Unravelling the environmental influences on the reproductive output of Australian merino sheep using non-invasive physiological tools Gregory J. Sawyer1* and Dr Edward J. Narayan1** 1School
of Science and Health, Hawkesbury Campus, Western Sydney University, Locked Bag 1797 Penrith NSW 2751 Australia *Masters of Philosophy Candidate. Email:
[email protected] ** Principal Supervisor, Senior Lecturer in Animal Science. Email:
[email protected]
INTRODUCTION Reproductive wastage is a big problem in sheep production globally(1). Reproductive wastage is the early embryo losses in sheep due to a combination of environmental and biological stress factors, such as heat stress(2). We are investigating how heat stress influences the reproductive and stress physiology of merino sheep during early pregnancy. The research outcomes will deliver new knowledge for technology enhancement for a wide range of animal health and reproductive enhancement.
METHODOLOGY
OBJECTIVES 1 – Determine physiological stress and thermal profiles of merino ewes participating in Al/natural joining programs using non-invasive hormone monitoring tools.
Key biological parameters recorded (study in progress). I. Thermal profiling–using thermal camera and internally(3)
2 – Evaluate the relationship(s) between environmental temperature and data obtained in objective 1 (above).
II. Faecal cortisol metabolites - Enzyme-immuno assay kits (EIA) modifying methods(4) III. Epigenetics – Next-gen Sequencing(5)
3 – To assess the potential epigenetic effects of heat stress on sheep phenotypic traits (e.g. wool micron).
Above: Rams and Ewes in a natural joining environment Below: Early results showing the relationship between percentage (%) of transferable embryos of donor ewes and body temperature either under or above 39.5 oC.
Above and below: Live early results from the trial producing an epigenetic effect of the environment on the next generation of merino sheep
Dam name 14-0014 14-0014 14-0014 14-0014 12-0009 12-0009 12-0009 12-0027 12-0027
Body Temperature Yearling Weight 39.4 82 39.4 83 39.4 80 39.4 62.5 39.3 72 39.3 68 39.3 59.5 38.9 67 38.9 73.5
Wool Micron 16.5 15.8 16.5 17.9 16.8 17.4 18.1 16.7 15.6
Epigenetic change in lambs through changes in yearling weight and wool micron (shown in purple –above)
Discussion
1) The key differences in percentage of transferable eggs clearly shows that body temperature greater than 39.5oC has significant impact on the percentage of embryos transferred in the AI program. 2) Early results from raw on-farm data of the lambs born in the trial shows that yearling body weight and fleece microns are epigenetically influenced by environmental stressors in an AI/ET program. 3) Our study is promising and will provide significant impact through new knowledge on the effects of climate on breeding more merinos in various reproduction programs, in a wide variety of environments. REFEREN CE 1) Narayan, E., & Parisella, S. (2017). Influences of the stress endocrine system on the reproductive endocrine axis in sheep (Ovis aries). Italian Journal Of Animal Science, 1-12. 2) Sawyer, G. (1979). The influence of radiant heat load on reproduction in the Merino ewe. II. The relative effects of heating before and after insemination. Australian Journal Of Agricultural Research, 30(6), 1143. Http://dx.doi.org/10.1071/ar9791143
4) Stubsjøen, S., Bohlin, J., Dahl, E., Knappe-Poindecker, M., Fjeldaas, T., & Lepschy, M. et al. (2015). Assessment of chronic stress in sheep (part I): The use of cortisol and cortisone in hair as non-invasive biological markers. Small Ruminant Research, 132, 25-31
3) O’Neill, C.J,. Swain, D.L,. (2015) Improving Livestock Productivity in Stressful Rangeland Environments. Univeristy of Queensland , School of Medical and Applied Science, Rockhampton Queensland.
5) Suzuki, M., Bird, A.,DNA methylation landscapes: provocative insights from epigenomics: Nature Reviews Genetics, 6/2008, Vol.9(6), pp.465-476
Acknowledgement: We thank Roseville Park Merino Stud, Towalba Merino Stud, Merinolink, Ooranook Pastoral Company, Australian Wool Network, NSW Stud Merino Breeders for their support in this research. Animal Ethics Approval A12345
Research Week HDR Showcase 2017
