Genetic parameter estimates for gastrointestinal nematode parasite resistance and maternal efficiency indicator traits in Santa Inês breed.

Infection with Haemonchus contortus is the most economically important gastrointestinal nematode parasitosis and the most important cause of mortality in sheep production. The aim of this study was to estimate variance components of gastrointestinal parasite resistance traits, maternal efficiency (ME) and ewe adult weight (AW) in Santa Inês breed in tropical conditions. The phenotypic records were collected from 700 animals, belonging to four flocks located south-east and north-east in Brazil. The evaluated traits were as follows: degree of anaemia assessed using the FAMACHA chart (FMC), haematocrit (HCT), white blood cell (WBC), red blood cell (RBC), haemoglobin (HGB), platelets (PLT), faecal egg count (EPGlog ), ME, metabolic maternal efficiency (MME), AW and metabolic ewe adult weight (MAW). From the 700 animals, 576 (82% of the evaluated population) were genotyped with the Ovine SNP12k BeadChip (Illumina, Inc.). Markers with unknown genomic position, located on sex chromosomes, monomorphic, with minor allele frequency <0.05, call rate <90% and with excess heterozygosity were excluded. The variance components were estimated using a single-trait animal model with ssGBLUP procedure. The correlation between the parasite's resistance indicators and the ME suggested that selecting animals with both higher adult weight and ME will also favour the selection of animals with better resistance to gastrointestinal nematodes parasites, specially H. contortus. Therefore, since there are few or no studies with Santa Inês breed in this area, it is important to study those traits to better manage selection programs.

Assessment of oxidative/nitrosative stress biomarkers and DNA damage in Haemonchus contortus, following exposure to zinc oxide nanoparticles.

Drug resistance in helminth parasites has incurred several difficulties to livestock industry and ranked among the top public health concerns. Therefore, seeking for new agents to control parasites is an urgent strategy. In the recent years, metallic nanoparticles have been considerably evaluated for anthelmintic effects. The current research was conducted to assess possible anthelmintic impacts of zinc oxide nanoparticles (ZnO-NPs) on a prevalent gastrointestinal nematode, H. contortus. Moreover, several biomarkers of oxidative/nitrosative stress and DNA damage were measured. Various concentrations of the nanoparticle were prepared and incubated with the worms for 24 hours. The parasite mobility, mortality rate, antioxidant enzymes activities (SOD, Catalase and GSH-Px), lipid peroxidation, total antioxidant status as well as nitric oxide (NO) contents and DNA damage were determined. ZnO-NPs exerted significant wormicidal effects via induction of oxidative/nitrosative stress and DNA damage. Conclusively, ZnO-NPs can be utilized as a novel and potential agent to control and treatment of helminth parasitic infections.

Experimental infection of calves with Haemonchus placei and Haemonchus contortus: Assessment of parasitological parameters.

The present study evaluated the viability and possible effects of Haemonchus contortus infections in experimentally prime infected calves, comparing them to infections by Haemonchus placei. Ten male Holstein newborns were used. All calves were individually weighed for subsequent group formation, in which two animals were kept as a control group, inoculated with water (GI); four animals were inoculated with 10,000 third stage (L3) Haemonchus contortus larvae (GII); and the remaining four calves were inoculated with 10,000 third stage (L3) H. placei larvae (GIII). All experimental animals were necropsied on the 42nd day after inoculation. Based on results obtained by the present study, it can be concluded that bovine calves were susceptible to infections by both Haemonchus species (placei and contortus). H. contortus presented an inferior pre-patent period when compared to H. placei. No significant difference (P>0.05) was observed between Haemonchus burdens recovered from both infected groups (GII and GIII). Moreover, H. contortus females maintained an egg production rate similar to H. placei females in young animals, which can contribute to pasture contamination by both Haemonchus species. This could possibly lead to negative reflexes on helminth control based on a mixed pasture with bovines and ovines, especially when it involves younglings.

Fungal Antagonism Assessment of Predatory Species and Producers Metabolites and Their Effectiveness on Haemonchus contortus Infective Larvae.

The objective of this study was to assess antagonism of nematophagous fungi and species producers metabolites and their effectiveness on Haemonchus contortus infective larvae (L3). Assay A assesses the synergistic, additive, or antagonistic effect on the production of spores of fungal isolates of the species Duddingtonia flagrans, Clonostachys rosea, Trichoderma esau, and Arthrobotrys musiformis; Assay B evaluates in vitro the effect of intercropping of these isolates grown in 2% water-agar (2% WA) on L3 of H. contortus. D. flagrans (Assay A) produced 5.3 × 10(6) spores and associated with T. esau, A. musiformis, or C. rosea reduced its production by 60.37, 45.28, and 49.05%, respectively. T. esau produced 7.9 × 10(7) conidia and associated with D. flagrans, A. musiformis, or C. rosea reduced its production by 39.24, 82.27, and 96.96%, respectively. A. musiformis produced 7.3 × 10(9) spores and associated with D. flagrans, T. esau, or C. rosea reduced its production by 99.98, 99.99, and 99.98%, respectively. C. rosea produced 7.3 × 10(8) conidia and associated with D. flagrans, T. esau, or A. musiformis reduced its production by 95.20, 96.84, and 93.56%, respectively. These results show evidence of antagonism in the production of spores between predators fungi.

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.

Haemonchus contortus: a multiple-resistant Brazilian isolate and the costs for its characterization and maintenance for research use.

The aim of this work was to determine the resistance level of Haemonchus contortus isolated from the Santa Inês flock of the Embrapa (Brazilian government's Agricultural Research Company), Southeast Livestock Unit (CPPSE), as well as to determine costs of characterizing and maintaining this isolate in host donors. Forty-two male Santa Inês lambs were experimentally infected with 4000 H. contortus infective larvae of the field isolate of CPPSE, called Embrapa2010, and divided into six treatment groups, which received triclorfon, albendazol plus cobalt sulfate, ivermectin, moxidectin, closantel and levamisole phosphate, as well as a negative control group (water). Egg per gram (EPG) counts were performed at 0, 3, 7, 10 and 14 days post treatment when the animals were slaughtered for parasite count. The data were analyzed using the RESO statistical program, considering anthelmintic resistance under 95% of efficacy. EPG and worm count presented a linear and significant relation with 94% determination coefficient. The susceptibility results obtained by RESO through both criteria (EPG and worm count) were equal, except for closantel, showing that the isolate Embrapa2010 is resistant to benzimidazoles, macrocyclic lactones and imidazothiazoles. The need of a control group did not appear to be essential since the result for susceptibility in the analyses with or without this group was the same. Suppression in egg production after treatment did not occur in the ivermectin and moxidectin groups. In the control group, the establishment percentage was just 12.5 because of the low number of third-stage larvae, resistance (innate and infection immunity) of the animals studied plus good nutrition. Drug classes presented similar efficacy between adults and immature stages. The costs for isolate characterization were calculated for 42 animals during 60 days. The total cost based on local market rates was approximately US$ 8000. The precise identification of Brazilian isolates and their establishment in host donors would be useful for laboratorial anthelmintic resistance diagnoses through in vitro tests, which has an annual cost of approximately US$ 2500 for maintenance in host donors.