Effect of Freezing on Somatic Cell Count of Quarter Milk Samples as Determined by a Fossomatic Electronic Cell Counter

Abstract

The objective of this study was to determine the effect of freezing and the duration of freezing on somatic cell count (SCC) in milk samples from quarters with no signs of clinical mastitis. Effect was determined by a fluoro-opto-electronic cell counter. Samples were frozen in a commercial freezer at approximately -20 degrees C. The milk samples were thawed at 1, 2, 3, 4, 7, 14, or 28 d. Another batch of samples was frozen 1 d, thawed, frozen again for 1 d, and then thawed. The SCC was determined on the fresh samples and after any one of the freezing periods. On average, the SCC were lower after all freezing periods than they were before freezing. However, the difference in SCC before and after freezing was small and relatively constant on the natural logarithm scale. The decrease in SCC was larger with longer freezing periods. When SCC thresholds of 200,000, 250,000, and 500,000 cells/ml were used to predict infection, freezing appeared to have little impact on the sensitivity and specificity of diagnostic parameters. Therefore, SCC, as determined by a fluoro-opto-electronic cell counter, determined for frozen quarter milk samples can be used in mastitis control and research programs.

Lactoferrin Concentrations in Milk from Normal and Subclinical Mastitic Cows.

“…Somatic cell count (SCC) score: SCC in milk was determined with a Fossomatic cell counter [2] at the Hokkaido Official Approval Milking Cow Association, Sapporo, Japan. The SCC was converted into the SCC score by the number of somatic cells as shown in Tables 1 and 2.…”

Quarter milk somatic cell count in infected dairy cows: a meta-analysis

“…Samples had SCC slightly lower (minus 25 000 c/mL) when stored for 10 days at 4 o C than when stored at room temperature [16]. Freezing at -20 o C was associated with a slight decrease in SCC [3], and with a reduction in the number of positive samples to E. coli and Corynebacterium pyogenes and an increase in the number of positive samples to Staphylococci [41].…”

“…Geometric mean SCC (᭜) and its 95% CI (-) of bacteriologically negative quarters (SCC in × 1 000 c/mL whatever of the measurement equipment used). 3 Results observed in three different herds called V, D and W in the study. 4 LSCC: herds with a low SCC (≤ 150 000 c/mL); HSCC: herds with a high SCC (≥ 700 000 c/mL).…”

“…The prevalence of IMI due to Streptococcus dysgalactiae in the selected studies Hogan et al [17] Timms and Schultz [45] Hogan et al [18] Lilius and Pesonen [27] Rainard et al [39] Davidson et al [10] Nickerson and Boddie [33] Schepers et al [40] Woolford et al [ Chaffer et al [8] Detilleux et al [12] Leitner et al [25] Somatic cell count (x 1000 c/mL) Hogan et al [17] Timms and Schultz [45] Hogan et al [18] Lilius and Pesonen [27] Rainard et al [39] Davidson et al [10] Nickerson and Boddie [33] Schepers et al [40] Woolford et al [ Chaffer et al [8] Detilleux et al [12] Leitner et al [25] Somatic cell count (x 1000 c/mL) Sheldrake et al [44] Herd V 3 Sheldrake et al [44] Herd D 3 Sheldrake et al [44] Herd W 3 Figure 1. Geometric mean SCC (᭜) and its 95% CI (-) of bacteriologically negative quarters (SCC in × 1 000 c/mL whatever of the measurement equipment used).…”

“…The way of preserving milk samples has an effect on SCC: samples which were kept using potassium-bichromate had SCC (450 000 c/mL) higher than the same samples not preserved (400 000 c/mL) [28]. The temperature and duration of storage may also influence both SCC [3,16] and bacteriological results [15,41,47]. Samples had SCC slightly lower (minus 25 000 c/mL) when stored for 10 days at 4 o C than when stored at room temperature [16].…”