A bull known to have introduced a serious genetic disease to the national dairy herd now looks like a genetic equivalent of "Typhoid Mary" for Holstein Friesian cattle.
The former elite bull, Carlin-M Ivanhoe Bell, is responsible for the spread of bovine leukocyte adhesion deficiency (BLAD) in New Zealand's Friesian cattle.
Two
artificial breeding companies, Livestock Improvement and Ambreed, said the same bull was also thought to be responsible for a genetic defect that produced malformed calves, a higher percentage of abortions, heart and lung disorders and reduced birth-weights.
Carlin-M Ivanhoe Bell was an American bull never used in New Zealand but its descendants' semen was used here, said Livestock Improvement genetic general manager Peter Gatley.
The mutation, known as complex vertebral malformation (CVM), occurred in calves where both parents were carriers of the gene. It caused deformities of the neck, chest, limbs and twisted spines.
The gene that caused CVM was thought to occur only in the Holstein Friesian breed. It was strongly represented in herds with pedigrees traced back to Carlin-M Ivanhoe Bell.
Cows with BLAD had infections that included gingivitis, periodontitis, pneumonia, loss of teeth and stunted growth.
The "heredity disease" was first reported in Denmark and the United States last October.
Livestock Improvement and Ambreed planned to identify carrier cows and screen them out.
Mr Gatley and Ambreed general manager Graham Bowen said they wanted to plan matings which captured the "good" genes from the bulls.
- NZPA
