The endoparasitism challenge in developing countries as goat raising develops from smallholder to commercial production systems: A study from Laos.

Progressing economic development in Southeast Asia has increased regional demand for goat meat, leading to expanding production by smallholders and recently, development of commercial farms. In Laos, an emerging export market for goats into Vietnam has led to increased goat numbers, with potential increases in risk of disease, particularly endoparasitism. A cross-sectional survey investigated the prevalence of gastrointestinal parasites in indigenous Kambing-Katjang goats on smallholder farms (n = 389) in 8 villages where no anthelmintic treatments were in use, providing comparisons with a case study of imported Boer crossbred goats (n = 45) on a commercial farm where intensive anthelmintic treatments were required to manage mortalities attributable to Haemonchosis. Clinical examinations, collection of faecal samples, and pathological examination on the commercial farm, accompanied collection of information on animal gender, age and body weight, with data analyses performed in Genstat. Faecal samples contained eggs of multiple endoparasitic species, with Strongyles spp. and coccidian oocysts of Eimeria spp. most prevalent. Significant associations between the presence of endoparasites and the farm type (smallholder versus commercial; p < 0.008 and 0.001) were observed, with the odds ratios of the commercial farm having Stronglyes spp. and Eimeria spp. of 1.3 (CI = 0.6-2.9) and 4.8 (CI = 2.5-9.1). Mortalities from endoparasitism were only recorded at the commercial farm, with the loss of 24 goats in the final 3 months of the dry season (Feb-April). This study identified a moderate prevalence of multiple endoparasitic species in smallholder goat farms that appeared well-tolerated, whereas in the developing commercial system, endoparasites posed significant risks to enterprise viability, even with use of anthelmintics. Further studies on endoparasite control are required if commercial tropical goat meat production is to prove sustainable and assist in addressing regional food security, plus provide a pathway to improve the livelihoods of Lao goat smallholders seeking to expand and intensify their enterprises.

Haemonchotolerance in West African Dwarf goats: contribution to sustainable, anthelmintics-free helminth control in traditionally managed Nigerian dwarf goats.

West African Dwarf (WAD) goats are extremely important in the rural village economy of West Africa, but still little is known about their biology, ecology and capacity to cope with gastrointestinal nematode (GIN) infections. Here, we summarise the history of this breed and explain its economic importance in rural West Africa. We review recent work showing that Nigerian WAD goats are highly trypanotolerant and resist infections with Haemonchus contortus more effectively than other breeds of domestic goat (haemonchotolerance). We believe that haemonchotolerance is largely responsible for the generally low level GIN infections and absence of clinical haemonchosis in WADs under field conditions, and has contributed to the relatively successful and sustainable, anthelmintics-free, small-scale system of goat husbandry in Nigeria's humid zone, and is immunologically based and genetically controlled. If haemonchotolerance can be shown to be genetically controlled, it should be possible to exploit the underlying genes to improve GIN resistance among productive fibre and milk producing breeds of goats, most of which are highly susceptible to nematode infections. Genetic resistance to GIN and trypanosome infections would obviate the need for expensive chemotherapy, mostly unaffordable to small-holder farmers in Africa, and a significant cost of goat husbandry in more developed countries. Either introgression of resistance alleles into susceptible breeds by conventional breeding, or transgenesis could be used to develop novel parasite-resistant, but highly productive breeds, or to improve the resistance of existing breeds, benefitting the local West African rural economy as well as global caprine livestock agriculture.

Assessment of benzimidazole resistance in Haemonchus contortus in sheep flocks in Ontario, Canada: comparison of detection methods for drug resistance.

In 2011, a field study was conducted to assess drug resistance of gastro-intestinal nematodes in sheep flocks in Ontario, Canada. Benzimidazole resistance in Haemonchus contortus was assessed by genetic analysis of eggs; measurement of resistant allele percentages at codons 167, 198 and 200 in the ß-tubulin gene was determined on pools of H. contortus eggs using pyrosequencing. Susceptibility to benzimidazoles in gastro-intestinal nematodes was also determined using a Faecal Egg Count Reduction Test (FECRT) and a Larval Development Assay (LDA). In total, 16 farms were assessed with the genetic test. Based on resistant allele frequencies, all of the farms (16/16) tested had benzimidazole resistance in H. contortus; the overall percentage of benzimidazole-resistant H. contortus (estimated prior to treatment using the Hardy-Weinberg formula) was 68.5%. The FECRT and LDA were performed on 11 and 13 farms, respectively. Resistance to fenbendazole was detected on 100% (11/11) of the farms where the FECRT was performed. The LDA revealed the presence of thiabendazole resistance in H. contortus in 92% (12/13) of the farms. Estimated percentages of resistant parasites in H. contortus populations obtained with the two biological tests and the genetic test were compared. The results of the genetic test were in agreement with the biological tests and confirmed that benzimidazole resistance in H. contortus is present in Ontario sheep flocks. Differences between the different methods of drug resistance detection are discussed in terms of cost, time and sampling.