Table: Relative weights on traits included in the total
merit index used for selection of Norwegian Red (NRF) bulls.
| Traits |
Relative weight |
| Milk production |
28
|
| Mastitis |
21
|
| Fertility |
18
|
| Udder conformation |
15
|
| Leg conformation |
6
|
| Growth rate |
6
|
| Temperament |
2
|
| Disease other than mastitis |
2
|
| Milkability |
1
|
| Calving difficulty |
0.5
|
| Stillbirth |
0.5
|
NRF cows have a live weight of 550-650 kg (1213-1433 lbs.). Genetic trends for NRF show that selection for increased production and improved animal health and fertility can be obtained simultaneously, if the breeding objective is properly defined, and if the breeding program is designed to include selection for traits with low heritability.
Health, fertility and milk yield
Health and fertility has been included in the NRF breeding program since the 1970’s. The relative weight on these traits in the total merit index has gradually increased over time. With the current breeding program we obtain simultaneous genetic improvements for milk yield, mastitis resistance and female fertility.
Figure 1: Weight on groups of traits (ppt)
Calving traits
Levels of stillbirth and calving difficulty in NRF are low, with an overall mean (all parities) stillbirth rate of about 2%, and 95% of the cows reported to have an easy calving.
Polled
A large proportion of NRF cows are polled. Systematic selection of polled sons from polled elite sires during recent years has increased the frequency of polled animals. It is expected that Norwegian Red will become a polled breed within the next 20-25 years.