Somatic cell count as a decision tool for selective dry cow therapy in Italy

Figures & data

Table 1. Analysis of variance of somatic cell count (log₁₀ cell/mL) distribution based on parity and on type of milk test (last one before drying off or average of lactation tests).

Parity	N	Last milk test		Lactation average		Mean difference
		Mean	Std. dev.	Mean	Std. dev.	p
One	20,584	5.00^a	.51	5.04^a	.45	<.0001
Two	12,745	5.19^b	.50	5.18^b	.48	Not significant
Three or more	12,353	5.37^c	.51	5.35^c	.50	.0018
Total	45,682	5.16	.53	5.16	.49	Not significant

Different letters are statistically different (α < .05).

Table 2. Proportion of cows (%) below the four defined SCC threshold values measured at drying off (LMT) or as lactation average (AMT) by parity.

Parity	Threshold value, cells/mL
	50,000		100,000		150,000		200,000		250,000
	LMT^a	AMT^b	LMT	AMT	LMT	AMT	LMT	AMT	LMT	AMT
One	29.60	25.50	54.70	51.70	67.90	65.60	76.00	73.50	81.10	78.80
Two	14.20	16.80	37.00	40.90	53.00	55.10	63.80	63.40	70.60	69.30
Three or more	7.00	9.00	22.50	26.90	36.80	40.00	47.80	49.00	56.00	55.90
Total	19.20	18.60	41.00	42.00	55.30	55.70	65.00	64.00	71.40	70.00
P, χ^2 test	<.0001		<.0001		<.0001		.0023		Not significant

^a Last milk test record before drying-off.

^b Average of milk test records performed during the lactation before drying-off.

Table 3. Analysis of variance of somatic cell count distribution at first milk test after calving, classified by parity.

		SCC, log10 cell/mL
Parity	N	Mean	Std. dev.
One	20,552	4.86^a	.63
Two	12,725	4.97^b	.67
Three or more	12,330	5.10^c	.71
Total	45,607	4.96	.67

Different letters are statistically different (α < .05).

Table 4. Frequency of cows with subclinical mastitis (95% confidence limits) at first milk record after calving in relation to the five thresholds defined for the last milk record before drying-off classified by parity.

Parity	Threshold, cells/mL
	50,000	100,000	150,000	200,000	250,000
One	14.27^a. (13.42–15.80)	16.49^b (15.82–17.19)	17.66^b (17.03–18.28)	18.47^b (17.87–19.08)	19.04^b (18.45–19.65)
Two	19.02^a (17.27–20.89)	20.36^a (19.23–21.53)	21.6^a (20.64–22.6)	22.63^a (21.73–23.55)	23.52^a (22.66–24.41)
Three or more	22.26^a (19.61–25.15)	24.4^a (22.83–26.03)	26.34^a (25.08–27.64)	27.34^a (26.22–28.49)	28.61^a (27.56–29.69)
Total	16.05^a (15.29–16.83)	18.63^b (18.08–19.2)	20.27^b (19.78–20.77)	21.37^c (20.91–21.84)	22.31^d (21.86–22.76)

Frequencies with different letters are statistically different (α < .05).

Table 5. Frequency of cows with subclinical mastitis (95% confidence limits) at first milk record after calving in relation to the five thresholds defined for the average of lactation milk records classified by parity.

Parity	Threshold, cells/mL
	50,000	100,000	150,000	200,000	250,000
One	13.03^a(12.14-13.96)	15.20^b (14.53-15.90)	16.76^c (16.13-17.40)	17.61^c (17.01-18.22)	18.35^c (17.76-18.95)
Two	15.07^a (13.61-16.65)	17.57^b (16.56-18.63)	19.36^c (18.45-20.30)	20.66^d (19.79-21.56)	21.78^e (20.93-22.65)
Three or more	15.22^a (13.22-17.46)	20.06 ^b (18.73-21.46)	22.17^c (21.04-23.36)	23.92^d (22.86-25.01)	25.67^e (24.65-26.71)
Total	13.89^a (13.17-14.64)	16.69^b (16.17-17.22)	18.52^c (18.05-19.01)	19.76^d (19.30-20.22)	20.93^e (20.48-21.38)

Different letters are statistically different (α ≤ .05).