Individual Cow Somatic Cell Count Research Articles

An evaluation of the validity of individual cow somatic cell counts from cows in early lactation

Individual cow somatic cell counts (SCC) from the first 4 weeks of lactation were obtained from all cows on a cell-counting program in Prince Edward Island for a period of 4 years. The prevalence of elevated counts (over 200 000 cells ml −1) declined sharply in heifers (primiparous animals) from Day 5 to Day 10 of lactation, and then gradually from Day 10 to Day 28. For multiparous cows, the end of the steep decline occurred at approximately 12 days post-calving. Similar patterns were observed in the arithmetic and geometric mean SCC. The bias associated with including the post-calving SCC (i.e. SCC from the first 9–11 days) in estimates of the prevalence of elevated counts in early lactation was determined. The bias was most serious in herds with a low true prevalence of elevated counts, and was substantial if the early lactation period was defined to be 40 days or less. It is recommended that SCC from heifers in the first 9 days of lactation and from multiparous cows in the first 11 days be discarded before estimates of the early lactation prevalence of elevated SCC are determined.

Economic analysis of a mastitis monitoring and control program in four dairy herds

Summary: Mastitis monitoring and control programs were instituted in 4 Illinois dairy herds for 12 months. Two herds had high mean monthly bulk tank somatic cell counts (> 490,000 cells/ml) and 2 had low mean monthly bulk tank somatic cell counts (< 260,000 cells/ml) at the start of the study. The mastitis monitoring and control programs included mandatory mastitis control measures, as well as individualized control measures that were based on results of bacterial cultures of milk, bulk tank milk analyses, milking machine and milking procedure evaluations, and environmental inspections in each herd. Changes in mastitis prevalence, clinical mastitis incidence, milk yield, and individual cow somatic cell counts were evaluated, and an economic analysis was performed for each herd. Mastitis-associated economic losses during the study period ranged from $161.79 to $344.16/lactating cow in the 4 herds. Gross economic benefits resulted when mastitis-associated losses were lower with the monitoring and control program than predicted without it. There were no gross economic benefits in the herds with low somatic cell counts, and, when the marginal costs of the programs were added, there were large net losses ($84.06 and $113.01/lactating cow) in those herds. Gross economic benefits resulted in both of the herds with high somatic cell counts. However, in 1 of the herds, the marginal costs of the program exceeded the benefits, resulting in a net loss of $12.96/lactating cow. The net loss was attributed primarily to poor producer compliance with recommendations. There was a net economic benefit of $19.11/lactating cow in the other herd with high somatic cell counts, in which producer compliance was better. The study demonstrates the need for more research to identify mastitis control measures that are both effective and economical in herds with low somatic cell counts.

Epidemiologic Considerations in Reporting Herd Somatic Cell Counts

The reporting of herd summaries of individual cow somatic cell counts differs between the nine Dairy Records Processing Centers. The objectives of this paper are 1) to review the present reporting; 2) to compare the methods used to calculate herd somatic cell counts; and 3) to discuss the epidemiologic implications of these methods.Estimates of central tendency and frequency distributions are the most commonly used herd summary statistics for somatic cell counts. Analyses of the frequency distributions are less widely available.Potential uses of herd somatic cell counts are 1) to measure one aspect of herd milk quality; 2) to estimate the prevalence of mastitis; 3) to analyze mastitis patterns within the herd; and 4) to investigate new areas for mastitis control research. Presently, the best available methods for these applications appear to be 1) bulk tank somatic cell counts or weighted arithmetic means for gauging milk quality; 2) frequency distributions for estimating mastitis prevalence; 3) analyses of frequency distributions or mean linear score by lactation and stage of lactation for identifying mastitis patterns within a herd; and 4) frequency distributions or estimated incidence rates, adjusted for differences in age and stage of lactation, for investigating new areas for mastitis control research.

Impact on Producer and Processor

The Food and Drug Administration's lowering of the acceptable somatic cell count in bulk milk to 1 million/ml in 1986 may affect 10 to 15% of the US herds at the onset. However, considerable benefit can be expected from lower somatic cell counts due to less clinical mastitis, increased yields of milk and cheese, higher milk fat test (and price of milk), and improved milk quality, with less risk of antibiotic-contaminated milk, fewer problems with rancidity and other off-flavors, and longer shelf-life of pasteurized dairy products. To reduce somatic cells, dairy producers will need to emphasize prevention of new intramammary infections rather than treatment of mastitis problems. Attention must be given to cow preparation at milking, teat dipping and dry cow therapy, proper use and maintenance of milking equipment, sanitation, housing, and other environmental conditions, monitoring individual cow somatic cell counts, and antibiotic residue testing.

A method to measure herd udder health by combining individual cow somatic cell counts

A method is presented for computing an index of herd udder health from a frequency distribution of milk somatic cell counts (SCC). The herd udder health index (HUHI) is a summation of weighted percentages of cows in SCC groups presented in Dairy Herd Improvement program monthly reports. Weights are the inverse of the ratio of the respective group SCC midpoint to that for the lowest SCC group. Values of HUHI approach zero from 100; an index of 100 represents a distribution in which the L 2 score for all cows tested was less than 2. For four dairies, coefficients of determination for HUHI and arithmetic mean SCC weighted by production ranged from 0.698 to 0.938.

Use of Individual Cow Somatic Cell Counts and Bulk Tank Samples to Monitor Herd Mastitis Status

With the advent of automated cell counting, there has been a proliferation of milk somatic cell count (SCC) data for bothbulk tank samples and individual cows. The optimal use of this data in monitoring mastitis is still being debated. Thepurpose of this paper is to discuss the use of SCC data from both individual cow and bulk tank samples for monitoringmastitis on a herd basis.