From this survey it is evident that anthelmintics are an integral part of parasite control strategies. However, the gastrointestinal nematode control practices revealed by the survey highlight the need for communication on 'best' dosing practices. Departures from these 'best' practices will encourage the development and spread of anthelmintic resistance. Despite the widely available information on appropriate dosing practices the results indicate a lack of implementation of some of the basics, such as how the dose rate is determined and whether dosing equipment is checked before use. If a sub-optimal amount is administered this will increase the selection pressure for resistant worms [11–15] and result in a poor anthelmintic response, which may in turn select for anthelmintic resistance  and lead to the need for more dosing.
In the current climate of emerging anthelmintic resistance it is clear that parasite control practices that were used in the past and yielded favourable production outcomes in terms of managing parasites must be re-evaluated. Strategies based on suppressive and frequent treatments will select strongly for resistance and do not represent a sustainable approach to parasite control in general. Results on frequency of treatment revealed, unsurprisingly, that ewes and rams were treated less frequently than lambs for gastrointestinal parasites. The treatment frequency in lambs does suggest that a suppressive anthelmintic treatment strategy was being used on the majority of farms. Moreover, the routine treatment of adult sheep needs to be questioned. For instance, ewes pre-mating will generally have a low parasite burden and will not benefit from anthelmintic treatment. As pasture contamination in the autumn/winter will also be lower, treatment of ewes at this time will select for anthelmintic resistance as any worms that survive treatment will have a prolonged reproductive advantage and so become the dominant contributor to infection on pasture . It is now regarded that treatment of ewes pre-mating should be restricted to ewes in poor condition or ewe lambs.
Withholding feed from livestock for 12 hours prior to the administration of an oral benzimidazole or macrocyclic lactone has been reported as a good practice in achieving improved efficacy of these drugs [17, 18]. While 30% of respondents indicated they withheld feed prior to administration of drugs (question did not ask to specify class of drug), the withholding period was not the recommended 12 hours for the majority of respondents. Withholding food for less than 12 hours has minimal impact on anthelmintic efficacy.
Another factor considered to increase the risk of developing resistance on a farm is the inadvertent importation of drug-resistant worms in purchased sheep. The practices of treating and quarantining purchased animals and delaying the move of treated stock to 'clean' pasture are now considered important in curbing the spread of resistance . While almost all farmers (94%) reported that purchased animals were treated with an anthelmintic prior to mixing with the rest of the flock, 68% indicated this would be with the anthelmintic being used in the current year. Up until recently, in light of the high prevalence of benzimidazole resistance, it was recommended that purchased sheep be treated sequentially with macrocyclic lactone and levamisole to minimise the risks involved . With increasing reports of resistance to ivermectin and levamisole and the advent of a fourth class of anthelmintic on the market the advice has become more specific in that moxidectin (3-ML) and monepantel (4-AD) are ideally used as quarantine treatments. While there is no critical evidence to support the proposition that the annual alternation of anthelmintic class slows the development of resistance [11, 19], results from this survey clearly indicate this message has been widely accepted.
In the past 'drench/treat and move' to 'safe' pasture was a globally recommended parasite control practice for lambs [3, 20] which, providing drug efficacy was high, ensured that 'safe' pasture maintained this minimally contaminated status for a longer period thus negating the need for frequent treatment of young livestock. Van Wyk  has questioned the wisdom of this system, indicating that it can hasten the development of resistance as the anthelmintic resistant worms, that have survived treatment, will be the dominant contributor to the population on the 'safe' pasture. Conder and Campbell  state that drench-and-move systems should be considered only on a case-by-case basis and not for widespread use. Today it is commonly listed as a practice to be avoided especially on farms where resistance is a problem [3, 16, 21, 22].
Research results have indicated that improved nutrition (metabolisable protein) enhances the host's resilience to parasites . As an extension to this, one might expect that lambs being fed concentrate are less exposed to parasite challenge and as such should need fewer treatments. In this study, the absence of any evidence for this is probably a reflection of the set approach to treatment used by the majority of respondents. Moreover, it was interesting to note that while the enterprises did differ in the number of livestock units per hectare this did not impact on the number of anthelmintics administered.
Overall, the evidence indicates a need for a greater awareness of the principles that underpin the sustainable use of anthelmintics and the practices that preserve anthelmintic efficacy should be given a very high priority in the design of helminth control programmes on each farm. To this end, the potential of veterinary practitioners and agricultural advisors as sources of information on best practice should be targeted.