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An analysis of fertility and fecundity in the Australian sheep flock between 2006 and 2019.

ABSTRACT: After decades of decline, the Australian sheep flock aspires to rebuild its population of breeding ewes. A successful, rebuild will rely on high pregnancy rates and number of lambs born and reared. To examine this potential, a cross-sectional study of historical ultrasound pregnancy scanning records was undertaken using records collated from two experienced sheep pregnancy scanning businesses (years 2006 to 2019) from 15,397 mobs of ewes, totalling 7,443,314 ewes. Client details were de-identified and excluded from analyses, but details describing the mobs were retained when available, such as season of mating, production zone, ewe age, and breed. The key finding was a mean pregnancy rate (ewes pregnant per ewe scanned) of 0.76 ± 0.24, with a median of 0.83. Mobs scanned to identify fetal number had a higher mean (0.84 ± 0.15) and median (0.89) pregnancy rate. The mean reproduction rate (fetuses per ewe scanned) was 1.21 ± 0.27 and the median was 1.25. Differences were observed between the factors including age, breed, season, year or production zone but all results were lower than anticipated. The unexpected findings imply a problem exists with the fertility of many Australian sheep flocks.

SUBMITTER: Refshauge G

PROVIDER: S-EPMC11294327 | biostudies-literature | 2024 Aug

REPOSITORIES: biostudies-literature

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An analysis of fertility and fecundity in the Australian sheep flock between 2006 and 2019.

Refshauge G G Golledge M M Rickard J J de Graaf S S

Scientific reports 20240801 1

After decades of decline, the Australian sheep flock aspires to rebuild its population of breeding ewes. A successful, rebuild will rely on high pregnancy rates and number of lambs born and reared. To examine this potential, a cross-sectional study of historical ultrasound pregnancy scanning records was undertaken using records collated from two experienced sheep pregnancy scanning businesses (years 2006 to 2019) from 15,397 mobs of ewes, totalling 7,443,314 ewes. Client details were de-identifi ...[more]

PMID: 39090169

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Project description:ImportanceMore than 20% of births globally are by cesarean delivery, including more than 30% in the US. Prior studies have reported lower rates of childbearing after cesarean delivery, but it is not clear if this is due to maternal choice or lower conception rates.ObjectiveTo investigate the association between mode of first delivery and subsequent conceptions and live births.Design, setting, and participantsThe First Baby Study was a multicenter prospective cohort study of women aged 18 to 35 years with singleton pregnancies, enrolled and interviewed before first childbirth, who delivered in Pennsylvania from 2009 to 2011 and were followed up for 36 months after delivery (until April 2014). Data analysis for this study took place between May and July 2019 and in January 2020.ExposuresMode of first delivery (cesarean or vaginal).Main outcomes and measuresRates of subsequent conceptions and live births. Discrete-time Cox proportional hazard regression models were used to compare the rate of subsequent conception (vaginal vs cesarean) among those who completed the 36-month survey, accounting for reported months of unprotected intercourse during the follow-up period and adjusting for relevant covariates. A log binomial regression was used to compare the age-adjusted rate of subsequent live birth (vaginal vs cesarean) among those who completed the 36-month survey.ResultsThe study population consisted of 2423 women who were retained to the 36-month survey (mean [SD] age at baseline was 27.2 [4.4] years and 712 [29.4%] delivered by cesarean). There were 2046 women who had unprotected intercourse during the follow-up period, 2021 of whom provided data on months of unprotected intercourse. Cesarean delivery was associated with lower rates of conception after unprotected intercourse during the follow-up period (413 of 599 [68.9%]) compared with vaginal delivery (1090 of 1422 [76.7%]) (adjusted hazard ratio, 0.85; 95% CI, 0.74-0.96). Cesarean delivery was also associated with reduced likelihood of a subsequent live birth (305 women [42.8%]) compared with vaginal delivery (857 women [50.1%]), with an age-adjusted risk ratio of 0.83 (95% CI, 0.75-0.92).Conclusions and relevanceIn the 3 years following first childbirth, women who delivered their first child by cesarean had lower rates of conception after unprotected intercourse, and fewer of these women had a second child than those who delivered vaginally.

Project description:Reproductive traits play a vital role in determining the production efficiency of sheep. Maximizing the production is of paramount importance for breeders worldwide due to the growing population. Circular RNAs (circRNAs) act as miRNA sponges by absorbing miRNA activity through miRNA response elements (MREs) and participate in ceRNA regulatory networks (ceRNETs) to regulate mRNA expression. Despite of extensive research on role of circRNAs as miRNA sponges in various species, their specific regulatory roles and mechanism in sheep ovarian tissue are still not well understood. In this study, we performed whole genome sequencing of circRNAs, miRNA and mRNA employing bioinformatic techniques on ovine tissues of two contrasting sheep breeds "Small tail Han (X_LC) and Dolang sheep (D_LC)", which results into identification of 9,878 circRNAs with a total length of 23,522,667 nt and an average length of 2,381.32 nt. Among them, 44 differentially expressed circRNAs (DECs) were identified. Moreover, correlation between miRNA-mRNA and lncRNA-miRNA provided us with to prediction of miRNA binding sites on nine differentially expressed circRNAs and 165 differentially expressed mRNAs using miRanda. miRNA-mRNA and lncRNA-miRNA pairs with negative correlation were selected to determine the ceRNA score along with positively correlated pairs from lncRNA and mRNA network. Integration of ceRNA score and positively correlated pairs exhibit a significant ternary relationship among circRNAs-miRNA-mRNA demonestrated by ceRNA, comprising of 50 regulatory pairs sharring common nodes and predicted potential differentially expressed circRNAs-miRNAs-mRNAs regulatory axis. Based on functional enrichment analysis shortlisted key ceRNA regulatory pairs associated with reproduction including circRNA_3257-novel579_mature-EPHA3, circRNA_8396-novel130_mature-LOC101102473, circRNA_4140- novel34_mature > novel661_mature-KCNK9, and circRNA_8312-novel339_mature-LOC101110545. Furthermore, expression profiling, functional enrichments and qRT-PCR analysis of key target genes infer their implication in reproduction and metabolism. ceRNA target mRNAs evolutionary trajectories, expression profiling, functional enrichments, subcellular localizations following genomic organizations will provide new insights underlying molecular mechanisms of reproduction, and establish a solid foundation for future research. Graphical abstract summarizing the scheme of study.

Dataset Information

An analysis of fertility and fecundity in the Australian sheep flock between 2006 and 2019.

Publications

An analysis of fertility and fecundity in the Australian sheep flock between 2006 and 2019.

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