	0.10	1.99
Ash, % DM	MSC	1,8,8,1	11	2	167	0.83	0.55	0.75	0.66	1.99
uNDF, % DM	None	2,5,5,1	6	2	167	0.69	2.56	0.45	3.40	1.35
uNDF, %NDF	None	2,5,5,1	5	5	164	0.60	4.50	0.33	5.78	1.23
N-NDS, % DM	D	1,8,8,1	11	6	163	0.67	0.12	0.51	0.14	1.43

^aDM: dry matter of pre-dried samples; aNDF: amylase treated neutral detergent fibre expressed as inclusive of residual ash; N-aNDF: nitrogen bound to neutral detergent fibre; ADF: acid detergent fibre expressed as inclusive of residual ash; N-ADF: nitrogen bound to acid detergent fibre; ADLom: acid detergent lignin expressed as exclusive or residual ash; N: nitrogen; uNDF: undigestible neutral detergent fibre evaluated after 240 h of fermentation; N-NDS: nitrogen soluble in neutral detergent.

^bD: detrending; SNV: standard normal variate; SNV + D: standard normal variate and detrending; MSC: multiplicative scatter correction.

^cLF: latent factors.

^dn: number of samples of the calibration dataset, excluding the outliers, with which the calibration curve was developed.

^eR²_C: coefficient of determination of calibration.

^fSE_C: standard error of calibration.

^gR²_CrV: coefficient of determination of cross-validation.

^hSE_CrV: standard error of cross-validation.

ⁱRPD: residual predictive deviation of cross-validation.

^jSamples were pre-exsiccated at 50 °C for at least 24 h.

Table 6. Average total-tract apparent (tta) nutrients digestibility estimated (De, %) using dietary and faecal uNDF as an internal marker (n of matches= 164).

Trait^a	Mean	SD^b	Min	Max	CV^c
ttaDMDe	68.96	7.96	40.83	87.47	11.54
ttaNDFDe	56.80	9.17	28.98	80.67	16.14
ttaADFDe	51.23	10.31	21.51	77.73	20.13
ttaCPDe	60.27	11.08	21.42	84.53	18.38
ttaN-NDFDe	52.01	16.26	11.63	85.99	31.26
ttaN-ADFDe	47.03	16.69	12.86	87.12	35.50
ttaAshDe	49.84	14.80	14.09	96.41	29.69
tttrueNDe	57.31	10.52	21.75	78.61	18.36

^attaDMDe: total-tract apparent dry matter digestibility estimated; ttaNDFDe: total-tract apparent neutral detergent fibre digestibility estimated; ttaADFDe: total-tract apparent acid detergent fibre digestibility estimated; ttaCPDe: total-tract apparent crude protein digestibility estimated; ttaN-NDFDe: total-tract apparent nitrogen bound to neutral detergent fibre digestibility estimated; ttaN-ADFDe: total-tract apparent nitrogen bound to acid detergent fibre digestibility estimated; ttaAshDe: total-tract apparent ash digestibility estimated; tttrueNDe: total-tract true nitrogen digestibility estimated.

^bSD: standard deviation.

^cCV: coefficient of variation.

Table 7. Fitting statistics of modified partial least squares regression models in leave-one-out cross-validation for total-tract apparent (tta) nutrients digestibility estimated (De, %) using undigestible NDF as a marker in total mixed ration for beef cattle.

Trait^a	Scatter correction^b	Mathematical treatment	LF^c	Outliers	n^d	R^2C^e	SEC^f	R^2CrV^g	SECrV^h	RPD^i
ttaDMDe	SNV + D	1,4,4,1	12	13	151	0.79	3.11	0.56	4.53	1.51
ttaNDFDe	None	1,8,8,1	5	12	151	0.51	5.73	0.40	6.33	1.30
ttaADFDe	D	1,4,4,1	11	11	150	0.66	5.50	0.33	7.65	1.22
ttaCPDe	SNV	1,8,8,1	12	15	149	0.82	4.20	0.62	5.99	1.64
ttaN-NDFDe	SNV + D	2,10,10,1	5	10	151	0.79	7.50	0.66	9.65	1.71
ttaN-ADFDe	None	0,0,1,1	11	10	144	0.73	8.70	0.64	9.93	1.68
ttaAshDe	SNV	1,4,4,1	6	11	148	0.61	8.29	0.51	9.35	1.43
tttrueNDe	SNV	2,5,5,1	7	1	163	0.82	4.48	0.40	8.15	1.29

^attaDMDe: total-tract apparent dry matter digestibility estimated; ttaNDFDe: total-tract apparent neutral detergent fibre digestibility estimated; ttaADFDe: total-tract apparent acid detergent fibre digestibility estimated; ttaCPDe: total-tract apparent crude protein digestibility estimated; ttaN-NDFDe: total-tract apparent nitrogen bound to neutral detergent fibre digestibility estimated; ttaN-ADFDe: total-tract apparent nitrogen bound to acid detergent fibre digestibility estimated; ttaAshDe: total-tract apparent ash digestibility estimated; tttrueNDe: total-tract true nitrogen digestibility estimated.

^bD: detrending; SNV: standard normal variate; SNV + D: standard normal variate and detrending; MSC: multiplicative scatter correction.

^cLF: latent factors.

^dn: number of samples of the calibration dataset, excluding the outliers, with which the calibration curve was developed.

^eR²_C: coefficient of determination of calibration.

^fSE_C: standard error of calibration.

⁷R²_CrV: coefficient of determination of cross-validation.

^gSE_CrV: standard error of cross-validation.

^hRPD: residual predictive deviation of cross-validation.

Table 8. Fitting statistics of modified partial least squares regression models in leave-one-out cross-validation for total-tract apparent (tta) nutrients digestibility estimated (De, %) in cattle faeces.

Trait^a	Scatter correction^b	Mathematical treatment	LF^c	Outliers	N^d	R^2C^e	SEC^f	R^2CrV^g	SECrV^h	RPD^i
ttaDMDe	SNV	1,8,8,1	4	7	154	0.48	5.62	0.38	6.11	1.27
ttaNDFDe,	None	1,4,4,1	4	9	149	0.41	6.47	0.30	6.99	1.20
ttaADFDe	None	2,5,5,1	2	11	148	0.35	7.84	0.25	8.38	1.16
ttaCPDe	MSC	1,8,8,1	4	7	154	0.46	8.46	0.36	9.21	1.25
ttaN-NDFDe	SNV + D	2,10,10,1	5	6	154	0.61	10.73	0.38	13.49	1.28
ttaN-ADFDe	SNV + D	0,0,1,1	9	2	149	0.41	13.28	0.25	14.95	1.16
ttaAshDe	D	1,4,4,1	2	4	152	0.19	13.09	0.13	13.51	1.07
tttrueNDe	MSC	2,5,5,1	4	4	157	0.53	7.06	0.31	8.55	1.21

^attaDMDe: total-tract apparent dry matter digestibility estimated; ttaNDFDe: total-tract apparent neutral detergent fibre digestibility estimated; ttaADFDe: total-tract apparent acid detergent fibre digestibility estimated; ttaCPDe: total-tract apparent crude protein digestibility estimated; ttaN-NDFDe: total-tract apparent nitrogen bound to neutral detergent fibre digestibility estimated; ttaN-ADFDe: total-tract apparent nitrogen bound to acid detergent fibre digestibility estimated; ttaAshDe: total-tract apparent ash digestibility estimated; tttrueNDe: total-tract true nitrogen digestibility estimated.

^bD: detrending; SNV: standard normal variate; SNV + D: standard normal variate and detrending; MSC: multiplicative scatter correction.

^cLF: latent factors.

^dn: number of samples of the calibration dataset, excluding the outliers, with which the calibration curve was developed.

^eR²_C: coefficient of determination of calibration.

^fSE_C: standard error of calibration.

^gR²_CrV: coefficient of determination of cross-validation.

^hSE_CrV: standard error of cross-validation.

ⁱRPD: residual predictive deviation of cross-validation.

Figure 1. Average raw spectra of pre-exsiccated faeces and total mixed rations from NIRS DS2500 spectrometer.

Data availability statement

The data that support the findings of this study are available from the corresponding author upon reasonable request.