17 May 1996

Fertility is falling

DAIRY herd fertility is much lower than it was 20 years ago.

Proof is supplied by Scottish Agricultural College research.

The SACs Peter Ball reports an increase in cow infertility in early lactation.

He expected over 90% of cows in a cattle breeding study at Auchincruive, Ayr, to have shown signs of cycling five weeks after calving. But only 68% were cycling normally by that time. Many of the 150 cows, in four dairy herds, had cystic ovaries.

Dr Ball said: "The cows studied showed poor post-calving fertility compared with previous studies in the late 70s and early 80s."

"It would be unwise to draw firm conclusions from our early results, but it looks as though dairy herd fertility is lower than 20 years ago."

He said foetal loss of 20% was now the rule rather than the exception in modern dairy cows. He also confirmed that cows in their fifth lactation or greater were more likely to suffer early embryo loss. Stress such as housing was a key trigger.