Heterosis is a bonus that dairy crossbreeding producers can expect in addition to the positive effects of using top A.I. bulls within a breed.
Inbreeding
The global Holstein population has become more inbred over time. Inbreeding is increasing at about 0.1% per year in the Holstein breed. This is causing increased inbreeding depression, especially for mortality, cow fertility, cow health, and survival. As relationships between individuals rise, it becomes more and more likely that bulls and cows that are mated to each other will be closely related. Inbreeding robs dairy producers of income by increasing stillbirths, reducing cow fertility, reducing disease resistance, and shortening herd life. Reducing cow fertility should be a major negative consequence of inbreeding, because highly inbred embryos are not as viable.
Why crossbreeding ?
Concerns about inbreeding are eliminated with crossbreeding. The effects of heterosis are the opposite of the effects of inbreeding depression. The heterosis will be an extra benefit on top to the parent advantage and is especially valuable for traits like vitality, fertility, disease resistance and health.
Effective crossbreeding begins with two superior breeds. These breeds must complement each other well and must independently have a large enough selection base to continue their own unique breeding goals. Bringing together two breeds with desirable genes is called complementarity. A crossbreeding program should be well planned and organized and should use the best bulls from breeds that suit your dairy farm conditions.
NRF for health and fertility
The Norwegian Red (NRF) is a high producing dairy cow that has been selected for health and fertility traits for the past 30 years. The NRF is a breed that decreases costs through lower calf mortality rates, higher female fertility and lower disease incidence. The NRF also carries the polled gene, which reduces calf setbacks and dehorning labour and materials.