Test-retest repeatability of the National Animal Health monitoring system dairy heifer health report in New York and Pennsylvania, USA

Economic impacts of the mortality rate for suckling pigs in the United States

OBJECTIVE

To measure economic impacts attributable to the mortality rate for suckling pigs in the United States.

DESIGN

Economic analysis that incorporated data from various sources.

SAMPLE POPULATION

Suckling pigs on U.S. swine farms.

PROCEDURE

Economic impacts associated with the mortality rate for suckling pigs during 1995 were estimated from supply-and-demand curves for pork and from an estimate of the elasticity of production for pigs entering the grower-finisher phase of production.

RESULTS

A decrease in the mortality rate for suckling pigs would have caused an increase in pork production and a decrease in price and total value of production. Assuming no suckling pigs had died during 1995, consumer surplus would have increased by (mean +/- SE) 430 +/- 160 million dollars, whereas producer surplus would have decreased by 180 +/- 140 million dollars. The total gain to the US economy would have been 250 +/- 30 million dollars.

CONCLUSIONS AND CLINICAL RELEVANCE

Researchers who attempt to estimate the economic impact of mortality and morbidity rates of livestock should not ignore the influence of demand and the possibility of price adjustments. Consumers would stand to benefit from an increase in pork production associated with a reduction in the mortality rate for suckling pigs, whereas the swine industry would experience an economic loss. Individual producers need to compare the costs of measures intended to reduce the mortality rate for suckling pigs with the anticipated benefits.

Economic impacts of reduced pork production associated with the diagnosis of Actinobacillus pleuropneumoniae on grower/finisher swine operations in the United States

An examination of the economic impacts of the diagnosis of Actinobacillus pleuropneumoniae on grower/finisher swine operations indicated that reduced pork production, associated with the diagnosis of A. pleuropneumoniae on the operation, diminished consumer surplus by $53+/-52 million, and resulted in a total loss of $32+/-30 million to the US economy in 1995. Most of the economic surplus lost by consumers was transferred to producers, whose economic surplus increased by $21+/-25 million (which was not significantly different from zero). Uncertainty analysis showed that an estimate of the decline in production associated with the diagnosis of A. pleuropneumoniae accounted for most of the uncertainty of the change in consumer surplus and of the total loss to the economy. The estimate of the price elasticity of demand for pork also contributed towards a lot of the uncertainty in the estimated change in producer surplus.

A review of approaches to quality assurance of veterinary systems for health-status certification

Regarding national and international trade of animals and animal products, certificates are required to document specific health levels. The credibility of such certificates depends on the quality of the data used to establish the status. Credibility also depends on the quality of the design and protocols used in the data-gathering process (i.e. on the quality of the surveillance-and-monitoring systems (SMS) and on the quality of the veterinary administrative systems (VAdminS)). The major requirements for the assessment of the SMS and VAdminS are: objectivity, accuracy, transparency, practicality, quantitative in nature. To assess the quality of SMS and VAdminS, systems analysis might provide a suitable framework. Systems analysis requires the identification and description of all components of the system-how they interact with each other and with other systems. Graphical methods (e.g. fault trees) are available to support this procedure. To assess the quality of SMS, scoring systems have been suggested. Their main weakness is the inherent subjectiveness. Alternatively, performance indicators (PI) could be used. For the assessment of VAdminS, questionnaires have been developed and applied. Their main limitations are that they focus on the input rather than on the output and that they are purely descriptive in nature. Thus, comparisons between countries are almost impossible. Semi-quantitative questionnaires using scores now are being developed and tested, although their limitations will be similar to those mentioned above. Another approach is the use of risk assessment including standardised data files assembled by countries volunteering to be assessed. This was applied successfully by the European Union (EU) in the geographic risk assessment for bovine spongiform encephalopathy (BSE). In general, the publication and documentation of veterinary systems needs to be encouraged to make them accessible to peer review.

Factors associated with fecal-shedding of Salmonella spp by horses on US operations

In a cross-sectional national study that included 972 operations with > 3 horses on 1/1/98 in 28 states in the USA, 8,417 fecal specimens were collected from horses and cultured to test for the presence of Salmonella spp. Operations were characterized as Salmonella spp-positive if at least one fecal specimen tested positive for Salmonella spp. Percentages of Salmonella spp-positive operations were computed by management and other factors (collected from operation-level questionnaires) that were hypothesized to be related to fecal shedding of Salmonella spp. A logistic-regression model was constructed to identify factors associated with horses’ shedding Salmonella spp in feces on an operation. The odds of an operation being Salmonella spp positive increased as the number of resident horses increased. In addition, the following factors were found to be associated with increased odds of an operation being Salmonella spp positive: horses were used primarily for breeding; operation cleanliness was characterized as poor by the data collector; and new resident equids had been added to the operation without routine quarantine.

Operation-management factors associated with early-postnatal mortality of US foals

Of 7320 equine foals reported born alive during 1997 on 1043 operations that had equids on 1 January 1997, and that participated in the United States National Animal Health Monitoring System (NAHMS) Equine 1998 Study, 120 foals were reported to have died (by either euthanasia or natural causes) within the first 2 days of a live birth. The weighted estimate was 1.7% mortality (standard error=0.5) within the first 2 days of live birth for all foals born on operations in the 28 states included in the study.A multivariable logistic-regression model revealed that foals born in the southern region were more likely to have been reported to have died within the first 2 days of live birth than in the western region. In addition, the following operation-level factors were associated with increased odds of a foal dying within the first 2 days of live birth: not routinely testing newborn foals for adequate absorption of colostral immunoglobulins during the first 2 days of life; adding new resident equids to the operation during 1997; having non-resident equids stay on the operation for 1-30 days during 1997; never requiring an official health certificate (for operations that had non-resident equids stay on the operation for 1-30 days); using something other than straw or hay as the predominant bedding type; and feeding equids a vitamin-mineral supplement/premix with forage and/or grain.

Diagnostic alternatives used by veterinary surgeons for the recording of udder diseases in the Norwegian Health Card System for Cattle

A questionnaire, in which 7 cases of udder disease were described, was distributed to 890 veterinarians in Norway. They were requested to classify the cases according to the diagnostic alternatives listed in the Norwegian Health Card System for Cattle (NHCSC). The NHCSC recordings are used for progeny testing of bulls, for disease monitoring, and for research purposes. The aim of this study was to evaluate the quality of the recordings for udder diseases. The questionnaire was answered by 633 veterinary surgeons. Four cases of clinical mastitis (CM) with abnormal secretion as well as other clinical signs of inflammation were correctly classified as CM by almost 100% of the veterinary surgeons. A cow in the final stage of lactation, showing no clinical signs except for clots in the milk, was considered not to be a clinical case by more than 25% of the veterinary surgeons. A typical case of subclinical mastitis (SM) was reported as SM by 83% of the veterinary surgeons, and as CM by 16%. A subclinical case with a recent history of clots in the secretion was classified as SM by 66% of the veterinary surgeons, but almost 40% either reported CM as their sole diagnosis or considered the case to be CM in combination with SM. Of the clinical cases, those exhibiting marked local signs of inflammation and a systemic reaction were correctly classified as acute clinical mastitis (ACM) by 96%-98% of the veterinary surgeons. In the NHCSC, the diagnostic alternatives for cases of CM are ACM and chronic clinical mastitis (CCM). One case, for which the diagnosis subacute clinical mastitis was appropriate according to standard definitions, was classified as CCM by 66%, and as ACM by 6%. Based on the information given in the questionnaire, the diagnosis for 2 of the clinical cases could have been either ACM or CCM, and for both cases each of these 2 alternatives was reported by more than 43% of the veterinary surgeons. A teat lesion, which was present together with ACM in one cow, was reported by 91% of the veterinary surgeons.

The dependence of kappa on attribute prevalence when assessing the repeatability of questionnaire data

The objective of this paper was to illustrate the dependence of the kappa statistic on the underlying population prevalence of a measured outcome, and the related difficulties in interpreting kappa values for assessing the repeatability of survey data. An example was taken from a test-retest study of the repeatability of a questionnaire administered to dairy producers in Ontario, Canada. Ten producers completed two questionnaires, which contained numerous identical questions. Kappa was used to assess repeatability between the questionnaires for questions with responses which were measured on a dichotomous scale. The magnitude of the kappa statistic is shown to be a function of the prevalence of the trait measured by a question as well as the number of discordant responses.

An analysis of mortality in the grower/finisher phase of swine production in the United States

Over a 6-month period, the mean mortality risk (based on 393 operations participating in the United States National Animal Health Monitoring System 1995 National Swine Study, and representing operations with > or = 300 market hogs in 16 states), was 2.3 +/- 0.2% in the grower/finisher production phase (where figures after the +/- represent the standard error of the estimate). Mortality > or = 4% was experienced by 13.5 +/- 2.9% of grower/finisher operations, while 63.6 +/- 5.3% had < or = 2% mortality. To identify factors associated with > or = 4% mortality, stepwise logistic regression [Statistical Analysis Systems, 1989. SAS/STAT User's Guide, Version 6, 4th edn, Vol. 2. SAS Institute, Cary, NC, 794 pp.] was performed twice: once using operations with all mortality rates, and again excluding operations with between 2% and 4% mortality. Final models were run with SUDAAN [Shah, B.V., Barnwell, B.G., Bieler, G.S., 1996. SUDAAN User's Manual, Version 6.40, 2nd edn. Research Triangle Institute, Research Triangle Park, NC, 492 pp.] to take the sample design into account. In addition, SAS and SUDAAN logistic regression models were developed to analyze factors associated with > 2.3% mortality among grower/finisher pigs. Mean weaning age < or = 28 days entered all models as being associated with increased mortality in the grower/finisher unit. Not obtaining all grower/finisher pigs from farrowing units belonging to the operation was associated with > or = 4% mortality among grower/finisher swine. Not typically giving grower/finisher pigs antibiotics or other agents as disease-preventives or growth-promotants in the feed or water, and ranking producer organizations as very or extremely important sources of antibiotic information were associated with < or = 2.3% mortality in the grower/finisher phase.

An analysis of age and body weight at first calving for Holsteins in the United States

In a national survey of US dairy producers, only 2.7 +/- 0.5% of Holstein dairy operations reported achieving recommended target ranges of age < or = 24 months and body weight (BW) > or = 550 kg at first calving. Allowing for wider target ranges, still only 14.6 +/- 1.3% of Holstein dairy operations reported achieving age < or = 25 months and BW > or = 544.3 kg at first calving. Ages of individual first-calf heifers observed at calving were heavily skewed toward older individuals. Dairy producers reported an average age at first calving that was 1.3 months lower than the mean and 1.0 months lower than median age of first-calf heifers' observed calving on the operations. Stepwise logistic regression was used to identify the herd characteristics associated with producers reporting first calvings within the wider age and BW target ranges for Holsteins. Rolling herd average milk production > or = 7711 kg/yr, using a computer for recordkeeping, and not tying preweaned heifers in a barn with cows, were associated with achieving the target BW and age at first calving.