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- Title
Production benefits of breeding for worm resistance in Merino sheep.
- Authors
Greeff, J. C.; Karlsson, L. J. E.
- Abstract
Context: Production losses, due to worms and anthelmintic costs to control the infection, can affect the profitability of sheep production systems. Aims: This study was carried out to quantify the production benefits of worm-resistant sheep. Methods: Genetically worm-resistant and unselected control Merino rams were mated annually to 150 ewes in each of the Resistant and Control lines respectively over an 8-year period. All ewes and their progeny were managed in small replicated paddocks to prevent any cross-contamination between paddocks and groups. Fertility, growth, wool production, wool quality and worm resistance were measured on the ewes and their progeny. The data were analysed using mixed model methodology. Key results: The progeny of the Resistant sires were on average 21–25% more worm resistant than the progeny of the Control sires. No significant differences were recorded in reproduction between mature ewes of the Resistant and Control lines, or in the survival rate of their lambs. Resistant line progeny were on average 1.6 kg heavier at weaning, received 15–17% less drenching during the experiment and produced on average 0.3 μm finer wool at hogget shearing than the Control line progeny. Conclusions: It is concluded that the Resistant line coped better with a worm challenge and that this resulted in increased production. Implications: This study shows that apart from improved worm resistance, there are associated production benefits in breeding for worm resistance. Intestinal worms have been estimated to cost the sheep industry annually $436 million in production losses and from anthelmintic treatment costs. The inappropriate use of anthelmintic drenches has also resulted in an increase in the parasites becoming genetically resistant to the drenches. This study showed that sheep that were genetically similar in production, but differed genetically only in resistance to worms, were more productive and required fewer anthelmintic treatments.
- Subjects
MERINO sheep; SHEEP breeding; INFECTION control; WORMS; SHEEP industry; COST control
- Publication
Animal Production Science, 2020, Vol 60, Issue 13, p1643
- ISSN
1836-0939
- Publication type
Article
- DOI
10.1071/AN19368