An automated in-line clinical mastitis detection system using measurement of conductivity from foremilk of individual udder quarters

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 teatcups 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 alter- native ‘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.     

Handling of slaughter cattle in pre and post transport situations including loading and unloading on journeys up to 8 hours in Germany

In a field study 63 commercial cattle transports to German slaughter plants including 580 bulls, cows and heifers were investigated to estimate the impact of pre and post transport aspects on animal welfare. Study 1 evaluated these aspects as part of a large model covering all possible influences at transport and slaughter on biochemical stress response and carcass and meat quality. Included were keeping system, behavioural and clinical observations at loading, unloading and lairage, transport time, loading density, mounting prevention, regrouping and lairage time. In study 2 more detailed questions about loading and unloading were answered by investigating the impact of facility design and handling criteria on cattle behaviour and heart rate. Cattle from tied housing show an increased stress response to all transport procedures. Many aspects of facility design and handling contribute to quality of loading. Cattle show calmer behaviour, turn, balk or fall less if they are not mixed and driven in small groups on driveways without impediments but with regular sideblock, not wider than the vehicle ramp. Vehicle ramps should have high and closed side gates, be inclined less than 20 degrees, and the step towards ramp should be less than 15 cm. Unloading is improved if performed level and to the back of the vehicle (behaviour, heart rate, cortisol, CK). Direct reloading should be avoided and mounting should be prevented during transport and lairage (CK, lactate, bruising). But mounting prevention devices may increase bruising if set too low (< 20 cm above withers). Longer lairage time is disadvantageous (CK, energy metabolism).     

Human psittacosis associated with commercial processing of turkeys.

Between May 1 and Aug 1, 1974, 114 of approximately 1,000 employees in 7 turkey processing plants in Texas (5), Missouri (1), and Nebraska (1) had an illness compatible with psittacosis. The illness was characterized by fever, severe headache, and pneumonia. Treatment with tetracycline was effective in most cases. Psittacosis was confirmed in 41 (36%) of the cases by a fourfold change in complement-fixation titer to the Chlamydia group antigen. Investigations implicated several turkey flocks from Texas as the source of the disease. Control measured, including screening turkey flocks before slaughter and assuring treatment of infected birds, were instituted by a special task force of state and federal veterinarians.     

Chondrodysplasia in Australian Dexter cattle

Objective To describe the occurrence of chondrodysplasia in Australian Dexter cattle.
Design A pathological and genetic case report.
Procedure Congenital lethal chondrodysplasia was studied in two female Dexter foetuses aborted mid to late gestation. Clinicopathological findings including histological changes in limb bones, and analysis of pedigree information were evaluated.
Results Characteristic features of congenital lethal chon-drodysplasia (Dexter bulldog) include abortion, disproportionate dwarfism, a short vertebral column, marked micromelia, a relatively large head with retruded muzzle, cleft palate and protruding tongue and a large abdominal hernia. Histological changes in limb bones are consistent with failure of endochondral ossification. Dexter chondrodysplasia is considered to be inherited in an incompletely dominant manner with the homozygous form producing the congenital lethal condition. A preliminary minimum estimate of heterozy-gote frequency is 19% within the registered Australian Dexter herd, based on analysis of the contribution of three obligate heterozygotes whose semen has been widely used by artificial insemination in Australia.
Conclusion Dexter chondrodysplasia is present in Australian cattle and further cases of the homozygous form, congenital lethal chondrodysplasia, are likely to occur.
Recommendation It is requested that spleen and liver tissue from bulldog foetuses and blood from their parents be collected to assist research into Dexter chondrodysplasia.     

Estimation of sensitivity and specificity of pregnancy diagnosis using transrectal ultrasonography and ELISA for pregnancy-associated glycoprotein in dairy cows using a Bayesian latent class model

AIMS: To determine the sensitivity (Se) and specificity (Sp) of pregnancy diagnosis using transrectal ultrasonography and an ELISA for pregnancy-associated glycoprotein (PAG) in milk, in lactating dairy cows in seasonally calving herds approximately 85–100 days after the start of the herd’s breeding period.

METHODS: Paired results were used from pregnancy diagnosis using transrectal ultrasonography and ELISA for PAG in milk carried out approximately 85 and 100 days after the start of the breeding period, respectively, from 879 cows from four herds in Victoria, Australia. A Bayesian latent class model was used to estimate the proportion of cows pregnant, the Se and Sp of each test, and covariances between test results in pregnant and non-pregnant cows. Prior probability estimates were defined using beta distributions for the expected proportion of cows pregnant, Se and Sp for each test, and covariances between tests. Markov Chain Monte Carlo iterations identified posterior distributions for each of the unknown variables. Posterior distributions for each parameter were described using medians and 95% probability (i.e. credible) intervals (PrI). The posterior median estimates for Se and Sp for each test were used to estimate positive predictive and negative predictive values across a range of pregnancy proportions.

RESULTS: The estimate for proportion pregnant was 0.524 (95% PrI?=?0.485–0.562). For pregnancy diagnosis using transrectal ultrasonography, Se and Sp were 0.939 (95% PrI?=?0.890–0.974) and 0.943 (95% PrI?=?0.885–0.984), respectively; for ELISA, Se and Sp were 0.963 (95% PrI?=?0.919–0.990) and 0.870 (95% PrI?=?0.806–0.931), respectively. The estimated covariance between test results was 0.033 (95% PrI?=?0.008–0.046) and 0.035 (95% PrI?=?0.018–0.078) for pregnant and non-pregnant cows, respectively. Pregnancy diagnosis results using transrectal ultrasonography had a higher positive predictive value but lower negative predictive value than results from the ELISA across the range of pregnancy proportions assessed.

CONCLUSIONS AND CLINICAL RELEVANCE: Pregnancy diagnosis using transrectal ultrasonography and ELISA for PAG in milk had similar Se but differed in predictive values. Pregnancy diagnosis in seasonally calving herds around 85–100 days after the start of the breeding period using the ELISA is expected to result in a higher negative predictive value but lower positive predictive value than pregnancy diagnosis using transrectal ultrasonography. Thus, with the ELISA, a higher proportion of the cows with negative results will be non-pregnant, relative to results from transrectal ultrasonography, but a lower proportion of cows with positive results will be pregnant.     

Wintersweet (Chimonanthus praecox) toxicity in four goats

CASE HISTORY: A one-year-old female goat presented with acute onset of recumbency, seizures and vocalisation approximately 5 hours after being given access to branch trimmings from a neighbour's garden. The plant from which the pruned branches came was subsequently identified as wintersweet (Chimonanthus praecox). Three other goats kept in the same paddock displayed similar clinical signs over a period of 4 hours following the initial presentation.

CLINICAL FINDINGS: All four goats were ataxic, displayed tetanic seizures and were in lateral recumbency; they had dilated pupils and were hyperaesthetic, with elevated heart and respiratory rates. After symptomatic treatment, including sedation with diazepam, one of the three goats continued to deteriorate and was subjected to euthanasia. The remaining three goats recovered over 1–14 days with nursing care and physiotherapy.

DIAGNOSIS: Toxicity due to ingestion of wintersweet, which contains the alkaloid calycanthine.

CLINICAL RELEVANCE: Calycanthine is a central nervous system toxin, causing convulsions. Wintersweet shrubs are present in many New Zealand gardens. Practitioners should be aware that the seeds and flowers, and possibly the leaves, of this plant are highly toxic with signs of toxicity including ataxia, hyperaesthesia and seizures.