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Van Wettere WHEJ, Culley S, Swinbourne AMF, Leu ST, Lee SJ, Weaver AC, Kelly JM, Walker SJ, Kleemann DO, Thomas DS, Hayman PT, Gatford KL, Kind KL, Westra S. Heat stress from current and predicted increases in temperature impairs lambing rates and birth weights in the Australian sheep flock. Nat Food 2024; 5:206-210. [PMID: 38459392 DOI: 10.1038/s43016-024-00935-w] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/30/2021] [Accepted: 02/12/2024] [Indexed: 03/10/2024]
Abstract
Livestock heat stress threatens production, particularly in semi-arid, arid and tropical regions. Using established temperature thresholds for sheep, we modelled +1 °C and +3 °C temperature increases over the historical baseline, estimating that 2.1 million potential lambs are lost annually due to heat stress alone, increasing to 2.5 and 3.3 million, respectively, as temperatures rise. Heat stress poses risks at key periods of the reproductive cycle, with consequences across the Australian sheep flock.
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Affiliation(s)
- William H E J Van Wettere
- Davies Livestock Research Centre, School of Animal and Veterinary Sciences, University of Adelaide, Adelaide, South Australia, Australia.
| | - Sam Culley
- School of Civil, Environmental and Mining Engineering, University of Adelaide, Adelaide, South Australia, Australia
| | - Alyce M F Swinbourne
- South Australian Research and Development Institute, Primary Industries and Regions SA, Reproductive Biology, Livestock Sciences, Turretfield Research Centre, Rosedale, South Australia, Australia
| | - Stephan T Leu
- Davies Livestock Research Centre, School of Animal and Veterinary Sciences, University of Adelaide, Adelaide, South Australia, Australia
| | - Stephen J Lee
- Davies Livestock Research Centre, School of Animal and Veterinary Sciences, University of Adelaide, Adelaide, South Australia, Australia
| | - Alice C Weaver
- South Australian Research and Development Institute, Primary Industries and Regions SA, Reproductive Biology, Livestock Sciences, Turretfield Research Centre, Rosedale, South Australia, Australia
| | - Jennifer M Kelly
- South Australian Research and Development Institute, Primary Industries and Regions SA, Reproductive Biology, Livestock Sciences, Turretfield Research Centre, Rosedale, South Australia, Australia
| | - Simon J Walker
- South Australian Research and Development Institute, Primary Industries and Regions SA, Reproductive Biology, Livestock Sciences, Turretfield Research Centre, Rosedale, South Australia, Australia
| | - David O Kleemann
- South Australian Research and Development Institute, Primary Industries and Regions SA, Reproductive Biology, Livestock Sciences, Turretfield Research Centre, Rosedale, South Australia, Australia
| | - Dane S Thomas
- Waite Research Institute, School of Agriculture, Food and Wine, The University of Adelaide, Urrbrae, South Australia, Australia
- South Australian Research and Development Institute, Primary Industries and Regions SA, Government of South Australia, Climate Applications, Waite Research Precinct, Urrbrae, South Australia, Australia
| | - Peter T Hayman
- Waite Research Institute, School of Agriculture, Food and Wine, The University of Adelaide, Urrbrae, South Australia, Australia
- South Australian Research and Development Institute, Primary Industries and Regions SA, Government of South Australia, Climate Applications, Waite Research Precinct, Urrbrae, South Australia, Australia
| | - Kathryn L Gatford
- Robinson Research Institute, School of Biomedicine, The University of Adelaide, Adelaide, South Australia, Australia
| | - Karen L Kind
- Davies Livestock Research Centre, School of Animal and Veterinary Sciences, University of Adelaide, Adelaide, South Australia, Australia
| | - Seth Westra
- School of Civil, Environmental and Mining Engineering, University of Adelaide, Adelaide, South Australia, Australia
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Abstract
microRNA (miRNA) are promising candidates for disease biomarkers as they are abundant in circulation, highly stable in biological fluids and may yield diagnostic biomarker signatures. The reported issues with miRNA isolation using traditional RNA reagents necessitates the optimisation of miRNA isolation from challenging samples. In this study we compared six commercial RNA extraction kits to evaluate their ability to isolate miRNA from ovine plasma. We also compared three methods for quantification of small RNA extracted from plasma to determine the most reliable. Using minimal sample inputs of fresh and frozen plasma from five sheep, we compared the six kits (Kit A-F) using quantitative PCR. Operational factors were also assessed for each kit. Kits A and B provided the best detection of the miRNA qPCR reference genes across fresh and frozen samples (p < 0.001) followed by Kit C. The Qubit and microRNA assay provided the least variation (% CV 5.47, SEM ± 0.07), followed by the NanoDrop (% CV 7.01, SEM ± 0.92) and Agilent Bioanalyzer (% CV 59.21, SEM ± 1.31). We identify Kit A to be optimal for isolating miRNA from small volumes of fresh and frozen ovine plasma, and Kit B the top performing kit taking into consideration miRNA detection and operational factors. The Qubit fluorometer using a microRNA assay was the most reliable miRNA quantification method.
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Affiliation(s)
- Kathryn Wright
- The University of Sydney, Faculty of Science, Sydney School of Veterinary Science, Sydney, Australia
| | - Kumudika de Silva
- The University of Sydney, Faculty of Science, Sydney School of Veterinary Science, Sydney, Australia.
| | - Auriol C Purdie
- The University of Sydney, Faculty of Science, Sydney School of Veterinary Science, Sydney, Australia
| | - Karren M Plain
- The University of Sydney, Faculty of Science, Sydney School of Veterinary Science, Sydney, Australia
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Nordberg EJ, Schwarzkopf L. Predation risk is a function of alternative prey availability rather than predator abundance in a tropical savanna woodland ecosystem. Sci Rep 2019; 9:7718. [PMID: 31118446 PMCID: PMC6531519 DOI: 10.1038/s41598-019-44159-6] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2018] [Accepted: 05/07/2019] [Indexed: 11/09/2022] Open
Abstract
Typically, factors influencing predation risk are viewed only from the perspective of predators or prey populations but few studies have examined predation risk in the context of a food web. We tested two competing hypotheses regarding predation: (1) predation risk is dependent on predator density; and (2) predation risk is dependent on the availability of alternative prey sources. We use an empirical, multi-level, tropical food web (birds-lizards-invertebrates) and a mensurative experiment (seasonal fluctuations in abundance and artificial lizards to estimate predation risk) to test these hypotheses. Birds were responsible for the majority of attacks on artificial lizards and were more abundant in the wet season. Artificial lizards were attacked more frequently in the dry than the wet season despite a greater abundance of birds in the wet season. Lizard and invertebrate (alternative prey) abundances showed opposing trends; lizards were more abundant in the dry while invertebrates were more abundant in the wet season. Predatory birds attacked fewer lizards when invertebrate prey abundance was highest, and switched to lizard prey when invertebrate abundance reduced, and lizard abundance was greatest. Our study suggests predation risk is not predator density-dependent, but rather dependent on the abundance of invertebrate prey, supporting the alternative prey hypothesis.
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Affiliation(s)
- Eric J Nordberg
- College of Science and Engineering, James Cook University, Townsville, QLD 4811, Australia.
| | - Lin Schwarzkopf
- College of Science and Engineering, James Cook University, Townsville, QLD 4811, Australia
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