Dataset Information

Lower Reproductive Rate and Lamb Survival Contribute to Lower Lamb Marking Rate in Maiden Ewes Compared to Multiparous Ewes.

ABSTRACT: Suboptimal reproductive performance of maiden (primiparous) ewes remains a source of inefficiency for the Australian sheep industry. However, the extent and causes of the poorer reproductive performance of maiden ewes on Australian sheep farms are not well understood. Here, we show the reproductive performance of maiden ewes relative to their multiparous counterparts on the same farms across Australia using a cohort survey. The difference in marking rate for non-Merino maiden ewe lambs compared to multiparous ewes was 58% (74 vs. 132%; p < 0.001), and this was attributable to a 50% difference in reproductive rate (109 vs. 159%; p < 0.001) and 16% difference in lamb survival to marking (67 vs. 83%; p < 0.001). The difference in marking rate for maiden Merino two-tooth ewes lambing at approximately 2 years-of-age compared to mature multiparous ewes was 22% (80 vs. 102%; p < 0.001) and this was attributable to a 24% difference in reproductive rate (108 vs. 132%; p < 0.001) and 3% difference for lamb survival (75 vs. 78%; p < 0.05). Positive correlations for reproduction traits (reproductive rate, lamb survival and marking rate) between maidens and multiparous ewes were observed for maiden Merino two-tooth ewes (p < 0.001), but these correlations were weak or non-existent for non-Merino ewe lambs. Strategies to improve both reproductive rate and lamb survival can address the poorer and more variable reproductive performance of maiden ewes.

SUBMITTER: Hutchison D

PROVIDER: S-EPMC8868299 | biostudies-literature | 2022 Feb

REPOSITORIES: biostudies-literature

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Lower Reproductive Rate and Lamb Survival Contribute to Lower Lamb Marking Rate in Maiden Ewes Compared to Multiparous Ewes.

Hutchison Dayna D Clarke Bronwyn E BE Hancock Serina S Thompson Andrew N AN Bowen Elise E Jacobson Caroline C

Animals : an open access journal from MDPI 20220218 4

Suboptimal reproductive performance of maiden (primiparous) ewes remains a source of inefficiency for the Australian sheep industry. However, the extent and causes of the poorer reproductive performance of maiden ewes on Australian sheep farms are not well understood. Here, we show the reproductive performance of maiden ewes relative to their multiparous counterparts on the same farms across Australia using a cohort survey. The difference in marking rate for non-Merino maiden ewe lambs compared ...[more]

PMID: 35203221

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Project description:BackgroundIn the modern sheep production systems, the reproductive performance of ewes determines the economic profitability of farming. Revealing the genetic mechanisms underlying differences in the litter size is important for the selection and breeding of highly prolific ewes. Hu sheep, a high-quality Chinese sheep breed, is known for its high fecundity and is often used as a model to study prolificacy traits. In the current study, animals were divided into two groups according to their delivery rates in three consecutive lambing seasons (namely, the high and low reproductive groups with ≥ 3 lambs and one lamb per season, n = 3, respectively). The ewes were slaughtered within 12 h of estrus, and unilateral ovarian tissues were collected and analyzed by 10× Genomics single-cell RNA sequencing.ResultsA total of 5 types of somatic cells were identified and corresponding expression profiles were mapped in the ovaries of each group. Noticeably, the differences in the ovary somatic cell expression profiles between the high and low reproductive groups were mainly clustered in the granulosa cells. Furthermore, four granulosa cell subtypes were identified. GeneSwitches analysis revealed that the abundance of JPH1 expression and the reduction of LOC101112291 expression could lead to different evolutionary directions of the granulosa cells. Additionally, the expression levels of FTH1 and FTL in mural granulosa cells of the highly reproductive group were significantly higher. These genes inhibit necroptosis and ferroptosis of mural granulosa cells, which helps prevent follicular atresia.ConclusionsThis study provides insights into the molecular mechanisms underlying the high fecundity of Hu sheep. The differences in gene expression profiles, particularly in the granulosa cells, suggest that these cells play a critical role in female prolificacy. The findings also highlight the importance of genes such as JPH1, LOC101112291, FTH1, and FTL in regulating granulosa cell function and follicular development.

Project description:The aim of the present study was to derive individual methane ( CH4 ) emissions in ewes separated in CH4 respiration and eructation traits. The generated longitudinal CH4 data structure was used to estimate phenotypic and genetic relationships between ewe CH4 records and energy efficiency indicator traits from same ewes as well as from their lambs (intergenerational perspective). In this regard, we recorded CH4 emissions via mobile laser methane detector (LMD) technique, body weight (EBW), backfat thickness (BFT) and body condition score (BCS) from 330 ewes (253 Merinoland (ML), 77 Rhön sheep (RH)) and their 629 lambs (478?ML, 151?RH). The interval between repeated measurements (for ewe traits and lamb body weight (LBW)) was 3 weeks during lactation. For methane concentration ( µ L?L -1 ) determinations in the exhaled air, we considered short time measurements (3?min). Afterwards, CH4 emissions were portioned into a respiration and eructation fraction, based on a double normal distribution. Data preparation enabled the following CH4 trait definitions: mean CH4 concentration during respiration and eructation ( CH4r+e ), mean CH4 concentration during respiration ( CH4r ), mean CH4 concentration during eructation ( CH4e ), sum of CH4 concentrations per minute during respiration ( CH4rsum ), sum of CH4 concentrations per minute during eructation ( CH4esum ), maximal CH4 concentration during respiration ( CH4rmax ), maximal CH4 concentration during eructation ( CH4emax ), and eructation events per minute ( CH4event ). Large levels of ewe CH4 emissions representing energy losses were significantly associated with lower LBW ( P<0.05 ), lower EBW ( P<0.01 ) and lower BFT ( P<0.05 ). For genetic parameter estimations, we applied single- and multiple-trait animal models. Heritabilities and additive genetic variances for CH4 traits were small, i.e., heritabilities in the range from <0.01 ( CH4r+e , CH4r , CH4rmax , CH4esum ) to 0.03 ( CH4rsum ). We estimated negative genetic correlations between CH4 traits and EBW in the range from - 0.44 ( CH4r+e ) to - 0.05 ( CH4rsum ). Most of the CH4 traits were genetically negatively correlated with BCS ( - 0.81 for CH4esum ) and with BFT ( - 0.72 for CH4emax ), indicating same genetic mechanisms for CH4 output and energy efficiency indicators. Addressing the intergenerational aspect, genetic correlations between CH4 emissions from ewes and LBW ranged between - 0.35 ( CH4r+e ) and 0.01 ( CH4rsum , CH4rmax ), indicating that breeding on reduced CH4 emissions (especially eructation traits) contribute to genetic improvements in lamb weaning performance.

Dataset Information

Lower Reproductive Rate and Lamb Survival Contribute to Lower Lamb Marking Rate in Maiden Ewes Compared to Multiparous Ewes.

Publications

Lower Reproductive Rate and Lamb Survival Contribute to Lower Lamb Marking Rate in Maiden Ewes Compared to Multiparous Ewes.

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