9 April 1999

TICKGETSSTICKINCUMBRIA

Ticks are a major concern

on some farms, and one

Cumbria producer takes

drastic action to protect his

flock – and his profits.

Jeremy Hunt reports

WHEN Lake District farmer Eddie Eastham starts buying his 20 new Swaledale tups each autumn he knows they could all become infertile before tupping time in November unless he follows a strict management routine.

Despite his diligence, all new tups being used for the first time at Naddle Farm, Haweswater, can only be turned out with the ewes for two weeks.

The reason for this unusual practice is to reduce the risk of newly purchased rams being bitten by ticks. If rams become severely bitten by ticks prior to tupping time the resulting high temperature caused by the tick-borne fever can quickly render rams infertile.

A large percentage of the land grazed by Naddle Farms 2500 Swaledale ewes is infected with ticks, including the extensive areas of common grazing. Fell land rises to 820m (2700ft) and although this part of the farm poses a tick problem in varying degrees, it is the lower rough-grazing ground – used for tupping and lambing – where tick infestation is most severe.

"We buy about 20 Swaledale shearling tups each autumn and most come from farms that do not have a tick problem so they have no immunity. We have to ensure that rams are not exposed to ticks before we need to use them or we risk them becoming infertile," says Mr Eastham.

Newly bought tups are dipped on arrival at the farm and housed for about six weeks until tupping time in November. They are then turned out with other established flock sires and run at the ratio of one tup to 40 ewes in batches of 100 to 600 ewes.

"As soon as the new tups are turned out with the ewes they are at risk of being bitten and becoming infected with tick-borne fever. We keep a close watch to identify any showing signs of fever and running a high temperature; these are signs that could affect future fertility."

Limiting the new tups to two weeks of work is considered the maximum amount of time that will enable them to work effectively without suffering any adverse effect from tick bites.

"Yes, they probably do get bitten as soon as they are turned out but our experience suggests that they can cope initially. As the days pass and the tups are working harder they obviously start to lose some condition and become more susceptible to the fevers effect.

"If any are clearly looking unwell during the two weeks we withdraw them and treat them with antibiotic."

But Mr Eastham says the biggest risk to the flocks performance comes in the second year when new tups which have been bitten as shearlings and subsequently recovered from the fever could have been rendered infertile.

"Unless you semen test every tup you have no means of knowing. We are working in the dark. One year we did send a batch of tups to be semen tested but the vets found it impossible to get the Swaledale tups to provide a sample of semen. All we were left with was a big vets bill so testing is impractical."

The policy of withdrawing tups after two weeks work appears to be effective and most dont seem to suffer any obvious signs of tick fever even though many will have been bitten.

"Two weeks seems to be the maximum amount of time they can cope. If we left them a third week they would be more susceptible as they are working harder and start to lose condition as they compete with older, experienced rams."

The farm carries 80 tups in total. This number is necessary to provide cover for any tups that may have become infertile through tick bites as shearlings. "If we didnt have to take infertility into account we could run a tup:ewe ratio of one:60, particularly with two shear rams. "

Away wintered

Tups are away wintered but return to the farm in spring. Rams bought as shearlings the previous autumn are kept close to home when they return. "The tick rise can start as early as March so we graze new rams close to the farm to keep an eye on them. They are at risk of being bitten again in April and May but after that they seem to develop sufficient immunity."

Tick control measures at Naddle Farm include treating all ewes pre-lambing in March with either a pour-on or by dipping. Lambs are treated with a pour-on at lambing time and those easily gathered from enclosed land are treated again in early June. All sheep are dipped again at clipping in July and ewes are dipped again in autumn.

Up to 10% of the lamb crop can be affected by the louping-ill virus that is transmitted by the tick and can cause death or leave lambs severely crippled.

"Ideally lambs should be treated at three weeks old but because we have limited in-bye land and we need to move ewes and lambs we tend to treat them with a pour-on when they are about two weeks old and before they are moved off to summer grazing.

"Because of lamb growth rate the amount of pour-on we apply at two-weeks old probably doesnt give protection for long enough.

"Ewes and lambs have to be taken several miles by trailer to their grazing. If we gave a double dose of pour-on we would increase the risk of mis-mothering."

FERTILITY BLIGHTED BY BITES

NORTH Yorks vet Neil Roberts, who runs a practice near Settle, says any fever that causes the temperature in a tup to increase up to 1C (2-3F) can cause infertility.

Mr Roberts, who is involved with the ongoing tick eradication scheme underway on farms in Lancashires Trough of Bowland, says sperm production takes two months.

"Anything that raises the temperature during this time can affect fertility for at least two months. Any rams bitten by ticks which results in a temperature rise at a critical period of the year poses a risk to fertility," says Mr Roberts.

Hugh Reid of the Moredun Institute, a leading expert on ticks, says it may be that ambient temperature has some effect on the virus.

"The virulence of tick-borne fever may be temperature related. In countries where ambient temperatures are 10-15 degrees higher than the UK a tick bite can be more serious to humans. But I have to say the link with temperature may be pure conjecture."

His advice to flock owners facing a possible impact on ram fertility through tick-borne fever is to seek vet advice on treatment with a long-acting antibiotic during the breeding cycle.

"It would prevent the tick-borne fever agent multiplying and prevent infection but rams would be susceptible after treatment ended." &#42

&#8226 Tick-borne fever.

&#8226 Tups can become infertile.

&#8226 Control program vital.

Eddie Easthams new rams only run with ewes for two weeks to cut risk of infertility caused by ticks.