29 December 1995

Observation crucial for heat detection

HOUSING cows at ADAS Bridgets this autumn increased the numbers seen bulling. According to herd manager, Robert Bull, this was due to cows having more time to show signs of heat, better feeding and easier heat detection. "To get good fertility in the autumn, cows need to be fed well before calving and in early lactation," he says. Cows also need adequate loafing area, in a level yard with good traction, to display good signs of heat.

"Good lighting is essential for cows and herdsman. Ideally the cows should have 18 hours good light and six hours subdued light for a normal, stable cycle."

Above all, good observation is vital to achieving fertility targets and this should begin three weeks before serving starts, Mr Bull stresses.

At least four heat detection sessions are needed daily, each lasting half an hour. Cows fail to show signs of bulling at 5am when about to go into the parlour and also for the first hour after feeding. Detection rates will also be poor at midday, as this is the quietest time of day when they lie down and cud. "At Bridgets the first group are observed when they come out of the parlour. At this time the other groups are waiting for milking," he says.

"The next session is at 10am, more than an hour after feeding. Then between 3pm and 4pm cows are observed again, before milking at 4pm. The late evening session at 10pm is most crucial; 70% of cows come bulling between 9pm and 4am."

He recommends fertility courses for inexperienced herdsmen and using pocket diaries to note details of bulling cows. Records should then be transferred to fertility data that is easy to use and understand, helping herdsmen identify cows 42 days after calving, he advises.

Mr Bull also recommends practical breeding aids such as tail paint. By these means, cows that fail to show signs of bulling by 60 days after calving can be presented to the vet promptly.

Early pregnancy diagnosis from scanning cows 30 days after service is also a useful aid to managing fertility. He also suggests monitoring non-return rates for cows served over 24 days – deducting 5% can give a prediction of pregnancy rate. &#42