In the 1980's the Derbyshire Gritstone began to play an important role as the polling factor on other breeds of horned hill sheep.
The purpose of polling these sheep being twofold: a) to to reduce and eradicate the problems of headfly damage and b) to meet the head skinning requirements of the EEC slaughter regulations. Where tradition retains the local horned breeds with their natural hardiness, the Gritstone ram began to be used as the polling factor.
To this day the Derbyshire Gritstone continues to provide the ideal genetic material as it is polled in both sexes, lives under hill conditions, and is the ideal colour. Though the emphasis on the polling of sheep didn't become prominent until the 80s, some flockmasters in the north of England had been using Gritstone rams with success on their native ewes for many years and many continue to do so today with the demans for Gritstones now spanning the length and breadth of the UK.
The reasoning polling became evermore important was due to the fact that headfly damage is costly, not only in its treatment, but in its wider effects. Affected ewes are ill-tempered and refuse to suckle their lambs with a resultant drop in the lambs' growth. This naturally affects the sale price, particularly of store lambs and buyers will usually expect to pay less for sheep which show signs of headfly damage.
Headfly damage is caused by the sheep, irritated by the flies, rubbing and scratching themselves to make open sores and wounds at the base of the horns. The flies then feed on the blood and sweat of the wounds. The problem peaks during July and August.
Polled sheep do not have the same susceptibility to the problem and, whilst their horned brethren are wasting their time rubbing their horns against the bracken stalks to ease the irritation, they are happily able to go about their business of producing and rearing healthy Iambs. The advantage of polled heads in the abattoirs is quicker throughput and consequent cheaper handling of carcasses.