Prevalence and spatial distribution of Coxiella burnetii seropositivity in northern Australian beef cattle adjusted for diagnostic test uncertainty.

Q fever is a zoonotic disease caused by infection with Coxiella burnetii transmitted from animals including, but not limited to, cattle, sheep and goats. The infection in cattle is typically sub-clinical with some evidence suggesting associated reproductive loss. There is currently limited data on the true prevalence and distribution of coxiellosis in beef cattle across northern Australia. During this study, 2,012 sera samples from beef cattle managed on commercial farms located in Queensland and the Northern Territory were tested using an indirect immunofluorescent assay (IFA) for serological evidence of IgG antibodies against C. burnetii. Bayesian latent class models were used to estimate the true prevalence, adjusted for diagnostic test sensitivity and specificity and incorporating the hierarchical structure of the cattle within farms and regions. In this study, cattle in the Northern Territory had lower estimated true prevalence than cattle within most regions of Queensland with the exception of south-east Queensland. Results from this study have described the geographic distribution and estimated the true prevalence of antibodies to C. burnetii in a sample of extensively managed beef cattle located across the tropical grazing regions of northern Australia.

Genetic analysis of porcine circovirus type 2 (PCV2) in Queensland, Australia.

OBJECTIVE: To determine the current porcine circovirus type 2 (PCV2) genotypes circulating in pigs in Queensland (QLD). METHODS: The PCV2 infection status of pigs was determined by real-time PCR testing of 210 lymph nodes and 30 serum samples derived from 45 QLD farms. PCV2-positive samples from 22 pigs from 15 farms were subjected to conventional polymerase chain reaction (PCR) and sequencing of the full PCV2 genome. Phylogenetic analysis of 17 of these sequences in relation to published PCV2 sequences was then performed, and the genotypes were compared. RESULTS: PCV2 DNA was detected in 95 lymph nodes and 15 serum samples. Phylogenetic analysis of 17 PCV2 sequences demonstrated that seven belonged to genotype PCV2b, two to PCV2d, one to PCV2f and seven to an "intermediate group" that clustered with PCV2d on the full genome analysis. CONCLUSION: This work confirms earlier studies reporting the presence of PCV2b in Australia. It is the first study to report that PCV2d and PCV2f are also present in this country. PCV2d is currently a fast-spreading genotype globally, with reported high virulence. The potential implications of these findings with respect to pathogenicity and vaccine efficacy require further investigation.

Linear body measurements and productivity of subtropical Holstein-Friesian dairy calves.

OBJECTIVE: The study aimed to describe growth parameters and to quantify the association between linear body measurements as predictors of liveweight (LW) of Holstein-Friesian (HF), and HF crossbred dairy calves in Queensland. A secondary objective was to quantify the effect of disease events on LW change. STUDY DESIGN: Longitudinal study. METHODS: Fortnightly LW, hip height (HH), hip width (HW) and heart girth (HG) measurements were recorded from 16 male and 28 female HF calves from birth until weaning. The association between linear body measurement and the effect of a disease event on LW change were explored using linear mixed-effects modelling with random intercepts and random slopes. RESULTS: HG was the best body measure used individually as a predictor of calf LW (R2 = 82%; P < 0.001), while the combined use of HG, HW and HH was the most accurate predictor of calf LW between birth and weaning (R2 = 90%; P < 0.001). HW, average feed intake and total feed intake were significantly affected by disease events (P < 0.05). On average, total average LW loss associated with a single pneumonia event was estimated at 14.6 kg (95% CI = 10.5 to 18.7 kg; P < 0.05). CONCLUSIONS: Calves of this study performed at a level consistent with the previously published reports. Growth performance was significantly compromised by pneumonia. HW was found to be the least predictive individual measure, and the combined use of HH, HW and HG had the most accurate prediction of calf liveweight from birth to weaning.

The effect of a commercial probiotic product on the milk quality of dairy cows.

Probiotics intended to improve plant health and productivity of pastures grazed by dairy cow are becoming commercially available in Australia. Great Land (GL; Terragen Biotech Pty Ltd., Coolum Beach, QLD, Australia) is one such biologic soil conditioner and spray-on probiotic with a label claim of "acting to improve plant health and productivity." The objective of this study was to quantify the effect of GL on the milk quality of cows grazing pasture top-dressed with GL. Lactating dairy cows of mixed age and breed (primarily Holstein-Friesian), in their second lactation or greater, and at least 80 d in milk were enrolled and randomly allocated into 1 of 2 study groups: a treatment cow group (n = 98; cows grazed pasture that was top-dressed with GL according to the product label) and a control cow group (n = 114; cows grazed untreated pasture). As required, both groups were supplemented at the same rate with a mixed ration during the grazing period. Composite milk samples were collected weekly from each cow during the study and analyzed to determine milk components. Milk volumes were recorded at each milking using the herd management software of the study farm. Mean differences in the milk component variables were compared using mixed-effects linear regression models. After controlling for the effect of days in milk, cow lactation, and time since a cow entered the study, the treatment cows produced an average of 1.21 L/cow per day more milk (95% confidence interval: 0.34-2.08 L/cow per day) and more milk protein (0.03 kg/d; 95% confidence interval: 0.01-0.05 kg/d) than the control cows. Pasture cover and pasture consumption did not differ between the GL-treated and the untreated study paddocks grazed by the treatment or control cows. A limited amount of published data have examined the effect of probiotic pasture treatment on the milk quality of dairy cows. This study suggests that application of such products may be beneficial. The mechanisms associated with this type of outcome remain to be investigated.

Noncatastrophic and catastrophic fractures in racing Thoroughbreds at the Hong Kong Jockey Club.

BACKGROUND: Reports of fractures in racehorses have predominantly focused on catastrophic injuries, and there are limited data identifying the location and incidence of fractures that did not result in a fatal outcome. OBJECTIVE: To describe the nature and the incidence of noncatastrophic and catastrophic fractures in Thoroughbreds racing at the Hong Kong Jockey Club (HKJC) over seven racing seasons. STUDY DESIGN: Retrospective cohort study. METHODS: Data of fractures sustained in horses while racing and of race characteristics were extracted from the HKJC Veterinary Management Information System (VMIS) and Racing Information System (RIS), respectively. The fracture event was determined from the first clinical entry for each specific injury. The incidence rates of noncatastrophic and catastrophic fractures were calculated per 1000 racing starts for racetrack, age, racing season, sex and trainer. RESULTS: One hundred and seventy-nine first fracture events occurred in 64,807 racing starts. The incidence rate of noncatastrophic fractures was 2.2 per 1000 racing starts and of catastrophic fractures was 0.6 per 1000 racing starts. Fractures of the proximal sesamoid bones represented 55% of all catastrophic fractures, while the most common noncatastrophic fractures involved the carpus and the first phalanx. Significant associations were detected between the incidence of noncatastrophic fractures and sex, trainer and racing season. MAIN LIMITATIONS: The first fracture event was used to calculate the incidence rate in this study and may have resulted in underestimation of the true incidence rate of fractures in this population. However, given the low number of recorded fracture events compared with the size of the study population, this underestimation is likely to be small. CONCLUSIONS: There were 3.6 times as many noncatastrophic fractures as catastrophic fractures in Thoroughbreds racing in Hong Kong between 2004 and 2011. Noncatastrophic fractures interfere with race training schedules and may predispose to catastrophic fracture. Future analytical studies on noncatastrophic racing fractures should be a priority for the racing industry.

Description of the pig production systems, biosecurity practices and herd health providers in two provinces with high swine density in the Philippines.

A cross-sectional study was conducted between October 2011 and March 2012 in two major pig producing provinces in the Philippines. Four hundred and seventy one pig farms slaughtering finisher pigs at government operated abattoirs participated in this study. The objectives of this study were to group: (a) smallholder (S) and commercial (C) production systems into patterns according to their herd health providers (HHPs), and obtain descriptive information about the grouped S and C production systems; and (b) identify key HHPs within each production system using social network analysis. On-farm veterinarians, private consultants, pharmaceutical company representatives, government veterinarians, livestock and agricultural technicians, and agricultural supply stores were found to be actively interacting with pig farmers. Four clusters were identified based on production system and their choice of HHPs. Differences in management and biosecurity practices were found between S and C clusters. Private HHPs provided a service to larger C and some larger S farms, and have little or no interaction with the other HHPs. Government HHPs provided herd health service mainly to S farms and small C farms. Agricultural supply stores were identified as a dominant solitary HHP and provided herd health services to the majority of farmers. Increased knowledge of the routine management and biosecurity practices of S and C farmers and the key HHPs that are likely to be associated with those practices would be of value as this information could be used to inform a risk-based approach to disease surveillance and control.

The use of liveweight change as an indicator of oestrus in a seasonally calving, pasture-fed dairy herd.

This was an observational study of 828 lactations in 542 mixed-age dairy cows that calved seasonally in a single, pasture-fed herd in New Zealand in 2008 and 2009. The study objectives were to: (i) document daily liveweight change (∆LW) before and after observed oestrus for cows subsequently diagnosed pregnant or non-pregnant and (ii) quantify the sensitivity and specificity of ∆LW as a test for oestrus. The sensitivity and specificity of ∆LW when combined with other commonly used oestrous detection methods was also evaluated. In cows that conceived as a result of service at detected oestrus, liveweight loss began 1 day before the day of detection and was greatest on the day of detection (-9.6 kg, 95% CI -11.3 kg to -7.8 kg; p < 0.01) compared with LW recorded 2 days before the day of detection. In cows that did not conceive to a service at a detected oestrus, the lowest liveweights were recorded 1 day before the day oestrus was detected (-4.3 kg, 95% CI -7.7 to -0.8 kg; p = 0.02) compared with LW recorded 4 days before the day of detection. The sensitivity and specificity of ∆LW as a means of oestrous detection were 0.42 (95% CI 0.40-0.45) and 0.96 (95% CI 0.95-0.97), respectively. When ∆LW was combined with tail paint and visual observation, the oestrous detection sensitivity and specificity were 0.86 and 0.94, respectively. Monitoring LW change holds promise to enhance the sensitivity and specificity of oestrous detection in combination with other oestrous detection methods.

The effects of liveweight loss and milk production on the risk of lameness in a seasonally calving, pasture fed dairy herd in New Zealand.

Dairy herd managers have attempted to increase and maintain profits by selectively breeding dairy cattle for high production. Selection for milk production may have resulted in a tendency for greater liveweight (LW) loss postpartum. This study aimed to: (1) determine if excessive LW loss and milk yield in the first 50 days in milk (DIM) was associated with the development of lameness after 50 DIM, and (2) estimate the incidence risk of lameness in this herd attributable to excessive liveweight loss. The dataset comprised details from 564 mixed age cows from a single, seasonally calving, pasture fed dairy herd in New Zealand. After adjusting for the confounding effects of parity, LW at calving, breed, the presence of specified disease events in the first 50 DIM and milk yield, LW loss in the first 50 DIM increased the risk of lameness after 50 DIM by a factor of 1.80 (95% CI 1.00-3.17). The risk of lameness was greatest for high yielding cows that lost excessive LW (risk ratio 4.36, 95% CI 4.21-8.19), but the effect LW loss on lameness risk at the herd level was relatively small. Based on data accumulated during the study we estimate that for this herd, there would be a 3% (95% CI 1-6%) reduction in the incidence risk of lameness if excessive LW loss was prevented. Twenty three percent of the incidence of lameness in this herd was attributable to excessive LW loss. We conclude that policies and interventions to reduce the rate and amount of LW loss in the first 50 DIM will have a non-negligible impact on the incidence risk of lameness in this herd.

Interval between detection of lameness by locomotion scoring and treatment for lameness: a survival analysis.

Estimates of point prevalence suggest that locomotion scoring identifies three times as many lame cows than when estimated by farmers. The aim of this study was to ascertain the impact of this under-recognition on the interval between identification of lameness (using locomotion score) and treatment. The study was undertaken on a 463-cow, spring-calving, pasture-fed herd in the lower North Island of New Zealand. All cows were locomotion scored (using a 1-5 scale) weekly during one milking season (July 2008 to May 2009). Survival analyses were then used to quantify the number of days between identification of a specific locomotion score and presentation, by farm staff, of a cow for lameness treatment. All cows which had a locomotion score of >3 were presented for lameness treatment subsequently, although >40% were treated more than 3 weeks after being identified. Only 75% of events where cows had a locomotion score of 3 were followed by treatment with >65% of those treatments occurring >3 weeks after the first score of 3. Improving the recognition of lameness by farm staff is thus likely to appreciably reduce the interval between reduced mobility and lameness treatment.

The effect of clinical lameness on liveweight in a seasonally calving, pasture-fed dairy herd.

This study investigated the effect of lameness on liveweight (LW) in pasture-fed dairy cattle. The data comprised 222,446 averaged daily LW measurements from 828 lactations of 542 mixed-age cows in a seasonally calving, pasture-fed New Zealand dairy herd. The LW measurements for individual cows were aggregated into weekly averages and analyses conducted to evaluate the effect of a diagnosis of lameness on LW change after controlling for the effect of week in milk, parity, LW at calving, breed, calendar month, and season. In lame cows, LW decreased for up to 3 wk before lameness was diagnosed and for up to 4 wk after treatment. Total LW loss arising from a single lameness episode was, on average, 61 kg (95% confidence interval: 47 to 74 kg). The results from this study demonstrate how LW records for individual animals can be used to enhance a herd manager's ability to detect lame cows and present them for treatment. The methods presented here show how daily LW monitoring might be used as a tool for early detection of lameness in dairy cattle.

The effect of lameness on the fertility of dairy cattle in a seasonally breeding pasture-based system.

The effect of lameness on the fertility of dairy cattle is well recognized. But, the effect of lameness on the fertility of seasonally breeding cattle in pasture-based systems is less well characterized. This prospective cohort study of 463 cows on 1 farm in the lower North Island of New Zealand was designed to assess the effect of clinical lameness, as identified by farm staff, on the hazard of conception after the planned start-of-mating date. A Cox proportional hazards model with time-varying covariates was used. After controlling for the effect of parity, breed, body weight at calving, and calving-to-planned start of mating interval, the daily hazard of conception for cows identified as lame was 0.78 (95% confidence interval: 0.68-0.86) compared with non-lame cows. Lame cows took 12 d longer to get pregnant compared with their non-lame counterparts.

Does perfusion computed tomography facilitate clinical decision making for thrombolysis in unselected acute patients with suspected ischaemic stroke?

BACKGROUND: Despite use in clinical practice and major positive trials of thrombolysis, non-contrast computed tomography (NCCT) is not sensitive for identifying penumbral tissue in acute stroke. This study evaluated how physiological imaging using CT perfusion (CTP) could add to the diagnostic utility of an NCCT and inform clinical decisions regarding thrombolysis. METHODS: Forty imaging datasets containing NCCT and CTP were retrospectively identified from a cohort of consecutive acute stroke patients. Two sets of observers (n = 6) and a neuroradiologist evaluated the images without knowledge of clinical symptoms. Inter-observer agreement was calculated using the κ statistic for identifying acute ischaemic change on NCCT: perfusion abnormalities (namely cerebral blood volume, cerebral blood flow and time to peak), and penumbral tissue on perfusion maps obtained by two image processing algorithms. RESULTS: Inter-rater agreement was moderate (κ = 0.54) for early ischaemic change on NCCT. Perfusion maps improved this to substantial for cerebral blood volume (κ = 0.67) and to almost perfect for time to peak (κ = 0.87) and cerebral blood flow (κ = 0.87). The agreement for qualitative assessment of penumbral tissue was substantial to perfect for images obtained using the two different perfusion algorithms. Overall, there was a high rate of decision to thrombolyse based on NCCT (81.25%). CTP strengthened the decision to thrombolyse based on NCCT in 38.3% of cases. It negatively influenced the decision in 14.6% of cases, this being significantly more common in experienced observers (p = 0.02). CONCLUSIONS: We demonstrate that the qualitative evaluation of CTP produces near perfect inter-observer agreement, regardless of the post-processing method used. CTP is a reliable, accessible and practical imaging modality that improves confidence in reaching the appropriate diagnosis. It is particularly useful for less experienced clinicians, to arrive at a physiologically informed treatment decision.

Automatic recording of daily walkover liveweight of dairy cattle at pasture in the first 100 days in milk.

Daily walkover liveweight (WoLW) records (n=79,697) from 463 pasture-fed dairy cows from a single dairy herd in the lower North Island of New Zealand were recorded over the first 100 d of lactation. The aims of this study were to (1) describe LW records retrieved by a standalone automatic Wo daily weighing system; (2) describe the frequency and nature of outlier LW records measured by the system and develop an approach for excluding identified outlier LW records; (3) quantify the agreement between cow LW measured using the Wo system and those measured statically; and (4) describe the autocorrelation between daily LW measurements to provide an indication of how frequently management decisions need to be reviewed to effectively monitor cow LW change in the early-lactation period. The standard deviation of daily LW measurements across parities was 17 kg, on average. A near perfect association between LW measured statically and WoLW (concordance correlation coefficient 0.99, 95% CI 0.99-1.0) was observed. After controlling for the effect of LW at calving and long-term LW change using a mixed-effects linear regression model, the autocorrelation between WoLW recorded on successive days was 0.21, decaying to zero by 8 d. This study shows that by using a standalone automatic Wo weighing system positioned in the exit race of a rotary milking parlor, it was possible to record LW of individual cows on a daily basis and, with controlled cow flow over the weighing platform (allowing for sufficient succession distance to prevent congestion), results were similar to those recorded using conventional, static weighing techniques using the same scales. Based on the autocorrelation analyses, we recommend that LW are recorded on a daily basis to allow changes in physiological status such as the onset of acute illness or estrus to be detected. For managerial purposes, such as using LW change as a guide for adjusting the herd feeding program, we recommend a 7-d decision interval to effectively monitor significant changes in cows' recorded daily LW measurements.

Comparison of a camera - software system and typical farm management for detecting oestrus in dairy cattle at pasture.

AIM: To compare the sensitivity, specificity, predictive values and accuracy of detection of oestrus using a novel oestrus detection strip (ODS) and a camera-software device (CSD) with typical farm management practices of visual observation and use of tail paint in dairy cattle at pasture. METHODS: Dairy cows (n = 480) in a seasonal-calving herd managed at pasture under typical commercial conditions in New Zealand were stratified by age, body condition score and days in milk, then randomly allocated to one of two groups prior to the planned start of mating (PSM). Tail paint was applied to all cows and oestrus detected by visual observation of oestrous behaviour and removal of paint, by farm staff. One group (n = 240) was fitted with ODS and also monitored for signs of oestrus using a CSD, while the Control group (n = 240) was monitored using tail paint and visual observations only. Cows detected in oestrus were artificially inseminated (AI), and pregnancy status determined using rectal palpation and ultrasonography, 51-52 days after the end of a 55-day A period. Results of pregnancy diagnosis were used to confirm the occurrence of oestrus, and the sensitivity, specificity, predictive value and accuracy of detection of oestrus compared between oestrus detection methods. RESULTS: The sensitivity and accuracy of oestrus detection in the Control group, using visual observation and tail paint, were low. Compared with the Control group, detection of oestrus using the ODS and CSD resulted in greater sensitivity (85% vs 78%; p = 0.006), specificity (99.6% vs 98.0%; p < 0.001), positive predictive value (PPV; 88% vs 51%; p < 0.001) and overall accuracy (99.0% vs 98.0%; p < 0.001). Negative predictive value (NPV) did not differ significantly between groups (99.4% vs 99.3%; p = 0.28). Pregnancy rate to first service was higher in the CSD group than in the Control group (72% vs 39%; p < 0.05). Use of the CSD significantly increased the cumulative proportion of cows pregnant to AI over the breeding period (p = 0.044). CONCLUSION AND CLINICAL RELEVANCE: The ODS and CSD was satisfactory for detection of oestrus in seasonal calving dairy herds grazing on pasture and could improve the sensitivity and accuracy of detection of oestrus in herds where these are low.

Epidemiological studies of clinical and subclinical ovine mastitis in Awassi sheep in northern Jordan.

Forty-six Awassi sheep flocks selected by stratified random sampling were subjected to a cross-sectional study to determine the prevalence of intramammary infections, to assess the influence of flock size and parity on the prevalence of somatic cell count (SCC) and to identify major udder pathogens. Of the 3472 udder halves examined, 29.8% had over 10(6) SCC/ml and 0.03% had dry teats due to chronic mastitis. Flocks with 30-49 milking ewes (small flock size) were much younger (P < 0.001) than flocks with 50-99 ewes (medium) and flocks with > or = 100 ewes (large). Pairwise analysis of the InSCC of both halves of the udders revealed significant mean differences for small and large flock size (P < 0.05), and for medium and large flock size (P < 0.001). Mean InSCC was lower (P < 0.05) in samples obtained from the left half compared with samples of the right half of the udder. Multiparous ewes had higher (P < 0.001) mean InSCC than primiparous ewes. Also, ewes with twin lambs had higher (P < 0.001) mean InSCC in the right half of the udder compared with single-lamb ewes. Samples collected in January (winter) had lower (P < 0.05) mean InSCC compared with samples collected in June. The most common organisms isolated from subclinical mastitis cases were coagulase-negative Staphylococci (17.8%), E. coli (13.6%), Streptococcus agalactiae (6.8%) and Staphylococcus aureus (6.8%). Of the 46 flocks, 20 were monitored monthly for 9 consecutive months to determine the incidence of clinical mastitis diagnosed by shepherds or/and sheep farmers with major pathogens. The incidence of clinical mastitis (expressed as the number of clinical cases per 100 ewe-months) were 2.1 +/- 1.9 (SD), 1.9 +/- 1.1, and 1.2 +/- 2.1 for small, medium and large flocks size strata, respectively. The overall population estimate was 1.7 +/- 0.02 cases per 100 ewe-months. The most-common clinical isolates were S. aureus (22% of all clinical isolates) and E. coli (14.2%).