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A Genetic Approach to Internal Parasite Control in Australian Cattle
The primary objective of this project was to demonstrate that parasite resistance in cattle herds could be established and maintained via genetic selection without compromising enterprise profitability.
The control of the effects of internal parasites on production and profitability presents a significant cost to Australian beef cattle producers. Current methods of internal parasite control rely heavily on the strategic use of chemicals. The useful life of these chemicals is shortened by the rapid development of resistance by the parasites. Failure of these chemicals is widespread. In addition, there is growing pressure on cattlemen to reduce costs whilst remaining open to increasing scrutiny and traceability regarding safe, residue free food. There is also an increasing interest in organic food production with emphasis on chemical free production methods.
This project demonstrated that it is possible to select cattle with enhanced resistance to internal parasites in pasture based breeding herds in southeastern Australia. Using faecal egg counts (FEC) of paternal half-sibling lines of weaner cattle as a phenotypic indicator of internal parasite resistance, it was possible to develop EBVs for parasite resistance for sires. The heritability of this trait was found to be 41%.
With 41% of the total variation in faecal egg output within weaner groups being due to genetics, there is ample opportunity for selection if half-sibling sire-lines containing adequate numbers are made available. Breedplan, with its use of link sires, provides genetic linkages and large half-sibling sire groups from herds over a wide range of environments and management situations. The Angus Long Fed/CAAB Dollar index was very similar for animals with high or low parasite resistance EBVs. This gives an early indication that progress could be made in selection for parasite resistance without compromising progress with production traits.
The potential benefits to industry from adopting the technology include:
1. Increased usage of genetic selection (via sire EBVs) for enhanced parasite resistance within breeds.
2. Decreased reliance on chemical control of internal parasites.
3. Improved productivity and profitability of beef enterprises.
4. Improvements in aspects of animal welfare and environmental stewardship.
Initial benefits will be to progressive seedstock producers who adopt the technology to obtain a marketing advantage. The gathering of phenotypic information for this trait is cumbersome. Therefore, future research on seedstock herds with wide commercial acceptance would provide the maximum industry benefit. Benefits would be transferred to those clients who use EBVs in their selection decisions. This process will be facilitated by the dissemination of useful information via such mechanisms as targeted media outlets, sire catalogues, extension activities and field days, as well as via scientific discourse.
The collection of phenotypic data for calculation of EBVs for enhanced genetic resistance presents difficulty in comparison to easy to measure traits such as 400day weight. Therefore, future progression of research would preferably involve collecting data from Breedplan enrolled herds using link sires selected by Australian Genetics and Breeding Unit (AGBU) at New England University. From these herds, sires can be identified for commercial industry and to be used in breeding trials to establish populations of cattle for genomic studies. Development of marker assisted EBVs for enhanced parasite resistance would serve as a realistic objective of future research on this hard to measure trait.
This page was last updated on 24/07/2017
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