Disease recording systems and herd health schemes for production diseases

Assessment of on-farm welfare for dairy cattle in southern Spain and its effects on reproductive parameters

In this Research Communication we analyse the animal welfare status of dairy farms located in southern Spain and test the hypothesis that monitoring of wellbeing could increase the profitability of dairy herds by improving indices of reproduction. Twenty dairy farms were visited and a total of 1650 cows were assessed using the Welfare Quality® (WQ) protocol to determine their welfare status. These farms were selected as representatives of the main types of dairy farms found in the south of Spain. No farms attained a welfare status of 'excellent', but all obtained an adequate score for most parameters. Feeding assessment showed relatively low variability among farms, whereas housing and health assessments exhibited high variability. Significant correlations were found between a number of welfare parameter pairings: between percentage of collisions and time needed to lie down; between cleanliness of water points and cleanliness of various animal parts; between farms with access to an outdoor loafing area and an inadequate body condition score and with animal cleanliness; between the frequency of animals lying partly or completely outside of the lying area and the percentage of integument alterations and finally between the presence of respiratory problems and farm hygiene parameters. Furthermore, significant correlations between welfare parameters, reproductive indices and milk production were found. The percentage of cows exhibiting an inadequate body condition score and farms where cows took longer to lie down were correlated with the calving-first insemination interval. Animals showing a higher incidence of coughing and hampered respiration presented lower heat detection rates and milk production and finally farms with dirtier animals had lower milk production. This study is the first step towards including welfare in the recording of routine data in dairy cattle farms in southern Spain.

On-farm deaths of dairy cows are associated with features of freestall barns

On-farm death (OFD) of a dairy cow is always a financial loss for a farmer, and potentially a welfare issue that has to be addressed within the dairy industry. The aim of this study was to explore the associations between OFD of dairy cows, housing, and herd management in freestall barns. To achieve the goal, we followed 10,837 cows calving in 2011 in 82 herds. Data were gathered with observations and a structured interview during farm visits and from a national dairy herd improvement database. The hazard of OFD was modeled with a shared frailty survival model, with SAS 9.3 PHREG procedure (SAS Institute Inc., Cary, NC). The study population was 58% Ayrshire and 42% Holstein cows. The median herd size and mean milk yield in the study herds were 116 cows and 9,151 kg of milk per cow per year. The overall probability of OFD was 6.0%; 1.8% of the cows died unassisted and 4.2% were euthanized. Variation in OFD percentage between individual herds was large, from 0 to 16%, accounting for 0 to 58% of all removals in the herds. Keeping close-up dry cows in their own group was associated with higher hazard of OFD [hazard ratio (HR) = 1.37] compared with keeping them in the same pen with far-off dry cows. Higher hazard on OFD was observed when barns had only one kind of calving pen; single (HR = 2.09) or group pens (HR = 1.72), compared with having both of those types. The hazard of OFD was lower if the whole herd was housed in barns or pens that had only 1 type of feed barrier at the feed bunk, namely post-and-rail (HR = 0.51) or a type with barriers between the cow's heads (HR = 0.49), compared with having 2 types. Lower OFD hazard was observed with wider than 340 cm of walking alley next to the feeding table (HR = 0.75), and with housing a whole herd in pens with only 1 type of walking alley surface, specifically slatted (HR = 0.53) or solid (HR = 0.48), compared with having both types. The hazard of OFD was higher with stalls wider than 120 cm (HR = 1.38) compared with narrower stalls. The hazard of OFD was also associated with breed, parity, and calving season. This study identified many factors that contribute to the incidence of OFD of dairy cows. The solutions for reducing on-farm mortality include housing, management, and breeding choices that are most probably herd specific.

Voluntary monitoring systems for pig health and welfare in the UK: Comparative analysis of prevalence and temporal patterns of selected non-respiratory post mortem conditions

Collection of abattoir data related to public health is common worldwide. Standardised on-going programmes that collect information from abattoirs that inform producers about the presence and frequency of disease that are important to them rather than public health hazards are less common. The three voluntary pig health schemes, implemented in the United Kingdom, are integrated systems which capture information on different macroscopic disease conditions detected in slaughtered pigs. Many of these conditions have been associated with a reduction in performance traits and consequent increases in production costs. The schemes are the Wholesome Pigs Scotland in Scotland, the British Pig Health Scheme in England and Wales and the Pig Regen Ltd. health and welfare checks in Northern Ireland. In this study, four post mortem conditions (pericarditis, milk spots, papular dermatitis and tail damage) were surveyed and analysed over a ten and half year period, with the aim to compare the prevalence, monthly variations, and yearly trends between schemes. Liver milk spot was the most frequently recorded condition while tail damage was the least frequently observed condition. The prevalence of papular dermatitis was relatively low compared to liver milk spot and pericarditis in the three schemes. A general decreasing trend was observed for milk spots and papular dermatitis for all three schemes. The prevalence of pericarditis increased in Northern Ireland and England and Wales; while Scotland in recent years showed a decreasing trend. An increasing trend of tail damage was depicted in Scotland and Northern Ireland until 2013/2014 followed by a decline in recent years compared to that of England and Wales with a decreasing trend over the full study period. Monthly effects were more evident for milk spots and papular dermatitis. Similarity of the modus operandi of the schemes made the comparison of temporal variations and patterns in gross pathology between countries possible over time, especially between countries with similar pig production profile. This study of temporal patterns enables early detection of prevalence increases and alerts industry and researchers to investigate the reasons behind such changes. These schemes are, therefore, valuable assets for endemic disease surveillance, early warning for emerging disease and also for monitoring of welfare outcomes.

Incidence and duration of increased somatic cell count in Swedish dairy cows and associations with milking system type

Mastitis is one of the most costly diseases in dairy cows worldwide. Increased somatic cell count (SCC) is an indication of mastitis, often subclinical, which implies bacterial infection without clinical signs of inflammation. The aim was to investigate the occurrence of elevated udder SCC (defined as ≥200,000 cells/mL) over the lactation period, and before and after the dry period, for cows of different parity. The aim was also to analyze the association between prevalence and incidence of increased udder SCC and information on cow and herd level, such as breed and milking system type. Data were extracted from the Swedish Official Milk Recording Scheme between January 1, 2008, and December 31, 2011, including all herds with a yearly average of >60 cows. The data include descriptive information on herd and cow level and the results from the systematic test milking. The data included the following: for 2009, 239,182 cows in 1,633 herds; for 2010, 251,852 cows in 1,680 herds; and for 2011, 247,746 cows in 1,596 herds. The results show a peak in elevated udder SCC during the late summer season and that the highest proportion of cases occurs during the first lactation month; the latter was most prominent for primiparous cows. Forty-seven percent of all cows with elevated SCC recovered during dry period (went from high to low SCC), whereas 34% of all cows with low SCC before the dry period had an elevated SCC at first testing after calving. For first lactation cows, 19% had an elevated SCC at first test milking. When the outcomes for the 3 consecutive years were reanalyzed, it was confirmed that the effect of fixed factors such as breed, milk yield, and parity did not change over time, whereas the effect of milking system type did. For the incidence of becoming a new case and the prevalence of cows with elevated udder SCC, automatic milking system (AMS) was associated with reduced SCC in 2009 but associated with increased SCC in 2011. Regarding the proportion of new cases of elevated SCC per cow and year, AMS appeared to be a risk factor for all 3 yr, but the effect decreased over time. The shift for AMS from protective to risk factor regarding incidence of new cases and number of recordings with elevated SCC might reflect a change of the AMS population over these years. The findings indicate the need for appropriate udder health management customized to the system.

Descriptive and temporal analysis of post-mortem lesions recorded in slaughtered pigs in New Zealand from 2000 to 2010

AIMS

To complete a retrospective analysis of data from a national abattoir-based lesion recording system (PigCheck) in the New Zealand pig industry, in order to establish the prevalence of 20 post-mortem disease lesions, describe long-term trends in the prevalence of these lesions, and identify the proportion of the monthly variation in lesion prevalence that could be attributed to individual farms or abattoirs.

METHODS

Slaughter lesion data were collected and reported at the lot level (a cohort of pigs delivered from one farm, at one time). Data on the prevalence of lesions between January 2000 and December 2010 was aggregated by month, and time-series analysis of the data for each lesion was conducted. The time series pattern for each lesion was described with an auto-regressive integrated moving average (ARIMA) model; seasonality of lesion occurrence was assessed separately. To determine the proportion of variance in lesion prevalence that could be attributed to farms relative to that attributed to abattoirs, a hierarchical binomial generalised linear mixed model was created incorporating two random effect levels, at the farm (within abattoir) and abattoir levels.

RESULTS

A dataset comprised of 124,407 lots (6,220,664 pigs, 279 farms, five abattoirs) was compiled for analysis. The most prevalent conditions across the 11-year time series were antero-ventral pneumonia (7.6%), pleuropneumonia (11.4%), and milk spots (9.2%). Of the 15 lesions shown to have a significant annual change in prevalence, 10 decreased over time and five increased. The variance in prevalence that was observed for pyogenic lesion (92%), mange (73%), and ileitis (62%) was attributed primarily to variation between abattoirs. By contrast, the farm of origin explained the greatest percentage of variance in prevalence for rectal prolapse (98%), pneumonia (97%), and antero-ventral pneumonia (96%).

CONCLUSIONS

The overall prevalence of most lesions recorded in PigCheck for the period was low relative to published data from other countries. Common lung pathologies contributing to lesions such as antero-ventral pneumonia and pleuropneumonia were primarily a function of farm management and were not likely due to variability in lesion recording at different abattoirs.

CLINICAL RELEVANCE

Based on the low frequency of lesions in pigs at commercial abattoirs, the health status of pigs in the New Zealand pig industry is considered to be very good. Pneumonia, pleurisy, and ascariasis are some of the most prevalent conditions that should be focussed on through development of herd health management plans.

Nordic veterinarians' threshold for medical treatment of dairy cows, influence on disease recording and medicine use: mild clinical mastitis as an example

National databases for dairy cows in the four Nordic countries, Denmark, Finland, Norway and Sweden, have been found to capture varying proportions of disease events on farm. A variation in the thresholds of veterinarians to initiate medical treatment may be a reason for this. Studying these thresholds may increase the understanding of prudent use of antibiotics. The primary objective of this study was to investigate whether Nordic veterinarians, on a between country-level, vary in their intention to start medical treatment of a dairy cow with mild clinical mastitis, on the same day as making the diagnosis. The threshold for initiating treatment was quantified as an intention score. Secondary, underlying behavioural components of the intention score was studied within each country. A social psychology model, the Theory of Planned Behaviour (TPB), was used to design a questionnaire that was distributed to 1047 veterinarians in cattle practice in the four countries during autumn 2010. The response rate was around 50% in all the countries, and 543 observations were retained for analysis. The between-country differences in intention were tested with one-way analysis of variance. Multivariable linear regression was used to estimate the proportion of variability in intention explained by the three behavioural components, attitude, subjective norm and perceived behavioural control. The Spearman rank correlations between specific beliefs about the behaviour and intention scores were estimated to find beliefs of high influence on the decision to treat or not. Intention scores differed between all countries (p<0.05) except between NO and SE (p=0.06). The mean intention scores were 0.71, 0.42, 0.58 and 0.50 in DK, FI, NO and SE, respectively. As measured by the adjusted R(2) in linear regression models, the underlying behavioural components of the TPB explained 0.37, 0.41, 0.40 and 0.48 of the variation in intention scores in DK, FI, NO and SE, respectively. Attitude was the most important predictor in DK, NO and SE, but perceived behavioural control was most important in FI. In all countries the specific attitude belief of highest influence was that starting treatment the same day as diagnosing a case of mild clinical mastitis gives the best result, compared to delaying treatment. The varying intentions of veterinarians to initiate medical treatment are likely to influence centrally registered mastitis incidence. This study has given an improved understanding of this behaviour, which may be useful in intervention studies or campaigns aiming at prudent use of antibiotics on dairy farms.

A longitudinal study of the dynamics of bovine corona virus and respiratory syncytial virus infections in dairy herds

The objective of this study was to examine the dynamics of bovine corona virus (BCV) and bovine respiratory syncytial virus (BRSV) infections in dairy herds over a 3-year period. The status of 79 dairy herds located in two Northern and two Southern Regions of Sweden were surveyed by measuring antibody concentrations to BCV and BRSV in pooled milk samples from primiparous cows, and in bulk-tank milk twice annually. In the Southern Regions the percentage of antibody-positive herds remained persistently high (75-100%), whereas in herds based in the Northern Region, the percentage of positive herds for BCV and BRSV was 38-80% and 0-80%, respectively, with antibody levels to BRSV decreasing over time. Pooled milk samples of 'home-bred' primiparous animals were found to be most useful in terms of monitoring herd status but could gradually be replaced by bulk-tank sampling once freedom from infection was established.

Data quality in the Norwegian dairy herd recording system: agreement between the national database and disease recording on farm

The majority of herds in Norway participate in the national dairy herd recording system. For disease events, this involves transferring information registered on farm, using individual cow health cards (CHC), to the central cattle database (CCD). Before using data from such a database, validation with an aim of describing data quality should be performed, but is rarely done. In this study, diagnostic events from CHC and CCD from 74 dairy herds were compared. Events in 2008 from female cattle with minimum age of 1 yr were included (n=1,738). Discrepancies between the 2 data sources and assessment of data quality were evaluated using agreement between events on CHC and in CCD, calculating completeness and correctness for the CCD, and using a multivariable regression model for agreement (1/0). The agreement evaluation described the concordance between the 2 data sources, whereas the calculations of completeness and correctness depended on a reference data source assumed to be more reliable. Completeness of the CCD was defined as the proportion of diagnostic events on the CHC that was recorded therein. Correctness was defined as the proportion of the CCD events that was also recorded on the CHC, and with the same date and diagnostic code. The agreement was up to 87.5%, the majority of disagreement being caused by unreported events on the CHC (between 10 and 12% of all events). Completeness of the CCD was regarded as high, between 0.87 and 0.88, and correctness excellent, between 0.97 and 0.98. The multivariable regression model found 4 factors that increased the odds for diagnostic events being in agreement between CHC and CCD. These were the events occurring during the 305-d lactation period; the herd size being 75 cows or less; the event occurring during the spring, summer, or winter rather than autumn; and lastly, the diagnostic code for the disease event being preprinted on the CHC, involving a simple check mark as opposed to writing a 3-digit code. The model found a high degree of clustering within herd. In conclusion, disease data in the Norwegian national database for dairy cows are valid to use for epidemiologic research, having in particular an excellent correctness, but it is of concern that at least 10% of data are missing. The proportion of unreported data should be taken into consideration whenever data from this database are used. Reasons for discrepancies found are important to be aware of in any work aiming to improve data transfer from farm to central databases.

Increases in the completeness of disease records in dairy databases following changes in the criteria determining whether a record counts as correct

BACKGROUND

The four Nordic countries: Denmark (DK), Finland (FIN), Norway (NO) and Sweden (SE), all have national databases in which mainly records of treated animals are maintained. Recently, the completeness of locomotor disorder records in these databases has been evaluated using farmers' recordings as a reference level. The objective of the present study was to see how previous estimates of completeness figures are affected by the criteria determining whether a recording in the database is to be judged correct. These demands included date of diagnosis and disease classification. In contrast with the previous study, a period of time between the date of disease recording in the database and by the farmer was allowed. Further, the calculations were brought to bear on individual locomotor diagnoses instead of a common locomotor disease complex code.

METHODS

Randomly selected dairy herds (≥15 cows) were invited to participate. During two 2-month periods in 2008 the farmers recorded the diseases they observed on the farm and their recordings constituted a farmer database (FD). These recordings were compared to disease recordings in the National Databases (ND). Earlier calculations of completeness for locomotor complex cases assuming an exact match on date were compared with ±7 day and ±30 day discrepancies calculated in this study.

RESULTS

The farmers in DK, FIN, NO and SE recorded 426, 147, 97 and 193 locomotor disorders, respectively. When a window of ±7 days was allowed there was a relative increase in completeness figures lying in the range of 24-100%. Further increases were minor, or non-existent, when the window was expanded to ±30 days. The same trend was seen for individual diagnoses.

CONCLUSION

In all four of the Nordic countries a common pattern can be observed: a further increase in completeness occurs when individual locomotor diagnoses recorded by the farmer are permitted to match any locomotor diagnosis recorded in the ND. Completeness increased when both time span and different diagnoses within the locomotor complex were allowed.

Nordic dairy farmers' threshold for contacting a veterinarian and consequences for disease recording: mild clinical mastitis as an example

Previous studies have addressed the differences in registered disease incidence between the Nordic dairy disease recording systems. The main objective of this study was to investigate whether Nordic dairy farmers have varying intention to contact a veterinarian the same day as detecting signs of mild clinical mastitis (MCM) in a lactating dairy cow. This is the first, and necessary, step in the process leading to a disease event being recorded. The second objective was to study underlying behavioural components influencing this threshold for action. A questionnaire-based survey was carried out in Denmark, Finland, Norway and Sweden. The questionnaire was based on the Theory of Planned Behaviour from the field of social psychology. After performing qualitative face-to-face elicitation interviews a set of statements about treatment of MCM was identified. These were grouped into behavioural, normative and control beliefs. The most frequently mentioned beliefs were rephrased as questions. Behavioural intention, a proxy for the behaviour of interest, was assessed using case scenarios. The target and eligible herds were in milk recording and had an average herd size of at least 15 cows. The questionnaire was distributed to 400 randomly sampled dairy producers per included country. The response rate was around 50% in all four countries. The hypothesis of differences in behavioural intention between the countries was tested using Wilcoxon's rank-sum tests. Multivariable linear regression was used to estimate the country-specific variability in behavioural intention as explained by attitude, subjective norm or perceived behavioural control alone, or in combination. The Spearman rank correlations between behavioural intention and each belief, weighted by its outcome evaluation or the motivation to comply, were estimated to find the most important drivers, constraints and social referents for the behaviour of interest. There were significant (p<0.01) differences in behavioural intention between all countries except Denmark and Norway. Swedish farmers had the weakest behavioural intention and Finnish farmers the strongest. Attitude explained most of the variability in behavioural intention in all four countries. The most important driver in all countries was to achieve a quick recovery for the cow. The varying behavioural intention partly explain the differences in completeness of disease data in the Nordic countries: if farmers have different thresholds for contacting a veterinarian the registered incidence of clinical mastitis will be affected. Knowledge about the importance of attitudes and specific drivers may be useful in any communication about mastitis management in the Nordic countries.

Completeness of the disease recording systems for dairy cows in Denmark, Finland, Norway and Sweden with special reference to clinical mastitis

Background

In the Nordic countries Denmark, Finland, Norway and Sweden, the majority of dairy herds are covered by disease recording systems, in general based on veterinary registration of diagnoses and treatments. Disease data are submitted to the national cattle databases where they are combined with, e.g., production data at cow level, and used for breeding programmes, advisory work and herd health management. Previous studies have raised questions about the quality of the disease data. The main aim of this study was to examine the country-specific completeness of the disease data, regarding clinical mastitis (CM) diagnosis, in each of the national cattle databases. A second aim was to estimate country-specific CM incidence rates (IRs).

Results

Over 4 months in 2008, farmers in the four Nordic countries recorded clinical diseases in their dairy cows. Their registrations were matched to registrations in the central cattle databases. The country-specific completeness of disease registrations was calculated as the proportion of farmer-recorded cases that could be found in the central database. The completeness (95% confidence interval) for veterinary-supervised cases of CM was 0.94 (0.92, 0.97), 0.56 (0.48, 0.64), 0.82 (0.75, 0.90) and 0.78 (0.70, 0.85) in Denmark, Finland, Norway and Sweden, respectively. The completeness of registration of all CM cases, which includes all cases noted by farmers, regardless of whether the cows were seen or treated by a veterinarian or not, was 0.90 (0.87, 0.93), 0.51 (0.43, 0.59), 0.75 (0.67, 0.83) and 0.67 (0.60, 0.75), respectively, in the same countries. The IRs, estimated by Poisson regression in cases per 100 cow-years, based on the farmers’ recordings, were 46.9 (41.7, 52.7), 38.6 (34.2, 43.5), 31.3 (27.2, 35.9) and 26.2 (23.2, 26.9), respectively, which was between 20% (DK) and 100% (FI) higher than the IRs based on recordings in the central cattle databases.

Conclusions

The completeness for veterinary-supervised cases of CM was considerably less than 100% in all four Nordic countries and differed between countries. Hence, the number of CM cases in dairy cows is underestimated. This has an impact on all areas where the disease data are used.

Effect of supplemental feeding with glycerol or propylene glycol in early lactation on the fertility of Swedish dairy cows

The aim of this field study was to evaluate the effect of supplemental feeding with glycerol (GLY) or propylene glycol (PG) during early lactation on the fertility of Swedish dairy cows. Within 17 commercial dairy herds, 798 cows were randomized to three groups that were daily fed supplements with 450 g GLY, 300 g PG or nothing (control, C). The supplements were given twice daily during 0-21 days in milk as a top dress on concentrates. Data on calving date, insemination dates, gynaecological examinations, as well as breed, parity and monthly milk yield were collected. From a subset of 308 cows in seven herds, milk samples for progesterone analysis were taken twice weekly and used to determine the time for onset of luteal activity. The effects of supplements on the intervals from calving to first luteal activity (FLA), first AI (FAI) and conception (CON), respectively, were analysed using semi-parametric survival models (Cox proportional hazards models) controlling for the effect of parity, breed, calving season, milk yield and the clustering effect of herd. There was no difference in time to FLA between the cows in group C and in group GLY or PG. No differences in time to FAI or in time to CON were found between cows in group PG and group C. However, cows in the GLY group tended to get their FAI later compared with cows in the control group but without at subsequent delaying of time to CON.

Can pre-collected register data be used to identify dairy herds with good cattle welfare?

Abstract

Risk factors for seropositivity to bovine coronavirus and bovine respiratory syncytial virus in dairy herds

A cross-sectional study was conducted to evaluate the association between herd-level characteristics, management routines and farm-level antibody status of bovine coronavirus (BCV) and bovine respiratory syncytial virus (BRSV) in 257 Swedish dairy herds. The possible spatial clustering of positive herds compared with negative herds was also investigated. For each herd, a pooled milk sample from five primiparous cows was analysed for the presence of antibodies to BCV and BRSV. Herd-level information was obtained by a questionnaire. Logistic regression was used to evaluate the association between predictors and antibody status to BCV and BRSV. Large herd size, being located in southern Sweden, and not providing boots for visitors were found to be associated with being antibody-positive to BCV and BRSV. A short distance to the nearest cattle herd was an additional risk factor for BCV. One of the studied areas was suitable for spatial analysis. Positive herds were not spatially autocorrelated when compared with negative herds as estimated by the K-function regarding both BCV and BRSV. This indicates that local factors such as daily visiting milk trucks and wild animals were unlikely to be important sources of infection in this area. Moran's I statistics and semi-variogram showed no evidence of spatial autocorrelation in the residuals, indicating that remaining unidentified factors are not spatially dependent in the areas under study.

The relationship between antibody status to bovine corona virus and bovine respiratory syncytial virus and disease incidence, reproduction and herd characteristics in dairy herds

Background

Bovine respiratory syncytial virus (BRSV) and bovine corona virus (BCV) affects cattle worldwide. Our objective was to evaluate the effects of these infections on general health and reproduction parameters measurable on herd level and to explore the association between antibody status and some herd characteristics.

Methods

We collected a pooled milk sample from five primiparous cows from 79 Swedish dairy herds in September 2006. The samples were analysed for immunoglobulin G antibodies to BCV and BRSV with indirect enzyme-linked immunosorbent assays. Herd level data from 1 September 2005 to 30 August 2006 were accessed retrospectively. The location of the herds was mapped using a geographical information system.

Results

Ten herds were antibody negative to both viruses and were compared with 69 herds positive to BCV or BRSV or both. Positive herds had a higher (P = 0.001) bulk tank milk somatic cell count (BMSCC) compared with negative herds. The medians for all other analyzed health and reproductive parameters were consistently in favour of the herds negative to both viruses although the differences were not statistically significant. A higher proportion (P = 0.01) of herds used professional technicians for artificial insemination, rather than farm personnel, amongst the 33 herds negative to BCV compared with the 46 positive herds.

Conclusions

Our result shows that herds that were antibody positive to BCV and/or BRSV had a higher BMSCC compared with herds negative to BCV and BRSV. There was also tendency that negative herds had a better general herd health compared with positive. A higher proportion amongst the BCV negative herds used external technicians for AI instead of farm personnel, indicating that it is possible to avoid infection although having regular visits. Negative herds were located in close proximity to positive herds, indicating that local spread and airborne transmission between herds might not be of great importance and that herds can stay free from these infection transmission although virus is circulating in the area.

Associations between bovine coronavirus and bovine respiratory syncytial virus infections and animal performance in Swedish dairy herds

To assess the economic impact of bovine coronavirus (BCV) and bovine respiratory syncytial virus (BRSV) infections, accurate estimates of their associated effects on animal performance are needed. This study aimed to quantify the variation in individual test-day milk yield and somatic cell count, risk of reproductive failure after first service of dairy cows, and risk of death of calves and heifers according to the BCV and BRSV status of the herd. Three types of status were defined for BCV and BRSV infections, based on 1) the dynamics over a 7-mo period of BCV- and BRSV-specific antibody levels in pooled milk of primiparous cows; 2) the possible occurrence of presumably BCV- and BRSV-related clinical outbreaks; and 3) the combination of both pieces of information. A total of 36,184 test days, 2,716 cows with a first service, and 4,104 calves and heifers in 65 Swedish herds were included in the analyses. Animal performance associated with BCV and BRSV infections was quantified using hierarchical mixed generalized and survival models, after adjustment for covariates known to influence the performance under study. A significant reduction in milk yield was observed for cows in presumably BRSV recently infected herds, as well as in herds having a presumably BRSV-related clinical outbreak (of 0.57 and 0.91 kg/d, respectively), compared with cows in presumably infection-free herds. There was also a significant increase in somatic cell count (of 12,000 cells/mL) for cows located in herds with a BRSV outbreak. The risk of failure after first service, as well as the risk of death in calf and heifer, was numerically higher in BRSV-infected herds, although this was not statistically significant. In contrast, BCV infection herd status, as defined in the present study, was not significantly associated with any production losses in animals from infected herds compared with those in infection-free herds.

Using a national dairy database to identify herds with poor welfare

This research project was carried out by the Swedish Dairy Association as part of the development of a ‘Scheme for Animal Welfare’. As a first step, on-farm, animal-based measurements on calves, young stock and cows in 55 randomly selected herds were performed. Nine animal-based measurements formed the basis for a classification of welfare at the herd level: cleanliness and body condition in calves, cows and young stock, in combination with lameness, injuries/inflammations and rising behaviour which were recorded for cows only. The threshold (gold standard) for being a case herd with poor welfare, was a score lying among the worst 10% on two or more of the nine welfare measurements. Thirteen of the 55 herds were cases fitting this criterion. As a second step, 65 potential welfare indicators from seven different focus areas in a pre-collected data register were identified by expert opinion. In the final step, the extent to which suggested potential welfare indicators predicted farms’ risk of having poor welfare according to the definition was assessed. The final set of welfare indicators, taken from the national dairy database, included two fertility measures and calf mortality, and it correctly classified 77% of the herds, with a sensitivity of 0.62. The inclusion of cow and young stock mortality led to it correctly classifying 76% of the herds with a sensitivity of 0.77. We propose that this approach could be useful in helping to allocate advisory services to farms at risk of poor welfare.

Validation of a national disease recording system for dairy cattle against veterinary practice records

In Sweden, morbidity in dairy cattle is monitored through a national disease recording system. This system gives valuable information for research as well as advisory work and genetic evaluation. Our main objective was to evaluate the completeness in the disease recording system. Farm copies of veterinary records (n=851) from 112 herds, from March 2003 to April 2004, were compared with the information registered in the recording system. The evaluation of completeness was performed at two stages: (i) in the raw data transferred from the Swedish Board of Agriculture (SBA) to the Swedish Dairy Association (for records, cases and diagnostic events) and (ii) in the dairy disease database (DDD) at the Swedish Dairy Association (for diagnostic events). The evaluation was stratified by record type: manual and computerized records from state-employed veterinarians and private veterinarians, respectively. The completeness was high both for records (95-100%) and cases (90-99%) except manual records from private veterinarians (76% for records and 74% for cases). The overall completeness for diagnostic events was 75% in the DDD, with significant differences between record types. For all record types other than manual records from private veterinarians, the majority of diagnostic events lost disappeared after registration in the raw data from the SBA. The reasons for loss found suggest that there is potential for improvement. A multilevel logistic regression analysis showed that the completeness of diagnostic events in the DDD depended on region, diagnosis and veterinary employment. The random effect of veterinarian accounted for 35% of the modeled variation. Future studies are needed to assess how the differential misclassification affect estimates based on the data, and how to account for it.

Herd and cow characteristics affecting the odds of veterinary treatment for disease - a multilevel analysis

Background

Research has indicated that a number of different factors affect whether an animal receives treatment or not when diseased. The aim of this paper was to evaluate if herd or individual animal characteristics influence whether cattle receives veterinary treatment for disease, and thereby also introduce misclassification in the disease recording system.

Methods

The data consisted mainly of disease events reported by farmers during 2004. We modelled odds of receiving veterinary treatment when diseased, using two-level logistic regression models for cows and young animals (calves and heifers), respectively. Model parameters were estimated using three procedures, because these procedures have been shown, under some conditions, to produce biased estimates for multi-level models with binary outcomes.

Results

Cows located in herds mainly consisting of Swedish Holstein cows had higher odds for veterinary treatment than cows in herds mainly consisting of Swedish Red cows. Cows with a disease event early in lactation had higher odds for treatment than when the event occurred later in lactation. There were also higher odds for veterinary treatment of events for cows in January and April than in July and October. The odds for veterinary treatment of events in young animals were higher if the farmer appeared to be good at keeping records. Having a disease event at the same date as another animal increased the odds for veterinary treatment for all events in young animals, and for lameness, metabolic, udder and other disorders, but not for peripartum disorders, in cows. There were also differences in the odds for veterinary treatment between disease complexes, both for cows and young animals.

The random effect of herd was significant in both models and accounted for 40–44% of the variation in the cow model and 30–46% in the young animal model.

Conclusion

We conclude that cow and herd characteristics influence the odds for veterinary treatment and that this might bias the results from studies using data from the cattle disease database based on veterinary practice records.

Comparison between dairy cow disease incidence in data registered by farmers and in data from a disease-recording system based on veterinary reporting

Sweden has a national disease-recording system based on veterinary reporting. From this system, all cattle-disease records are transferred to the dairy industry cattle database (DDD) where they are used for several purposes including research and dairy-health statistics. Our objective was to evaluate the completeness of this data source by comparing it with disease data registered by dairy farmers. The proportion of veterinary-treated disease events was estimated, by diagnosis. Disease incidence in the DDD was compared, by diagnosis and age, with disease data registered by the farmers. Comparison was made, by diagnosis, for (i) all disease events and (ii) those reported as veterinary-treated. Disease events, defined as "observed deviations in health, from the normal" were recorded by the farmers during January, April, July and October 2004. For the diagnoses calving problems, peripartum disorders, puerperal paresis and retained placenta, incidence proportions (IP) with 95% confidence intervals (CIs) were estimated. For all other disease problems, incidence rates (IR) were used. In total, 177 farmers reported at least 1 month and 148 reported all 4 months. Fifty-four percent of all disease events in the farmers' data were reported as veterinary-treated. For several of the most common diagnoses, the IRs and IPs for all events were significantly higher in farmers' data than in the DDD. Examples are, in cows: clinical mastitis, cough, gastro-intestinal disorders and lameness in hoof and limb; and in young stock: cough and gastro-intestinal disorders. For veterinary-treated events only, significant differences with higher IR in the farmers' data were found in young stock for sporadic cough and sporadic gastro-intestinal disorders. The diagnosis "other disorders" had significantly more events in the DDD than in farmers' data, i.e. veterinarians tended to choose more unspecific diagnoses than the farmers. This result indicates that the true completeness is likely to be higher than our estimate. We conclude that for the time period studied there was differential under-reporting associated with the diagnosis, the age of the animal and whether the herd was served by a state-employed or private veterinarian.

Supplementation of RRR-α-Tocopheryl Acetate to Periparturient Dairy Cows in Commercial Herds with High Mastitis Incidence

Dietary vitamin E supplementation of dairy cows around calving has been associated with improved udder health. However, few studies have been performed in Europe and in commercial dairy herds. Therefore, the main aim of the study was to evaluate whether extra daily dietary supplementation of 1,610 mg of alpha-tocopherol, in the form of RRR-alpha-tocopheryl acetate, to dairy cows around calving could improve the udder health in commercial herds with a high incidence of veterinary-treated clinical mastitis. In addition, the effects of supplementation on other cow diseases, fertility, milk production, culling, and stillbirth were also studied. Cows in 21 herds in southeast Sweden were assigned to 1 of 2 groups, 1) daily supplementation with 1,610 mg of RRR-alpha-tocopherol from 4 wk before to 2 wk after calving (n = 196), or 2) no extra supplementation (n = 203), on top of the normal diet containing average vitamin E supplementation (on average, 386, 664, and 957 mg/d to cows at 1 mo prior to calving, at calving, and at 15 d after calving, respectively). Multivariable generalized linear mixed models were used for statistical analyses of the effects of supplementation on the cumulative incidence risk of veterinary-treated clinical mastitis and of veterinary-treated diseases other than mastitis within 1 and 2 mo after calving, culling (due to udder health or other reasons) within 2 and 9 mo after calving, the risk of stillbirth or calf death within 24 h after calving, time from calving to first insemination, number of inseminations per service period, and cow composite natural logarithm of somatic cell count and daily milk production at the first monthly testing after calving. A significant effect of supplementation was observed only for stillbirth or calf death within 24 h after birth, which was significantly lower in the supplemented group. The reasons for this finding require further study.

Risk factors associated with the incidence of veterinary-treated clinical mastitis in Swedish dairy herds with a high milk yield and a low prevalence of subclinical mastitis

We conducted a case-control study to investigate factors associated with the incidence rate of veterinary-treated clinical cases of mastitis (IRVTCM) in Swedish dairy herds with the overall objective to reduce the incidence of clinical mastitis (CM) and excessive use of antibiotics. Herds with documented high milk yield, low prevalence of subclinical mastitis and high (27.3-67.5 cases/100-cow years=case) or low (0.0-10.8 cases/100-cow years=control) IRVTCM were selected for this study. One hundred and fifty-eight herds participated. Logistic-regression models were used to assess statistically significant risk factors associated with a high or low IRVTCM. HI-herd farmers more often contacted a veterinarian for treatment of a cow with CM as soon as the milk appearance was altered, compared to LO-herd farmers that more often waited until the general condition of a cow was altered. HI-herd farmers also treated more cows due to high somatic-cell counts during lactation and/or at drying off. There were more high-yielding cows with dirty lower hind-legs, a higher percentage of first-parity cows and a higher incidence of veterinary-treated teat injuries in HI-herds. HI-herd farmers had their cows claw-trimmed more than once per year, compared to LO-herd farmers that had their cows claw-trimmed only once per year, and the condition of silage storage at HI-farms more often had one or more remarks. LO-herds consisted more often of cows of the Swedish Red and White breed, and their roughage diet was more often complemented with only commercial concentrates compared to HI-herds that more often fed grain in combination with commercial concentrates. The herds participating in this study were all well managed herds, and the attitude towards treatment and production seemed to influence the IRVTCM more than environmental factors.

Mortality in Swedish Dairy Calves and Replacement Heifers

The mortality of 8,964 heifer calves born in 122 dairy herds in southwest Sweden in 1998 to 2000 was monitored from January 1998 until December 2000. Farmers were requested to send carcasses for necropsy from animals that died from 1 d of age to first calving. Age and seasonal patterns of mortality were investigated using Kaplan-Meier curves. The median herd-level mortality risk was 2.1%. In total, 3.1% of the animals died before 90 d of age, 0.9% between d 91 and 210, and 2.2% between d 211 and first calving or d 810 (27 mo of age). The median age at death was 50 d and the risk of dying was highest during the first week of life. Of the 421 dead animals, 236 (56%) were subjected to either postmortem examination or were diagnosed as having died from trauma based on information from the farmers. In total, pneumonia was the most common cause of death (27%). However, in calves less than 31 d old, enteritis was the most common cause of death; in young stock 211 to 450 d old, trauma dominated; and in young stock more than 450 d old, trauma and calving-related diseases accounted for a majority of the mortality. The largest proportion of deaths was observed from January to March, and in June. Kaplan-Meier curves suggested that housing in small-group pens was associated with the lowest mortality (other housing systems were single pens and large-group pens with automatic milk feeders), but the association was not significant.

Effects of Housing, Management, and Health of Dairy Heifers on First-Lactation Udder Health in Southwest Sweden

Data on health, management, and housing from birth to first calving were collected for 2,126 heifers on semi-monthly visits made by project veterinarians to 107 dairy herds from southwest Sweden. Additional data were obtained from the official milk- and health-recording program. Factors associated with incidence of veterinarian-treated clinical mastitis (VTCM) in the period 7 d before (d -7) to 30 d after first calving and of elevated cow composite somatic cell count (SCC, > or =200,000 cells/mL) at first test milking after first calving, respectively, were investigated using a 2-level (animal and herd) logistic regression analysis after initial screening by univariate analyses. The incidence risk of VTCM during the complete first lactation (305 d) was 10.8%. Ten percent of the diseased animals had more than 1 case of VTCM and 51% of total cases occurred from -7 to 30 d postcalving. The incidence rate of VTCM during the complete first 305-d lactation was 1.13 cases per 100 cow-mo. In total, 18.1% of the animals had elevated SCC at first test milking (mean 21 d) after calving. Veterinarian-treated clinical mastitis at -7 to 30 d postcalving was associated with higher overall incidence of mastitis in the herd and with reproductive disorders (i.e., retained placenta, endometritis, pyometra, dystocia, or twin birth). The risk of elevated SCC increased with increasing percentage of cows in the herd that, some time during the year, had had an increased udder disease score (chronically increased SCC). Other factors associated with increased risk of elevated SCC were increasing amounts of concentrates fed to 11- to 16-mo-old heifers, moving to confined housing the day of calving instead of earlier, and use of restraint measures at milking. In addition, growth rate from birth to weaning, and several feed-related variables (e.g., amount of concentrates and type of roughage given) were associated with VTCM at -7 to 30 d post-calving or elevated SCC at first test milking in the univariate analyses.

Cumulative risk of bovine mastitis treatments in Denmark, Finland, Norway and Sweden

Data from the national dairy cow recording systems during 1997 were used to calculate lactation-specific cumulative risk of mastitis treatments and cumulative risk of removal from the herds in Denmark, Finland Norway and Sweden. Sweden had the lowest risk of recorded mastitis treatments during 305 days of lactation and Norway had the highest risk. The incidence risk of recorded mastitis treatments during 305 days of lactation in Denmark, Finland, Norway and Sweden was 0.177, 0.139, 0.215 and 0.127 for first parity cows and 0.228, 0.215, 0.358 and 0.204 for parities higher than three, respectively. The risk of a first parity cow being treated for mastitis was almost 3 times higher at calving in Norway than in Sweden. The period with the highest risk for mastitis treatments was from 2 days before calving until 14 days after calving and the highest risk for removal was from calving to 10 days after calving in all countries. The study clearly demonstrated differences in bovine mastitis treatment patterns among the Nordic countries. The most important findings were the differences in treatment risks during different lactations within each country, as well as differences in strategies with respect to the time during lactation mastitis was treated.