VN October 2021

Vetnews | October 2021 37 Regulars I Zoetis Livestock Column The potential impact of excessive gastrointestinal infection Looking at the above example of the pathogenesis of the brown stomach worm, it is easy to recognise that gastrointestinal helminths can impair normal digestion, disrupt electrolyte balance and lead to a loss of nutrients. 1 In addition to the disruption of normal digestion and tissue damage, the integrity of the tight junctions may be impaired, leading to leakage of enzymes into general circulation. 1 As a result of the pathogenesis of the respective nematodes, expected consequences are loss of appetite, reduced average daily weight gain, decreased productivity and reproductive performance. 1,3,6 Each of these consequences have subsequent economic impacts for the producer. Decreased appetite will naturally lead to reduced weight gain but also inefficient utilisation of pasture. 4 Decreased daily weight gain can have long term side effects and may lead to a higher age at first mating, lowered milk production and lower calf birth weights. 1,3,4 To add to this, many studies have also shown a positive response in milk yield after anthelmintic treatment - milk yield response following treatment in pastured dairy herds can be approximately 1 – 2 kg/cow per day or up to 4 % over an entire lactation, depending on the parity, region and stage of lactation. 1,3,4,6 Excessive helminth infections can also impair the capability of the immune system to fight off concurrent infections or to respond satisfactorily to vaccination, which can also have far-reaching effects. 1 Control An essential aspect of helminth control that is often overlooked is the role that dung beetles can play in decreasing the number of larvae on pastures. An experimental study has shown that dung beetles that bury manure can reduce the number of Ostertagia ostertagi larvae within 96 hours and up to 14.7-fold. 1 Worm burden was also found to be inversely related to the size of the dung beetle population. 1 This is just one of the many reasons why an anthelmintic should not harm the dung beetle population. Cydectin ® , Antiparasitic Pour-On for Cattle, has been shown to have no practical effect on the development and survival of the dung beetle ( Onthophagus Taurus ) when they fed off manure from treated animals. 5 Strategic deworming involves selecting the correct dewormer, applying it at the right time in strategically selected animals and combining it with soundmanagement practices. Healthy, well-nourished animals will have good immunity and will be able to withstand parasite infections better. It is crucial to use dewormers correctly, responsibly and strategically. The key is balance - ensuring that a high proportion of the parasites remain in refugia without adverse effects on the animal’s welfare and production and will help avoid resistant worms from developing. 1,3,4 Cydectin ® Anti-parasitic Pour-On for Cattle is registered for treating roundworms, mange mites, red (biting) and blue (sucking) lice, horn flies and blue ticks of cattle. The residual efficacy against re-infection is excellent at up to 42 days for certain roundworms and 74 days for lice. It also controls blue lice for up to 21 days. A bonus is that the efficacy of Cydectin ® Anti-parasitic Pour-On for Cattle is not adversely affected if applied when the hide is wet or if rain occurs shortly after application. However, the treatment of animals under these conditions is not recommended practice. 7 References: 1. Stromberg BE, Gasbarre LC. Gastrointestinal nematode control programs with an emphasis on cattle. Vet. Clin. Food Anim. 2006;22:543-565. 2. Rapiya M et al . Rotational grazing approaches reduces external and internal parasite loads in cattle. African Journal of Range & Forage Science . 2019; 36(3): 151–159. 3. Charlier J, H ö glund J, Von Samson-Himmelstjerna G, Dorny P, Vercruysse J. Gastrointestinal nematode infections in adult dairy cattle: impact on production, diagnosis and control. Veterinary Parasitology . 2009;164: 70-79. 4. Geurden T et al . A multi-country study to assess the effect of a treatment with moxidectin pour-on during the dry period on milk production in dairy cows. Veterinary Parasitology. 2017;237:104-109. 5. Wardhaugh KG, Longstaff BC, Morton R. A comparison of the development and survival of the dung beetle, Onthophagus Taurus (Schreb.) when fed on the faeces of cattle treated with pour-on formulations of eprinomectin or moxidectin. Veterinary Parasitology . 2001;99:155-168. 6. Murphy AW. The effect of treatment with Moxidectin, a long-acting endectocide, on milk production in lactating dairy cows. World Buiatrics Congress Sydney 1998. 7. Clymer BC, Guerino F, Janes T, BartonW. Evaluation of the wash-off potential of Cydectin Pour-On from cattle following simulated rainfall. American Association of Bovine Practitioners. 1998. FOR ANIMAL USE ONLY Cydectin® Antiparasitic Pour-On for cattle: Reg. No.: G2678 (Act 36/1947). Moxidectin 0,5 % m/v . For full prescribing information refer to the package insert approved by the medicines regulatory authority. Full product information available from Zoetis South Africa (Pty) Ltd., Co. Reg. No.: 2012/001825/07, 6th Floor, North Wing, 90 Rivonia Road, Sandton, 2196. PostNet Suite 53, Private Bag 9976, Sandton, 2146. South Africa. Tel.: +27 11 245 3300 or 0860 ZOETIS (0860 963847). www.zoetis.co.za. Reference No.: RU/CE/07/21/08 v