Modeling of energy balance in early lactation and the effect of energy deficits in early lactation on first detected estrus postpartum in dairy cows.

The general pattern of energy balance in early lactation was modeled. For this purpose, several lactation curves were investigated. The best fitting curve was fit in a random regression model that provided predicted energy balance curves for all lactations. By use of these curves, total energy deficit per lactation, postpartum interval of return to positive energy balance, and nadir of energy balance was determined. In predicted energy balances, nadir of energy balance was present, but variation in postpartum interval to nadir was small. First lactation cows had a smaller energy deficit in early lactation than did older cows. Differences among cows in nadir and total energy deficits in early lactation were large. Both were related to the postpartum interval to first detected estrus with a larger energy deficit and a smaller nadir corresponding to a larger postpartum interval to first detected estrus. From this study, it can be concluded that large energy deficits in early lactation delay first detected estrus.

Relationships between dairy cow mastitis and fertility management and farm performance.

A field study was carried out on 38 dairy farms in the Netherlands to determine the relationship between mastitis and fertility management with 305-day milk production and gross margin. Questionnaires were used to get insight into the farmers' management. Out of 150 variables related to mastitis and fertility management, and technical and economic results, 44 variables were selected based on correlation of > or = 0.25 or < or = -0.25 with milk production and/or gross margin. These variables were used in two separate partial least squares (PLS) analyses. PLS has the advantage that it can handle a large number of variables in relation to the number of cases. The PLS-model of 305-day milk production had R2 = 0.54 and showed a positive relation between 305-day milk production and awareness of the farmer regarding bulk somatic-cell count (BSCC), the goal level of the farmer for BSCC, and hygiene of the milking parlour. Fertility was negatively related to 305-day milk production, in spite of a relatively good fertility management on high-producing farms. R2 = 0.46 for gross margin. The aspiration level of fertility did not seem to affect gross margin, but awareness of BSCC and calving interval (CI) had positive effects. Such awareness seemed a general parameter for good economic results, because it was correlated with different aspects of gross margin.

Estimation of variance components for somatic cell counts to determine thresholds for uninfected quarters.

The objective of this study was to determine the factors affecting somatic cell count (SCC), to estimate variance components of these factors, and to calculate and evaluate the thresholds for intramammary infection based on SCC. The infection status from 22,467 quarter milk samples from 544 cows in seven herds was determined. Infections status was the most important factor affecting SCC. The increase in SCC was more pronounced for major pathogens than for minor pathogens. Even after adjustment for infection status, the interaction between stage of lactation and parity was significant. For culture-negative samples within a lactation, the shape of the SCC curve was inversely related to the shape of the milk production curve. The shape of the SCC curve was flat for first lactation cows compared with the shape of the SCC curve for cows in subsequent lactations. The effect of clinical mastitis on SCC was significant. The use of SCC thresholds for specific parities and stages of lactation to detect intramammary infection improved quality parameters only slightly over a fixed threshold of 200,000 cells/ml.

An analysis of the costs of a hospital-wide Picture Archiving and Communication System with the software package CAPACITY.

Within the scope of the Dutch PACS project, the costs of a hospital wide PACS in the Utrecht University Hospital were estimated, with the help of the software package CAPACITY. The cost analysis was based on the most recent specifications of the costs of the equipment, on extrapolations, and on the experience acquired with a PACS prototype in the Utrecht University Hospital. Savings due to a possible reduction in the length of stay, or due to logistic improvements were not taken into account. The results indicate that the extra costs of a hospital wide PACS would amount to 3.2% of the total hospital budget. By taking into account the expected price movements, it is predicted that a hospital wide PACS may allow enough savings to pay itself back, when installed near the turn of the century. The result of this cost analysis depends on a large number of assumptions. Therefore two sensitivity analyses are carried out, i.e., concerning the number of workstations required and concerning the organizational impact of PACS.

A package for cost and critical analysis of picture archiving and communication indicating its true yield (CAPACITY).

The hospital-wide use of picture archiving and communication systems (PACS) promises a number of advantages in the future. These benefits will only be obtained at considerable costs, however. In view of the rapidly developing technology the costs of hardware can be expected to decrease. The ideas about the expected moment when the benefits will exceed the costs show wide variation. In order to get a better view on the cost comparison between PACS and the classical film-based system and also to stimulate discussions on this topic, a software package called CAPACITY (cost and critical analysis of picture archiving and communication indicating its true yield) has been developed by BAZIS within the scope of its IMAGIS (image information system) project. CAPACITY calculates the costs in the year of introduction for both situations, conventional and PACS, based on the consumption or use of the various resources (e.g. film, optical disks, manpower in the archive, operators, network, workstations etc.) needed for the production of the radiological department. These two costs are calculated for a series of years, thus giving an indication for the moment of breakeven. User-supplied data is interrelated and checked for plausibility against a number of expert given rules of thumb by CAPACITY's critique module. The first results and experiences acquired during a pilot study using a prototype version of the package will be discussed. The CAPACITY package is available for evaluation and trial (only distribution costs will be charged if experiences and results are returned).