Combining total and differential somatic cell count to better assess the association of udder health status with milk yield, composition and coagulation properties in cattle

Figures & data

Table 1. Mean and standard deviation (SD) of test-day milk yield, composition, somatic cell count (SCC), differential somatic cell count (DSCC) and milk coagulation properties of four cattle breeds.

Trait	Holstein Friesian		Brown Swiss		Simmental		Rendena
	Mean	SD	Mean	SD	Mean	SD	Mean	SD
Milk yield, kg/d	33.3	9.6	27.2	8.0	25.2	8.3	19.8	6.6
Milk composition, %
Fat	3.83	0.74	4.06	0.72	3.85	0.72	3.53	0.58
Protein	3.35	0.36	3.63	0.38	3.46	0.37	3.30	0.36
Lactose	4.84	0.20	4.81	0.20	4.78	0.22	4.85	0.23
SCC, 10^3/mL	168	246	162	234	158	234	202	253
DSCC, %	61.8	16.7	60.8	16.5	61.1	16.6	66.6	15.6
Milk coagulation properties
RCT, min	21.5	7.0	19.8	7.1	21.2	7.4	19.1	7.2
a30, mm	17.5	11.3	21.4	12.0	18.8	11.7	20.5	12.1
k20, min	8.5	2.2	6.7	2.1	8.0	2.2	7.7	2.2
No. records	238,100		22,305		21,947		9175
No. cows	77,897		7111		6644		2863

RCT: rennet coagulation time; k₂₀: curd-firming rate to a curd firmness of 20 mm; a₃₀: curd firmness 30 min after rennet addition to milk.

Table 2. Classification of cow’s udder health status, combining the information of somatic cell count (SCC) and differential somatic cell count (DSCC), according to breed and parity.

	Overall	Holstein Friesian		Brown Swiss		Simmental		Rendena
Classification^a		P1	P2+	P1	P2+	P1	P2+	P1	P2+
Healthy, %	55.7	58.6	54.3	62.5	55.6	60.3	56.0	48.4	40.8
Susceptible, %	21.7	26.0	19.2	23.7	18.1	25.8	19.2	32.7	25.1
Mastitic, %	19.0	13.9	22.0	11.5	20.4	12.0	20.1	17.2	30.1
Chronic, %	3.6	1.5	4.5	2.3	5.9	1.9	4.7	1.7	4.0
N. records	291,527	87,718	150,382	6895	15,410	6197	15,750	2469	6706

P1: primiparous cows; P2+: pluriparous cows.

^aHealthy: cows with SCC ≤ 200,000 cells/mL and DSCC ≤ cut-off; Susceptible: cows with SCC ≤ 200,000 cells/mL and DSCC > cut-off; Mastitic: cows with SCC > 200,000 cells/mL and DSCC > cut-off; Chronic: cows with SCC > 200,000 cells/mL and DSCC ≤ cut-off. Cut-offs were retrieved from Zecconi et al. (2019).

Figure 1. Least squares means (with standard errors) of (a) milk yield, (b) protein percentage, (c) fat percentage and (d) lactose percentage according to udder health status classification. Different letters mark statistical significance (p <.01).

Figure 2. Least squares means (with standard errors) of (a) rennet coagulation time (RCT), (b) curd firmness 30 min after rennet addition to milk (a₃₀), and (c) curd-firming rate to a curd firmness of 20 mm (k₂₀) according to udder health status classification. Different letters mark statistical significance (p<.01).

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(1):460–465.

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