Cattle drenching
[5] Pour-on has, however, been one of the causes of increased resistance to drench products due to the process of back application which once dried allows flies and ticks to become accustomed to the chemical at a low effect level.
[5] Injecting cattle needs to be done carefully as irritation can cause large lumps on the side of the beast and be rendered ineffective.
[9][2] Cattle ticks are found most commonly in warm bush areas and are most prevalent in late spring to early summer.
The fluke lives inside a cow's liver after they have hatched in water or swampy areas and grown.
The health impacts include anaemia, loss of appetite, bottle jaw and liver failure, which can result in death.
[2][11] Liver fluke is most commonly found in areas with high rainfall due to their natural habitat patterns.
[2][13] Small brown worms do not feed on blood but damage the lining of the stomach as they reach adulthood.
[13] In more severe cases they cause death, collapses, weight loss, damage and inflammation of the gut resulting in diarrhoea and scours.
[15] There are a wide range of anthelmintic drugs that can be used however three classes are available for sale on the livestock market including Macrocyclic Lactones, Benzimidazoles and Levamisole.
[16] Macrocyclic lactones (avermectins and milbemycins) are chemical products of soil microorganisms developed in the 1970s/1980s for cattle use.
[14] They have been open to for producers for over 40 years in the commercial form and continue to be effective in expelling parasites even with the increasing resistance issues.
[14] Five types of macrocyclic lactones active ingredients are used: eprinomectin, moxidectin, ivermectin, doramectin and abamectin.
[2] Benzimidazoles are another chemical family which is effective in the eradication of some parasite infections with particular focus on nematodes and trematodes.
[2] All but one benzimidazole product must be administered orally which has led to their reduction in use as pour-on drenches are more popular due to their easy administration.
[2] Levamisole is another chemical that has more impact in expelling the adult parasites in livestock however exhibits less effective rates in reducing larvae.
[2] Levamisole is available for administration by injection, pour-on and oral routes which offers a variety of choice which is found in the commercial chemicals.
[14] In addition, the chemicals used to expel parasites are often still present in faeces that is excreted by cattle the impact of this on the environment comes in a few forms.
[14] In particular, ivermectin from treated cattle is still present in their faeces which reduces the invertebrate colonisation of faecal pats in both numbers and diversity, thus hindering the natural breakdown process.
If the genetic selection becomes a major part of the gene makeup of the colony, then issues arise in controlling and new drenches must be manufactured.
Causing drench resistance is a common occurrence on smaller isolated communities and is an issue for agricultural industries that relies on clean cattle to trade.
