Lactoferrin concentration in bovine milk: validation of radial immunodiffusion technique, sources of variation, and association to udder health status

Figures & data

Table 1. Repeatability relative standard deviation (RSD_r, %; n = 15), reproducibility relative standard deviation (RSD_R, %; n = 45) and z-scores (z) for lactoferrin concentration (mg/dL) in raw milk (RM), raw frozen milk (RFM) and raw milk with preservative added (RPM).

Milk	Day 1		Day 2		Day 3		RSDR	z
	Mean	RSDr	Mean	RSDr	Mean	RSDr
RM	13.22	4.23	12.92	7.08	12.94	1.04	6.06	–
RMF	12.26	6.46	11.78	8.85	12.15	7.75	7.73	1.14
RMP	12.29	5.39	11.61	8.35	12.41	7.35	7.54	1.08

Table 2. Descriptive statistics of milk lactoferrin concentration, production-related traits and milk quality traits in Holstein Friesian and Simmental cows.

	Holstein Friesian			Simmental
Trait	n	Mean	CV^a, %	n	Mean	CV^a, %
Lactoferrin, mg/dL	1516	13.06	55.01	230	13.64	51.74
Production related traits
Milk yield, kg/day	1514	34.76	26.87	230	26.40	30.69
Days in milk, days	1516	157.91	74.58	230	156.94	72.35
Parity, n	1516	2.43	61.73	230	2.80	63.13
Milk quality traits
Fat, %	1503	4.03	23.24	229	4.18	22.04
Protein, %	1512	3.41	11.50	230	3.67	11.10
Casein, %	1514	2.69	12.23	229	2.88	11.52
Lactose, %	1510	4.81	3.90	229	4.79	3.65
Urea, mg/dL	1505	21.16	25.84	230	21.90	28.79
Somatic cell count,  cell/µL	1512	179.98	229.41	230	175.21	225.95
Differential somatic  cell count, %	1178	59.29	28.07	161	59.01	26.14

^aCV: coefficient of variation.

Table 3. Pearson correlations of milk lactoferrin with milk yield and quality traits.

Trait	Lactoferrin, mg/dL
Milk yield, kg/day	−0.22***
Milk quality traits
Fat, %	0.12***
Protein, %	0.28***
Casein, %	0.27***
Lactose, %	−0.33***
Urea, mg/dL	−0.02
Somatic cell score, units	0.40***
Differential somatic cell count, %	0.13***

***p < .001.

Table 4. F-values and significance of fixed effects, and variance accounted by herd test-day nested within breed effect (σ²_HTD(Breed), %) for lactoferrin concentration, milk yield and quality traits.

Trait	Fixed effects^a					Random effect	Residual standard deviation
	DIM	P	Breed	DIM × P	UHS	σ^2HTD(breed)
Lactoferrin, mg/dL	41.03***	10.91***	0.27	1.18	51.30***	15.59	5.95
Milk yield, kg/day	101.47***	41.47***	19.71***	5.89***	14.02***	38.20	6.19
Milk quality traits
Fat, %	10.41***	1.16	1.24	1.36	4.51**	24.42	0.79
Protein, %	95.39***	6.25***	45.53***	1.14	5.35***	7.64	0.31
Casein, %	97.34***	7.83***	32.13***	1.09	4.37**	9.19	0.25
Lactose, %	23.44***	57.98***	0.25	1.74**	23.29***	13.77	0.16
Urea, mg/dL	11.76***	1.02	0.32	1.39	3.00*	56.77	3.82

^aDIM: class of stage of lactation; P: parity class; UHS: udder health status.

*p < .05,

**p < .01,

***p < .001.

Figure 1. Least squares means (with standard error) of milk lactoferrin concentration across classes of lactation stage (A) and parity classes (B). Means with different letters differ significantly (p <.05).

Figure 2. Distribution of the data and least squares means of milk lactoferrin concentration (mg/dL) according to udder health status classification proposed by Zecconi et al. (2019): healthy (SCC ≤ 200 cells/µL and DSCC ≤ 66.3%), susceptible (SCC ≤ 200 cells/µL and DSCC ≥ 66.3%), mastitic (SCC ≥ 200 cells/µL and DSCC ≥ 66.3%) and chronic (SCC ≥ 200 cells/µL and DSCC ≤ 66.3%). Means with different letters differ significantly (p <.05).

Zecconi A, Vairani D, Cipolla M, Rizzi N, Zanini L. 2019. Assessment of subclinical mastitis diagnostic accuracy by differential cell count in individual cow milk. Ital J Anim Sci. 18:460–465.

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Data availability statement

None of the data were deposited in an official repository. The data that support the findings presented in this study are available from the first author or corresponding author upon reasonable request.