Herd level approach to high bulk milk somatic cell count problems in dairy cattle

Figures & data

Figure 1. Association between bulk milk somatic cell count and prevalence of cows with somatic cell count (SCC) > 200,000 cells/ml (Barkema, H.W., unpublished data from 300 Dutch dairy farms).

Figure 2. Scatterplot of linear score (LS) versus linear score of the previous milk test (PLS) (adapted from DairyComp 305 output; ▴ = 1st parity, • = 2nd parity, ▄ = parity >2; PLS=0 indicates that they were not lactating at the previous milk test).

Table 1. Tables to determine whether an increase of bulk milk somatic cell count (cells/ml) should prompt intervention (Lam et al. 1998)^a.

	Action Value^b
Goal	1 month	3 months	6 months	12 months
A. Farm with 50 cows and an average production of 9000 milk kg/cow/year
150,000	195,000	175,000	170,000	160,000
200,000	275,000	245,000	230,000	220,000
250,000	355,000	310,000	290,000	280,000
300,000	435,000	380,000	355,000	340,000
B. Farms with 70 cows and an average production of 9000 milk kg/cow/year
150,000	180,000	165,000	160,000	160,000
200,000	260,000	235,000	220,000	220,000
250,000	340,000	300,000	285,000	275,000
300,000	420,000	370,000	350,000	335,000

^aAnalyses are based on BMSCC data of all Dutch dairy farms over a one-year period. Average BMSCC in that period was approximately 220,000 cells/ml.

^bCalculated for 95% chance on true-positive if > value. For example, if the goal is BMSCC <150,000 cells/ml and average BMSCC over a 6-month period is >160,000 cells/ml, in a 70 cow herd the odds that BMSCC is really too high is >95%.

Figure 3. New infections at the 1st milk test in heifers (red) and older animals (yellow) (adapted DairyComp 305 output; ▴ = 1st parity, • = 2nd parity, ▄ = parity >2; LS= linear score, PLS = previous LS; PLS=0 indicates that the heifers were not lactating at the previous milk test).

Figure 4. Example of a herd with an increasing prevalence of high SCC with increasing parity and increasing days in milk (adapted from DairyComp 305 output; ▴ = 1st parity, • = 2nd parity, ▄ = parity >2; high SCC = SCC > 200,000 cells/ml).

Lam TJGM, Grijsen EG, Schukken YH, Kaal-Lansbergen L, Hogeveen H. 1998. Mastitis management planner: a new approach to mastitis in dairy herds. Proceedings 20^th World Buiatrics Conference; Sydney, Australia, 251–254.

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