[Heifer breeding farms as a source for spreading the BVD virus?]

It is well known that, in Switzerland, communal grazing of livestock on alpine pastures plays an important role in the spread of BVD virus. Analogously, we might expect that the communal raising on farms specialising in raising heifers of animals born on different farms would also favour the spread of BVDV. This study investigated whether a persistently infected (PI) breeding heifer kept on this type of farm over a period of 26 months would put the other animals at risk of being infected.The PI-animal was in contact with 75 heifers (here defined as contact animals) on this farm. Thirty-two of the contact animals that were probably pregnant (animals at risk of giving birth to a PI-calf) were moved to 8 different breeding farms (here defined as farms at risk). On these 8 farms, 246 calves were found to be at risk of being infected with BVDV. We examined 78 calves and investigated whether the move of the pregnant animals from their original farm had permitted the virus to spread to these 8 other farms.The contact animals had a seroprevalence of 92% and the animals at risk a seroprevalence of 100%. Only one PI-animal was found on the farms at risk.This BVD infection, however, occurred independently of the PI-breeding animal. Seropositive calves were found only on 2 farms. This study did not provide any proof for a spread of BVDV with the PI-breeding animal as a source; likewise, no persistent infection was proven to exist on the farms at risk. This result is likely to be representative for the endemic situation of BVD in Switzerland. Thus, PI-animals present on heifer raising farms infect calves well before servicing. Hence, no new PI-animals are generated, and the infection becomes self-limiting. When we reconstructed the animal movements between the farms and determined the animals to be examined with the aid of the Swiss national animal traffic database (TVD) we found the data of 37% of the heifers to be incomplete and failed to successfully establish the whereabouts of 3 animals.

[Herd problem: udder health. Retrospective study of farms assessed by the Swiss Bovine Health Service (BHS) from 1999 to 2004]

Data from 59 farms with complaints of udder health problems and insufficient quality of delivered milk that had been assessed by the Swiss Bovine Health Service (BHS) between 1999 and 2004 were retrospectively analysed. Data evaluated included farm characteristics such as farm size, herd size, average milk yield, milking system and housing system, deficits of the milking equipment and the milking practices, and bacteriological results of milk samples from all cows in lactation. The average size of the farms assessed by the BHS was larger than the size of the were evaluated, 42 showed obvious failures which the farm managers could have noticed. Only 5 of the 57 milkers carried out their work according to the generally valid guidelines of the National Mastitis Council. More than 2 basic mistakes were observed in the milking practices of 36 milkers. In 51 farms, mixed infections with several problem bacteria (those present in at least 20 % of the tested cows on a farm) were found. Staphylococcus aureus proved to be the most common problem germ. As the bacteria responsible for the herd problem (the sole problem bacteria detectable on a particular farm) Staphylococcus aureus was detected in 4 farms. The current study revealed that education in the area of milking techniques and milking practices of farmers should be improved in order to reduce the incidence of udder health problems on herd level. Staphylococcus aureus is the most important problem bacteria involved in herds with udder health problems in Switzerland. Staphylococcus aureus might be used in practice as the indicator germ for early recognition of management problems in dairy farms.

Data quality of animal health records on Swiss dairy farms

High-quality data are essential for veterinary surveillance systems, and their quality can be affected by the source and the method of collection. Data recorded on farms could provide detailed information about the health of a population of animals, but the accuracy of the data recorded by farmers is uncertain. The aims of this study were to evaluate the quality of the data on animal health recorded on 97 Swiss dairy farms, to compare the quality of the data obtained by different recording systems, and to obtain baseline data on the health of the animals on the 97 farms. Data on animal health were collected from the farms for a year. Their quality was evaluated by assessing the completeness and accuracy of the recorded information, and by comparing farmers' and veterinarians' records. The quality of the data provided by the farmers was satisfactory, although electronic recording systems made it easier to trace the animals treated. The farmers tended to record more health-related events than the veterinarians, although this varied with the event considered, and some events were recorded only by the veterinarians. The farmers' attitude towards data collection was positive. Factors such as motivation, feedback, training, and simplicity and standardisation of data collection were important because they influenced the quality of the data.