Current and predicted temperatures impair reproduction in the Australian sheep flock

Climate change threatens global livestock production1,2. We modelled the impact of recent temperatures and a 1°C and 3°C temperature increase over the historical baseline on risks of heat stress at key periods of the reproductive cycle and consequences for reproduction across the entire Australian sheep flock. We estimate that 2.1 million potential lambs are currently lost annually due to heat stress, increasing to 2.5 and 3.3 million as temperatures rise.

Conditional knockdown of transformer in sheep blow fly suggests a role in repression of dosage compensation and potential for population suppression

The transformer (tra) gene is essential for female development in many insect species, including the Australian sheep blow fly, Lucilia cuprina. Sex-specific tra RNA splicing is controlled by Sex lethal (Sxl) in Drosophila melanogaster but is auto-regulated in L. cuprina. Sxl also represses X chromosome dosage compensation in female D. melanogaster. We have developed conditional Lctra RNAi knockdown strains using the tet-off system. Four strains did not produce females on diet without tetracycline and could potentially be used for genetic control of L. cuprina. In one strain, which showed both maternal and zygotic tTA expression, most XX transformed males died at the pupal stage. RNAseq and qRT-PCR analyses of mid-stage pupae showed increased expression of X-linked genes in XX individuals. These results suggest that Lctra promotes somatic sexual differentiation and inhibits X chromosome dosage compensation in female L. cuprina. However, XX flies homozygous for a loss-of-function Lctra knockin mutation were fully transformed and showed high pupal eclosion. Two of five X-linked genes examined showed a significant increase in mRNA levels in XX males. The stronger phenotype in the RNAi knockdown strain could indicate that maternal Lctra expression may be essential for initiation of dosage compensation suppression in female embryos.

Glenthenamines A–F: Enamine pyranonaphthoquinones from the Australian pasture plant-derived Streptomyces sp. CMB-PB042

Chemical investigations into solid phase cultivations of an Australian sheep station pasture plant-derived Streptomyces sp. CMB-PB042, yielded the rare enamine naphthopyranoquinones BE-54238A (1) and BE-54238B (2), together with four new analogues, glenthenamines B–D (4–6) and F (8), and two handling artifacts, glenthenamines A (3) and E (7). Single crystal X-ray analyses of 1–2 resolved configurational ambiguities in the scientific literature, while detailed spectroscopic analysis and biosynthetic considerations assigned structures inclusive of absolute configuration to 3–8. We propose a plausible sequence of biosynthetic transformations linking structural and configurational features of 1–8, and apply a novel Schiff base "fishing" approach to detect a key deoxyaminosugar precursor. These enamine naphthopyranoquinone disclose a new P-gp inhibitory pharmacophore capable of reversing doxorubicin resistance in P-gp overexpressing colon carcinoma cells.

Using a Bayesian Network Predictive Model to Understand Vulnerability of Australian Sheep Producers to a Foot and Mouth Disease Outbreak

To maintain and strengthen Australia's competitive international advantage in sheep meat and wool markets, the biosecurity systems that support these industries need to be robust and effective. These systems, strengthened by jurisdictional and livestock industry investments, can also be enhanced by a deeper understanding of individual producer risk of exposure to animal diseases and capacity to respond to these risks. This observational study developed a Vulnerability framework, built from current data from Australian sheep producers around behaviors and beliefs that may impact on their likelihood of Exposure and Response Capacity (willingness and ability to respond) to an emergency animal disease (EAD). Using foot and mouth disease (FMD) as a model, a cross-sectional survey gathered information on sheep producers' demographics, and their practices and beliefs around animal health management and biosecurity. Using the Vulnerability framework, a Bayesian Network (BN) model was developed as a first attempt to develop a decision making tool to inform risk based surveillance resource allocation. Populated by the data from 448 completed questionnaires, the BN model was analyzed to investigate relationships between variables and develop producer Vulnerability profiles. Respondents reported high levels of implementation of biosecurity practices that impact the likelihood of exposure to an EAD, such as the use of appropriate animal movement documentation (75.4%) and isolation of incoming stock (64.9%). However, adoption of other practices relating to feral animal control and biosecurity protocols for visitors were limited. Respondents reported a high uptake of Response Capacity practices, including identifying themselves as responsible for observing (94.6%), reporting unusual signs of disease in their animals (91.0%) and daily/weekly inspection of animals (90.0%). The BN analysis identified six Vulnerability typologies, with three levels of Exposure (high, moderate, low) and two levels of Response Capacity (high, low), as described by producer demographics and practices. The most influential Exposure variables on producer Vulnerability included adoption levels of visitor biosecurity and visitor access protocols. Findings from this study can guide decisions around resource allocation to improve Australia's readiness for EAD incursion and strengthen the country's biosecurity system.

Bacterial communities in the gastrointestinal tract segments of helminth-resistant and helminth-susceptible sheep

Background Helminth parasitism is a world-wide problem in livestock industries, with major impacts on health, welfare and productivity. It has been the subject of decades of research, but little attention has been paid to the role of the gut microbiota in the responses to infection. The present study characterized the microbiome along the gastro-intestinal tract (GIT) of sheep and tested whether it had been affected by three decades of breeding for resistance to helminth infection. Australian Sheep Breeding Values (ASBVs) for faecal egg count (FEC) were used to select the 10 most worm-susceptible (High-FEC) and 10 most worm-resistant (Low-FEC) animals. DNA was extracted and sequenced for 16S rRNA gene from faeces and from the lumen of the rumen, abomasum, duodenum, jejunum, ileum, caecum, and colon. Results The most frequent genera identified along the GIT were Eubacterium, Oscillibacter, and Ruminococcus. Intersectoral-specialization zones were identified along the GIT, with the duodenum revealing major differences between the High-FEC (helminth-susceptible) and Low-FEC (helminth-resistant) animals in values for Alpha and Beta diversity. The High-FEC and Low-FEC sheep differed significantly for three phyla (Firmicutes, Elusimicrobia, Chloroflexi) and 11 genera. At other GIT sites, Firmicutes was the most abundant phylum followed by Bacteroidetes, and Proteobacteria presenting no major differences between High-FEC and Low-FEC. Conclusions The gastro-intestinal microbial profile varies widely between helminth-resistant and helminth-susceptible sheep. Each GIT section appears to supports a particular bacterial composition leading to inter-sectoral differences among the various microbial communities. The animal’s duodenum creates the right environment which results in a more diverse and richness microbial population in the helminth-resistant sheep and suggests that this population favours bacterial genera that generally ferment carbohydrates. The energy metabolism of sheep is largely based on the production of volatile fatty acids (acetate, butyrate, propionate) in the rumen, raising the possibility that butyrate-producing bacteria in the duodenum of helminth-resistant sheep, modulate the host’s metabolism and assist in the regulation of the parasite burden.

Characterization of Breed Specific Differences in Spermatozoal Transcriptomes of Sheep in Australia

Reduced reproductive efficiency results in economic losses to the Australian sheep industry. Reproductive success, particularly after artificial insemination, is dependent on a number of contributing factors on both ewe and ram sides. Despite considerable emphasis placed on characterising ewe side contributions, little emphasis has been placed on characterising ram side contributions to conception success. Over 14,000 transcripts are in spermatozoa of other species, which are transferred to the ova on fertilisation. These transcripts conceivably influence early embryonic development and whether conception is successful. Semen was collected (n = 45) across three breeds; Merino, Dohne, and Poll Dorset. Following collection, each ejaculate was split in two; an aliquot was assessed utilising Computer Assisted Semen Analysis (CASA) and the remaining was utilised for RNA extraction and subsequent next-generation sequencing. Overall, 754 differentially expressed genes were identified in breed contrasts and contrast between ejaculates of different quality. Downstream analysis indicated that these genes could play significant roles in a broad range of physiological functions, including maintenance of spermatogenesis, fertilisation, conception, embryonic development, and offspring production performance. Overall results provide evidence that the spermatozoal transcriptome could be a crucial contributing factor in improving reproductive performance as well as in the overall productivity and profitability of sheep industries.

Quality, proximate composition, and sensory characteristics of Dorper, domestic commercial crossbred, and Australian sheep meat: a comparative study

The objective of this study was to compare the proximate, quality, and sensory attributes of Dorper sheep meat (Dorper), domestic commercial crossbred (DCC) and Australian commercial crossbred (ACC). A total of 60 untrimmed loins from the three sheep sources were purchased (20 sheep loins/source) and processed. The objective color, objective tenderness [Warner–Bratzler Shear Force (WBSF)], and proximate composition of the sheep meat were evaluated. A consumer panel and a trained sensory panel were also conducted to evaluate the sensory attributes. Dorper had greater (P = 0.04) carbohydrate content compared to DCC, but was not (P = 0.86) different from ACC. In addition, Dorper had the greatest WBSF value, followed by DCC, with ACC having the least WBSF out of the three (P < 0.0001). For the consumer panel, Dorper was rated to be less tender than ACC (P = 0.01), but was not different from DCC (P = 0.76). Dorper was also rated with lower flavor acceptability compared to DCC (P = 0.02), but was not different from ACC (P = 0.86). In addition, Dorper had the lowest overall acceptance rating by the consumers (P = 0.01). Trained sensory panel results followed the same trend as the consumer panel results which rated Dorper to be less tender than ACC (P = 0.002), but was not different from DCC (P = 0.10). Dorper was also rated with greater off-flavor intensity compared to DCC (P = 0.009), but was not different from ACC (P = 0.53). Finally, no differences were found for all other attributes evaluated among the sheep sources. The results indicated that consumers did not prefer Dorper over ACC and DCC. However, additional research with a more controlled environment is needed to shed light on the true palatability traits of Dorper.