Fertility Of Ewes Research Articles

Response of maiden ewes to the ‘ram effect’ is a robust management practice and a candidate selection trait for enhanced reproductive performance in drylands

Management of reproduction that relies on naturally based solutions is extremely important to counter the negative perception around hormone-based interventions. In Mediterranean latitudes and wider regions of non-tropical drylands, sheep do not normally ovulate during spring but exposure to a ram can induce oestrus and ovulation. This study assesses the response of maiden Barbarine ewes in drylands to the ‘ram effect’ during springtime and estimates the genetic parameters of this response. The study uses a database documenting, for 24 consecutive years, the response of nulliparous 18-month-old ewes when mated after stimulation by the ‘ram effect.’ In addition to the oestrous and fertility database, a pedigree database was also available. Nearly half of the maiden ewes responded to the ‘ram effect,’ while 24% exhibited spontaneous reproductive activity and displayed oestrus during the first 14 days following the introduction of rams. Nearly 5% of females did not exhibit oestrus, and these animals are proposed for early culling. Average annual values of Normalised Difference Vegetation Index (NDVI), reflecting vegetation cover, and the percent of maiden ewes spontaneously cycling were positively correlated (P = 0.006). Interestingly, NDVI was negatively correlated with the percentage of anoestrus females that did not respond to the ‘ram effect’ but exhibited oestrus beyond the hypothetical time frame commonly used to describe it. Average fertility was 82.8% and was significantly affected by mating year, live weight at mating, and the response to the ‘ram effect.’ The highest fertility (88.39%) was for females spontaneously cycling at the time of ram introduction, and the lowest (83.35%) was for females coming into oestrus beyond the time frame for a ram-induced oestrus and ovulation. Heritability from a univariate logit-transformed analysis for fertility was 0.10 and the genetic correlation between fertility and the interval between ram introduction and oestrus was 0.26, suggesting that a shorter interval is associated with higher fertility. Thus, the interval between ram introduction and oestrus is a good candidate for selective breeding for high fertility of maiden ewes in drylands mated out-of-season using the ‘ram effect.’

PSVII-11 Genetic parameter estimates for lamb survival in prolific and nonprolific ewes

Abstract Given the increasing global demand for animal products, increasing lamb survival is a key breeding objective for sheep. However, high prolificacy can be associated with increases in fetal and lamb mortality. Therefore, the goal of this study was to estimate the variance components and genetic parameters for lamb survival (LS), using a: 1) single-trait model, where all ewes are analyzed together; and 2) two-trait model, where ewes are grouped in two groups based on birth type [i.e., Group 1 (G1) = single lamb/ewe, and Group 2 (G2) = multiple lambs/ewe]. In both models, LS was defined as the survival of lamb from birth to weaning and analyzed as a threshold trait. A total of 1,040,629 records (215,075 from single and 825,554 from multiple birth) from 319,467 ewes from several breeds/breed groups were available for the study. There were no females with two different types of births. Variance components were estimated through Bayesian inference via Gibbs sampling implemented in the GIBBSF90+ program, fitting a two-trait animal model with maternal effects, in which breed/breed groups were included as fixed effects. Average number of lambs/ewe in G2 was 2.57 (SD = 0.72). Heritability estimated (± SE) for LS on the underlying scale using the single-trait (0.04 ± 0.10) and two-trait model (0.010 ± 0.001 for LSG1 and 0.031 ± 0.004 for LSG2) were low. Maternal heritability estimated by the single-trait model was 0.007 ± 0.043, while by the two-trait model the estimates were 0.010 ± 0.006 and 0.040 ± 0.005 for LSG1 and LSG2, respectively. The genetic correlation estimated between LSG1 and LSG2 was weak and positive (0.25 ± 0.21). The low non-significant genetic correlation between single and multiple birth groups suggests that lamb survival is a different genetic trait in different birth types. Therefore, selecting for improving LS in nonprolific ewes may not necessarily translate to improving LS in prolific ewes. This underscores the need for careful consideration and targeted breeding strategies to achieve desired outcomes in nonprolific and prolific sheep simultaneously. Further studies to define the optimal statistical approach to genetically evaluate LS in prolific and nonprolific ewes are warranted.

Key role of CYP17A1 in Leydig cell function and testicular development in Qianbei Ma goats

Reproductive traits are vital economic parameters in goat production, and boosting the reproductive capacity of breeding rams is crucial for enhancing the profitability of goat farming. Currently, research on the reproductive performance of Qianbei Ma goats mainly centers on investigating mechanisms associated with prolificacy and estrous ovulation in ewes, with limited emphasis on ram reproductive aspects. This study used scanning electron microscopy and enzyme-linked immunosorbent assay (ELISA) to profile the morphology of testis and the dynamic changes of Luteinizing Hormone (LH), Follicle-Stimulating Hormone (FSH), and Testosterone (T) in serum at different developmental stages of Qianbei Ma goats. Meanwhile, transcriptome sequencing technology was used to investigate the mRNA expression patterns in testicular tissues at different developmental stages: newborn (0 M), puberty (6 M), sexual maturity (12 M), and physical maturity (18 M). The results showed that the diameter, circumference, and area of the testicular seminiferous tubules gradually increased with age. The levels of T and LH in serum significantly increased from 0 to 6 months after birth (p < 0.05), followed by a stabilization of T levels and a significant decrease in LH levels (p < 0.05). Meanwhile, FSH shows a decreasing trend between 0 and 18 months after birth. A total of 26,437 differentially expressed genes were identified in 6 comparison groups, which involve various biological processes such as immunity, growth, metabolism, development, and reproduction, and are significantly enriched in signaling pathways related to testicular development and spermatogenesis. WGCNA analysis identified 6 regions significantly associated with testicular development and spermatogenesis, and selected 320 genes for constructing a PPI network. Ten candidate genes related to testicular development and spermatogenesis were identified, including TP53, PLK4, RPS9, PFN4, ACTB, CYP17A1, GPX4, CLDN1, AMH and DHH. Of these, the CYP17A1 gene promotes interstitial cell proliferation, and promotes T synthesis. This study provides a theoretical basis and data support for promoting efficient breeding of goats and early breeding of excellent male goats.

Novel single nucleotide polymorphism G216A of hormone-sensitive lipase gene associated with Awassi sheep reproduction

BackgroundLitter size plays a crucial role in determining profitability in the sheep industry. Breeding sheep with high litter sizes could be enhanced by selecting candidate genes. One gene affecting sheep's reproductive performance is the hormone-sensitive lipase (HSL) gene. As a result, this study investigated whether the HSL gene variation influenced the fertility of Awassi ewes. The genomic DNA was extracted from 52 singleton ewes and 48 twin ewes. The HSL gene exon 9 (278 bp) was amplified using polymerase chain reaction (PCR).ResultsStudy results revealed two genotypes identified in the 278-bp amplicons: GG and GA. Molecular sequence analysis identified a novel mutation in the GA genotype 216G > A. The statistical analysis revealed a significant association between the single nucleotide polymorphism (SNP) 216A > G and reproductive performance. Ewes with the SNP 216G > A genotype exhibited significantly increased litter sizes, twinning rates, lambing rates, and fewer days to lambing compared to ewes with GG genotypes (P ≤ 0.05). The logistic regression analysis results provided strong evidence that the 216G > A mutation significantly increased litter sizes.ConclusionsThis study concluded that variant 216G > A SNP positively impacts Awassi sheep reproduction. There is a higher litter size and more prolificacy in ewes with the 216G > A SNP than in those without the SNP.

Screening of &lt;em&gt;FecLL&lt;/em&gt; prolific allele of the &lt;em&gt;B4GALNT2&lt;/em&gt; gene in Algerian sheep populations

Background: Research on the main genes controlling prolificacy in sheep, also known as fecundity genes (Fec genes), has highlighted the mechanisms involved in ewe fertility and the genetic improvement of prolificacy. The gene, FecL/B4GALNT2 (beta-1,4-N-acetyl-galactosaminyl transferase 2) and its prolific allele FecLL, which segregate in French Lacaune sheep and some local sheep breeds in Morocco and Tunisia, were found to influence ovarian function. However, their action differs from that of other major genes discovered previously, such as: FecX/BMP15 (bone morphogenetic protein 15); FecG/GDF9 (growth differentiation factor 9); and FecB/BMPR1B (bone morphogenetic protein receptor type 1B). The latter act in the bone morphogenetic protein (BMP) signalling pathway. Aim: The objective of this study is to investigate the segregation of the FecLL allele in Algerian sheep populations. Methods: A total of 338 animals from 12 breeds were genotyped using the PCR-RFLP technique. Results: Our results revealed the presence of FecLL in the Algerian D’man sheep population. Among the genotyped D’man sheep, 21% were carriers of the mutation in the heterozygous state. The frequency of the FecLL allele in the Algerian D’man population (0.11) is close to what is observed in Lacaune sheep and remains relatively low compared to Moroccan (0.58) and Tunisian (0.65) D’man sheep. Conclusions: The FecLL allele, which is shared by the French Lacaune population and the North African D’man populations, could indicate the ancestral origin of the mutation in B4GALNT2 or the occurrence of an ancient introgression event to improve prolificacy. Managing this mutation in Algerian D’man flocks could help improve the numerical productivity of D’man sheep in Algeria.

Correlation between BMPR1B Gene Polymorphism and some Reproductive Traits in Awassi Sheep

The (BMPR-1B) gene is one of the main genes for ewe fertility. This study was conducted to check the association between BMPR-IB gene polymorphisms and some traits of Awassi. This study was made in Anbar Governorate - (Agricultural Research Department) Al-Dawar. Date of experience collected from 34 ewes at the age of 4-6 years. Next, DNA was extracted and a PCR reaction was performed to amplify blood samples taken from the ewes to confirm the presence of the BMPR1B gene. The sequence was determined using Sanger sequencing technology. The data were then analyzed and compared between sample sequences to determine SNPs, genotype frequencies, allele frequencies, and their association with reproductive and growth traits. The results showed mutations in the heteroplasmy site rs410310346 (T&gt;C) and rs592447725 (G&gt;A). The results indicated that the TC genotype at the mutation site rs410310346 (T&gt;C) was significantly superior (P≤0.05) in ewes whose rates of fertility and body length were higher compared to the CC genotype. The genotypes haven’t got an important effect on the proportion of twins, fertility rate, chest circumference, front height, ewe birth weight, and lamb weight at birth. The relationship of genotype GG and GA at the mutation site rs592447725 (G &gt; A) showed a very significant effect (P≤0.01) on the percentage fertility rate and a noteworthy result (P≤0.05) on body length, height at the front and birth weight of lambs, but there isn’t a big impact. In the percentage of twins, fertility rate, chest circumference, and birth weight of ewes. Therefore, the effect of the BMPR1B gene can be used as a genetic marker to select ewes with good genotypes to improve herd performance.

Efficacy of Intravaginal Lactic Acid Bacteria, Cell-Free Supernatant, or Enrofloxacin on Vaginitis and Fertility in Ewes Synchronized with Progesterone-Based Protocol

An intravaginal sponge impregnated with progesterone is commonly used for estrus induction and synchronization in ewes. Although using an intravaginal sponge containing progesterone positively affects the synchronization rate, varying degrees of vaginitis occur during its application. This study aimed to investigate the impacts of various intravaginal treatment options on the vaginitis severity and pregnancy rate in Merino ewes synchronized with intravaginal sponges impregnated with progesterone. During the breeding period, 589 ewes, aged 2–6, received intravaginal sponges for 14 days. The control group (CON) received no treatment, whereas vaginal sponges absorbed with enrofloxacin (ENR), Lactobacillus plantarum (LAC), or Lactobacillus plantarum supernatant (CFS) were applied in the treatment groups. All groups received 500 IU of equine chorionic gonadotropin intramuscularly. The ENR group showed lower scores in vaginal discharge and sponge odor compared with the CON, LAC, and CFS groups. Although estrus responses did not differ between groups, the pregnancy rate tended to be higher in the ENR group. In conclusion, intravaginal ENR application, but not LAC or CFS, reduced vaginitis severity and tended to increase pregnancy rates in ewes synchronized with intravaginal sponges impregnated with progesterone.

Uterine tone influences fertility of Merino ewes following laparoscopic artificial insemination

Artificial insemination (AI) plays a critical role in facilitating rapid genetic and production gains within the sheep industry. However, variable rates of AI success remain a concern for the industry and a barrier to adoption. Furthermore, the degree to which female factors influence the success of intrauterine laparoscopic AI rather than natural mating remains unknown. As such, this study investigates the effect of several factors collected during the time of AI, on the success of intrauterine laparoscopic AI. Data was generously donated by artificial breeding companies and stud breeders during routine commercial AI operations. AI data was collected over 3 breeding seasons during commercial AI programs (N = 24 programs) using Merino ewes (N = 24,700). Sire ID (N = 253), time of AI following progesterone removal (approx. 43–59 h post removal), uterine tone and intra-abdominal fat (both scored 1–5) as well as age of the ewe were all recorded at the time of AI. Transcutaneous ultrasound subsequently determined pregnancy rate approximately 55 days post-AI. A multivariate regression analysis was performed and revealed pregnancy success to increase when semen was inseminated into a ewe with a uterine tone score of 4 or 5 (P < 0.001). The remaining factors fell short of significance within the multivariate model. An interclass coefficient variation matrix was also used to determine the proportion of variation contributed to AI success by random factors allocated in the model; site, sire, AI date and breeding season (45.99 %, 29.94 %, 15.15 % and 8.92 %, respectively). These results highlight the influence of uterine tone on ewe fertility following laparoscopic AI, but also that program location and the sire used can further modify this influence on pregnancy rate. These factors must now be considered in combination with semen factors per individual sire used during AI to ascertain the contribution of several factors to the success of laparoscopic AI in Australia.

Utilising male stimulus to improve the reproductive efficiency of 8-month-old nulliparous ewes and adult parous ewes

We tested whether utilising the male effect to stimulate ewes before the mating period can reduce the time to conception following the introduction of entire rams, and increase fertility, prolificacy, and reproductive rate (number of fetuses per 100 ewes exposed to fertile rams). A retrospective analysis was used to analyse records from 59,716 ewes collected over 34 years (1986–2020) from seven genotypes: Border Leicester, Composite (crossbred), Dorset, Merino, Dorset x Polypay, Rambouillet, White Suffolk. The dataset also included nulliparous young ewes (mated at age 8 months) and adult parous ewes. Vasectomized rams were used to stimulate 20,632 ewes before a mating period that lasted 2 or 3 estrous cycles, and the outcomes were compared with those from 39,084 ewes that had not been stimulated. Independently of genotype, utilising the male stimulus advanced the average conception date by 8 days for young ewes (P < 0.0001) and by 1 day for adult ewes (P < 0.0001). The male stimulus also increased the proportion of ewes that conceived in their first cycle by 33 % for young ewes and by 6 % for adult ewes (P < 0.0001). For the cycle of conception, there were significant (P < 0.0001) effects of two interactions: male stimulus x age at mating and male stimulus x live weight at mating. The male stimulus improved fertility in both adult ewes (99.8 % vs 89 %; P < 0.001) and young ewes (77.7 % vs 81.3 %; P < 0.001). The male stimulus increased the number of young ewes (41.9 % vs 11.1 %; P < 0.001) and adult ewes (16.6 % vs 2.7 %; P < 0.001) that conceived multiple fetuses in the first 17 days of the mating period. The reproductive rate was improved by the male stimulus in young ewes (129 % vs 135 %; P < 0.001) but not in adult ewes (120 % vs 122 %; P = 0.12). When all animals for all breeds were included in the analyses, there were improvements in fertility, prolificacy, and reproductive rate as age and live weight increased at mating (P < 0.0001). We conclude that, independently of genotype, utilising the male stimulus before the mating period reduces the time to conception and improves reproductive performance in both young and adult ewes.

The Novel PTX3 Variant g.22645332G>T Is Strongly Related to Awassi and Hamdani Sheep Litter Size.

The detection of polymorphisms in genes that control livestock reproduction could be highly beneficial for identifying and enhancing economic traits. One of these genes is pentraxin 3 (PTX3), which affects the reproduction of sheep. Therefore, this study investigated whether the variability of the PTX3 gene was related to the litter size of Awassi and Hamdani ewes. A total of 200 ewes (130 Awassi and 70 Hamdani) were used for genomic DNA extraction. Polymerase chain reaction was used to amplify the sequence fragments of exons 1, 2, 3, and 4 from the PTX3 gene (Oar_v4.0; Chr 1, NC_056054.1), resulting in products of 254, 312, 302, and 253, respectively. Two genotypes, GG and GT, were identified for 302 bp amplicon. A novel mutation was discovered through sequence analysis in the GT genotype at position g.22645332G>T. The statistical analysis revealed a significant association between single nucleotide polymorphism (SNP g.22645332G>T; Oar_v4.0; Chr 1, NC_056054.1) and litter size. The presence of the SNP g.22645332G>T (Oar_v4.0; Chr 1, NC_056054.1) genotype in ewes resulted in a significant difference compared to ewes with GG genotypes. The discrepancy became apparent in several aspects, including litter sizes, twinning rates, lambing rates, litter weight at birth, and days to lambing. There were fewer lambs born to ewes with the GG genotype than to ewes with the GT genotype. The variant SNP g.22645332G>T (Oar_v4.0; Chr 1, NC_056054.1) has positive effects on the litter size of Awassi and Hamdani sheep. The SNP g.22645332G>T (Oar_v4.0; Chr 1, NC_056054.1 has been associated with an increase in litter size and higher prolificacy in ewes.

INDUSTRIAL CROSSBREEDING AS EFFICIENT SHEEP FARMING PRODUCTION

The article examines the materials of industrial crossbreeding in sheep farming using ewes of the Dnipropetrovsk inbred type of the Prydniprovska meat breed (DT Pm) and breeding rams of the Merinolandschaf breed (Ml) and its effect on the quantitative and qualitative indicators of meat productivity. The level of productivity of breeding rams indicates their compliance with the meat type. Their body weight is in the range of 105.4-112.1 kg; shearing of wool initially – 5.4-6.2 kg, with the output of washed wool – 59.5-61.0%, respectively, from Prydniprovska meat breed and Merinolandschaf breed. Coefficient of woolliness is 30.4-33.9 g/kg. The level of reproductive capacity of ewes indicates that fertilization is in the range of 96.0-97.0%. Fertility of ewes of the second group in industrial crossbreeding was 168.1%, which is 23% more than of the first one. 163 lambs were obtained from the ewes of the second group, which is 20.7% more than in purebred breeding. The preservation of lambs before weaning was 97.0%. When crossing, the effect of heterosis is manifested, which is evidenced by the difference in body weight, when crossbred lambs dominate at birth by 9.5%, at the age of 4 months – by 13.3%, at the age of 8 months – by 14.9% compared to purebred peers. Carcass weight of crossbred lambs was 22.6 kg against 18.9 kg of purebred peers. According to the main slaughter parameters, crossbred lambs outperformed purebred lambs, while the slaughter weight of crossbreds was higher by 19.7%, with a slaughter yield of 51%, which is a good indicator for this characteristic for meat-type sheep within production focus. As a result of a comprehensive comparative analysis of meatiness indicators of lambs of different origins, an advantage in terms of desired components was found in crossbreds. The introduction of new genetic lines through industrial crossbreeding can contribute to the conservation and expansion of genetic potential among sheep populations, which is important for adaptation to changing conditions.

182 Effect of P.G. 600 dose on expression of estrus, fertility, and prolificacy in ewes synchronized out-of-season using a short-term progesterone-based protocol

182 Effect of P.G. 600 dose on expression of estrus, fertility, and prolificacy in ewes synchronized out-of-season using a short-term progesterone-based protocol

Single-cell sequencing reveals the reproductive variations between primiparous and multiparous Hu ewes

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.

Evaluation of the effect of melatonin implantation in rams and eCG dose in ewes synchronized by a CIDR-eCG protocol on reproductive performance of Lacaune sheep breed during non-breeding season

Sustainable production of milk is favorable in dairy sheep industry, which necessitates year-round reproduction of rams and ewes even during non-breeding season. Hence, protocols facilitating reproduction of rams and ewes during non-breeding season are of importance for this purpose. Therefore, the present study was conducted to investigate the effect of melatonin implantation in rams and administration of 400 IU eCG (E400) versus 300 IU eCG (E300) in ewes on reproductive performance of Lacaune sheep breed during non-breeding season. Rams were allocated to two groups including untreated (control, CON; n = 36) and melatonin-treated (MEL; n = 37). A subset of rams from CON (n = 7) and MEL (n = 7) groups were used for assessment of scrotal circumference, kinematic and functional characteristics of sperm, total antioxidant capacity (TAC) of semen and circulating testosterone on Days 0 (the beginning of study) and 60 (60 days after melatonin implantation). Further, the study had a 2 × 2 factorial design with four experimental groups including 1) ewes treated with E300 and introduced to CON rams (E300CON; n = 17 rams and 172 ewes), 2) ewes treated with E300 and introduced to MEL rams (E300MEL; n = 18 rams and 177 ewes), 3) ewes treated with E400 and introduced to CON rams (E400CON; n = 19 rams and 192 ewes), and ewes treated with E400 and introduced to MEL rams (E400MEL; n = 19 rams and 190 ewes). Melatonin implantation improved scrotal circumference, concentration, progressive motility, velocity, mitochondrial membrane potential and viability of sperm, TAC of semen, concentration of testosterone and fertility of rams (P < 0.05). Besides, E400 compared with E300 enhanced synchronization of estrus and fertility in ewes (P < 0.05). In conclusion, melatonin implantation promoted reproductive performance in Lacaune rams, and increase in dose of eCG improved reproductive performance in Lacaune ewes.

CREB1 Is Involved in miR-134-5p-Mediated Endometrial Stromal Cell Proliferation, Apoptosis, and Autophagy.

The successful establishment of endometrial receptivity is a key factor in ensuring the fertility of ewes and their economic benefits. Hu sheep have attracted attention due to their high fecundity and year-round estrus. In this study, we found that in the luteal phase, the uterine gland density, uterine coefficient, and number of uterine caruncles of high-fertility Hu sheep were higher than those of low-fertility Hu sheep. Thousands of differentially expressed genes were identified in the endometrium of Hu sheep with different fertility potential using RNA sequencing (RNA-Seq). Several genes involved in endometrial receptivity were screened using bioinformatics analysis. The qRT-PCR analysis further revealed the differential expression of cAMP reactive element binding protein-1 (CREB1) in the Hu sheep endometrium during the estrous cycle. Functionally, our results suggested that CREB1 significantly affected the expression level of endometrial receptivity marker genes, promoted cell proliferation by facilitating the transition from the G1 phase to the S phase, and inhibited cell apoptosis and autophagy. Moreover, we observed a negative linear correlation between miR-134-5p and CREB1 in the endometrium. In addition, CREB1 overexpression prevented the negative effect of miR-134-5p on endometrial stromal cell (ESC) growth. Taken together, these data indicated that CREB1 was regulated by miR-134-5p and may promote the establishment of uterine receptivity by regulating the function of ESCs. Moreover, this study provides new theoretical references for identifying candidate genes associated with fertility.

Effect of ewe birth litter size and estimation of genetic parameters on ewe reproductive life traits.

Ewe lifetime productivity has economic implications for producers because shorter lifetime productivity results in less profit. Productive years of ewes from extensive, range-based systems of the United States West are generally less than ewes from more temperate regions of the United States. Accordingly, ewes from range-based systems, especially those employing shed-lambing strategies, have been selected for increased litter size to offset decreased lifetime productivity. However, the relationship of the ewe's birth litter size (ELSB) has not been considered a potential contributor to lifetime productivity. Longevity (number of productive years, n=1 per population) and stayability (probability to survive to the next age; ages 2-7years, n=6 per population) were investigated to understand ELSB effects on productive life. Columbia, Polypay, Rambouillet, and Targhee breeds were used in this study. Across-breed (n=11550) and within-breed (Columbia, n=4398; Polypay, n=4534; Rambouillet, n=5922; Targhee, n=6482) analyses were used. Depending on the population, records spanned from 1950 to 2008, where ewe's birth year was included as a fixed effect in the animal model using restricted maximum likelihood estimation procedures. Fixed effects investigated included ELSB (single-, twin-, or triplet-born) and ewe breed (across-breed analyses only). Regardless of trait or population used, heritability ranged from 0.06±0.02 to 0.34±0.03, where stayability at younger ages had the highest estimates. The breed effect was significant in all across-breed analyses (0.0001≤P≤0.038; n=7), where Polypay, a breed selected for accelerated lambing and increased fertility, averaged shorter productive life or had a lower probability of survival to the next age compared with other breeds (longevity: 0.009≤P≤0.223; stayability: 0.000≤P≤0.842). The ELSB was significant in 60% (n=5) and 37% (n=30) of longevity and stayability analyses, respectively. Except for Targhee, all analyses showed ewes born in smaller litter sizes were associated with longer productive lives or higher probability of surviving to the next age, particularly in across-breed analyses (e.g., longevity: single- vs twin-born ewes, P=0.004; vs triplet-born ewes, P=0.003). This study provides evidence that increasing prolificacy in ewes from extensive, range-based production systems may impact productive life. Due to the low heritability of these traits, additional investigation into modeling these traits with dominance effects and litter size needs to be conducted.

P21 Effect of dietary energy on late-gestation metabolism in prolific ewes

P21 Effect of dietary energy on late-gestation metabolism in prolific ewes

Supplementation of Moringa oleifera leaf concentrate pellets on nutrient utilization, antioxidant status, and reproductive performance of prolific ewes during extreme summer months in semi-arid tropical conditions.

A feeding trial was conducted for a period of 60 days during extreme summer months to observe the effect of supplementation of Moringa oleifera leaves containing concentrate pellets on nutrient utilization, antioxidant status, and reproductive performance in Avishaan ewes reared under semi-arid condition. Forty adult non-pregnant cyclic ewes (2-3 years, 31.8 ± 0.81 kg body weight) were selected and randomly allocated into 2 groups of 20 animals each, viz., G-I (control) and G-II (treatment). The ewes were grazed on natural pasture for 8 h, offered ad libitum Cenchrus ciliaris hay after grazing and concentrate pellets @ 300 g/animal/day. The ewes in G-I were offered conventional concentrate pellets, whereas G-II ewes were offered concentrate pellets containing 15% Moringa leaves. The mean temperature humidity index during the period of study was 27.5 ± 0.3 and 34.6 ± 0.4 at 0700 h and 1400 h, respectively, indicating severe heat stress. Nutrient intake and utilization were comparable between the two groups. The antioxidant status was higher in G-II ewes as the values of catalase, superoxide dismutase, and total antioxidant capacity were higher (P < 0.05) in G-II ewes compared to G-I. The conception rate was higher (100%) in G-II ewes than G-I ewes (70%). Multiple birth percentage was 77.8% in G-II ewes, and it was comparable with the herd average of Avishaan (74.7%). However, ewes in G-I group exhibited a marked decline in multiple birth percentage (28.6%) than the normal herd average. Hence, it can be concluded that inclusion of Moringa oleiferaleaves in feeding of prolific Avishaan ewes improved their antioxidant status resulting in optimum reproductive performance during stressful summer months.

One intron variant in the oocyte expressed protein (OOEP) gene is associated with twinning rate, prolificacy, and several body measurement traits in Awassi ewes

Awassi breed is an important sheep in the Middle East, but its lower twinning potential is a limitation against improvement. Due to the dynamic role of oocyte-expressed protein (OOEP) gene in controlling folliculogenesis, this study was conducted to evaluate the possible association between OOEP and twinning rate, as well as body measurement traits, in Awassi ewes. A total of 232 Awassi ewes (123 ewes-producing singletons and 109 ewes-producing twins) were included in this study. Three PCR fragments (OOEP-1 to OOEP-3) were designed to cover the majority of OOEP sequences and genotyped by single-strand conformation polymorphism (SSCP) method. One nucleic acid variant was identified in the intron-2 of OOEP-3, or rs430263839:A>G. Ewes with rs430263839:AG genotype showed variable significant values of larger head length, chest and abdominal circumferences, and higher prolificacy and twinning rates than ewes with the rs430263839:AA genotype. The conducted computations predicted that the detected SNP had caused altered splicing mechanisms in ewes with rs430263839:AG genotype. The increased abdominal and chest diameters in ewes with the rs430263839:AG genotype were thought to help the uterus accommodate more lambs. The predicted splicing alteration caused by this SNP is the putative mechanism by which these ewes may improve reproductive and productive traits. This is the first study that demonstrated the importance of OOEP as a potential biomarker for the twinning rate, prolificacy, and some body measurement traits in Awassi ewes with an opportunity to be introgressed to other breeds using large-scale association analysis.

Ovarian follicle dynamics in ewes treated with intra-vaginal progesterone pessaries. 2. Factors affecting timing of estrus and reproductive outcomes following artificial insemination.

This study extends observations on the effects of intra-vaginal progesterone treatment on the relationships between the time of luteolysis, emergence of the ovulatory follicle, timing of estrus and ewe fertility. Observations were made in progesterone - treated ewes in autumn, the spring equinox and late spring (Experiment 1, Data set 1) and in progesterone - treated ewes and naturally cycling ewes in autumn and the spring equinox (Experiment 1, Data set 2). In Data set 1, the day of emergence of both the first and second ovulatory follicle was positively related to the day luteal regression within each season. In turn, the day of emergence influenced the timing of estrus by means of a season by day of luteal regression interaction (P<0.001) indicating that the relationship was positive in autumn and the spring equinox but negative in late spring. In autumn, older ovulatory follicles were associated with an earlier onset of estrus compared with younger ovulatory follicles. In late spring, this relationship was reversed and was influenced by whether or not ewes were cycling at the time of pessary insertion. In Data set 2, the relationship between the day of follicle emergence and luteal regression was influenced by a treatment by day of regression interaction indicating the relationship was positive in treated ewes and negative in naturally cycling ewes. Timing of estrus was positively related (P<0.001) to both the day of luteal regression and the day of follicle emergence (P<0.05), with both relationships being stronger in naturally cycling ewes than in treated ewes. In Experiment 2, pregnancy rate following artificial insemination in autumn was highest (90.2%) when luteolysis occurred during Days 7-9 of the pessary period compared with Days 1-6 (77.8%, P=0.16), 10 to 12 (68.8%, P<0.05) or Days ≥13 (71.2%, P<0.05). Timing of estrus was not affected. The mean diameter of ovulatory follicles that emerged during Days 7-9 was larger on Day 12 (5.8±0.13mm) compared with other periods (range 4.7±0.05 to 5.6±0.14mm). This study provides two potential strategies to improve the success of AI programs. Firstly, appropriately timed treatment with PGF2α to control the time of emergence of ovulatory follicles and, secondly, earlier treatment with eCG to improve the development of ovulatory follicles that emerge late in the pessary period. Each is likely to be influenced by season and the cyclical status of the ewe.