5 July 2002


With many herds struggling to improve cow fertility, could

there be a high-tech solution to help? Richard Allison finds

out from two producers, one using progesterone sampling

and the other with activity sensors fitted to cows

USING radio transmitters to track cow activity has allowed one Wilts producer to cut the time needed for routine heat observations and improve cow fertility.

Following advice from independant consultant Peter Kelly, activity sensors were fitted to cow collars at Northleaze Farm, near Swindon after a new parlour was installed, says Robert Mallett. "This has cut time spent watching cows for signs of heat, allowing cow numbers to be increased to 200, while maintaining the same staffing level."

Cow fertility results have improved since introducing the system. He believes heat detection is a greater challenge with a high yielding herd. His herd is currently averaging 9100 litres. "High genetic merit cows are less inclined to show signs of oestrus.

"Since adopting the system last autumn, there has been a half-a-straw reduction in the number of straws/conception, indicating a saving of half a cycle. In addition, the interval between services has reduced from 32 to 26 days, as fewer repeats are being missed."

Both these improvements add up to a potential 18 day reduction in calving interval. This is significant when each one day increase in calving interval costs £2.50/cow, making the total saving £45/cow.

More cows pregnant

The benefits of using activity sensors are most apparent during pregnancy diagnosis sessions. Before the system was used, typically 15-20% of cows scanned were found to be empty, this season only 4% cows presented were negative, says Mr Mallett. But he is cautious whether these improvements can be attributed to adopting cow activity monitoring alone.

Despite this, the DeLaval system should easily pay for itself within three years. The full system costs about £10,000 for 150 collars, sufficient for a 200-cow herd plus followers.

The sensor contains a small metal ball which moves about hitting sensors and the number of movements each hour are counted. This information is then transmitted hourly from the cow to an aerial on the shed roof, which has a range of 80m (260ft), he explains.

When the monitor is unsuccessful in transmitting the information, it stores the data and tries an hour later. The storage of up to 24 hours data is also useful when cows are outside grazing, allowing heat detection outdoors. To ensure maximum data collection, he buffer feeds cows for three hours after morning milking allowing data to be transmitted to the aerial.

Each evening, a report is automatically printed by the computer highlighting which cows have increased activity and are possibly on heat (see graph). Mr Mallett then spends 20 minutes watching animals to confirm bulling.

"Those seen bulling are then inseminated. When there is a clear peak in activity, some cows are served without signs of bulling being observed. But care is needed as some cows can give a false positive heat based on increased activity alone."

This includes cows with a higher activity which subsequent progesterone monitoring and scanning at day 21 reveals they are already pregnant. When Mr Mallett is unsure, milk progesterone monitoring is used to check fertility status. Cows showing no sign of increased activity 80 days after calving are also checked for progesterone levels.

"Changes in environment can also lead to false positive results, such as when cows are moved into another group or have been turned out. Heifers are a particular challenge as their natural activity is higher than cows, probably due to restricted feed intakes. This is solved by reducing the sensitivity of the system."

The system also helps highlight cows with cystic ovaries or those which are not cycling. This helps target vet resources and cystic cows can be treated earlier. With high yielding cows, Mr Mallett does not intervene with non-cycling cows until after day 80 of lactation.

By this time last year, 86 cows were pregnant and this summer there are already 97 confirmed pregnant. If this translates into less barren cows at the end of the year, it will be a great improvement, he says.

"The system is easy to use once you have learnt how to use it and avoid false positives. I couldnt manage my herd fertility without it now."

Benefits of using activity monitors are most apparent during pregnancy diagnosis sessions, with only 4% of tested cows being negative, says Robert Mallett.

&#8226 Easy to use.

&#8226 Little labour required.

&#8226 Reduced semen use.

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