Breeding for resistance to gastrointestinal nematodes - the potential in low-input/output small ruminant production systems

AbstractThe control of gastrointestinal nematodes (GIN) is mainly based on the use of drugs, grazing management, use of copper oxide wire particles and bioactive forages. Resistance to anthelmintic drugs in small ruminants is documented worldwide. Host genetic resistance to parasites, has been increasingly used as a complementary control strategy, along with the conventional intervention methods mentioned above. Genetic diversity in resistance to GIN has been well studied in experimental and commercial flocks in temperate climates and more developed economies. However, there are very few report outputs from the more extensive low-input/output smallholder systems in developing and emerging countries. Furthermore, results on quantitative trait loci (QTL) associated with nematode resistance from various studies have not always been consistent, mainly due to the different nematodes studied, different host breeds, ages, climates, natural infections versus artificial challenges, infection level at sampling periods, among others. The increasing use of genetic markers (Single Nucleotide Polymorphisms, SNPs) in GWAS or the use of whole genome sequence data and a plethora of analytic methods offer the potential to identify loci or regions associated nematode resistance. Genomic selection as a genome-wide level method overcomes the need to identify candidate genes. Benefits in genomic selection are now being realised in dairy cattle and sheep under commercial settings in the more advanced countries. However, despite the commercial benefits of using these tools, there are practical problems associated with incorporating the use of marker-assisted selection or genomic selection in low-input/output smallholder farming systems breeding schemes. Unlike anthelmintic resistance, there is no empirical evidence suggesting that nematodes will evolve rapidly in response to resistant hosts. The strategy of nematode control has evolved to a more practical manipulation of host-parasite equilibrium in grazing systems by implementation of various strategies, in which improvement of genetic resistance of small ruminant should be included. Therefore, selection for resistant hosts can be considered as one of the sustainable control strategy, although it will be most effective when used to complement other control strategies such as grazing management and improving efficiency of anthelmintics currently

Cinemaethnographic specta(c)torship: discursive readings of what we choose to (dis)possess

This article examines critical methodological issues emerging from the interstices of applied educational research, social science research, and arts-based research, bringing criticality into the field of childhood. The author aims to question how she might w(rest)le (un)comfortably with "what is worth looking at" when studying children. Maneuvering between observations of children in classrooms and representations of children in film, the author will not only consider ways she enacts discrete performances of specta(c)torship but also how she might resist revoking one performance for another within her "practices of looking" by conjuring the menace of ambivalent narratives. Rather than falling into familiar framing devices that serve to embrace some, but prohibit other ways of seeing, she will procure notions of colonialism and restless hybridity to incite antagonistic play on the edges of ethnographic specta(c)torship, drawing on Stronach’s notion of "lean-to" concepts

Self-adaptive Systems: Facilitating the Use of Combinatorial Problem Solvers.

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