Algometer Precision for Quantifying Mechanical Nociceptive Threshold When Applied to the Udder of Lactating Dairy Cows

Reliability, the consistency of a test or measurement, is frequently quantified in the movement sciences literature. A common metric is the intraclass correlation coefficient (ICC). In addition, the SEM, which can be calculated from the ICC, is also frequently reported in reliability studies. However, there are several versions of the ICC, and confusion exists in the movement sciences regarding which ICC to use. Further, the utility of the SEM is not fully appreciated. In this review, the basics of classic reliability theory are addressed in the context of choosing and interpreting an ICC. The primary distinction between ICC equations is argued to be one concerning the inclusion (equations 2,1 and 2,k) or exclusion (equations 3,1 and 3,k) of systematic error in the denominator of the ICC equation. Inferential tests of mean differences, which are performed in the process of deriving the necessary variance components for the calculation of ICC values, are useful to determine if systematic error is present. If so, the measurement schedule should be modified (removing trials where learning and/or fatigue effects are present) to remove systematic error, and ICC equations that only consider random error may be safely used. The use of ICC values is discussed in the context of estimating the effects of measurement error on sample size, statistical power, and correlation attenuation. Finally, calculation and application of the SEM are discussed. It is shown how the SEM and its variants can be used to construct confidence intervals for individual scores and to determine the minimal difference needed to be exhibited for one to be confident that a true change in performance of an individual has occurred.

Costs and feasibility of extensive sample collection and processing are major obstacles to mastitis epidemiology research. Studies are often consequentially limited, and fundamental mastitis researchers rarely have the opportunity to conduct their work in epidemiologically valid populations. To mitigate these limitations, the Canadian Bovine Mastitis Research Network has optimized research funds by creating a data collection platform to provide epidemiologically meaningful data for several simultaneous research endeavors. This platform consists of a National Cohort of Dairy Farms (NCDF), Mastitis Laboratory Network, and Mastitis Pathogen Culture Collection. This paper describes the implementation and operation of the NCDF, explains its sampling protocols and data collection, and documents characteristics, strengths and limitations of these data for current and potential users. The NCDF comprises 91 commercial dairy farms in 6 provinces sampled over a 2-yr period. Primarily Holstein-Friesian herds participating in Dairy Herd Improvement milk recording were selected in order to achieve a uniform distribution among 3 strata of bulk tank somatic cell counts and to reflect regional proportions of freestall housing systems. Standardized protocols were implemented for repeated milk samplings on clinical mastitis cases, fresh and randomly selected lactating cows, and cows at dry-off and after calving. Just fewer than 133,000 milk samples were collected. Demographic and production data were recorded at individual cow and farm levels. Health management data are documented and extensive questionnaire data detailing farm management and cleanliness information are also captured. The Laboratory Network represents coordinated regional mastitis bacteriology laboratories using standardized procedures. The Culture Collection archives isolates recovered from intramammary infections of cows in the NCDF and contains over 16,500 isolates, all epidemiologically cross-referenced between linked databases. The NCDF is similar to Canadian dairies in relation to mean herd size, average production, and freestall percentages. Pathogen recovery was greater than anticipated, particularly for coagulase-negative staphylococci and Corynebacterium spp. International scientists are encouraged to use this extensive archive of data and material to enhance their own mastitis research. Copyright © 2011 American Dairy Science Association. Published by Elsevier Inc. All rights reserved.

The objectives of this study were to (1) evaluate the use of a pressure algometer and an automated rumination monitoring system to assess changes in pain sensitivity and rumination time in response to endotoxin-induced clinical mastitis and (2) evaluate the effect of the nonsteroidal antiinflammatory drug meloxicam on pain sensitivity and rumination time, as well as other clinical signs, in dairy cattle with endotoxin-induced clinical mastitis. Clinical mastitis was induced in 12 primiparous and 12 multiparous lactating dairy cows by intramammary infusion of 25 µg of Escherichia coli lipopolysaccharide (LPS) into 1 uninfected quarter. Immediately after, half the cows were injected subcutaneously with meloxicam (treated group) and half with the same volume of a placebo solution (control group). Pain sensitivity was assessed by measuring the difference in pressure required to elicit a response on the control and challenged quarter using an algometer 3 d before, immediately before, and at 3, 6, 12, and 24h after LPS infusion and either meloxicam or placebo injection. Rumination was continuously monitored from 2 d before to 3 d after LPS infusion using rumination loggers. Udder edema, body temperature, somatic cell score, and dry matter intake were also monitored to evaluate the occurrence and the duration of the inflammation after LPS infusion. In control animals, the difference in the pressure applied to the control and challenged quarters (control - challenged quarter) increased by 1.1 ± 0.4 kg of force 6h after LPS infusion compared with the baseline, suggesting an increase in pain sensitivity in the challenged quarter. Neither the LPS infusion nor the meloxicam treatment had an effect on daily rumination time. However, the rumination diurnal pattern on the day of LPS infusion showed an overall deviation from the baseline pattern. Cows spent less time ruminating in the hours following LPS infusion and more time ruminating later in the day. Meloxicam did not alter somatic cell score or dry matter intake. However, meloxicam-treated animals had less udder edema and a lower body temperature in the hours following LPS infusion compared with control animals. In conclusion, pressure algometers and rumination loggers show promise as tools to detect mastitis and monitor recovery on farm. Further, meloxicam has a beneficial effect in relieving pain and decreasing udder edema and body temperature in LPS-induced clinical mastitis. Copyright © 2013 American Dairy Science Association. Published by Elsevier Inc. All rights reserved.