Control Of Gastrointestinal Nematodes Research Articles

Evaluation of the nematicidal and enzymatic activity of Pleurotus djamor on Trichostrongylus spp. and Strongyloides papillosus

ABSTRACT Parasitic gastrointestinal nematodes (GINs) cause diseases that are a major challenge to livestock production. Chemical control is the most widely used method, but it has many economic and environmental problems. This study was to evaluate in vitro the nematicidal and enzymatic activity of Pleurotus djamor against Trichostrongylus spp., and Strongyloides papillosus. The fungus was cultivated in a solid medium composed of wheat seeds for 25 days. The enzyme extraction was then performed using distilled water in the ratio of 1:5. Subsequently, by means of filtration and then centrifugation, the cell-free crude extract (CFCE) was obtained. Proteolytic activity was measured at pH 5 using the caseinolytic assay. The nematophagous assay of the P. djamor on the infective larvae (L3) was performed for 6 h. The nematicidal effect of the CFCE (active and denatured) was analysed over a period of 48 h. The CFCE showed proteolytic activity of 8.9 ± 0,5 U mL−1. P. djamor reduced the number of L3 by 75% (p < 0.01). The active CFCE showed a statistical difference compared to the control and the denatured (p < 0.01). On the other hand, there was no significant difference between the denatured group and the control group (without enzymes). The percentage reduction of L3 was 57%. This result suggests that the nematicidal action occurred mainly due to the activity of the proteases present in the CFCE. This study reports for the first time the applicability of proteases produced by P. djamor in the biochemical control of GINs, which could become an alternative biopesticide in the future.

Living with parasites: exploiting tolerance of infection to reduce the impact of gastrointestinal nematodes in sheep

Gastrointestinal nematodes are among the most prevalent and damaging infections faced by ruminant livestock. Anthelmintic resistance means that sustainable control is essential and selective breeding has been part of this for decades. Breeding, however, has focused on promoting resistance to infection, yet almost no empirical work has been done on the other means by which hosts mitigate the impact of parasites, namely tolerance of infection. This review defines the concepts of resilience, resistance and tolerance, with particular attention to gastrointestinal nematode infections of sheep. How selection has thus far been implemented is discussed, and the pros and cons of each trait are evaluated. Tolerance has been almost completely neglected in livestock science, and its potential mechanisms with regard to gastrointestinal nematodes in sheep are discussed. The authors' work to understand more about tolerance to gastrointestinal nematodes and its potential role in sustainable control of gastrointestinal nematodes in the future is also disscussed.

Farmers' and Experts' Knowledge Coping with Sheep Health, Control and Anthelmintic Resistance of Their Gastrointestinal Nematodes.

Gastrointestinal nematodes are common in grazing sheep, but the intensity of the infection is not easily appreciated by farmers. For decades, they have relied on anthelmintic treatments to control these gastrointestinal nematodes. This has led to anthelmintic resistance and poor control of infection in most regions of the world. Using face-to-face semidirective interviews with farmers, we recorded their views on gastrointestinal nematode infection and its control. Ten organic and nine conventional meat sheep farmers from central France and 20 milk sheep farmers from the Basque region were interviewed and the data were analysed using a health model based on the importance of the disease and the barriers to implementing control. It was found that gastrointestinal nematodes were not the main health concern, and therefore farmers were not willing to invest too much time and money in their control. The conventional farmers relied on their veterinarians (the experts) to organise and select the anthelmintics, although they complained about the limited investment of their veterinarians in this matter. Organic farmers complained about their lack of knowledge about complementary and alternative medicines. Farmers rarely used faecal egg counts to build control of gastrointestinal nematodes and were unaware of the intensity of their infection. Knowledge of anthelmintic resistance was general (it exists) but farmers did not know if it existed on their farm. Resistance was often considered to have come from elsewhere, so the farmer did not feel at fault and did not take measures to prevent resistance. There is a need for all stakeholders to use faecal egg counts to assess the intensity of infection as well as the level of anthelmintic resistance to establish individual farm control programmes rather than standard blanket treatments.

Association of β-globin polymorphisms and tolerance to haemonchosis in ewes and lambs of different sheep breeds

Gastrointestinal nematodes (GIN), especially Haemonchus contortus, represent a significant challenge for sheep production. Given the global concern about GIN anthelmintic resistance, alternative control methods able to reduce the dependence on these drugs are highly advisable. Since previous studies have shown that sheep carrying the Hb-A allele of β-globin are more resistant to H. contortus, this study aimed to investigate the relationship between the different haplotypes (Hb-AA, Hb-AB and Hb-BB) and phenotypes in Santa Inês (SI), Texel (TX) and White Dorper (DO) breeds infected with H. contortus. Blood samples were collected from 180 ewes and 123 lambs of the three breeds for DNA extraction followed by qPCR using a hydrolysis probe to identify the β-globin haplotypes. Phenotypic data, including fecal egg count (FEC), packed cell volume (PCV), FAMACHA score and body condition score for ewes and lambs, as well as weight gain for lambs, were collected. The genotypic frequencies of β-globin for ewes and lambs were, respectively: 21.7% and 21.4% Hb-AA, 50% and 50% Hb-AB and 28.3% and 28.6% Hb-BB in SI; 0% and 0% Hb-AA, 18.6% and 9.4% Hb-AB and 81.4% and 90.6% Hb-BB in TX; and 0% and 0% Hb-AA, 13.1% and 0% Hb-AB and 86.9% and 100% Hb-BB in DO. In ewes, mean PCV differed (p<0.05) between the three haplotypes, with higher PCV in Hb-AA animals, followed by Hb-AB and Hb-BB. When considering each breed separately, SI Hb-AA ewes presented higher PCV (p<0.05), highlighting that even in a breed already considered resistant, animals with Hb-AA haplotype showed superior performance. Lambs with the Hb-AA haplotype exhibited a higher (p<0.05) mean PCV compared to those with Hb-AB and Hb-BB. The same pattern was found in SI when analyzing each breed separately. No significant association was found between β-globin haplotypes and FEC, FAMACHA score, body condition score, or weight gain. Nevertheless, given that anemia is the major clinical sign of haemonchosis, our findings on PCV reinforce that sheep carrying the Hb-A allele of β-globin are more tolerant to haemonchosis. This study may support the development of a valuable tool, targeting genetic selection for GIN control, reducing the dependence on anthelmintics and boosting sheep production worldwide.

A SURVEY OF ANTHELMINTIC EFFICACY IN DAIRY GOAT FARMS IN SOUTH-EAST FRANCE

Goat’s milk production is an important activity in France. Gastrointestinal nematodes (GIN) remain a main threat for grazing goats, usually controlled using anthelmintic drugs (AH). However, 1) eprinomectin (EPN) is the sole molecule yet available without withdrawal time for milk in France; 2) nematodes AH resistances increase dramatically. First, a survey was performed on 13 farms in the Auvergne-Rhône-Alpes (AURA) region to evaluate the efficacy of 2 AH authorized for dairy goats: a benzimidazole (BZ) and a macrocyclic lactone (EPN pour-on). Fecal Egg Count Reduction Tests (FECRT) were carried out using 3 groups of 10 goats per farm: a control group, one treated with BZ (oxfendazole) and one treated with EPN. The results indicate a resistance to BZ in 11 out of 13 farms (84.6%) and a lack of efficacy for EPN pour-on in at least 10 farms (76.9%). Secondly, EPN was given orally or subcutaneously in 4 farms of the previous trial showing a lack of efficacy to EPN pour-on. A resistance to EPN was confirmed in 3 out of 4 farms. Although based on a few farms, these results confirm the high prevalence of resistance of GIN to BZ in dairy goat farms. They also highlight a high level of resistance to EPN and the lack of efficacy of EPN when used pour-on. Given the level of resistance to marketed drugs, there is an urgent need to explore alternative options to AH to prepare integrated, sustainable control of GIN.

73 Deworming to improve growth in early-weaned spring born hair sheep lambs

Abstract In lambs, the stress of weaning and the lack of a fully developed immune system can increase susceptibility to gastrointestinal nematodes (GIN). Lack of an effective GIN control strategy around this time can have a significant impact on lamb growth, productivity and mortality. The objective of this study was to determine the influence of deworming at weaning on growth performance in hair sheep lambs. St. Croix (STX) and Barbados Blackbelly (BB) lambs used in the study were born on pasture, weaned at 60.2 ± 0.4 d of age, and transitioned in pens for 87 d post-weaning before turning out to pasture. After accounting for initial FAMACHA eyelid color score, breed, and birth type (single or multiple) at weaning, 54 STX (n = 32) and BB (n = 22) lambs weighing 11.7 ± 0.4 kg were dewormed (DEW) or not (CON) with a combination of levamisol (Prohibit; 8 mg/kg BW) moxidectin (Cydectin; 0.2 mg/kg BW) and albendazole (Valbazen; 7.5 mg/kg BW). To evaluate the effect of deworming treatment, BW and body condition scores (BCS; scale 1-5) were recorded at weaning and at end of transition to pasture. Blood and fecal samples were also collected for determination of packed cell volume (PCV) and fecal egg counts (FEC). Pooled treatment group feces (d 0 – 98) were collected and cultured to determine GIN genera at weaning. Data were analyzed using repeated measures in a mixed model, and FEC were log transformed prior to analysis. There was a mixed population of GIN at weaning averaging 65% and 35% for H. contortus and Tricostrongylus spp. At weaning, BCS, PCV, and FEC were similar between treatment groups and averaged 1.6 ± 0.07, 36.5 ± 0.6%, and 399 ± 54.4 epg, respectively. Combination deworming reduced FEC by 99%. At turnout, DEW lambs (2.3 ± 0.1) tended (P = 0.08) to have greater BCS than CON lambs (2.0 ± 0.1) and PCV was greater (P &amp;lt; 0.001) in DEW versus CON lambs (37.2 ± 0.9 and 33.3 ± 0.8%, respectively). There was also a tendency (P = 0.09) for breed to influence BCS (2.3 ± 0.1 and 2.0 ± 0.1 for BB and STX, respectively). The FEC at turnout was not influenced by treatment or breed (496.7 ± 75.1 epg). Additionally, DEW lambs (131.8 ± 5.2) tended (P = 0.09) to grow faster than CON (119.9 ± 4.7 g/d) lambs, a difference more pronounced in STX DEW (g/d) than STX CON lambs (136 ± 6.1 vs 110 ± 6.5 g/d; P &amp;lt; 0.05). Even though deworming tended to promote faster growth rates in lambs used in this study, alternative, more sustainable, parasite control strategies should be considered in the wake of increasing dewormer resistance.

Utilisation of indigenous knowledge to control gastrointestinal nematodes in Southern Africa

Gastrointestinal nematodes (GIN) exacerbate the impact of droughts on the survival of cattle. The inadequacies of the conventional system make it increasingly important to explore indigenous knowledge (IK) to create drought-tolerant and GIN resilient herds. The objective of the study was to assess the indigenous strategies for controlling GIN during droughts. Face-to-face interviews with experts on IK were conducted to give insight into the importance, methods and ranking of GIN control. The experts identified 86 cattle that were used to test their assertions. The control methods used were identifying cattle that were susceptible to high GIN loads using predisposing factors, diagnosis of GIN burdens using faecal appearance, and treatment using phytotherapy. Experts ranked predisposing factors as the most critical control strategy and identified body condition, class, sex, coat colour, pregnancy status and lactation status as predisposing factors to high GIN burdens. Thin, older, dark-coloured cattle, as well as pregnant and lactating cows, were considered susceptible to GIN. However, pregnancy status, coat colour and sex were significantly associated with high GIN burdens. Cows were 2.6 times more likely to have high GIN burdens than bulls. Dark-coloured cattle were 3.5 times more likely to have high GIN burdens than light-coloured ones, and the likelihood of pregnant cows was 4.9 times higher than non-pregnant cows. A dark-coloured pregnant cow was extremely susceptible to high GIN burdens. In conclusion, knowledge of predisposing factors informs selection decisions when purchasing foundation stock. Cattle that are susceptible to high GIN loads are prioritised during droughts or culled where resources are scarce.

The feeding of heather (Calluna vulgaris) to Teladorsagia circumcincta infected lambs reduces parasitism but can detrimentally impact performance

Gastrointestinal nematode (GIN) infections impact small ruminant health, welfare, and production across farming systems. Rising anthelmintic resistance and regulation of synthetic drug use in organic farming is driving research and development of sustainable alternatives for GIN control. One alternative is the feeding of plants that contain secondary metabolites (PSMs) e.g., proanthocyanidins (PA, syn. condensed tannins) that have shown anthelmintic potential. However, PSMs can potentially impair performance, arising from reduced palatability and thus intake, digestibility or even toxicity effects. In this study, we tested the trade-off between the antiparasitic and anti-nutritional effects of heather consumption by lambs. The impact of additional feeding of a nematophagous fungus (Duddingtonia flagrans) on larval development was also explored. Lambs infected with Teladorsagia circumcincta or uninfected controls, were offered ad libitum heather, or a control chopped hay for 22 days during the infection patent period. Eight days into the patent period, parasitised lambs were supplemented (or remained unsupplemented) with D. flagrans for a 5-day period. Performance and infection metrics were recorded, and polyphenol levels in the heather and control hay were measured to investigate their association with activity.The lambs consumed heather at approximately 20% of their dry matter intake, which was sufficient to exhibit significant anthelmintic effects via a reduction in total egg output (P = 0.007), compared to hay-fed lambs; the magnitude of the reduction over time in heather fed lambs was almost 10-fold compared to control lambs. Negative effects on production were shown, as heather-fed lambs weighed 6% less than hay-fed lambs (P < 0.001), even though dry matter intake (DMI) of heather increased over time. D. flagrans supplementation lowered larval recovery in the faeces of infected lambs by 31.8% (P = 0.003), although no interactions between feeding heather and D. flagrans were observed (P = 0.337). There was no significant correlation between PA, or other polyphenol subgroups in the diet and egg output, which suggests that any association between heather feeding and anthelmintic effect is not simply and directly attributable to the measured polyphenols. The level of heather intake in this study showed no antagonistic effects on D. flagrans, demonstrating the methods can be used in combination, but provide no additive effect on overall anthelmintic efficacies. In conclusion, heather feeding can assist to reduce egg outputs in infected sheep, but at 20% of DMI negative effects on lamb performance can be expected which may outweigh any antiparasitic benefits.

A Review of Ethnomedicinal Plants as Potential Anthelmintic Agents to Alternatively Control Gastrointestinal Nematodes of Ruminants in South Africa.

Small ruminant production is one of the most important animal productions for food security in the world, especially in the developing world. Gastrointestinal nematode (GIN) infection is a threat to this animal's production. Conventional drugs that are used to control these parasites are losing their efficacy due to the development of resistant parasites. These drugs are not biologically degradable, taint meat products and are also expensive for communal farmers. Hence, research is now exploring ethnomedicinal anthelmintic plants for an alternative remedy. The objective of this paper was to review ethnomedicinal plants as a potential alternative to unsustainable commercial anthelmintics. This review sought to understand common GINs infecting ruminants, resistance manifestation in GINs to conventional treatment, reasons communal farmers choose ethnomedicine, and modes of action in anthelmintic plants. It also examined the usage of plants and plant parts, dosage forms, methods for improving bioactivity, convectional validation procedures, and restrictions on ethnomedicinal plant use as anthelmintics in ethnomedicine. Such insight is essential, as it highlights the importance of ethnoveterinary medicine and ways to adopt or improve it as a potential alternative to conventional anthelmintics.

Machine learning prediction of multiple anthelmintic resistance and gastrointestinal nematode control in sheep flocks.

The high prevalence of Haemonchus contortus and its anthelmintic resistance have affected sheep production worldwide. Machine learning approaches are able to investigate the complex relationships among the factors involved in resistance. Classification trees were built to predict multidrug resistance from 36 management practices in 27 sheep flocks. Resistance to five anthelmintics was assessed using a fecal egg count reduction test (FECRT), and 20 flocks with FECRT < 80% for four or five anthelmintics were considered resistant. The data were randomly split into training (75%) and test (25%) sets, resampled 1,000 times, and the classification trees were generated for the training data. Of the 1,000 trees, 24 (2.4%) showed 100% accuracy, sensitivity, and specificity in predicting a flock as resistant or susceptible for the test data. Forage species was a split common to all 24 trees, and the most frequent trees (12/24) were split by forage species, grazing pasture area, and fecal examination. The farming system, Suffolk sheep breed, and anthelmintic choice criteria were practices highlighted in the other trees. These management practices can be used to predict the anthelmintic resistance status and guide measures for gastrointestinal nematode control in sheep flocks.

A pilot study of the in vitro efficacy of different concentrations of Duddingtonia flagrans for the control of gastrointestinal nematodes of sheep.

Duddingtonia flagrans is a nematode trapping fungus used for the control of gastrointestinal nematodes in livestock. The quantity of chlamydospores of D. flagrans required for the reduction of third-stage larvae (L3) of sheep gastrointestinal nematodes (GIN) is largely unknown, and a matter of discussion. The aim of this experiment was to determine in vitro the nematophagous activity of four different concentrations of D. flagrans (1000, 3000, 6250, or 11000 chlamydospores/ml) in the presence of varying numbers of GIN third-stage larvae (L3) (500, 1000, 1500). Additionally, the study sought to evaluate the efficacy of this fungus on Haemonchus contortus, Teladorsagia circumcincta, Trichostrongylus colubriformis and Chabertia ovina. The results showed that as fungal concentrations increased, so did the larval reduction of third-stage infective larvae in each test. L3s number was not a determining factor in the efficacy against GIN. The comparison between various concentrations of chlamydospores revealed significant differences, particularly between 1000 and 11000 chlamydospores (P≤0.05). Regarding the larval reduction of the GIN species considered, D. flagrans demonstrated the same effectiveness across all species tested. The results of the current study confirm the efficacy and underscore the importance of D. flagrans as an alternative for controlling of GIN.

Anti-parasitic activities of four synthetic chemicals anthelmintics on Haemonchus contortus

Synthetic anthelmintic (AHs) have always been used in veterinary medicine. The increasing development of resistance to these AHs in livestock parasites threatens animal health and global production, calling into question their effectiveness. In vitro egg hatch inhibition assay (EHA) and larval development test (LDT) performed showed ovicidal and larvicidal activities of four AHs compared to the control (PBS). However, a suspicion of Haemonchus contortus resistance to Bolumisole M1 (IC50 = 0.122µg/mL) and Ivomec-D (IC50 = 0.130µg/mL) was recorded after the EHA. Similarly, resistance was observed to Bolumisole M1 (IC50 = 0.024µg/mL), Ivomec-D (IC50 = 0.07µg/mL) and Kelanthic (IC50 = 0.144µg / mL) following the LDT. These results show that cases of parasite resistance to AHs exist in small ruminants in Burkina Faso. Therefore, a reasoned use of AHs could be a good approach in the control of gastrointestinal nematodes of small ruminants in Burkina Faso. Subsequent in vivo studies should be conducted to confirm this resistance in the real conditions of these ruminants.

Assessment of worm control practices recommended by equine veterinarians in Australia.

This study aimed to assess Australian veterinarians' knowledge, perceptions and treatment strategies for worm control in horses with an online questionnaire. The questionnaire comprised 64 questions covering various aspects of: (i) veterinary practice; (ii) the veterinarian's knowledge of gastrointestinal nematodes (GINs) and the importance of parasites in different age groups of horses; (iii) the diagnosis and control of worms; (iv) anthelmintics and anthelmintic resistance (AR); (v) grazing management; and (vi) the means of communication and the discussion between veterinarians and their clients regarding worm control. Following a pilot survey, a link for the questionnaire survey was sent to all (n = 1,148) registered members of Equine Veterinarians Australia in April 2020. The response rate for the questionnaire was 10% (118 of 1,148). The findings of this study illustrate veterinarians' good understanding of aspects of equine parasites, including control. However, respondents mainly recommended frequent, interval-based prophylactic deworming in young horses, and only 40% (96 of 239) diagnosed GIN infections based on faecal egg count (FEC) results in all age groups of horses. Furthermore, only 27% (88 of 330) of the respondents made deworming decisions based on FECs. Most of the respondents recommended macrocyclic lactones (MLs) for all age groups of horses (71%, 481 of 677), and the most frequently used method to calculate the dose of anthelmintics was by estimating the weight of animals visually (53%, 63 of 118). Although the majority of respondents (97%, 115 of 118) perceived AR to be a critical issue in managing worms in horses, 58% (67 of 118) of them were unaware of the status of AR on their clients' properties. Forty-two percent (50 of 118) of the respondents perceived the presence of AR in worms, including pinworms (16%), strongylins (15%), species of Draschia and Habronema (6%), Strongyloides westeri (2%) and tapeworms (1%). Twenty-seven percent (32 of 118) of the respondents rarely discussed equine worm control practices with their clients. This study provides insights into the perception and worm control practices recommended by Australian veterinarians to manage equine parasites. The findings highlight the importance of continued education and awareness of AR, and the use of non-chemical methods as well as consideration of the legislation of prescription-only use of anthelmintics based on FECs to achieve sustainable control of GINs in Australian horses.

Dose confirmation of a novel fixed dose combination injectable (0.2 mg/kg doramectin + 6.0 mg/kg levamisole hydrochloride) against naturally acquired gastrointestinal nematodes in US cattle

Macrocyclic lactone (ML) resistance in cattle gastrointestinal nematodes (GINs) is an increasing problem. Concurrent combination anthelmintic therapy incorporating an existing ML with a second drug class has been proposed to control cattle GINs while slowing the development of ML resistance. Two dose confirmation studies were conducted to investigate the efficacy of a new fixed-dose combination injectable (FDCI) anthelmintic against common cattle GINs known to negatively impact production. The FDCI is formulated with 5 mg/ml doramectin and 150 mg/ml levamisole hydrochloride (HCl). Cattle enrolled in the two studies were sourced from either the Southern (Study 1, n = 30) or Midwest (Study 2, n = 36) United States. Animals with GIN infections confirmed by fecal egg count (FEC) were randomly allocated to one of three treatment groups. On Day 0, cattle with positive FECs on Day −5( ± 2) were weighed and administered a single subcutaneous injection of either saline (0.9% sodium chloride) at 0.04 ml/kg, 10 mg/ml doramectin at 0.02 ml/kg (to provide 0.2 mg/kg doramectin) or the FDCI at 0.04 ml/kg (to provide 0.2 mg/kg doramectin and 6.0 mg/kg levamisole HCl). On Day 14, fecal samples were collected, animals were euthanized, and worms were collected from the intestinal tract of each animal. Treatment efficacy was calculated using worm burdens and the fecal egg count reduction test (FECRT). Pre-treatment (Day −5, Study 1; Day −3, Study 2) mean FECs were 999.4–1136.2 eggs per gram (EPG) in Study 1 and 137.1–226.6 EPG in Study 2. The FDCI was active against cattle GIN populations in both studies, with FECRT ≥ 99.98% in both studies. Compared to saline-treated cattle, FDCI-treated cattle had significantly fewer adult and immature worms of all identified species on Day 14. In Study 1, Day 14 efficacy of the FDCI was 96.9% for Cooperia spp. (C. oncophora (99.7%) and C. punctata (95.9%)), 99.1% for Nematodirus helvetianus, and 99.8% for Ostertagia spp. In Study 2, the FDCI provided 100% efficacy against all adult GIN species identified, including all GINs identified in Study 1 and Trichostrongylus axei. The FDCI also provided 95.5% efficacy against immature Ostertagia spp. and 100% efficacy against immature Cooperia spp. (Study 2). Doramectin was effective against all adult cattle GINs (except N. helvetianus) in Study 2 but was only effective against adult Ostertagia spp. in Study 1. Additionally, doramectin was only effective against immature Cooperia spp. (and not immature Ostertagia spp.) in Study 2. A single administration of the doramectin + levamisole HCl FDCI provides a new and effective approach to the treatment and control of common cattle GINs, including those exhibiting decreased susceptibility to doramectin alone.

Comparative growth performance of backgrounded beef heifers treated with an injectable fixed-dose combination (0.2 mg/kg doramectin + 6.0 mg/kg levamisole hydrochloride) or single-active (0.2 mg/kg ivermectin) endectocide

Gastrointestinal nematodes (GINs) can negatively impact all production classes of cattle, particularly growing cattle. A global decline in efficacy of broad-spectrum single-active anthelmintics requires alternative GIN control methods without the aid of novel drug classes. Here, we present a new fixed-dose combination injectable (FDCI) endectocide for cattle that combines doramectin (5 mg/ml) and levamisole hydrochloride (150 mg/ml). A 56-day comparative performance confinement backgrounding trial was conducted in stocker beef heifers (n = 1548) with confirmed GIN infections to (1) compare the Day 14 post-treatment effectiveness of the new FDCI endectocide to pen mates treated with the injectable single-active endectocide ivermectin, as evidenced by fecal egg counts (FECs) conducted for a randomly selected subset (10%) of both treatment groups, and (2) determine if the greater GIN control by the FDCI evidenced in the subsample improved growth performance in all FDCI-treated heifers. Heifers were procured in four cohorts, with a 10-week timeframe between enrollment of the first and last cohort. Treatment groups were comingled within dirt-floor pens (n = 31; 7–8 per cohort) and offered a standard backgrounding diet ad libitum for the study duration. Heifers with enrollment FEC ≥ 30 eggs per gram (EPG) were randomly allocated to receive the FDCI (n = 773) or ivermectin (n = 775) on Day 0. Day 0 FECs conducted on 10% of enrolled heifers (FDCI, n = 78; ivermectin, n = 79) were not different between treatment groups (p = 0.491). Day 14 FECs for the same heifers were reduced compared to Day 0 within each treatment group. Heifers given the FDCI had lower Day 14 AM FECs and higher FEC reduction test (FECRT) result (0.07 EPG; 0.999) than ivermectin-treated heifers (21.58 EPG; FECRT = 0.850). Mean body weight (BW) was not different between treatment groups on Day 0 (p = 0.2762) and Day 14 (p = 0.2010) but was significantly greater (p = 0.0007) for FDCI-treated heifers compared to ivermectin-treated heifers on Day 56. Compared to ivermectin-treated heifers, overall average daily gain from all evaluation periods (Day 0–14, Day 14–56, and Day 0–56) was greater (p ≤ 0.0052) in FDCI-treated heifers, and FDCI-treated heifers had 4.223 kg greater total weight gain over the 56-day study. The FDCI (0.2 mg/kg doramectin + 6.0 mg/kg levamisole hydrochloride) was highly effective in reducing GIN infections and thus promoted improved growth performance in beef heifers over a 56-day backgrounding period.

Effect of aqueous extract of Azadirachta indica leaves on gastrointestinal nematodes in ruminants: an in vitro study

High rates of gastrointestinal parasite infestation lead to the frequent use of anthelmintics for their control, resulting in resistance in the main species of gastrointestinal nematodes. Natural plant extracts, particularly those from Azadirachta indica A. Juss leaves, have been described as having antiparasitic, antimicrobial, insecticidal, antioxidant, and anticorrosive activities, which are related to the diversity of their chemical composition. This research aimed to evaluate the effect of the aqueous extract of A. indica leaves on the control of gastrointestinal nematodes in ruminants. To achieve this, an in vitro test was performed using the larval development assay, with fecal samples obtained from Pelibuey sheep, Criolla goats in the development category, and Criolla calf cattle for the culture of gastrointestinal nematode larvae. Three concentrations (minimum, medium, and maximum) were evaluated for each animal species against Haemonchus placei and Cooperia sp larvae for cattle and Haemonchus contortus, Trichostrongylus sp, and Trichuris for sheep and goats. The survival percentage indicator was evaluated at 0, 24, 48, and 72 h. The research concluded that the minimum concentration was valid for sheep and goats but not for cattle, and the medium and maximum concentrations were effective against all three animal species, resulting in 100% larval mortality. Keywords: Azadirachta, drug effects, Ruminants, Trichostrongyloidea

Supplementation of minerals and vitamins influences optimal targeted selective treatment thresholds for the control of gastro-intestinal nematodes in lambs

Targeted Selective Treatment (TST) is a gastrointestinal nematode (GIN) control strategy where anthelmintic treatment decisions are made at an individual animal level. TST has been proven to reduce anthelmintic use and subsequently slow down anthelmintic resistance development, however questions remain regarding optimal TST methods and their applicability across farms.In this study, the influence of Mineral and Vitamin (MV) supplementation on optimal energy utilisation (EU) TST thresholds was assessed on three Welsh farms. In total, 360 lambs were split into two groups, MV supplemented and control, and were treated with an anthelmintic against GIN at the midway point of the experiment. Lambs that improved their EU efficiency post treatment were deemed to have benefited from anthelmintic treatment. Optimal EU TST thresholds was determined for each treatment group per farm using Youden’s J statistic where the treatment threshold retrospectively exhibiting the greatest combined sensitivity and specificity in correctly identifying lambs benefiting from treatment was deemed to be optimal.Results demonstrated that the optimal EU TST threshold was higher in MV supplemented groups at 0.72, 0.71 and 0.56 versus 0.58, 0.67, 0.51 for control groups on each respective farm. Identification of lambs for TST was more effective when using an optimised EU TST threshold, compared to when using the standard EU TST threshold of 0.66.The study highlights that applying standard EU TST thresholds may not be appropriate on all commercial farms with factors including MV status as noted in this study likely to influence optimal EU TST thresholds. Additional refinement of TST systems can further strengthen their applicability across sheep flocks.

Anthelmintic effects of aqueous extract &lt;i&gt;Balanites aegyptiaca&lt;/i&gt; stem bark on strongyle larvae and the earthworm &lt;i&gt;Pheretima posthuma&lt;/i&gt;

The development of anthelmintic resistance and the high cost of conventional anthelmintics have led to the evaluation of medicinal plants as an alternative source of anthelmintics. In the current study, in vitro experiments were conducted to determine the possible anthelmintic effects of Balanites aegyptiaca stem bark aqueous extract on Strongyle larvae and the earthworm Pheretima posthuma. The in vitro studies revealed that the extract at graded concentrations of 300 mg/ml, 400 mg/ml, 500 mg/ml and 600 mg/ml exhibited larvicidal activity (p&lt;0.05) against earthworms with 600 mg/ml having the highest activity causing paralysis and death. In a similar vein, a graded concentration response was observed against Strongyle larvae. The highest effective concentration on larvae was 250 mg/ml which had a larval mortality rate of 100% and a mortality index of one (1) comparable with that of albendazole. The IC50 and IC99 values for the time of paralysis were 442.7mg/ml and 767.80mg/ml respectively. The anthelmintic activity exhibited by the extract could be linked to the presence of phytochemicals present in the plant. These findings support the folkloric use of this plant in the control and management of gastrointestinal nematodes in humans and animals.

Evidence of resistance to ivermectin in the gastrointestinal nematodes of horses from Mexican southeast.

Gastrointestinal nematodes (GIN) are a major impediment to breeding and exploitation of horses. Traditional control of GIN has generated resistance to main anthelmintics, including ivermectin. An analysis of five ranches with a history of IVM use was done to determine the efficacy and resistance of GIN to IVM treatment in horses from the Mexican southeast. Predesigned questionnaires were applied to collect information on previous treatment protocols. The fecal egg count reduction test (FECRT) was applied to determine resistance. Before IVM application, a McMaster test was used to diagnose GIN infection in horses, and feces cultures were done to identify L3 larvae for Strongylida eggs. Pre-treatment samples showed that 72.7% (80/110) of horses were GIN positive, with cyathostomins being the most frequent (91.8%), followed by Oxyuris equi (7.0%), Parascaris equorum (1.0%), and Strongylus vulgaris (0.2%). Based on the results, the horses at each ranch were divided in control (CG) and experimental (EG) groups with similar eggs per gram of feces (EPG). The EG (40/80) was dewormed with IVM (0.2mg/kg orally) and the CG (40/80) remained untreated. After 14days, EPG were measured, and feces cultures were done again to identify L3 larvae. After treatment of EG, 40% (16/40) of horses were positive, the most frequently identified GIN were cyathostomins (98.6%), followed by P. equorum (1.0%) and S. vulgaris (0.2%). Three of the five ranches were classified as resistant, according to the FECRT, with a percentage of reduction from 53 to 68%, all of which used IVM ≥4 times annually. This is the first evidence of resistance in cyathostomins to IVM treatment in horses from the Mexican southeast, adding to the current problem of anthelmintic resistance in equine GIN.

An Overview of Anthelmintic Resistance in Domestic Ruminants in Brazil

Gastrointestinal nematodes (GIN) significantly, negatively impact livestock worldwide, and their control depends on the use of chemotherapy drugs. However, this approach is unsustainable as anthelmintic resistance (AR) is growing widespread. This article provides a comprehensive overview of the historical and current data published on AR in domestic ruminants in Brazil. Alternative measures of GIN control have been discussed to provide helpful information to prevent the development of AR in the country. This review consisted of a search of technical and scientific publications between January 1960 to January 2023, using online sources such as PubMed, Scielo and Google Scholar. Eighty-three articles published over the last six decades reporting AR in sheep (n = 43), goats (n = 20) and cattle (n = 20) were included. A total of 37.3%, 25.4% and 37.3% evaluated one, two and three or more molecule classes, respectively. Among all studies, 82.1% used fecal egg count reduction test as a method of AR diagnosis. In conclusion, AR is an urgent and emerging issue for ruminant production in Brazil. It is necessary to evaluate on a large scale the distribution and management of anthelmintic drugs and discuss strategies that delay this phenomenon’s development.