Higher Faecal Egg Counts Research Articles

Nemabiome metabarcoding shows a high prevalence of Haemonchus contortus and predominance of Camelostrongylus mentulatus in alpaca herds in the northern UK

Gastrointestinal nematodes (GINs) are a common threat faced by pastoral livestock. Since their major introduction to the UK in the early 1990s, South American camelids have been cograzed with sheep, horses, and other livestock, allowing exposure to a range of GIN species. However, there have been no molecular-based studies to investigate the GIN populations present in these camelids. In the current study, we sampled nine alpaca herds from northern England and southern Scotland and used high-throughput metabarcoded sequencing to describe their GIN species composition. A total of 71 amplicon sequence variants (ASVs) were identified representing eight known GIN species. Haemonchus contortus was the most prevalent species found in almost all herds in significant proportions. The identification of H. contortus in other livestock species is unusual in the northern UK, implying that alpacas may be suitable hosts and potential reservoirs for infection in other hosts. In addition, the camelid-adapted GIN species Camelostrongylus mentulatus was identified predominantly in herds with higher faecal egg counts. These findings highlight the value of applying advanced molecular methods, such as nemabiome metabarcoding to describe the dynamics of gastrointestinal nematode infections in novel situations. The results provide a strong base for further studies involving cograzing animals to confirm the potential role of alpacas in transmitting GIN species between hosts.

Reducing fecal egg count through selective breeding alters dorper lamb response to Haemonchus contortus in an artificial challenge trial

Infection by gastrointestinal nematodes (GIN), particularly Haemonchus contortus, can be detrimental to sheep health and performance. Genetic susceptibility to GIN varies between breeds, with those lacking high levels of natural resistance often requiring frequent anthelmintic treatment when facing parasitic challenge. Genetic technology can serve as a tool to decrease GIN susceptibility via selection for sheep with reduced fecal egg count (FEC) estimated breeding values (EBVs). However, the physiological changes that result from implementation of this strategy are not well described. Additionally, there is a need for comparison of animals from recent selective breeding against breeds with inherent GIN resistance. In this study we administered a challenge of H. contortus to Dorper x White Dorper (DWD; n = 92) lambs that have been genetically selected for either low (DWD-) or high (DWD+) FEC EBVs and Barbados Blackbelly x Mouflon (BBM; n = 19) lambs from a genetically resistant breed backgrounds. Lamb FEC, packed-cell volume (PCV) and serum IgG were measured at intermittent levels over 5 weeks. At day 21 and day 35, the selectively bred DWD- had a lower mean FEC compared to DWD+, but were higher than BBM. Reductions in both PCV and serum IgG from initial day 0 levels were observed in DWD lambs, but not in BBM. Furthermore, from a subset of lambs (n = 24) harvested at day 21, DWD- only tended (p = 0.056) to have lower mean worm counts than DWD+, with BBM having the lowest mean worm count. Differentially expressed genes (DEGs) identified via RNA-sequencing of abomasal tissue at day 21 indicate a more pronounced Th2 immune response and more rapid worm expulsion occurred in iBBM than iDWD- and iDWD+ lambs. However, gene expression in DWD- suggests an association between reduced FEC EBV and gastric acid secretion and the ability to limit worm fecundity. Ultimately, selection of Dorper sheep for low FEC EBV can reduce susceptibility to GIN, but it will likely require multiple generations with this trait as a breeding priority before presenting a similar resistance level to Caribbean breeds.

66 Effect of copper oxide wire particles on parasitism and growth in Katahdin lambs divergently selected for fecal egg count estimated breeding value

Abstract Internal parasites are one of the greatest threats to small ruminant production across the United States and parasitic resistance to anthelmintics continues to increase. Genetic selection and copper oxide wire particles (COWP) are two tools that could help reduce effects of parasites in small ruminants. The objective of this project was to determine the effects and interactions of COWP and genetic selection based on fecal egg count (FEC) estimated breeding value (EBV) on gastrointestinal nematode (GIN) infection and performance in naturally infected Katahdin lambs. Spring-born Katahdin ram lambs (n = 52) selected for extremely high FEC EBV (HighFEC, PFEC EBV = +100%) or low FEC EBV (LowFEC, PFEC EBV = -81%) were managed on a fescue-based pasture at the Southwest Virginia Agricultural Research and Extension Center (Glade Spring, VA). At weaning (June 29), lambs were dewormed with a three-combination treatment and rested for 21 d. At the start of the project (July 18), a random subset of lambs (HighFEC, n = 11; LowFEC, n = 15) were given a 2 g copper oxide wire particle bolus, while an equal number of remaining lambs were managed as controls without a copper bolus. All lambs were managed as one contemporary group. Fecal egg counts, FAMACHA scores, body weights, and packed cell volume (PCV) were measured bi-weekly for 10 weeks. Statistical analysis was performed using PROC Mixed Procedure of SAS (SAS Institute, Cary, NC) and FEC data were log transformed for normality. There were no effects of COWP treatment on FEC (P = 0.18). However, LowFEC-selected lambs had less FEC than HighFEC-selected lambs (230 vs. 565 eggs/g, respectively; P < 0.01). There was no interaction of COWP treatment and FEC genotype (P = 0.37). Copper oxide wire particle treatment had no effect on lamb body weight (P = 0.21), PCV (P = 0.69), FAMACHA score (P = 0.41), or overall ADG (P = 0.12). Lamb FEC genotype did not affect FAMACHA score or overall ADG (P = 0.10 and P = 0.22, respectively). LowFEC-selected lambs had lighter body weights (27.7 vs. 30.6 kg, respectively) and PCV (29.2% vs. 30.4%, respectively) than the HighFEC-selected lambs (P < 0.05). None of the 52 lambs met the requirement for deworming (FAMACHA ≥ 3) during the study. These results indicate that lamb FEC genotype may have a greater effect on parasitism than COWP treatment when given once during the post-weaning period. Even so, multiple tools should be considered, in addition to selection, for an integrated parasite management plan.

PSII-5 Evaluating Haemonchus Contortus Resistance in Hair Sheep Lambs Under Divergent Selection for Reduced Fecal Egg Count

Abstract The gastrointestinal nematode (GIN) Haemonchus contortus is a major threat to global sheep production, a problem exacerbated by increasing levels of anthelmintic resistance. Genetic selection of sheep for reduced fecal egg count (FEC) is hypothesized to improve parasite resistance. This study measured the biological response and worm burden of Dorper x White Dorper (DWD) with high (average = +37.8) or low (average = -12.0) post-weaning FEC estimated breeding values (EBV) and Barbados Blackbelly x Mouflon (BBM) following oral inoculation with 10,000 H. contortus larvae. Lambs (aged 8 months) were grouped by breed and EBV (DWD+, DWD-, BBM) and treatment (inoculated or non-inoculated control) into 6 groups (n = 4/grp). At d 0 and 21, blood samples were collected to measure packed-cell volume (PCV) and serum IgG via enzyme linked immunosorbent assay and at d 21 FEC were additionally recorded. Lambs were subsequently harvested and adult H. contortus counts for each lamb were captured from the abomasum. Data analysis was performed in SAS v 9.4 and significance was set at P < 0.05. In the inoculated lambs, no difference was observed in PCV at d 21, but DWD+ had a greater mean FEC (1,400 + 297 epg) than both DWD- (263 + 167; P = 0.0157) and BBM (50 + 21; P = 0.004). Total serum IgG (ug/mL) was greater in DWD- than DWD+ lambs at both d 0 (686.37 + 50.7 v. 486.15 + 51.25; P = 0.0321) and d 21 (287.16 + 14.33 v. 197.24 + 12.82; P = 0.0034). In BBM, there was no difference in IgG from d 0 (172.80 + 22.44) to d 21 (185.08 ± 4.25). While BBM had reduced IgG at d 0 than both DWD groups, there was no difference between BBM and DWD+ at d 21 (P = 0.4026). Following harvest, inoculated DWD+ had greater worm burden than DWD- (1,330 + 76 v. 818 + 165; P = 0.0308) and both DWD groups were greater than BBM (263 + 120; P = 0.0003). These data confirm previous findings that BBM are more resistant to H. contortus than DWD, and selection for decreased FEC EBV decreased fecal egg output and worm burden within the DWD breed. Future studies will include RNA-sequencing of abomasal epithelial tissue from inoculated and control lambs in an effort to elucidate gene expression differences between divergently selected DWD and BBM sheep infected with H. contortus.

Immune markers in goats selected for reduced gastrointestinal nematode egg count under artificial infection conditions

This study aimed to further investigate the mechanisms responsible for inhibition of gastrointestinal nematode egg production in a line of Scottish Cashmere Goat selected for low faecal egg count. Animals were chosen as the lowest egg producers from a line selected for low egg output (selected group) with a second group from the wider herd based on high faecal egg count as controls. All animals were artificially infected with Teladorsagia circumcincta and Trichostrongylus vitrinus, then treated with anthelmintic and challenge infected prior to euthanasia and post mortem sampling.There was no effect on body weight between groups at any point in the study. Mean faecal egg count was reduced by 68 % in the selected group when compared with the controls. Circulating eosinophil counts were consistently elevated in the selected group, but this was only marginally significant (P = 0.045). Most of the circulating and tissue antibodies (IgG, IgA and IgE) measured were slightly elevated in the selected group but not significantly. Mucosal mast cells, eosinophils and globule leukocyte levels were higher in the abomasal and intestinal tissues in selected animals. Following challenge infection there was no difference in numbers of parasites, however there were more early stage parasite larvae and fewer late stage larvae in the both the abomasum and duodenum of the selected group compared with the unselected group, indicating some inhibition of parasite development.Overall, the study further demonstrated that selection based on low egg count has resulted in a line of goats producing significantly fewer parasites under identical infection with no effect on bodyweight. This appears to be associated with elevation in antibody and effector cells. Some evidence of host inhibition of parasite development was observed in the selected animals.

Biotic potential and pathogenicity of a Haemonchus contortus susceptible laboratory isolate compared to a resistant field isolate in Brazil

The high prevalence of anthelmintic resistance of Haemonchus contortus is threatening sheep farming. In this context, resistant populations’ replacement using susceptible isolates appears to be a strategy to overcome this situation. The aim of the present study was to evaluate the ability of a susceptible H. contortus laboratory isolate in comparison with a multiresistant field isolate to infect lambs and to study its behaviour in field conditions. Sixteen worm-free lambs were experimentally infected with 4000 infective larvae (L3) of a H. contortus anthelmintic-resistant field isolate (Group R, n = 8) or a laboratory isolate susceptible to anthelmintics (Group S, n = 8). Groups were placed in separate clean pastures, where they were kept for 266 days. Faecal egg counts (FEC) showed maximum values between 21- and 42-days post-infection (PI) and decreased over time, with no statistical differences between groups (P > 0.05). The pathogenicity of the isolates was similar, as lambs from both groups showed a decrease in packed cell volume and total plasma protein values in the beginning of the study, coinciding with the highest FECs. Production of L3 were similar for both groups, when evaluating faecal cultures kept in vitro or L3 recovered from pasture samples and from faecal pats collected from the paddocks, which suggests that both isolates have the same potential of development in vitro and in the environment. The degree of resistance/susceptibility to thiabendazole (TIA), levamisole (LEV), monepantel (MON) and ivermectin (IVE) was evaluated using the Larval Development Assay (RESISTA-Test©) 160 days PI. The resistant isolate showed a high resistance factor (RF) to TIA (141), LEV (822), MON (34) and IVE (196), while the RF of the susceptible isolate remained below three, which indicates high susceptibility to all drugs tested. Our study demonstrates that the susceptible isolate was able to infect lambs and did not show higher pathogenicity nor any differences on its biotic potential when compared to the resistant field isolate. These results indicate that the susceptible isolate has the potential to be used to replace a resistant population of H. contortus, which should be validated in long-term studies under commercial sheep farming conditions.

Evaluation of a refugia-based strategy for gastrointestinal nematodes on weight gain and fecal egg counts in naturally infected stocker calves administered combination anthelmintics

Refugia-based strategies associated with a combination of anthelmintic drugs belonging to different drug classes are becoming more common management practices to mitigate anthelmintic resistance (AR) in gastrointestinal nematodes (GIN) in small ruminants. Though refugia-based strategies have been largely demonstrated in small ruminants, cattle veterinarians and producers are considering such management strategies in grazing cattle production systems. Implementing refugia-based strategies lowers the amount of anthelmintics used in the herd and therefore slows the progression of AR by allowing a proportion of worms to escape drug selection pressure. The objective of this study was to observe the effect of a refugia-based strategy on body weight (BW), average daily gain (ADG) and fecal egg counts (FEC) of trichostongyle-type nematodes in naturally infected beef calves over a 131-day grazing season when compared with a whole herd treatment strategy, using the same combination of drugs. Stocker calves (n = 160) were ranked by body weight within sex then allocated to 16 paddocks, which were randomly assigned to one of two treatment groups. All calves in Group 1 (n = 80) were administered treatment, while in Group 2 (n = 80) the steer with the highest FEC in eggs per gram (EPG) within the paddock was left untreated. Treated calves received an extended release injectable 5 % eprinomectin (LongRange®, Boehringer Ingelheim Animal Health USA Inc.; 1 mL/50 kg of BW) and a 22.5 % oxfendazole oral suspension (Synanthic®, Boehringer Ingelheim Animal Health USA Inc.; 1 mL/50 kg of BW). Fecal egg counts and BW were recorded on days (D) −35, 0, 21, 131, and 148 to calculate the average fecal egg count reduction (FECR) and ADG for both groups. Linear mixed models, with paddock as the experimental unit, were used for analyses. The EPG differed on D21 (p < 0.01) and D131 (p = 0.057) with Group 2 having a higher average FEC (15.2 EPG D21; 57 EPG D131) compared with Group 1 (0.4 EPG D21; 37.25 EPG D131). However, there was no significant difference in average BW or ADG between treatment groups throughout the study. Results suggest refugia-based strategies could be implemented without significant negative impacts on average BW and ADG across other calves in the herd.

Effect of sire fecal egg count estimated breeding value on Katahdin lamb parasite resistance in pasture-based system

Significant genetic variability exits within sheep breeds for gastrointestinal nematode (GIN) resistance. Therefore, selection may be an important tool to combat anthelmintic resistance in GIN populations. To better understand the effect of selection based on the fecal egg count (FEC) estimated breeding value (EBV) on lamb GIN resistance in a pasture-based system, a divergent mating scheme was established. Over two years, Katahdin rams with exceptionally high (High FEC; n = 5) or low (Low FEC, n = 5) FEC EBV were mated to random groups of Katahdin ewes at the Southwest Virginia Agricultural Research and Extension Center (Glade Spring, VA). Lambs were born mid-March and managed as one contemporary group (Weaning: June 4). In Year 1 (YR1), FEC was collected on all lambs June 26 with no prior anthelmintic treatment. In Year 2 (YR2), beginning at 60 days of age, body weights and FAMACHA scores were collected weekly and FEC biweekly. Anthelmintic administration occurred based on FAMACHA ≥ 3 in YR2. Lamb survival determination excluded first 7 days of age. Statistical analysis was performed using SAS (SAS Institute, Cary, NC) with fixed effects of sire type. Lamb FEC EBV corresponded to sire type validating the mating scheme. Lamb FEC was similar and variable prior to and shortly after weaning. After this point, High FEC-sired lambs had greater FEC compared to Low FEC-sired lambs (P < 0.05) and anthelmintic treatment corresponded to FEC EBV type (P < 0.05). In YR1, death losses were greater for High FEC-sired lambs (P < 0.05) and those lambs that died had greater FEC EBV than those that survived (P < 0.05). In YR2, post-weaning FEC EBV difference between High FEC-sired lambs that survived to 120 days of age and those that died was significant (73% vs. 138%, P < 0.01). Therefore, selection for improved GIN resistance using FEC EBV is effective and the FEC EBV is also associated with lamb survival in a pasture-based system.

48 Disrupting hindgut microbiota through the diet alters strongyles infections in horses

Although little is known in horses, interactions between gut microbiota and intestinal parasites have been suggested in other species. Understanding how diet may affect these relationships could be a lead in the search for alternative anthelmintic solutions. In horses, the forage/cereal ratio can substantially influence the composition and functions of the hindgut microbiota. Additionally, polyphenols could carry natural anthelmintic activity. This study aimed at evaluating the effect of high-fiber or high-starch diets on the intestinal microbiota and strongyle infection in horses, and the impact of supplementation with sainfoin, a polyphenol-rich plant. Twelve naturally infected adult geldings (7 ± 2 years old,515 ± 53 kg BW) were enrolled in a 4 periods × 4 treatments Latin square design. Groups were formed based on fecal egg count (FEC) before the trial, age, and bodyweight. Experimental periods lasted 21 d (D0 to D21) and were separated by 21 d wash-out periods. The 4 iso-energy, iso-protein treatments consisted in high-fiber (HF; 18.5g DM hay/kg BW) or high-starch diets (HS; 8.0g DM hay+6.3g DM barley/kg BW; 1.9g starch/kg BW/meal), to which were added either control pellets (CONT; 3.1g DM sunflower meal+hay/kg BW) or sainfoin pellets (SF; 3.1g DM Equifolia [Multifolia]/kg BW). Feces were collected on D0, D7, D14, and D21 to assess strongyles excretion through FEC, and on D21 to investigatebacterial diversity and composition using both culture and sequencing technics. Mixed effect models were used to evaluate the effect of the day, the diet and supplementation on these parameters. A day*diet*supplementation interaction was found for FEC (P < 0.001): FEC did not differ between groups at D0, but horses fed the treatment HS CONT had higher FEC than the others at D21 (P < 0.01). Horses fed diet HS had a lower bacterial diversity (Shannon index; P = 0.03), higher relative abundances of Proteobacteria and Succinivibrionaceae (P < 0.01), and lower relative abundance of Lachnospiraceae (P < 0.001) than the horses fed diet HF. The Bacteroidota and Prevotellaceae were more abundant in horses supplemented with sainfoin (P < 0.01). Horses fed diet HS had a lower concentration of cellulolytic bacteria and higher concentrations of amylolytic and lactate-using bacteria (P < 0.001) than horses fed diet HF. These results show that diet and addition of sainfoin can impact both the hindgut microbiota and the intestinal parasitism in horses, which suggests existing relationships between them. Further microbiome analyses may provide data on the effects of specific bacterial taxa or microbial functions on intestinal parasitism.

Occurrence and control of equine strongyle nematode infections in Prince Edward Island, Canada.

Widespread overuse of anthelmintics has produced a growing population of intestinal parasites resistant to control measures. A paradigm shift in equine parasite control is warranted to prevent continued resistance development and maintain equine health. Small strongyles, which are ubiquitous in horses, are currently the most important intestinal parasites of adult horses. Sustainable management programs consider the variation in egg shedding by individual horses, and varied risks associated with age, use, density, climate, and environment. To develop regional recommendations for Prince Edward Island (PEI), Canada, it is important to first characterize strongyle egg shedding patterns and parasite management practices in use. Study objectives were to conduct a cross-sectional observational survey and risk factor analysis of parasite control programs, strongyle egg shedding and Strongylus vulgaris serology. A total of 339 horses from 40 PEI farms were sampled. Mean farm size was 8 horses and ranged from 2 to 30. Mean horse age was 11.6years (Std. Dev. =7.2) and ranged from 2months to 32years. Mean fecal egg count (FEC) was 322 eggs per gram (EPG) (Std. Dev. =648). On average, 32% (Std. Dev. =16%) of horses shed 80% of strongyle eggs across 32 eligible farms. When considering all horses (n=313) as one large herd, 18.7% of horses shed 80% of strongyle eggs. Use of FEC was identified in 4.6% of horses at 15% (n=6) of PEI farms. Reported deworming intervals included 37.4% (n=123) every 2-3months and 58% (n=191) every 3-4months. Positive S. vulgaris titers were identified in 60% of horses (n=200). Univariate analysis revealed that months since last deworming, age, and body condition score (BCS) were associated with strongyle shedding. The estimated odds of being in the high FEC category (>500 EPG) was 1.4 (95% CI, 1.1-1.8) times higher when last deworming increased by one month. Under-conditioned (BCS <4.5) horses had 3.6 (95% CI, 1.2-10.6) times odds of being in the higher FEC category than over-conditioned horses. Non-racing horses had 5.4 times odds of having a positive S. vulgaris titer than racehorses. This cross-sectional observational study is the first to report on the occurrence, risk factors and control of equine strongyle nematode infections in PEI, Canada. We conclude that the 80:20 rule can be used to develop control recommendations in PEI. Very few farms in PEI currently use FEC to guide parasite management. These findings provide a basis for future client education and investigations aimed at providing region specific recommendations.

STUDIES ON THE PREVALENCE OF GASTRO-INTESTINAL NEMATODES IN RUMINANT ANIMALS SLAUGHTERED IN BIU LOCAL GOVERNMENT ABATTOIRS, BORNO STATE, NIGERIA

An epidemiological study was conducted from September-November, 2022 on the prevalence of gastrointestinal nematodes species among naturally infected ruminants slaughtered in Biu Local Area of Borno state, using centrifugal flotation techniques. Out of three hundred and eighty four (384) ruminants (162 goats, 110 sheep and 112 cattle) examined in the three selected abattoirs (Biu, Maringa and Buratai), 239 (62.34%) were infected. Maringa had the prevalence rate of 64.65%, Biu 63.89% and Buratai 63.16%. Although the highest faecal egg counts was recorded in Cattle 66.07%, the difference in prevalence rate between the different location and species of the animal were statistically insignificant p&lt;0.05. The parasites identified were Ascaris lumbricoides 33.81%, Ancylostomidae spp 30.93%, Trichosrongylus spp 16.54%, Strongyloides stecoralis 11.27%, Haemonchus contortus 5.51%, and Entoribius vermicularis 1.91%. Fulani cattle breed had the prevalence rate of 20 (71.43%), Wad Sheep 45 (66.18%) and West African Dwarf goat 80 (65.57%). The difference in prevalence rate between the different breed of all the animals were not statistically significant p&lt;0.05.The prevalence rate was 47 (72.31%) in male goats, 20 (41.67%) sheep and cattle 31 (67.39%) whereas female counterparts had 50 (51.55%), 48 (77.41%) and 43 (65.15%) in goat, sheep and cattle respectively. Both young and adults were infected with GI nematodes. Gastrointestinal nematodes are endemic in the study area. Therefore, mass administration of anthelmintic drugs, regular vaccination as well as educating the livestock’s farmers toward insuring production of healthy meat and improvement of their welfare is required to control the parasite in the study areas.

Effect of sire fecal egg count estimated breeding value on parasite resistance traits in Haemonchus contortus infected Katahdin lambs

In the midst of anthelmintic resistance, genetic resistance to gastrointestinal nematodes (GIN) in lambs could reduce anthelmintic requirements; therefore, the fecal egg count (FEC) estimated breeding value (EBV) was developed as a measure of genetic merit for parasite burden. One of the first breeds to effectively implement the FEC EBV was Katahdin. To better understand the relationship between the FEC EBV and Haemonchus contortus (Hc) challenge infection, a divergent mating scheme was established with extremely high (High FEC, n = 5) or extremely low (Low FEC, n = 5) FEC EBV Katahdin rams over 2 years. Purebred lambs sired by these rams were born beginning in mid-March and managed on pasture until approximately 120 days of age. A primary infection was established based on FEC during this period. At this point, lambs (n = 109 in Year 1, n = 114 in Year 2) were removed from pasture, treated with an anthelmintic to reduce FEC and transported to the Animal Sciences Farm at West Virginia University. After a rest period, lambs were given 10,000 (Year 1) or 5000 (Year 2) Hc L3. Body weights, FEC, and packed cell volume were collected weekly. Lambs were harvested (n = 60/year) at 5 weeks post-infection. Abomasum worm counts were determined, and worm length was measured using Image J. Statistical analysis was performed by year using the Mixed Model procedure of SAS (SAS Institute, Cary, NC) with fixed effects of sire EBV type. Change in FEC after the prepatent period was greater in Year 1 High FEC-sired lambs compared to Low FEC-sired lambs (210 vs. 34 eggs/g, respectively; P < 0.05). At harvest in Year 2, a greater proportion of Low FEC- than High FEC-sired lambs had worm counts of zero (P < 0.05). Worm fecundity was lower in lambs sired by Low FEC rams (P < 0.05). Taken together, sire selection for low FEC EBV will lower FEC and worm count and improve GIN resistance in progeny.

Chromosome Instability in Pony of Esperia Breed Naturally Infected by Intestinal Strongylidae.

Simple SummaryIntestinal parasites are among the main causes of hidden economic losses in livestock farming. This study reports the results of chromosome instability analyses in Esperia ponies with different intestinal strongyles fecal egg counts. Interestingly, animals with higher fecal egg counts showed increased levels of chromosome instability. If this condition is confirmed in other horse breeds and livestock species, it will be important to understand the causes in order to implement therapeutic strategies for the management of intestinal parasites.The Pony of Esperia is an Italian autochthonous horse breed reared in the wild on the Aurunci and Ausoni Mountains. Currently, it is considered an endangered breed, as its population consists of 1623 animals. It is therefore essential to identify all aspects that can improve the management and economy of its breeding, favoring its diffusion. In this paper, the effects of intestinal strongyle infection on the chromosome stability of peripheral blood lymphocytes (PBLs) was evaluated through aneuploidy and chromosome aberration (gap, chromatid and chromosome breaks, and the number of abnormal cells) test. Statistical difference in the mean values of aneuploidy, cells with chromosome abnormalities, and chromosome and chromatid breaks were observed between ponies with high fecal egg counts (eggs per gram > 930) and those with undetectable intestinal strongylosis. The causes of this phenomenon and possible repercussions on the management of Pony of Esperia are discussed in the paper.

PSV-B-21 Genome-Wide Analysis of Sheep Artificially or Naturally Infected with Gastrointestinal Nematodes

Abstract Gastrointestinal nematodes (GIN) are detrimental to the health and productivity of sheep across the world, necessitating genetic selection for improved GIN resistance. In this study, we used genomic analyses across- and within- two important breeds in the United States (US), Rambouillet and Dorper, to investigate physiological mechanisms associated with GIN resistance. Genomic data were evaluated from two experiments where lambs were challenged with GIN, either in a natural environment or artificially. Lambs were genotyped with the Axiom™ Ovine Genotyping Array (50K) with 42,608 single nucleotide polymorphisms (SNP) remaining following quality control for minor allele frequency and variant call rate. In experiment 1, a fecal egg count (FEC) was collected from four- to eight-month-old Dorper and Rambouillet lambs (n=188 total) exposed to GIN on pasture. Using Plink v1.9, a genome-wide association study (GWAS) identified significant SNP (P &amp;lt; 6.0e-5) associated with either an increase or decrease of FEC on chromosomes 1, 2, 3, 4, 12, 15 and 20. In Experiment 2, Rambouillet lambs (n=77) were inoculated with 10,000 Haemonchus contortus L3 larvae and FEC and packed-cell volume (PCV) were recorded. An ensuing GWAS identified significant SNP (P &amp;lt; 2.0e-5) on chromosomes 1, 2, 3, 5, 7, 16, 17 and 23 associated with high and low FEC and SNP on chromosome 10 associated with decreased PCV. Multiple genes were in proximity to the identified SNP, including PIK3 subunits in both experiments. Pathway analysis of reported genes, including PIK3, IMP4, NDST3, MRPL22, HSPA2, TGFA, TGFBR1 and RUNX1 revealed involvement in tissue repair, T-cell differentiation and cytokine signaling in Rambouillet and Dorper sheep more resistant to GIN. Results from this study contribute to the genetic underpinnings of host response to GIN in two important breeds in the US, providing a foundation for future selection of animals more resistant to H. contortus infection.

Implementation of a targeted treatment strategy for the sustainable control of Ascaridia galli infections in laying hens.

Background Ascaridia galli is a widespread problem in cage‐free egg production. Sustainable control of nematode infections is a key component in this sector. This study investigates the effect of a treatment strategy against A. galli, aiming to propose a guideline for anthelmintic use on commercial poultry farms.MethodsA total of eight flocks of laying hens (a–h) from five commercial poultry farms were included in this study. Faecal samples were collected on a biweekly basis starting at 7–13 weeks post‐placement (WPP) and processed using the McMaster method to calculate ascarid egg shedding. Flocks were treated after the threshold of 200 eggs per gram of faeces (EPG) was reached.ResultsThe highest initial faecal egg count was 6700 EPG at 11 WPP, whereas the lowest was 50 at 8 WPP. The longest delay to detect A. galli was 7 weeks. The lowest and the highest number of treatments were four and six, respectively. The shortest and longest periods between any two treatments were 5 and 22 weeks, respectively.ConclusionsThese results suggest that monitoring for A. galli should start at approximately 7 WPP and should be repeated every 8 weeks until hens are 50 weeks old. Treatment should be given only if moderate to high faecal egg counts are observed. Treatments after this point may be repeated every 8 weeks without eventually performing a faecal test. These findings provide practical support to veterinarians and egg producers dealing with ascarid worm infection in laying hens in their production stage.

Effects of Vernonia amygdalina methanol leaf extract and fractions on Ascaridia galli in experimentally infected birds with regard to its pathological effect

BackgroundHelminthiasis, usually a chronic problem in poultry, is the major cause of economic losses in the poultry industry. This study was undertaken with the aim of evaluating the in vitro and in vivo anthelmintic effects of Vernonia amygdalina methanol leaf extract and fractions on Ascaridia galli in experimentally infected birds. Standard protocols for extraction, phytochemical screening, isolation and infection of parasite and histological examination were followed.ResultAt 50 mg/ml albendazole (ALB) caused the highest inhibition of embryonation (97.3%) followed by crude methanol extract (CME) (94.5%), ethyl acetate fraction (EAF) (81.3%) and butanol fraction (BF) (80.3%). The lowest faecal egg counts (FEC) and highest FEC at 21 days post-treatment were observed in the group treated with albendazole (99.2%) and CME at 800 mg/kg (96.9%). Deparasitization at 200 mg/kg caused by ALB was (93.8%), while at 200, 400 and 800 mg/kg, CME was (77.5%, 87.5% and 91.86%), BF was (75.51%, 79.61% and 85.73%) and EAF was (73.48%, 75.5% and 81.63%), respectively. At post-mortem, broiler chickens infected with A. galli and treated with CME, BF and EAF at 200 mg/kg had desquamation of the villi while at 400 and 800 mg/kg treatments, the intestines were intact.ConclusionThe extract and fractions of V. amygdalina were found to possess anthelmintic activity against A. galli due to the inhibition of embryonation of eggs and the reduction in faecal egg count; further research is required to fully ascertain their mechanism of action of the extract.

Evaluation of risk factors affecting strongylid egg shedding on Hungarian horse farms

In Hungary, equine parasite control is mostly based on traditional approaches involving rotational anthelmintic treatment at regular intervals. Almost no farms utilize fecal egg counts (FECs) on a regular basis to guide deworming treatments. This approach is certainly not sustainable and is the major factor responsible for the current high levels of anthelmintic resistance. The aims of this study were to statistically analyze risk factors associated with strongylid egg count magnitude and prevalence. Fecal samples and horse data (age, pasture history, stocking density, anthelmintic history) were collected from 216 horses on 13 farms in Pest county, Hungary, during the spring of 2020. FECs were determined by Mini-FLOTAC. Logistic regression models were used to evaluate the association of factors with pre-deworming strongylid egg counts. The data were highly overdispersed with approximately 22% (95% Confidence Interval: 17-28%) of the equids shedding 80% of the total strongylid egg output. Strongylid FECs were significantly associated with the age of equids and anthelmintic class used prior to the study. Equids younger than 5years of age had significantly higher FECs compared to equids in the 5-17-year age range (p=0.003) and compared to equids aged >17years (p<0.001). Equids treated regularly with benzimidazoles had significantly higher FECs than equids with no history of benzimidazole use (p=0.02). We found that FECs of horses kept at extremely high stocking density (>30 horses/ha) were significantly higher than those kept at low (1-2 horses/ha; p<0.001) or medium (3-10 horses/ha, p<0.001) stocking densities. The results demonstrate the value of FEC monitoring and indicate that the efficacy of benzimidazoles should be investigated in Hungary. Moreover our findings demonstrate that reducing stocking density should be considered in cases of high strongylid FECs.

Epigenetic regulation of SLC11a1 gene in horses infected with cyathostomins

Cyathostomins are the most prevalent nematode parasites of horses worldwide and the SLC11a1 gene has been found to modulate the host immune response against parasite infections. The objective of this work was to determine the DNA methylation profile of the SLC11a1 gene in naturally infected horses (n = 6) and correlate it with the cyathostomin fecal egg count (FEC). In silico analyzes showed two CpG islands, located in the body of the gene and DNA sequencing showed a statistically significant difference between the methylation profile of islands 1 and 2 (P < 0.0001). The data revealed that island 1 was hypermethylated (>95%), while island 2 was hypomethylated (<10%). Although there were no statistical differences in animals with low or high FEC in relation to methylation of island 1 (P = 0.177) or island 2 (P = 0.231), the analysis of island 2 showed a pattern in which samples with higher FEC also presented higher methylation for that island. This data indicates a possible correlation between the cyathostome FEC and the increased methylation of island 2. Animals with a high methylation rate presented a decrease in FEC after 4 months. The preliminary results indicate for the first time the possibility of epigenetic regulation of the SLC11a1 gene in horses. Moreover, it is suggested that methylation of island 2 of the SLC11a1 cascade might indicate the prognostic of parasite infection. Epigenetic processes such as these might be used as biomarkers for identifying individual animals for target treatments and specific breeding purposes.

PSXIV-22 Selection for low fecal egg count estimated breeding value correlates with greater circulating antibody in sheep

Abstract Sheep selected for resistance to gastro-intestinal parasites have been shown to have greater survivability to weaning. Data from Katahdin sheep indicates that selection based on post-weaning fecal egg count estimated breeding values (PWFEC EBV) may further improve generalized immunity. However, no data exists to confirm this increased circulating antibody occurs in breeds genetically unrelated to Katahdins. In the fall of 2020 post-weaning blood and fecal samples were collected from Shropshire sheep (n = 42) and Polypay sheep (n = 91). The blood samples were analyzed for total immunoglobulin-G (IgG) using ELISA. Shropshire sheep were sorted into low (PWFEC EBV &amp;lt; 0) and high (PWFEC EBV &amp;gt; 0) groups based on fecal egg count (FEC), which were analyzed via a modified McMaster’s method. Polypay sheep were sorted into three groups by PWEC EBV; A (&amp;lt; -50) B (&amp;gt;-50 &amp;lt; +50) and C (&amp;gt;+50). In Shropshire group, individuals with low FEC had greater average IgG concentration (87.9 µg/mL) than those with high FEC (62.4 µg/mL) (P &amp;gt; 0.05). In the Polypay group, sheep in PWFEC EBV group A had numerically higher IgG concentration (86.2 µg/mL) than sheep in group B (71.2 µg/mL) and group C (53.1 µg/mL) (P &amp;gt; 0.05). While data in either breed were not significant, the trend observed across breeds indicate that sheep with a lower PWFEC EBV have numerically greater circulating antibody.

366 Impact of Haemonchus Contortus on Feed Intake in Katahdin Sheep Selected for Parasite Resistance

Abstract Haemonchus contortous (Hc) infections have decreased profitability of flocks worldwide through loss of production efficiency and in severe cases death. Countless research efforts have been made in order to further understand the extensive impact of this gastrointestinal nematode (GIN). Quantifying the impact feeding behavior after Hc infection may prove vital, in understanding internal effect on growing lambs. The aim of this study was to evaluate Katahdin lambs with extensive genetic evaluation for feed efficiency and behavior utilizing a Growsafe™ system. Katahdin ewes from the Virginia Tech Southwest Agriculture Research and Extension Center in Glade Springs Virginia were divergently selected based on fecal egg count (FEC) EBV and mated to rams (n = 8) of similar genotype. A subset of lambs was selected for feedlot evaluation and transported to West Virginia University. Lambs were fed a complete pellet (16% CP) ad libitum while individual intake was measured in pen-fed groups with a GrowSafe™ system. Half of the lambs from each sire FEC EBV group were infected with 5,000 Hc L3 larvae and observed for 6 weeks alongside uninfected contemporaries. Artificial Hc infection resulted in lambs becoming modestly infected with FEC peaking in week 5 at 324 eggs/g. Infection level was not significant between all 4 groups (P &amp;lt; 0.05). Lambs administered H.C. had observably lower feed intake 2 days after infection. Both infected groups returned to normal intake with their control groups shortly after. Feed intake dropped again at day 10 and remained low until day 16 for LoFEC sired lambs and day 20 for HiFEC sired lambs. Offspring of low FEC rams exhibited an ability to return to normal intake levels earlier than lambs with high FEC EBV sires. Further analysis is needed with greater levels of parasite infection to confirm negative FEC EBV have a shorter duration of lower feed intake.