Reproductive Performance Of Ewes Research Articles

Rumen-protected l-carnitine supplementation during mating period altered metabolic status and reproductive performance of ewes.

Current study hypothesized that dietary l-carnitine (LC) inclusion during the mating period ameliorates both metabolic status and reproductive performance of ewes. Seventy Baluchi ewes (52 ± 4.2 kg of bodyweight and 18 ± 6 months old of age) were enrolled in this study. Animals were randomly allocated into two dietary treatments, control (only basal diet) or basal diet plus supplementation with a rumen-protected LC (Carneon 20 Rumin-pro; 20% LC; Kaesler Nutrition GmbH) at the rate of 10 g/head/day from 21 days before until 35 days after introducing rams to the ewes (MP). Feed intake was monitored by subtracting the ort from feed offered. Blood sample collection was conducted on Days -10, +10 and +20 relative to MP. Pregnancy was confirmed on Day 30 post-MP. Feed intake of the ewes in the LC group was higher than the control (p < 0.05). LC supplementation increased the cholesterol concentration in the ewes (p < 0.05). Blood urea concentration of animals in the LC group was significantly lower than the control (p < 0.05). The mRNA expression of toll-like receptor 4 was evidently lower in animals supplemented with LC than the control (p < 0.05). Both lambing and fecundity rates in the LC group tended to be higher compared with the control. LC supplementation showed potential to alter certain metabolites in the ewes. A tendency for higher lambing rate may partly be driven by dams efficient energy partitioning to support foetal growth and maintaining pregnancy.

Productive and Reproductive Efficiency of Ewes Kept on Tropical Pastures as a Function of the Suckling Lamb Treatments

The aim of the research was to evaluate the productive and reproductive performances of ewes as a function of the supplementation offered to suckling lambs. The lambs were divided into two experimental treatments. Treatment (1) suckling lambs kept in pastures of Brachiaria-grass receiving mineral supplementation; and treatment (2) suckling lambs kept in pastures of Brachiaria-grass receiving concentrate supplementation in creep-feeding. Regardless of the nutritional treatment offered to the lambs, all matrices (female lambs and ewes) received 350 g of supplementation daily. Ewes from treatment-1 presented average 49 days to return to estrus. Ewes from treatment-2 presented, on average, 36 days to return to estrus. The body condition score (BCS) at weaning showed a significant difference between treatments. Ewes from treatment-1 presented a mean BCS of 1.75. Ewes from treatment-2 presented a mean BCS of 2.39. The other productive variables of lambs, such as weaning weight (kg), age at weaning (days), total weight gain (kg), and average daily gain of lambs, presented a significant difference between the nutritional treatments. Variables such as return to estrus and BCS were positively influenced by supplementation offered to lambs, which directly impacts the production efficiency and profitability of the production system. The lamb supplementation promotes indirect gains in the body condition score of ewes at weaning and, consequently, in the time to return of estrus in 13 days. Protein-energy supplementation in creep feeding to suckling lambs is recommended to improve the body condition score at weaning and decrease the return to estrus (days) of ewes. This nutritional tool is recommended to improve the supply of leaves and provide the best conditions for the selection and use of nutrients present in the leaves.

On-station comparative analysis of reproductive and survival performance between Red Maasai, Dorper, and Merino sheep breeds.

The reproductive performance of ewes and the survivability of lambs to weaning have a critical economic impact on sheep farming worldwide. Further, knowledge of major mortality causes allows an opportunity for improved flock management to evade financial losses. The maximum likelihood estimates for generalised linear mixed models and chi-square test methods were used to examine 971 mating records, 839 and 763 lambs born and weaned (singles or twins) from the Naivasha Sheep and Goats station in Kenya for the years 2011 to 2020 consisting of Dorper, Red Maasai (RedM), and Merino breeds. The RedM (P<0.05) outperformed Dorper and Merino in weaning rate, whereas reproductive performance between the three breeds was not significantly different (P>0.05) in litter size and multiple lambings per ewe lambing. On the one hand, Dorper significantly (P<0.05) outperformed the other two breeds only in weaning weight per lamb born. In addition, among all the major causes of death, pneumonia appeared to be the one to which Dorper breeds were most susceptible (chi-square test, P<0.05). According to the findings of this study, neither the Dorper nor the Merino sheep breeds were reproductively superior to the RedM in an extensive semi-arid production environment. In addition, Dorper's susceptibility to the leading causes of mortality, particularly pneumonia and sheep pox, were relatively high compared to other breeds and could be a precursor to massive economic losses for Dorper sheep producers. In contrast to the indigenous RedM breed, imported sheep breeds appeared to be more susceptible to major mortality-related under an extensive production system. Therefore, regardless of weaning weight, RedM breed production appears to be a more viable investment for small-scale farmers, particularly in semi-arid regions.

Genetic and phenotypic relationships between ewe reproductive performance and wool and growth traits in Uruguayan Ultrafine Merino sheep.

This study reports genetic parameters for yearling and adult wool and growth traits, and ewe reproductive performance. Data were sourced from an Uruguayan Merino flock involved in a long-term selection program focused on reduced fiber diameter (FD), and increased clean fleece weight (CFW) and live weight (LW). Pedigree and performance data from approximately 5,700 mixed-sex yearling lambs and 2,000 mixed-age ewes born between 1999 and 2019 were analyzed. The number of records ranged from 1,267 to 5,738 for yearling traits, and from 1,931 to 7,079 for ewe productive and reproductive performance. Data on yearling and adult wool traits, LW and body condition score (BCS), yearling eye muscle area (Y_EMA), and fat thickness (Y_FAT), and several reproduction traits were analyzed. The genetic relationships between FD and reproduction traits were not different from zero. Moderate unfavorable genetic correlations were found between adult CFW and ewe lifetime reproduction traits (-0.34 ± 0.08 and -0.33 ± 0.09 for the total number of lambs weaned and total lamb LW at weaning, respectively). There were moderate to strong positive genetic correlations between yearling LW and all reproduction traits other than ewe-rearing ability (-0.08 ± 0.11) and pregnancy rate (0.18 ± 0.08). The genetic correlations between Y_EMA and reproduction traits were positive and ranged from 0.15 to 0.49. Moderate unfavorable genetic correlations were observed between yearling FD and Y_FAT and between adult FD and BCS at mating (0.31 ± 0.12 and 0.23 ± 0.07, respectively). The genetic correlations between adult fleece weight and ewe BCS at different stages of the cycle were negative, but generally not different from zero. This study shows that selection for reduced FD is unlikely to have any effect on reproduction traits. Selection for increased yearling LW and Y_EMA will improve ewe reproductive performance. On the other hand, selection for increased adult CFW will reduce ewe reproductive performance, whereas selection for reduced FD will negatively impact body fat levels. Although unfavorable genetic relationships between wool traits and both FAT and ewe reproductive performance existed, simultaneous improvements in the traits would occur using appropriately designed indexes.

Integrating dual-purpose crops mitigates feedbase risk and facilitates improved lamb production systems across environments: a whole-farm modelling analysis

Context The winter feed gap is a common problem for livestock grazing systems worldwide, and changes to climate have made these deficits more unpredictable and extreme. Dual-purpose crops are an important tool in many southern Australian mixed crop–livestock systems to help fill the winter feed gap. Providing more reliable feed over winter can remove feed constraints and allow for earlier lambing in autumn with potential whole-farm system benefits. Aims We simulated a whole-farm livestock enterprise in the Agricultural Production Systems Simulator (APSIM) to examine the implications of spring- and autumn-lambing systems relying on a standard pasture-only feedbase compared with a farm where 25% of its grazed area is allocated to dual-purpose crops. Methods Twelve simulations were run across four locations in New South Wales, Australia, that varied in climatic conditions (both rainfall total and distribution) including two lambing systems (spring vs autumn) × two feedbase types (100% pasture vs 75% pasture and 25% dual-purpose crops) × three stocking densities. Key results For autumn-lambing systems, integrating dual-purpose crops helped to fill the winter feed gap and reduced supplement demand on average by ~28% compared with a pasture-only system. Compared with the standard pasture-only spring-lambing system, integrating dual-purpose crops into spring- and autumn-lambing systems more than doubled gross margin returns due to economic grain yield and lower supplement demand. A shift from spring- to autumn-lambing facilitated by dual-purpose crops also led to better reproductive performance of ewes in the subsequent year. In higher-rainfall, cooler environments, autumn-lambing systems with dual-purpose crops had the highest system gross margins, lowest economic risk and allowed for a safe increase in stocking density. In lower-rainfall, warmer environments, integration of dual-purpose crops into spring-lambing systems returned marginally higher gross margins than for the autumn-lambing system, but differences were less apparent at high stocking density. In lower-rainfall environments, dual-purpose crops helped to mitigate some of the economic risk, but the benefits were less clear. Conclusions We show dual-purpose crops can help fill the winter feed gap and support earlier lambing in autumn across a range of environments, especially in higher-rainfall cooler environments, with significant improvements in total farm gross margins. Implications Integrating dual-purpose crops will enable farmers to change their livestock system to mitigate their risks, reduce supplementary feeding and capitalise on other potential benefits, such as improved marketing and avoiding animal health problems.

Effects of N-Acetylcysteine on the Proliferation, Hormone Secretion Level, and Gene Expression Profiles of Goat Ovarian Granulosa Cells.

The purpose of this paper was to investigate the effects of N-acetylcysteine (NAC) on the proliferation, hormone secretion, and mRNA expression profiles of ovarian granulosa cells (GCs) in vitro. A total of 12 ovaries from 6 follicular-stage goats were collected for granulosa cell extraction. The optimum concentration of NAC addition was determined to be 200 μM via the Cell Counting Kit 8 (CCK-8) method. Next, GCs were cultured in a medium supplemented with 200 μM NAC (200 μM NAC group) and 0 μ M NAC (control group) for 48 h. The effects of 200 μM NAC on the proliferation of granulosa cells and hormones were studied by 5-ethynyl-2'-deoxyuridine (EdU) assay and enzyme-linked immunosorbent assay (ELISA). mRNA expression was analyzed by transcriptome sequencing. The results indicate that 200 μM NAC significantly increased cell viability and the proportion of cells in the S phase but promoted hormone secretion to a lesser degree. Overall, 122 differentially expressed genes (DEGs) were identified. A total of 51 upregulated and 71 downregulated genes were included. Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment analyses indicated that the most DEGs were enriched in terms of cell growth regulation, cell growth, neuroactive ligand-receptor interaction, cytokine-cytokine receptor interaction, the cAMP-signaling pathway, and the Wnt-signaling pathway. Seven genes related to granulosa cell proliferation were screened, IGFBP4, HTRA4, SST, SSTR1, WISP1, DAAM2, and RSPO2. The above results provide molecular theoretical support for NAC as a feed additive to improve follicle development and improve reproductive performance in ewes.

Impact of Four Ovine TMEM154 Haplotypes on Ewes during Multiyear Lentivirus Exposure.

Polypeptide variation encoded by the ovine transmembrane protein 154 gene (TMEM154) is associated with susceptibility to ovine lentivirus, the causative agent of Ovine Progressive Pneumonia (OPP) and Visna/Maedi. Our aim was to compare the four most prevalent TMEM154 haplotypes on the incidence of infection and ewe productivity during natural multiyear virus exposure. Prospective cohort studies were designed to test gene action and estimate effects of TMEM154 haplotypes encoding distinctive variant residues: K35 (“1”), I70 (“2”), ancestral (“3”), and A4del/M44 (“4”). Exposure consisted of co-mingling infected ewes at a rate greater than 30% with serological status evaluated every four months. For ewes with one or two copies of the highly susceptible haplotypes “2” and ”3”, the infection prevalence steadily increased to nearly 100% at 55 months. Haplotypes “2” and “3” were equally susceptible and dominant to haplotype “1”. A difference was not detected (p < 0.53) in the magnitude of effect with haplotype combinations of “1” and ”4”. The ewe infection prevalence with “1,1”; “1,4”; and “4,4” was 10% to 40% at 55 months. The latter suggested that two copies of the K35 amino acid substitution (“1”) were as effective as a homozygous TMEM154 “knockout” with the frame-shift deletion mutation (“4”) in reducing infection susceptibility. When considering ewe reproductive performance, a difference was not detected when comparing haplotypes “2”, and “3” to each other, or “1” and “4” to each other. Our study indicated that ewes with two copies of the severely truncated versions of TMEM154 (“4,4”) had normal lamb productivity. Without complete understanding of the natural function of TMEM154 our recommendations to producers interested in using TMEM154 selection to reduce their flock’s genetic predisposition to OPP are encouraged to increase the frequency of TMEM154 haplotype K35 (“1”) since it encodes a full-length protein with minimal difference to the ancestral polypeptide.

Breeding Ewe Lambs: An Australasian Perspective.

A number of potential advantages have been identified for breeding ewe lambs at 7 to 9 months of age, including increased lifetime productivity and profitability. However, breeding at this young age in extensive pastoral systems, such as in Australasia, can be associated with a number of disadvantages resulting in uptake of this management procedure being relatively low. This review highlights the known differences between ewe lamb and mature ewe reproductive performance, thus differing in their management. The review then summaries the scientific literature of factors that affect ewe lamb reproductive success, with a focus on recent studies conducted under extensive pasture-based conditions in Australasia. In particular, this review outlines the importance of ewe lamb live weight and body condition score on their productivity. The potential long-term consequences of breeding a ewe lamb at a young age in terms of her future success and that of her offspring to weaning are briefly outlined. In addition, the potential impacts of selecting progeny born to ewe lambs as future replacement ewes are discussed. Throughout this review, optimal management guidelines from prior to breeding the ewe lambs until rebreeding at 2 years of age are provided. Lastly, areas requiring future research are identified and discussed.

Reproductive Performance of Ewes, Fed Flushing Diet at Different Management Feeding Program.

&lt;b&gt;Background and Objective:&lt;/b&gt; There is very rare information regarding data of reproduction performance of small ruminant with different management flushing program in Asian countries. The aim of this study was to evaluate the implementation of flushing diet program containing lemuru fish oil with time management difference, by evaluating the reproductive performance of local Garut ewes. &lt;b&gt;Materials and Methods:&lt;/b&gt; Twenty of garut ewes (average body weight 30.06±6.20 kg) were used in this experiment using Completely Randomized Block Design (CRBD), in four treatments with five animals of each treatment. The treatments were without flushing (F0 as control), flushing at the beginning of mating (F1 = 2 weeks pre-mating until 2 weeks just after-mating), two times flushing (F2 = F1 plus 4 weeks flushing during mid gestation) and three times flushing (F3 = F2 plus 2 weeks flushing at the end of gestation and 2 weeks after parturition). The ratio of flushing or basal concentrate to forage was 70:30. Basal concentrate was given during untreated. Nutrients consumption, body condition score (BCS), average daily gain (ADG), feed efficiency ratio (FER) and reproduction parameters were evaluated. The data of sex ratio and birth type were expressed descriptively. &lt;b&gt;Results:&lt;/b&gt; The results showed that the treatment had significant effect (p<0.05) on crude fat consumption, total digestible nutrients (TDN) and changes of BCS values, but had no effect on other nutrients consumptions. All treatments did not affect to total birth weight, the number of embryo, litter size, gestation period and sex ratio. The percentage of ewes pregnancy with the flushing treatment was 25% higher than the control. The flushing treatments were significantly effect on partus weight of ewes (p<0.05). &lt;b&gt;Conclusion:&lt;/b&gt; It was concluded that three times flushing program at early, middle and late of gestation could improve the nutritional status and reproductive performance of ewes, such as fat intake, partus weight, improved percentage of pregnancy and type of birth, but did not affect to total birth weight, litter size, pregnant period and sex ratio.

Seropositivity to Campylobacter and association with abortion and lamb mortality in maiden ewes from Western Australia, South Australia and Victoria.

This case‐control study investigated associations between Campylobacter fetus or Campylobacter jejuni titre and reproductive outcomes in 22 flocks of Merino and non‐Merino maiden ewes aged 1–2 years old. Campylobacter titres were also determined for multiparous ewes aged 3 years or older on the same farms. C. fetus ‘positivity’ (titre ≥1:80) was detected for 12% (57/462; 95% confidence interval [95% CI] 9.6 to 15.6) of maiden ewes and 31% (65/210; 95% CI 25.0 to 37.4) of mature ewes. The odds for failing to rear a lamb in C. fetus‐‘exposed’ maiden ewes (titre ≥1:10) was 2.01 times that of seronegative ewes (95% CI 1.09 to 3.77; P = 0.027), but there was no association between C. fetus‐‘positivity’ (titre ≥1:80) and failure to rise (OR 1.69; 95% CI 0.77 to 3.76; P = 0.191). C. fetus abortions were confirmed with microbial culture in one maiden ewe flock. In this flock, C. fetus titres fluctuated and often waned by lamb marking, highlighting the value of necropsies during abortion investigations. C. jejuni‐‘positivity’ (titre ≥1:80) was detected for 44% (204/462; 95% CI 39.7 to 48.7) maiden ewes, but odds of failing to rear were decreased for C. jejuni‐‘positive’ ewes (OR 0.52; 95% CI 0.32 to 0.83; P = 0.007). The association between Campylobacter serology and the reproductive outcome was inconsistent in these flocks. Serology should be considered in the context of other risk factors and used in conjunction with other strategies to investigate the impact of Campylobacter exposure on ewe reproductive performance such as monitoring for abortions and lamb necropsies to determine aetiological diagnosis, and vaccination trials.

Effects of flushing and various doses of β-Carotene and vitamin E applications on the reproductive performance of ewes

The aim of this study was to determine whether fertility could be enhanced in Kıvırcık ewes during the anoestrous period by flushing or by administering an injectable (Ovostim) containing β-Carotene and vitamin E. Three-year-old Kıvırcık ewes (n = 99) were used. The ewes were randomly divided into four groups: flushing, a single dose of Ovostim (5 ml/ewe) before the breeding season, a dose of Ovostim 10 days before the breeding season and a second dose at its start, and an untreated control. Results showed that pregnancy rate was higher in the treated groups than in the control (P &lt;0.001). The single dose of Ovostim produced more multiple births (72%) and the highest litter size (1.64) compared with the other treatments. Although the double-dose of Ovostim influenced the ewes in the anoestrous period to the point of becoming pregnant, it failed to favourably affect the number of lambs born per ewe lambing. In conclusion, flushing the ewes or administering a single dose of Ovostim was shown to be advantageous in comparison with untreated ewes or those given two doses of Ovostim.

Interplay Between Stress and Reproduction: Novel Epigenetic Markers in Response to Shearing Patterns in Australian Merino Sheep (Ovis aries).

In this study, we determined the effect(s) of early shearing on Australian Merino ewes (Ovis aries) and their lambs. To test this research question, we used a suite of field and laboratory methods including GPS collars, wool cortisol, and epigenetic change between ewes and lambs identified using Illumina NovaSeq RRBS. Once shorn ewes (n = 24) were kept on their full fleece throughout the entire gestation period, whereas twice (early) shorn ewes (n = 24) had their wool shorn pre-joining. Top-knot wool sample was taken from ewes during pre-joining, day 50 (mid-gestation), and day 90 (late gestation) for laboratory analysis. Ewes were pregnancy scanned at mid-gestation to determine whether they were early or late parturition (this confirmation is provided by the pregnancy scanner based on fetus size). Top-knot wool sample was also taken from the lambs at weaning for hormone and wool quality testing. Ear tissue was taken from ewes at day 50 (mid-gestation) and from lambs at lamb marking for DNA analysis. Results showed that twice or early shorn ewes grazed 10% higher and maintained stronger body condition than once shorn ewes. Wool cortisol levels were also significantly lower in the early shorn ewes between mid- and late gestation. Lambs bred from twice shorn ewes had on average better visual wool quality parameters in terms of micron, spin finesses, and curvature. For the DNA methylation results, when comparing a group of once sheared with twice sheared ewes, we have discovered one locus (Chr20:50404014) that was significantly differentially methylated [False Discovery Rate (FDR) = 0.005]. This locus is upstream of a protein-coding gene (ENSOARG00000002778.1), which shows similarities to the forkhead box C1 (FOXC1) mRNA using BLAST searches. To further our understanding of the potential interaction between pregnancy status and shearing frequency of the ewes, we performed further differential methylation analysis using a combination of shearing treatment and pregnancy scanning status. The comparisons (1) late pregnancy vs. early pregnancy for ewes with one shearing treatment and (2) late pregnancy vs. early pregnancy for sheep with two shearing treatments were carried out to identify associations between loci and pregnancy duration for sheep with either one or two shearing events. We discovered that 36 gene loci were significantly modulated either between different shearing treatments or late vs. early pregnancy status of ewes. This result suggests that maternal pregnancy and nutritional status during gestation influence DNA methylation. We further investigated DNA methylation in lambs and identified 16 annotated gene loci that showed epigenetic modulation as a result of being born from an early or late stage pregnancy. From the genomics data, we pointed out that ewes go through epigenetic modifications during gestation, and there is a degree of intra-individual variation in the reproductive performance of ewes, which could be due to combination of intrinsic (genetic and physiological) and extrinsic (management and climatic) factors. Collectively, this research provides novel dataset combining physiological, molecular epigenetics, and digital tracking indices that advances our understanding of how Merino ewes respond to shearing frequency, and this information could guide further research on Merino sheep breeding and welfare.

Effect of adding carrots as feed supplementation on reproductive performance in Awassi ewes

The present study was designed to estimate the effect of carrots supplementation on reproductive performance in ewes. Thirty Awassi ewes. Ewes were randomly divided into three equal groups, distributed as 10 ewes for each group. First group consider as control, second group feed 400 g carrot/animal daily, third group feed 800 g carrot/animal daily. Each group were synchronized with intra vaginal sponges and injected with 400 IU of eCG at the time of sponge withdrawal. Estrus ewes were conceived naturally with rams and pregnant ewes were followed until parturition. The results of current study demonstrated that G3 had high estrus response and fertility rate 90% compared with G2 and control 80 and 70% respectively. Fecundity rate increased significant in G3 200% compared to G2 and 125 and 100% respectively. Ewes in G3 showed the highest multiple lambing rate 66.67% compared with G2 25% and control 0%. Blood progesterone concentration was high increasing at the 18th day of estrus in the ewes for G3 and G2 compared with control, also, estrogen level at the day of estrus showed high increasing in G3 compared with G2 and control group. We concluded that carrots fed as a supplementation have essential effect on enhancement of reproductive performance in ewes.

Winter crop choice and body condition loss change the eco-efficiency of sheep flocks

Lamb survival (ewe reproductive performance) and lamb growth are key levers to changing eco-efficiency, particularly in hill country systems. New research has highlighted reproduction losses when feeding some winter crop options such as fodder beet. Current research findings are used to understand the impact of changes in reproductive performance of sheep flocks caused by body condition change and winter forage crop choices on whole farm eco-efficiency. Eight farms were anonymously selected from an existing database, four with ‘low rainfall’ and four with ‘high rainfall’, averaging 590 and 1090 mm/annum respectively to represent the cool temperate climates of southern New Zealand. Ewe and lamb survival, and lamb liveweight gain to weaning were altered to reflect the impacts of either losing or retaining body condition in late gestation, either on a fodder beet or brassica diet in mid-late gestation. Ewes retaining body condition with fodder beet scenarios were fed a supplement added to ensure adequate protein nutrition using a combination of Lucerne hay, soy meal, and urea. General adjustments made to maintain pasture use similar to the original farms included adjusting lamb sales date, supplement making, stocking rate and autumn nitrogen use. Eco-efficiency was reduced using fodder beet as a winter forage as greenhouse gas emissions were increased per unit of product. The loss of condition score during mid to late pregnancy also led to a reduction in eco-efficiency, though this was more severe when feeding fodder beet. The impacts of fodder beet were mitigated if the diet was balanced for protein. Nitrogen and phosphorus loss from soil was low, and reduced under fodder beet feeding conditions, due to the smaller area of cropping than traditional brassicas.

MTNR1A gene polymorphisms and reproductive recovery after seasonal anoestrus in different Mediterranean sheep breeds

The aims of this study were 1) to investigate the effect of MTNR1A gene polymorphisms on reproductive performance in ewes of one Italian and two Slovenian dairy sheep breeds (Sarda, Istrian Premenka and Boska, respectively) which were located at different latitudes, and 2) to highlight if the different season of the male placement with females that was utilized in the different breeding systems in Sardinia (Italy) and Slovenia resulted in different effects of these polymorphisms on reproductive functions. Reproductively mature ewes (n = 100) from each breed were utilized to conduct the study. To evaluate the reproductive efficiency, lambing dates and number of lambs born were recorded per ewe; additionally, the duration in days from ram placement with ewes to lambing (DRPEL), litter size and the fertility rate were determined based on lambing dates. In each breed, there were eight nucleotide variations within the MTNR1A gene exon II, two of which (g.17355358 and g.17355171), respectively, resulted in a valine to isoleucine, and alanine to aspartic acid substitution, in amino acid sequence. The SNPs at position g.17355452 and g.17355458 were determined to have effects on reproductive performance. Genotypes C/C and C/T at g.17355452 in Bovska and Sarda and genotype A/A at g.17355458 in Istrian Pramenka were associated with a greater fertility and a lesser duration in days from ram placement with ewes to lambing. These findings confirmed that the nucleotide sequences of the MTNR1A gene could affect reproductive functions of Mediterranean sheep.

A survey of producer practices and reproductive performance of containment and supplementary fed ewes.

Containment feeding, where ewes are fed complete rations, is used to maintain flock numbers in periods of inadequate pasture supply. Producer practices influence both the reproductive performance of ewes and the risk of health challenges. The aim of this study was to evaluate the reproductive, feeding and health management practices of producers using containment or supplementary feeding, and quantify any associations between practice and reproductive performance. An online survey of Australian producers was conducted in 2020. The number of responses (n=43) allowed benchmarking but was insufficient to determine correlations between practice and performance. The reported pregnancy rate of adult Merino ewes was variable between respondents (78%-95%; n=11), and lambs marked per ewe joined ranged from 60% to 110% (n=9). In non-Merino flocks, lambs marked ranged from 82% to 161% (n=4). Most respondents (9/11) fed cereal grain with hay or straw, either daily or two or three times a week. However, some respondents fed grain only or roughage only, such that the percentage of roughage in diets ranged from 0% to 100%. Ewes were most frequently separated into age groups for feeding, and shy feeders were only removed by 25% of respondents. Although generally the reported reproductive rate was high, wide variation indicates potential for improvement. Best practice management for containment remains unclear and requires further research given the diverse practices used. Veterinary practitioners should be aware that some of the practices used may contribute to reduced productivity or health issues in ewes.

Breeding heavier ewe lambs at seven months of age did not impact their subsequent two and three-year-old ewe live weight and reproductive performance

ABSTRACT The current study investigated the effects of growing ewe lambs to a heavier live weight at breeding on their subsequent reproductive performance and live weight at two and three years of age, and the growth of their progeny to weaning. Two groups of ewe lambs were bred at seven months of age at an average pre-breeding live weight of either 47.9 ± 0.36 kg (Heavy; n = 135) or 44.9 ± 0.49 kg (Control; n = 135). Breeding performance, fertility, litter size, lambing percentage, ewe wither height, live weight, progeny survival, and live weight were recorded at two and three years of age. None of the variables measured differed between the Heavy and Control ewes at either two or three years of age (P > 0.10). This suggests that farmers can breed their Romney-type ewe lambs at an average live weight of 48 kg without any negative impacts on reproductive performance at two or three years of age nor on their progeny’s live weight or growth to weaning. Although breeding heavier ewe lambs improved reproductive performance during their first year, further investigations are needed to assess their overall lamb production and efficiency over multiple breeding seasons.

The effects of supplementation with cobalt, and method of administration, on ewe reproduction and offspring performance to weaning

The concentration of Co in the herbage of a large proportion of grassland farms in Ireland is lower than that required by sheep. The effects of supplementing ewes with Co, and method of supplementation, on ewe and offspring performance, were evaluated over 2 years. The ewes (359 in year 1, 241 in year 2), representing 3 genotypes, were allocated to one of 3 treatments. The treatments were: Control - no supplementation; Drench – Co supplementation via oral drench (31.5 mg Co as CoSO4•7H2O) administered every 14 days; Bolus – Co supplementation via rumen bolus (effective life of ∼6 months) that only contained Co as CoSO4•7H2O with an expected Co release rate of 0.6 mg/day in year 1 and 1 mg/day in year 2. Drench treatment was administered from 7 weeks pre joining, until 6 weeks prior to expected lambing date (early – to mid - March). One bolus was administered to ewes on the bolus treatment at the start of the study (day 0) each year. The ewes were managed as one flock in a rotational-grazing system until housing in early December each year; they were shorn at housing and offered grass silage ad libitum plus a concentrate supplement during late pregnancy. Ewes and lambs were put to pasture within 3 days of lambing. Supplementation with Co, via drench or bolus, increased the concentration of Co (p< 0.001) and vitamin B12 in ewe plasma at ∼day 50 and ∼day 100 of pregnancy and these effects were generally greater for Drench than Bolus treatments. Supplementary Co had no effect (p > 0.05) on ewe BW or body condition score at joining (day 49), mid-pregnancy, lambing, 5 weeks post lambing or weaning. Likewise, supplementation had no effect (p > 0.05) on litter size, lamb mortality or number of lambs reared per ewe joined, or on lamb BW at birth or weaning. The only significant animal-performance difference detected between the Bolus and Drench treatments concerned the incidence of lambs classified as ‘born dead or died within 24 h of birth’ (3.1% for Drench, 6.5% for Bolus; p < 0.05). It is concluded that, whilst supplementing ewes (high proportion whom (30 to 60%) had marginal plasma B12 status) with Co from 7 weeks pre-joining until late pregnancy increased plasma Co and vitamin B12 concentrations and reduced the proportion classified as having marginal or low Co status. There was no effect on ewe or progeny performance.

The impact of maternal genetic merit and country of origin on ewe reproductive performance, lambing performance, and ewe survival.

The objective of this study was to investigate the impact of the ewe’s maternal genetic merit and country of origin [New Zealand (NZ) or Ireland] on ewe reproductive, lambing, and productivity traits. The study was performed over a 4-yr period (2016–2019) and consisted of three genetic groups: high maternal genetic merit (NZ), high maternal genetic merit Irish (High Irish), and low maternal genetic merit Irish (Low Irish) ewes. Each group contained 30 Suffolk and 30 Texel ewes, selected based on the respective national maternal genetic indexes; i.e., either the NZ Maternal Worth (NZ group) or the €uro-star Replacement index (Irish groups). The impact of maternal genetic merit on reproductive traits such as litter size; lambing traits such as gestation length, birth weight, lambing difficulty, mothering ability; and productivity traits such as the number of lambs born and weaned was analyzed using linear mixed models. For binary traits, the impact of maternal genetic merit on reproductive traits such as conception to first artificial insemination (AI) service; lambing traits such as dystocia and perinatal lamb mortality; and productivity traits such as ewe survival was analyzed using logistic regression. NZ ewes outperformed Low Irish ewes for conception to first AI (P < 0.05) and litter size (P = 0.05). Irish ewes were more likely to suffer from dystocia [6.84 (High Irish) and 8.25 (Low Irish) times] compared to NZ ewes (P < 0.001); birth weight and perinatal mortality did not differ between groups (P > 0.05). Lambs born from NZ ewes were 4.67 [95% confidence interval (CI): 1.89–11.55; P < 0.001] and 6.54 (95% CI: 2.56–16.71; P<0.001) times more likely to stand up and suckle unassisted relative to lambs born from High or Low Irish ewes, respectively. NZ and High Irish ewes had a greater number of lambs born and weaned throughout the duration of the study compared to their Low Irish counterparts (P<0.001). NZ ewes tended to be more likely to survive from one year to the next compared with Low Irish ewes (P=0.07). Irish ewes of high maternal genetic merit outperformed their low counterparts in total number of lambs born and weaned per ewe, but performance did not differ across other traits investigated. This highlights the importance of continuous development of the Irish maternal sheep index to ensure favorable improvements in reproductive, lambing, and productivity traits at the farm level. Overall, results demonstrate the suitability of NZ genetics in an Irish production system.

The Effect of Age of Dam and Birth Rank on the Reproductive Performance of Ewes as One- and Two-Year-Olds.

Simple SummaryLambs that are born to ewe lambs are not commonly selected as replacement ewes for sheep flocks in New Zealand, as they are born smaller and later than lambs born to mature ewes, hindering their chances of being heavy enough to breed as ewe lambs themselves. By selecting lambs born to ewe lambs, farmers can utilize animals that are available, and potentially increase genetic gain and ewe production efficiency. This experiment found that lambs born to ewe lambs are lighter than those born to mature ewes until two years of age, but have similar body condition scores, and rates of lamb production, if they are heavy enough to be bred as ewe lambs themselves. Therefore, farmers could select lambs born to ewe lambs that are heavy enough to achieve breeding targets.Currently, 30–43% of New Zealand sheep farmers breed their ewe lambs, but few retain the offspring as replacements for their flock. No difference in lamb production as a yearling among singletons and twins born to ewe lambs and twins born to mature ewes has been reported, provided the ewe lambs had reached the 60–65% of their likely mature weight prior to breeding at seven to eight months of age. The aim of this experiment was to determine the lamb production from singletons and twins born to ewe lambs and twins born to mature ewes during their first two years of lambing. The experiment included 8-month-old ewes born as twins to mature ewes (M2, n = 135), singletons born to ewe lambs (L1, n = 135), and twins born to ewe lambs (L2, n = 88), bred during the same period to the same rams, over two years. The efficiency of lamb production (total litter weight at weaning divided by the pre-breeding weight of the ewe, for all ewes presented for breeding) after two years of production was not significantly different (p > 0.05) among the groups (0.40 ± 0.02, 0.39 ± 0.02, and 0.39 ± 0.03, for M2, L1, and L2, respectively).