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This paper proposes and discusses a methodology to evaluate the performance of automated mastitis-detection systems with respect to their practical value on farm. The protocols are based on 3 on-farm requirements: (1) to detect cows with clinical mastitis promptly and accurately to enable timely and appropriate treatment, (2) to identify cows with high somatic cell count to manage bulk milk SCC levels, and (3) to report the mastitis infection status of cows at the end of lactation to support decisions on individual cow dry-cow therapy. Separate protocols for each requirement are proposed and discussed, including gold standards, evaluation tests, performance indicators, and performance targets. Aspects that require further research or clarification are identified. Actual field data are used as examples. Further debate is invited, the aim being to achieve international agreement on how to evaluate and report performance of different mastitis-detection technologies. Better performance information will allow farmers to compare different mastitis-detection systems sensibly and fairly before investing. Also, the use of evaluation protocols should help technology providers to refine current, or develop new, automated mastitis-detection systems. Such developments are likely to accelerate adoption of these systems, potentially leading to improved animal health, milk quality, and labor productivity., (Copyright © 2013 American Dairy Science Association. Published by Elsevier Inc. All rights reserved.)

Aim: To assess a novel method for automatic in-line detection of clinical mastitis., Methods: For a brief period at the start of milking for each cow, electrical conductivity of foremilk was measured for each quarter in turn, using a single sensor installed in the long milk tube (LMT) about 1.5 m downstream from the milking-machine claw. Sequential separation of flow between udder quarters was achieved by control of pulsation to individual teat cups within a conventional cluster. The ratio of conductivity values between quarters was used as an indicator of mastitis status. The concept was evaluated initially in a pilot trial in a 200-cow herd milked in a 23-stall swing-over herringbone milking parlour. It was then tested rigorously in a field trial in a 640-cow herd milked in a 50-stall rotary milking parlour. Both trials were conducted in the Waikato region of New Zealand. In the latter trial, sensor results were compared with visual inspection of a commercial in-line mastitis filter fitted to each milking unit. These filters were inspected for clots immediately after every cow's milking, for 3 weeks. The dataset of approximately 27,000 individual milkings was tested against several published or potential alternative 'gold standards' for diagnosing clinical mastitis., Results: In the pilot trial, 12-14 clinical events were detected out of 19 true clinical quarters, with a false-alert rate of between three and five false electrical-conductivity alerts per 1,000 individual milkings. In the more rigorous field trial, sensitivity ranged from 68 to 88%, and the false-alert rate (false-alert episodes per 1,000 individual milkings) ranged from 2.3 to 7.0., Conclusion: The novel clinical mastitis detection system, based on separation of the flow and measurement of electrical conductivity from foremilk of individual udder quarters, has the potential to provide a new tool for helping farmers to monitor clinical mastitis in herds milked with conventional clusters.

This study explored the potential value of in-line composite somatic cell count (ISCC) sensing as a sole criterion or in combination with quarter-based electrical conductivity (EC) of milk, for automatic detection of clinical mastitis (CM) during automatic milking. Data generated from a New Zealand research herd of about 200 cows milked by 2 automatic milking systems during the 2006-2007 milking season included EC, ISCC, monthly laboratory-determined SCC, and observed cases of CM that were treated with antibiotics. Milk samples for ISCC and laboratory-determined SCC were taken sequentially at the end of a cow milking. Both samples were derived from a composite cow milking obtained from the bottom of the milk receiver. Different time windows were defined in which true-positive, false-negative, and false-positive alerts were determined. Quarters suspected of having CM were visually checked and, if CM was confirmed, sampled for bacteriological culturing and treated with an antibiotic treatment. These treated quarters were considered as gold-standard positives for comparing CM detection models. Alert thresholds were adjusted to achieve a sensitivity of 80% in 3 detection models: using ISCC alone, EC alone, or a combination of these. The success rate (also known as the positive predictive value) and the false alert rate (number of false-positive alerts per 1,000 cow milkings) were used to evaluate detection performance. Normalized ISCC estimates were highly correlated with normalized laboratory-determined SCC measurements (r = 0.82) for SCC measurements >200 x 10(3) cells/mL. Using EC alone as a detection tool resulted in a range of 6.9 to 11.0% for success rate, and a range of 4.7 to 7.8 for the false alert rate. Values for the ISCC model were better than the model using EC alone with 12.7 to 15.6% for the success rate and 2.9 to 3.7 for the false alert rate. Combining sensor information to detect CM, by using a fuzzy logic algorithm, produced a 2- to 3-fold increase in the success rate (range 21.9 to 32.0%) and a 2- to 3-fold decrease in the false alert rate (range 1.2 to 2.1) compared with the models using ISCC or EC alone. Results suggest that the performance of a CM detection system improved when ISCC information was added to a detection model using EC information.

The rheological properties of the CMT gel were analysed. Data are presented to demonstrate that the gel is a non-homogenous, visco-elastic, non-Newtonian fluid with rheopectic, and rheodestructive behaviour. The fundamental chemistry of the CMT is reviewed and a modified theory of gel formation is presented. The implications of the rheological properties and modified theory of gel formation for an automatic sensor are discussed.

The effects of three selection strategies for dry cow therapy on prevention of new infections and rate of antibiotic usage were compared. Quarter infection status of 1044 cows in 12 herds was determined by bacteriological methods at drying off, calving and three to five months into the following lactation. Cows that were uninfected at drying off were randomly allocated to treatment (whole udder, dry cow therapy) and non-treatment groups. Infected cows were randomly allocated to whole udder or infected quarter only treatments. The strategies compared were blanket treatment (treat all quarters of all cows), selective cow treatment (treat all quarters of any cow infected in one or more quarters) and selective quarter treatment (treat infected quarters only). Selective cow treatment was identified as the preferred strategy. Blanket treatment resulted in increased antibiotic usage (15.5 vs 6.4 tubes per infection eliminated) with no additional benefit, and selective quarter treatment resulted in a higher new infection rate (6.4% vs 3.9% quarters) in the dry period. The prevalence of infection within a herd at drying off had no influence on new infection rates in the dry period or early lactation. The cure rate after dry cow treatment (mean of 66%) decreased significantly with increasing age (P < 0.001). Cows infected in the previous lactation contributed over 76% of infections at calving and nearly 70% at mid-lactation. To lower the incidence of mastitis in a herd, a greater emphasis on culling of older infected cows and prevention of new infections during lactation is needed.

Twenty-four Holstein cows, producing at least 21 kg of milk/d, were used in two replicate experiments to determine the effect of presence or absence of pulsation on loss of teat canal keratin during machine milking. Left quarters were milked without pulsation and right quarters were milked with pulsation. On d 0 and 10, keratin was collected from one left and from one right teat canal of each cow prior to milking and from the remaining two teat canals after milking. Milk was collected for assessment of SCC and bacteriological status on d 0 and approximately every 3 d until d 18. Quantity of keratin recovered before milking on d 10 did not differ between teats milked with or without pulsation, but loss of keratin because of milking was greater from teats milked with pulsation. By d 7, 30% (12 of 43) of quarters milked without pulsation had become infected, but no (0 of 47) quarters milked with pulsation were infected. By d 14 to 16, new infections had increased to 68% (28 of 41) of quarters milked without pulsation and 2% (1 of 43) in quarters milked with pulsation; mean SCC in pulsationless quarters increased sevenfold relative to pulsation quarters. Protein and water content of keratin did not differ because of treatment, and changes in lipid composition were minor. Histological analysis of the teats of 4 cows indicated that the mean diameter of the teat canal, within 2 h after milking, was greater without pulsation than with pulsation (680 vs. 483 microns).

Four strategies for selecting cows for intramammary therapy with benzathine cloxacillin at drying off were compared in 12 Victorian dairy herds. The bacteriological status of all quarters of all (1044) cows was determined just before drying off, within 2 d of calving, and again 3 to 5 months after calving. All cases of clinical mastitis (from calving to mid-lactation) were recorded. Cows not infected at drying off were allocated randomly to 2 subgroups of approximately 350 cows each: not infected, not treated (NI-NT), or not infected, all quarters treated (NI-AT). New infection rates in the dry period (3.8% for NI-NT vs 2.1% for NI-AT) and in early lactation (4.1% for NI-NT vs 3.9% for NI-AT) were low and these differences were not significant. Incidence of clinical mastitis in early lactation was almost 50% higher for the treated group of uninfected cows compared with the untreated group (0.05 less than p less than 0.1). Cows infected in one or more quarters at drying off were split randomly into 2 subgroups of approximately 170 cows each: infected, all quarters treated (I-AT), or infected quarters treated only (I-QT). The new infection rate during the dry period was nearly 4 times higher for I-QT (15.3%) due to significantly more new infections by Staphylococcus aureus and Streptococcus uberis.(ABSTRACT TRUNCATED AT 250 WORDS)

Deflector shields were inserted in the teatcup to prevent 'impacts' against the teat end, and their effect on the rate of new udder infections was studied on 15 commercial dairy farms in Britain and 16 in Australia. Small metal shields were fitted between the liner barrel and short milk tube of 2 teatcups in each cluster in a milking installation so that all cows in a herd always had the same 2 quarters shielded. Half-udder comparisons were made using 1039 cows in the British herds and 1268 in the Australian herds. Herds were quarter-sampled for cytological and bacteriological examination when shields were fitted at the start of the experiment and again after 6 months. The shield effects were similar in the 2 experiments. The combined results from the 31 farms showed that 10.5% fewer quarters became infected when protected by shields (P less than 0.05). In the 1287 cows that had no infected quarters at the start of the trial, 15% fewer quarters became infected when protected by shields (P less than 0.01). The shield effect was mainly confined to hind quarters in which 23% fewer shielded quarters became infected (P less than 0.001). The small reduction of 2% in forequarters was not significant. In the 16 herds in which post-milking disinfection of teats was practised, shielded quarters had 23.5% fewer new infections than unshielded quarters (P less than 0.01). In 6 British herds milked in installations classed as non-standard, shielded quarters had almost 50% fewer new infections than the unshielded quarters (0.05 less than P less than 0.10). The results provide evidence of a milking machine effect, at varying levels of intensity, to increase new infection rates on all or most farms. Control of this machine effect could lead to substantial reduction in new infections in some herds and a modest reduction in most.

Half-udder comparisons were made using 56 cows for 2 months, in an experiment involving high bacterial challenge, to assess the combined effects of 5 min overmilking and pulsation failure (resulting from the use of shortened teacup liners) on teat condition and mastitis. Only three new infections were confirmed in over 12500 quarter milkings in quarters milked with control liners (of 148 mm effective length) indicating little or no effect of prolonged overmilking in these quarters. A 3.5-fold increase in the new infection rate (NIR) based on bacteriological diagnosis alone (P less than 0.01), or a 9-fold increase in NIR based on bacteriological diagnosis plus raised cell count and/or N-acetyl-beta-D-glucosaminidase (P less than 0.01), occurred in quarters milked with the same liners shortened to an effective length of 120-130 mm. The mean interval to infection or teat canal colonization (41 v. 60 milkings), and for a quarter infection to be confirmed by other diagnostic tests (45 v. 79 milkings) was significantly less in quarters overmilked with short liners. The results confirm that NIR increases whenever pulsation fails. Overmilking may increase NIR when it is associated with pulsation failure.