Anthelmintic efficacy of fenbendazole and levamisole in native fowl in northern Iran

Pharmacokinetic profiles and egg residue patterns of levamisole in laying hens at two dosing rates and two routes of administration

The levamisole maximum residue limit for edible fat, kidney, and muscle of chickens is 0.01 mg/kg. However, no maximum residue limit has been established for eggs. In the present study, the pharmacokinetic profile and levamisole residue in the eggs from laying hens were investigated using ultra-performance liquid chromatography-tandem mass spectrometry. A single dose of levamisole (30 mg/kg) was administered via the intramuscular or oral route, and an additional egg residue study was performed with 300 or 600 mg/kg commercial LEV drug (30 or 60 mg/kg as levamisole) orally. The limit of quantification was 0.0056 μg/mL and 0.0015 mg/kg for plasma and eggs, respectively. The plasma concentration was below the limit of quantification 10 and 12 h after intramuscular and oral administration, respectively. The half-life of the absorption phase was comparable between the intramuscular and oral routes, which was approximately 1 h, and the mean maximum concentration value was significantly higher in intramuscular (2.29 ± 0.30 μg/mL) than in oral (1.45 ± 0.38 μg/mL) route. The relative oral bioavailability after intramuscular administration was 92.3%. In the egg residue study, dose-dependent area under concentration and maximum concentration were observed after single oral administration of 30 and 60 mg/kg egg residue, and the calculated withdrawal period for both 30 and 60 mg/kg groups based on the positive list system standard (0.01 mg/kg) was 7 d after the treatment.

Ascaridia galli - An old problem that requires new solutions

Reports of Ascaridia galli in laying hens in Europe have increased since the ban on conventional battery cages in 2012. As this parasite is transmitted directly via the faecal-oral route by parasite eggs containing a larva, it is reasonable to assume that the escalating problem is related to the increased exposure now occurring in modern welfare-friendly cage-free housing systems. On many farms, A. galli reappears in subsequent flocks, even though the birds have no access to the outdoors, biosecurity is high and empty houses are cleaned and disinfected during downtime. Since the egg production cycle lasts only ≈80 weeks and recombinant antigen production for helminth vaccines has not yet been solved, the development of a vaccine seems to be an unrealistic option. Therefore, disrupting the life cycle of the parasite by other means, including the strategic use of dewormers, appears to be the key to controlling infection. Of concern is that only one class of anthelmintics is licenced for poultry in Europe and that are usually administered indiscriminately through the birds' drinking water and often too late when the parasite is already established. If current calendar-based parasite control strategies are not changed, there is a risk that resistance to anthelmintics may develop, as has already been demonstrated with nematodes in livestock. We insist that treatments can be more effective and the risk of developing drug resistance can be mitigated if we invest in a better understanding of A. galli responses to more prudent and judicious use of anthelmintics. This review identifies knowledge gaps and highlights aspects of sustainable parasite control that require further research to support commercial egg producers.

A high level estimation of the net economic benefits to small-scale livestock producers arising from animal health product distribution initiatives

Introduction

A fundamental challenge for charities that facilitate distribution of animal health products to small-scale livestock producers (SSPs) in low and middle income countries (LMICs) is identifying the products and market mechanisms that provide the greatest positive impact for SSPs and estimating their associated impact. This paper describes a pragmatic approach to modeling the impact of market-led product distribution initiatives based on estimating the net economic benefit of administration of animal health products.

Methods

The model estimates the economic impact of diseases at the individual animal level for poultry, small ruminants, and cattle. The economic impact of mortality and growth inhibition associated with disease are then estimated in conjunction with the losses averted or recovered by preventing or treating the disease. Economic benefit is estimated in 2014-2017 values and also adjusted to 2023 values. The flexible model structure allows for addition of new geographies, new products, and increased granularity of modeled production systems.

Results

Applied to the Global Alliance for Livestock Veterinary Medicines (GALVmed) product distribution initiatives conducted in Africa and South Asia (SA) between 2014 and 2017, the model estimates an adjusted total net economic benefit of 139.9 million USD from sales of vaccines and poultry anthelminthics in these initiatives. Within SSA, the greatest net economic benefit was realized from East Coast fever and Newcastle disease vaccines, while in SA, peste des petits ruminants and Newcastle disease vaccines had the greatest net economic benefits. This translated to an adjusted $37.97 of net economic benefit on average per SSP customer, many of whom were small poultry producers.

Discussion

While the model currently estimates impacts from mortality and growth inhibition in livestock, there is the potential to extend it to cover impacts of further initiatives, including interventions targeted at diseases that impact production of milk, eggs, and reproduction.

Research on the Removal of Levamisole Residues in Bovine, Ovine, Caprine, Porcine and Poultry Tissues

In this paper, we set the waiting time for the elimination of levamisole residues at a safe level from tissues (muscles and organs) from animals treated with levamisole 10%—oral solution. We studied the depletion of levamisole residues by high performance liquid chromatography with a mass spectrometer (limit of quantification 2 μg/kg) in the tissues of bovine, ovine, caprine, porcine and poultry (chickens and pigeons) after administration of levamisole (10 mg levamisole/kg body weight for cattle, sheep, goats, pigs and 20 mg levamisole/kg body weight for birds). We found that in cattle, sheep and goats at 7 days after treatment, the residues of levamisole in the liver and at 14 days and in the other tissues were below the established limit value. In pigs at 7 days, residues from all tissues were below the set limit value. Residue depletion in chickens treated with levamisole was rapid, such that 3 days after treatment, the residues in all tissues were below the set limit. Residue depletion was slower in turkeys than in chickens.

In vitro evaluation of the effects of methanolic plant extracts on the embryonation rate of Ascaridia galli eggs

The present study aims to find efficient alternatives to synthetic anthelmintics among ethno-veterinary herbs. Ascaridia galli eggs isolated from the worm uterus were exposed in vitro to methanolic extracts (ME) of nine plant species such as Achillea millefolium (AM), Artemisia absinthium (AA), Artemisia vulgaris (AV), Cicerbita alpina (CA), Cichorium intybus (CI), Inula helenium (IH), Origanum vulgare (OV), Tanacetum vulgare (TV), Tanacetum parthenium (TP). Flubendazole (FL), 0.5% formalin with dimethylsulfoxide and Petri dishes without the addition of reagents were used as positive, negative and untreated control respectively. The effects of the different ME at concentrations 0.500, 0.325, 0.200 mg/ml were assessed on the embryonic development (ED) of the eggs in duplicate. Logit analysis was used to calculate EC₅₀ values. A generalized linear mixed model, having plant species and concentration as fixed effect and day as repeated measure, was used to determine differences in ED. Estimated EC₅₀ was the lowest for FL at 0.11 mg/ml. CA and TV followed with 0.27 mg/ml and 0.32 mg/ml. ED for FL was significantly lower (25%) than that of CA (47%). The analysis showed 0.5 mg/ml of the ME of CA and TV significantly affected the ED at 35% and 42% inhibitions respectively. The ED for all ME showed similar pattern i.e., relatively higher efficacy in the first experimental week compared to the rest of the experimental period. The effect from all multicomponent extracts is time and dose dependent. The plants have promising results in inhibiting ED, contributing to the identification of alternative anthelmintic treatments.