Markers/parameters for the evaluation of natural resistance status of small ruminants against gastrointestinal nematodes.

The high prevalence of anthelmintic-resistant gastrointestinal nematodes (GINs) throughout the world has led to the need for alternative worm control strategies. One of the possible substitutes to reduce the problems of drug resistance and residue is the evaluation/breeding of small ruminants for greater resistance to the GINs (organically produced), which in turn would be a helpful tool to predict the performance of an animal. At present, the existing diversity in the genetic potential to resist/tolerate GINs infection both within and between breeds has been validated. Successful selection of animals to define the genotype and identified resistance is related to the employed markers. A number of phenotypic traits such as faecal egg count (FEC), worm burden, serum antibodies, peripheral eosinophilia, packed cell volume, live weight, serum protein and albumin concentrations have been used for this purpose both in natural and artificial infections. Relatively resistant/tolerant animals have also been found to have mastocytosis, globule leucocytes, high levels of histamine and immunoglobulin (Ig) A and IgE concentrations. Of these traits, the principal and most practical measurement used to assess resistance status in animals undergoing similar parasite challenges is FEC. FEC has a positive/negative correlation with other biochemical, cellular and immunological parameters; however, the reliability of individual trial is often questioned and valuable information regarding the genetic makeup can be obtained from pooled data of a large number of trials and parameters. This paper covers all the aspects reported in the literature on various parameters considered to evaluate the resistance status of a range of small ruminant breeds.

Contrasting views of animal healthcare providers on worm control practices for sheep and goats in an arid environment.

A questionnaire survey was conducted to determine the worm control practices and anthelmintic usage of 150 key respondents involved in sheep and goat production in the arid Thal area of Pakistan. The information was collected by visiting farms, and interviewing the key respondents which included veterinary officers (n = 15), veterinary assistants (n = 51), traditional practitioners (n = 24), and small and large scale sheep/goat farm herders and owners (n = 60). Among all interviewed animal healthcare providers, the veterinary officers had the highest level of awareness of parasitic infection and advocated the use of modern available anthelmintics according to the predefined schedule. The farmers on the other hand, had the lowest level of knowledge about parasitic infections. They used modern anthelmintics at low frequencies (every six months) following an unusual practice of diluting the medicine. Veterinary assistants had a medium level of awareness about the parasitic infections using anthelmintic treatments when they deemed necessary rather than following a predefined treatment schedule. Traditional practitioners were also aware of parasitic infections and used traditional anthelmintics or a combination of the traditional and modern anthelmintics. The animal health providers had a different awareness and knowledge of parasitic infections which resulted in contrasting proposals for its' control. The farmers used worm control measures in accordance with their own views and those of animal healthcare advisors, combining modern and traditional treatments. This study provides the first insight into the differing views of those animal healthcare providers who form the basis for effective parasitic control within the sheep and goat industry of an arid region.

Evaluation of three Pakistani sheep breeds for their natural resistance to artificial infection of Haemonchus contortus.

This study was carried out to evaluate three Pakistani sheep breeds (Kachhi, Lohi and Thalli) for their natural resistance against artificial infection of Haemonchus contortus. Lambs were weaned at 3 months of age, housed in separate pens and treated with Avermectin to eliminate gastrointestinal nematode infection. Each lamb was infected orally with approximately 10,000 third stage larvae of H. contortus. Selected breeds were compared on the basis of parasitological, haematological, biochemical and histopathological parameters over a period of 9 weeks. Faecal egg counts were measured weekly while packed cell volume, total serum protein, serum albumin and live weight were determined fortnightly. At 9th-week post-infection, 10 animals of each breed were randomly selected and slaughtered for worm, eosinophil and mast cell counts from the abomasum of each animal. Faecal egg counts and worm burden were significantly lower (P<0.05) in Lohi sheep than Kachhi and Thalli breeds. Furthermore, the Lohi breed also exhibited the highest levels of packed cell volume, total serum protein, albumin as well as eosinophils and mast cell counts. Breed x week interaction also remained significant (P<0.05) in most of the parameters for Lohi breed. The results suggested that Lohi breed expressed a significant innate resistance to artificial infection of H. contortus.