29 September 2000

Low-energy silages put cow fertility in danger

DAIRY cow fertility is at risk this autumn because many silages are low in energy. There is also a danger that when trying to compensate for low protein silages, producers will feed the wrong type of protein to their cows, reducing productivity, says Edinburgh University researcher David Whittaker.

Conducting a cow health and fertility clinic at the EDFE, Mr Whittaker explained that metabolic profile results seen at the university were worrying.

"I have seen some poor blood tests so far this season, indicating that cows are low in energy. Many cows are milking well, however, they may be losing condition which will mean they only achieve a 30% conception rate to first service."

But it is more important to serve cows early than chase high conception rates to first service, added Mr Whittaker. "Producers are told by semen sellers to give cows a little longer before they serve them to increase conception rate. However, if calving interval slips and potential milk is lost, that is more costly than delaying service to ensure good conception rates to expensive bulls.

"Serving cows early and improving their nutrition is most important. There are 10,000 litre herds achieving 50% conception rates to first service, so yield should not be used as an excuse for poor fertility."

Balancing silages low in protein will also be a key issue for producers this winter, said Mr Whittaker. "Frequently rumen degradable protein is too low in low protein silages. But feed company sales representatives may advise producers to feed more expensive undegradable protein sources such as soya. Feeding undegradable protein sources such as rapemeal is necessary to correct the imbalance." &#42