Application of a NIR device for precision feeding in dairy farms: effect on metabolic conditions and milk production

Figures & data

Table 1. Experimental design.

Period	Oct	Nov	Dec	Jan	Feb / Mar / Apr				May / Jun / Jul
herd
A		Inst	Train	Pre	PF-OFF				PF-ON
B	Inst	Train		Pre	PF-ON				PF-OFF
C		Inst	Train	Pre	PF-OFF				PF-ON
D	Inst	Train		Pre	PF-ON				PF-OFF
E	Inst	Train		Pre	PF-ON				PF-OFF
F		Inst	Train	Pre	PF-OFF				PF-ON
G		Inst	Train	Pre	PF-OFF				PF-ON

Inst: precision feeding system installation; Train: training; Pre: pre-experimental period; PF-ON: PFS enabled, with adjustment of silage loaded in the TMR wagon according to the difference between the reference DM and the DM read by NIR system installed on the TMR wagon; PF-OFF: PFS disabled.

Table 2. Composition (mean and SD, expressed as DM) and main nutrient characteristics of TMRs used during the trial.

	Diets composition					Diet characteristics
	Silages	Corn silage	Ground grain corn silage	Hay	Concentrate	Crude protein	NFC	Starch	NDF
Herd	% of total DM	% of silages DM	% of silage DM	% of total DM	% of total DM	% DM	% DM	% DM	% DM
A	22.49 ± 1.15	100	–	19.29 ± 0.50	59.21 ± 0.75	16.07	43.5	27.20	29.46
B	36.38 ± 3.72	82.45 ± 15.40	17.55 ± 3.94	21.70 ± 0.60	41.91 ± 3.56	15.92	44.1	25.32	28.99
C	44.91 ± 6.67	73.27 ± 12.83	5.55 ± 2.38	1.58 ± 1.00	53.51 ± 7.43	16.41	40.5	27.90	32.09
D	44.48 ± 2.60	88.99 ± 9.67	11.00 ± 2.06	11.96 ± 0.84	46.55 ± 2.34	15.92	44.1	25.32	28.99
E	41.83 ± 2.93	68.16 ± 2.39	–	16.23 ± 0.81	41.94 ± 2.12	15.78	41.5	23.95	31.70
F	42.71 ± 1.88	65.06 ± 8.84	34.94 ± 8.84	25.63 ± 2.27	31.66 ± 2.30	16.88	41.2	25.89	30.89
G	23.96 ± 3.90	90.34 ± 17.28	–	20.10 ± 4.77	55.93 ± 3.55	16.81	41.8	21.82	30.43

NFC: Non-Fiber Carbohydrates; NDF: Neutral Detergent Fiber.

Table 3. Mean differences of DM distributed daily and of its content (%) of crude protein (CP), NDF and starch as consequence of the variability in the DM content of silages^a.

						Without operator error^d
	PF-OFF^b	PF-ON^c	SEM^5	p-value		PF-OFF^b	PF-ON^c	SEM^e	p-value
Parameter				PFS^f	PFS*WK^g				PFS^f	PFS*WK^g
DM (kg/d)	0.070	0.100	0.046	NS	0.003	0.120	0.060	0.026	.136	.008
CP (% DM)	−0.050	−0.060	0.029	NS	0.015	−0.070	−0.040	0.025	.107	.029
NDF (% DM)	0.003	0.010	0.044	NS	0.027	0.004	−0.020	0.029	NS	.011
Starch (% DM)	−0.010	0.010	0.021	NS	NS	0.020	0.020	0.016	NS	NS

NDF: Neutral Detergent Fiber.

^a Calculated subtracting to the DM (kg/head d) of target diet (calculated keeping fixed the amount of single ingredient according to the recipe and applying the DM determined in laboratory) the DM of real diet (calculated using the amount of each feed effectively loaded in the TMR wagon and applying the DM of feeds measured by the PFS).

^b PF-OFF: the PFS measured the DM of each silage loaded in the TMR wagon but did not suggest variation on the amount of silages to be loaded according their DM.

^c PF-ON: the PFS measured the DM of each silage loaded in the TMR wagon and the system suggested the amount of silages to be loaded.

^d without operator error. Deviations observed between the DM (kg/head d) of target diet and DM of real diet and corrected for the error of operator in the loads of dry feeds.

^e highest SEM

^f p values of PFS effect (PF-OFF vs. PF-ON);

^g p values of interaction between PFS and period (week).

Table 4. Difference of DM (kg/head d – in brackets calculated as %) of real diet with or without operator error respect to target diet as consequence of the variability in the DM content of silages^a.

					without operator error^d
	PF-OFF^b		PF-ON^c		PF-OFF^b		PF-ON^c
Min	−2.04 (90.2)		−1.36 (94.2)		−2.49 (88.0)		−1.50 (93.6)
5th percentile	−0.65 (97.0)		−0.08 (99.7)		−0.88 (96.0)		−0.28 (98.8)
95th percentile	2.11 (109.8)		1.55 (105.8)		1.54 (107.0)		0.36 (101.5)
Max	3.83 (118.7)		3.50 (113.6)		3.41 (116.6)		2.19 (108.5)

^a Calculated subtracting to the DM (kg/head d) of target diet (calculated keeping fixed the amount of single ingredient according to the recipe and applying the DM determined in laboratory) the DM of real diet (calculated using the amount of each feed effectively loaded in the TMR wagon and applying the DM of feeds measured by the PFS).

^b PF-OFF: the PFS measured the DM of each silage loaded in the TMR wagon but did not suggest variation on the amount of silages to be loaded according their DM.

^c PF-ON: the PFS measured the DM of each silage loaded in the TMR wagon and the system suggested the amount of silages to be loaded.

^d Without operator error. Deviations observed between the DM (kg/head d) of target diet and DM of real diet but corrected for the error of operator in the loads of dry feeds.

Figure 1. Urea (a), total cholesterol (b), Ca (c), and Zn (d) in plasma of dairy cows fed TMR managed by using the precision feeding. The precision feeding system measured daily the DM of each silage loaded in the TMR wagon and did not suggest correction on the amount of silages to be loaded (PF-OFF) or suggested the correction of the amount of silages to be loaded according the result of their DM (PF-ON). Values are least squares means, and vertical bars represent SEM. (α, β: p < .10; a, b: p < .05; A, B: p < .001).

Table 5. Plasma variables (Least Squares Means) observed in dairy cows fed TMR managed by using (PF-ON) or not (PF-OFF) a precision feeding system.

				p value
Parameter^a	PF-OFF^b	PF-ON^b	SEM^c	PFS^d	LP^e	PFS x LP^f
PCV, L/L	0.300	0.304	0.0028	NS	< .001	NS
Glucose, mmol/L	4.020	4.060	0.0271	NS	NS	NS
Total cholesterol, mmol/L	5.460	5.670	0.1432	NS	< .001	NS
Urea, mmol/L	4.880	4.630	0.1065	.115	.008	.074
Ca, mmol/L	2.470	2.540	0.0144	.004	NS	.028
P, mmol/L	1.790	1.890	0.0319	.028	.001	NS
Mg, mmol/L	1.030	1.000	0.0109	NS	NS	NS
Na, mmol/L	143.000	143.500	0.2013	NS	NS	NS
K, mmol/L	4.130	4.110	0.0390	NS	.089	NS
Cl, mmol/L	101.800	101.200	0.2322	.096	.008	NS
Zn, µmol/L	12.720	12.110	0.2096	.054	NS	NS
Ceruloplasmin, µmol/L	3.700	3.800	0.0883	NS	NS	NS
Total protein, g/L	83.100	83.000	0.5827	NS	NS	NS
Albumin, g/L	35.980	35.870	0.2410	NS	NS	NS
Globulin, g/L	47.110	47.130	0.7190	NS	NS	NS
AST, U/L	104.000	101.000	2.7551	NS	.028	.053
GGT, U/L	30.800	32.230	1.0179	NS	< .001	NS
Total bilirubin, µmol/L	1.390	1.330	0.0608	NS	< .001	NS
AP, U/L	46.980	51.060	1.6490	.101	NS	NS
Haptoglobin, g/l	0.231	0.249	0.0324	NS	NS	NS

AST: Aspartate Aminotransferase; GGT: Gamma Glutamyl Transferase.

^a PCV: Packed Cell Volume; AST: aspartate aminotransferase; GGT: γ-glutamyltransferase; AP: alkaline phosphatase.

^b The precision feeding system (PFS) measured daily the DM of each silage loaded in the TMR wagon and did not suggest correction on the amount of silages to be loaded (PF-OFF) or suggested the correction of the amount of silages to be loaded according the result of their moisture (PF-ON);.

^c highest SEM

^d p values of PFS effect (PF-OFF vs. PF-ON)

^e p values of lactation phase effect (early vs. mid-lactation)

^f p values of interaction between PFS and lactation phase effects.

Table 6. DM, pH, and VFA observed in samples of faeces collected from dairy cows fed TMR managed by using (PF-ON) or not (PF-OFF) a precision feeding system.

				p-value
Parameter	PF-OFF^a	PF-ON^a	SEM^b	PFS^c	LP^d	PFS × LP^e
DM, %	13.93	14.26	0.148	.137	NS	NS
pH	6.07	6.09	0.020	NS	NS	NS
VFA, mmol/kg DM	619	603.40	0.023	NS	NS	NS
Acetic acid
mmol/kg DM	448.50	437.30	9.161	NS	NS	NS
mol%	68.20	69.30	0.829	NS	NS	NS
Propionic acid
mmol/kg DM	95.90	92.40	2.111	NS	NS	NS
mol%	15.50	15.30	0.131	NS	NS	NS
Butyric acid
mmol/kg DM	60.70	59.90	1.948	NS	.037	.090
mol%	9.70	9.90	0.201	NS	.035	.035

^a The precision feeding system (PFS) measured daily the DM of each silage loaded in the TMR wagon and did not suggest correction on the amount of silages to be loaded (PF-OFF) or suggested the correction of the amount of silages to be loaded according the result of their moisture (PF-ON).

^b Highest SEM

^c p values of PFS effect (PF-OFF vs. PF-ON)

^d p values of lactation phase effect (early vs. mid-lactation)

^e p values of interaction between PFS and lactation phase effects.

Table 7. Milk yield and milk characteristics (Least Squares Means) observed in dairy cows fed TMR managed by using (PF-ON) or not (PF-OFF) a precision feeding system.

				p-value
Parameter^a	PF-OFF^b	PF-ON^b	SEM^c	PFS^d	LP^e	PFS × LP^f
Milk yield, kg/d	40.50	41.00	.90681	NS	<.0001	NS
Fat, % w/v	3.44	3.50	.071735	NS	.0055	NS
Protein, w/v	3.21	3.19	.023349	NS	<.0001	NS
Lactose, w/v	5.09	5.10	.019196	NS	<.0001	NS
CN, w/v	2.41	2.40	.018273	NS	<.0001	NS
CN, g/100 g protein	77.40	77.60	.108986	NS	.0094	NS
SH, °SH/50 mL	3.14	3.16	.031163	NS	NS	NS
SCC, log(n/mL)	5.21	5.10	.060046	NS	NS	NS
RCT, min	19.00	21.10	.604105	.0144	<.0001	NS
k20, min	8.11	7.31	.536452	.0980	.0134	NS
a30, mm	19.90	16.40	1.157441	.0350	NS	NS

^a Parameter – CN: casein; SH: Milk titratable acidity; RCT: rennet clotting time; k₂₀: curd firming rate; a₃₀: curd firmness.

^b The precision feeding system (PFS) measured daily the DM of each silage loaded in the TMR wagon and did not suggest correction on the amount of silages to be loaded (PF-OFF) or suggested the correction of the amount of silages to be loaded according the result of their moisture (PF-ON).

^c Highest SEM

^d p values of PFS effect (PF-OFF vs. PF-ON)

^e p values of lactation phase effect (early vs. mid-lactation)

^f p values of interaction between PFS and lactation phase effect (early vs. mid-lactation).

Figure 2. Global (a) and specific (b) cleanliness score of anatomical areas in dairy cows fed TMR managed by using the precision feeding. The precision feeding system measured daily the DM of each silage loaded in the TMR wagon and did not suggest correction on the amount of silages to be loaded (PF-OFF) or suggested the correction of the amount of silages to be loaded according the result of their DM (PF-ON). Values are least squares means, and vertical bars represent SEM. (a, b: p < .05).

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