Date Published: August 22, 2006
Publisher: BioMed Central
Author(s): C Fossing, M Vaarst, H Houe, C Enevoldsen.
A cross-sectional observational study with repeated observations was conducted on 16 Danish dairy farms to quantify the influence of observer, parity, time (stage in lactation) and farm on variables routinely selected for inclusion in clinical protocols, thereby to enable a more valid comparison of udder health between different herds. During 12 months, participating herds were visited 5 times by project technicians, who examined 20 cows and scored the selected clinical variables. The estimates of effect on variables were derived from a random regression model procedure. Statistical analyses revealed that, although estimates for occurrence of several the variables, e.g. degree of oedema, varied significantly between observers, the effects on many of these estimates were similar in size. Almost all estimates for occurrences of variables were significantly affected either parity and lactation stage, or by both e.g. udder tissue consistency. Some variables, e.g. mange, had high estimates for the farm component, and others e.g. teat skin quality had a high individual component. Several of the variables, e.g. wounds on warts, had a high residual component indicating that a there still was a major part of the variation in data, which was unexplained. It was concluded that most of the variables were relevant for implementation in herd health management, but that adjustments need to be made to improve reliability.
Mastitis control is a major part of dairy herd management. Important components hereof are the daily decisions regarding type of treatment, drying off of affected quarters and culling and replacement of cows. Many of these decisions are based on the dialogue and interaction with the local veterinarian. Approximately 40% of Danish dairy farmers have contracted their local veterinarian to visit the farm on a monthly basis . At these contracted visits the veterinarian is expected to provide the farmer with an overview of potential health problems in the herd, to suggest solutions to these problems, and to make recommendations regarding strategies for monitoring and reduction of expected herd-specific health risks. This applicability of such advice relies heavily on the quality of information collected regarding health and disease status on the individual farm.
The study, set up as a cross-sectional observational study with 5 repeated observations (visits per farm), was executed from January to December 2000
The results of the type 3 F-tests and the analyses of the variance components of farm and individual cow are presented in table 3. This table illustrates the significant terms remaining after reduction of the full model.