Abstract
The aim of the field study was to investigate factors influencing udder health and fertility in fifteen commercial
dairy farms in Schleswig-Holstein (Northern Germany). From January 1997 to December 1998 sterile quarter
foremilk samples of 960 +- 49 lactating cows were collected once monthly for cytobacteriological analysis.
Antimicrobial susceptibility was tested in 791 strains of mastitis pathogens. A clinical examination of the udders
was carried out between the 14th and the 80th day of lactation. Data concerning management, milking routine,
disease frequency and treatments, drying off, calving and culling were recorded every month.
Prevalence of quarters infected with mastitis pathogens was 16.0 % in 1997, slightly increasing to 18.5 % in
1998. Somatic cell count decreased from 78,462 (geometric mean) in 1997 to 70,272 in 1998. Staphylococcus
spp. were the predominant mastitis pathogens with a quarter prevalence of 12.9 % in 1997 and 15.7 % in
1998, resp., followed by Streptococcus spp. with 2.6 % and 2.9 %, resp. In both years less than 1 % of
quarters were infected with other mastitis pathogens including Sc. agalactiae. The percentage of ß-lactamase
producing staphylococci strains decreased from 59.6 % in 1997 to 44.7 % in 1998. The incidence of clinical
mastitis decreased from 4.8 +- 1.4 % per 100 cows and month to 4.4 +- 1.1 % in 1998. During the study 673 of
all recorded 1990 cows (33.8 %) suffered at least once from clinical mastitis, 34.4 % of these cows had at least
two episodes of clinical mastitis.
Throughout lactation 38.9 % of clinical cases of mastitis were observed during the first 50 days post partum.
Somatic cell count of quarters was significantly influenced by herd x season, calving season, parity, stage of
lactation, bacteriological status and milk yield. Udder and teat conformation had little influence on somatic cell
count. Factors with a significant influence on milk yield throughout lactation were herd x season, calving
season, breed, parity, stage of lactation, subclinical and clinical mastitis.
Clinical mastitis was detected in 11.2 % of multiparous and 7.4 % of primiparous cows during the first month of
lactation. The risk of multiparous cows to develop clinical mastitis post partum was increased with higher parity,
with subclinical mastitis before drying off, high prevalence of mastitis pathogens of the herd in the calving
month, high milk yield before drying off and with placenta retention. Primiparous cows had an increased risk to
develop clinical mastitis in the first month of lactation when calving occurred during winter. Greater teat
diameters, diseases during the early puerperium and high mean milk yields in the herd and deep udders were
also associated with an increased risk.
The risk for placenta retention in multiparous cows was higher in cows infected with Streptococcus spp. before
drying off than in cows without infection. Calving during winter, dry periods less than 40 days and high mean
milk yields in the herd were associated with an increased risk for retained placenta.
Mean calving to first insemination interval was 81.1 ? 31.3 days and was significantly influenced by herd x
season, parity, fat and protein corrected milk yield, placenta retention, reproductive and metabolic disorders.
In cows with subclinical mastitis the interval was prolonged by 11.7 days. Mean days open were 104.6. Factors
with significant influence on days open were herd x season, fat and protein corrected milk yield, as well as
reproductive and metabolic disorders. |
