98 B
. Heringstad et al. Livestock Production Science 64 2000 95 –106
more important. In addition, few antibiotics are Elleby and Veirup, 1977. The current health-re-
effective against Gram-negative bacteria. For exam- cording system in Denmark started in 1986 and was
ple, coliform mastitis appears to be unaffected by introduced nation-wide in 1990. Recordings are
¨ ¨ ¨ antibiotic treatment Pyorala et al., 1994. Mastitis
primarily made by veterinarians. vaccination can be viewed as an alternative strategy
In Finland, a health-recording system was started ¨
to genetic improvement Rinehart et al., 1996. for all dairy farms in the spring of 1982 Grohn et
However, problems remain in verifying its short- and al., 1986. The veterinarian records the date, diag-
long-term effects. In view of the adaptive nature of nosis, treatment and medicine used on the health
bacteria, it is questionable whether a single vaccina- card. Cases handled over the telephone may also be
¨ tion would offer prolonged protection. Even if
recorded by the dairy farmer Grohn et al., 1986. effective vaccination is available at low costs which
In Norway, a disease recording system was tested may be more cost effective in the short run, genetic
in one part of the country starting in 1970. The improvement has more advantage in the long run.
«health card system» was introduced on a national basis in 1975. Since then, diseases have been re-
corded in most milk-recorded herds in Norway 2.6. Ethics and animal welfare
Solbu, 1983. In 1996, 98 of cows in the milk- recording system were included in the disease-re-
The ethical aspects of disease are related to animal cording system NML, 1997. Each cow has her own
welfare considerations and consumer interests. Con- health card, and only veterinarians record data on
sumer interest in production methods and concern this card.
about animal welfare are growing. In general, con- In Sweden, the recording of disease treatments by
sumers want products produced by healthy animals veterinarians started in a single province in 1971
with as little use of antibiotics or other drugs as ´
Lindhe et al., 1978, and the system was introduced possible. Even if economic losses due to mastitis
on a nation-wide scale in 1984 Eriksson and Wre- could be offset by additional production, ethical
tler, 1987. The veterinarian records the disease considerations might not allow us to ignore the
diagnosis and the ID number of treated animals on a impact of selection for increased production on the
special form and then sends the data to the central health status and general welfare of cows Shook,
data base. 1989; Solbu and Lie, 1990.
3.2. Data and models used for breeding value estimation of mastitis resistance
3. Situation in the Nordic countries
Mastitis resistance is taken into account in Nordic 3.1. Data recording
breeding programmes by including a breeding value for mastitis in the total merit bull index. In Norway,
The Nordic health-recording systems, which have estimated breeding values for mastitis were first
been established over the last 20 years, combine data calculated in 1978, whereas in Sweden, Finland and
from three different sources; veterinary, milk record- Denmark breeding values were first published in
ing and AI records. Each case of a disease treated by 1984, 1986 and 1992 respectively. In the evaluation,
a veterinarian is recorded on a health card Denmark, Denmark uses data from 1990 onwards; Finland and
Finland and Norway or on a special form Sweden. Sweden use data from 1983 onwards, and Norway
The information is then matched against other data in currently uses data only from the most recent batch
the national milk recording system and stored on an of progeny tested bulls.
individual animal basis in a central data bank. The There are some differences between the Nordic
same general methods are used for disease recording countries in the way mastitis resistance is defined, in
in each of the four countries. the statistical models used and in the data used in the
The first health-recording project in the Nordic evaluation Ruane and Klemetsdal, 1996. However,
countries began as a pilot study in Denmark in 1966 in all four countries, breeding value estimation is
B . Heringstad et al. Livestock Production Science 64 2000 95 –106
99
based on a sire model using field records of vet- data, but do no create systematic differences between
erinary-treated cases of clinical mastitis, which is progeny groups.
considered as an all-or-none trait. Cows reported to To summarise, the models and data used for
have had mastitis within a defined period of the breeding value estimation vary slightly between the
lactation, from a few days before calving to about Nordic countries, but they nevertheless have far
the middle of the lactation, are treated as diseased, more in common than they have differences.
and the remainder are considered to be healthy. The period used varies between countries, stretching from
3.3. Nordic breeding programmes 10 days before to 180 days after calving in Denmark,
7 days before to 150 days after calving in Finland, Dairy cattle breeding in the Nordic countries
15 days before to 120 days after calving in Norway, includes a breeding goal with functional traits of low
and 10 days before to 150 days after calving in heritability, such as health and fertility, and is based
Sweden. The main reason for using only a short on progeny testing of large daughter groups. For
period of the lactation is to avoid bias due to culling example, the average size of daughter groups for AI
of cows. In the first part of the lactation the culling bulls in 1992 was 90, 220, 250 and 140 in Denmark,
¨ ¨ ´
rate is low and, according to Syvajarvi et al. 1986, Finland, Norway and Sweden respectively Lindhe,
two thirds of all mastitis treatments occur within two 1995. Participation in the milk and health-recording
months after calving. system is high. For example, in 1996, 90 of the
In Finland and Sweden, the reason for culling dairy cows in Norway were included in the milk-
reported by the farmers is used as an additional recording system NML, 1997. For the Nordic
source of information about mastitis. Cows culled countries, an average of 45 of the milk-recorded
´ due to udder health problems before 150 days after
cows are bred using young bulls Lindhe, 1995. calving are treated as diseased, even if they were not
Hence, most of the dairy cattle population is active recorded as having mastitis. Koenen et al. 1994
in the breeding programme. As a consequence, every found that heritability estimates for mastitis in
year a relatively large number 450 of young bulls Swedish data were significantly higher when in-
of red breeds can be progeny tested with large ´
formation on culling was included. In Denmark and daughter groups in the Nordic countries Lindhe,
Norway, the reason for culling is not used in the 1995. Another characteristic of the Nordic breeding
genetic evaluation. systems is the co-operative cattle breeding organisa-
In Denmark and Sweden, records are used from tions, which are owned by the dairy farmers, and
first-lactation cows, whereas in Finland records are which thus take a longer-term view of cattle breeding
used from the first three lactations. In Norway the and so include non-production traits in the breeding
first lactation is analysed separately, although «re- goal.
peated evaluations» are carried out based on the second- and third-lactation records of daughters of
potential bull sires. Other minor differences with
4. Selection for mastitis resistance
