Artykuły w czasopismach: „Sheep Reproduction”

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Joshi, Purushotam. "NUTRITION AND REPRODUCTION IN SHEEP". FOOD & AGRIBUSINESS MANAGEMENT 3, nr 2 (2022): 48–52. http://dx.doi.org/10.26480/fabm.02.2022.48.52.

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High nutrition, but not overfeeding, has a positive effect on ewe reproductive capability in terms of the number of estrous cycles, length of the breeding season, greater ovulation rate, and improved lambing %. Copper deficiency hurts lambing percentage and lamb health. Manganese is required for the ovarian activity to be maintained. Protein is necessary for sheep for optimum sperm capacitation, conception rate, pregnancy, and reduced abortions. Protein insufficiency causes lower feed intake, poorer feed utilization, lower growth rate, lower milk output, and lower wool production. A possible reason for the decline in adult reproductive function is nutritionally impaired ovarian development. Functional impairment in any component of the hormone complex has a direct impact on reproduction. Factors such as photoperiod, nutrition, and social sexual cues, genetics, affect the reproductive capacity of both male and female sheep. In mammals, reproduction is energetically more demanding for the females than for the males.

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Haresign, W. "Reproduction in Sheep". Livestock Production Science 14, nr 4 (czerwiec 1986): 386–87. http://dx.doi.org/10.1016/0301-6226(86)90018-7.

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Dzakuma, J. M., i D. L. Harris. "Computer Modeling of Sheep Reproduction: II. Accelerated Reproduction in Sheep". Journal of Animal Science 67, nr 9 (1.09.1989): 2212–21. http://dx.doi.org/10.2527/jas1989.6792212x.

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Brien, Forbes. "Foreword to ‘Sheep Reproduction’". Animal Production Science 54, nr 6 (2014): iv. http://dx.doi.org/10.1071/anv54n6_fo.

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Haresign, W. "Controlling reproduction in sheep". BSAP Occasional Publication 14 (styczeń 1990): 23–37. http://dx.doi.org/10.1017/s0263967x00002020.

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AbstractIntravaginal progestagen pessaries + pregnant mare's serum gonadotrophin (PMSG) for controlling the oestrous cycle and for inducing out-of-season breeding have been commercially available for many years. However, extremely good mating management is required if acceptable results are to be achieved. More recently the role of the pineal hormone, melatonin, in the regulation of seasonal breeding has been recognized, and this has led to the development of slow-release formulations for use under farm conditions. Early indications are that such preparations can advance the breeding season by about 4 to 6 weeks, with lambing percentages in early (January) lambing flocks comparable with those of traditional (March) lambing flocks.Recent developments in the use of laparoscopy as an aid to intrauterine insemination and multiple ovulation and embryo transfer (MOET) should play a major role in breed improvement. Intrauterine insemination can markedly improve conception rates following the use of frozen semen compared with the conventional cervical technique, as well as eliminating the incidence of fertilization failure in embryo transfer donors. In addition, laparoscopic collection and transfer of embryos permit repeated collections from the same donor ewes and are much more acceptable than surgical techniques from the welfare point of view.

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DEAC, Alexandru Marius, Adriana Sebastiana MUSCĂ, Marius Gavril AIPĂTIOAIE, Viorica COŞIER i Marius ZĂHAN. "Methods of Improving Reproductive Parameters in Sheep and The Major Genes Associated with Prolificacy: A Review". Bulletin of University of Agricultural Sciences and Veterinary Medicine Cluj-Napoca. Animal Science and Biotechnologies 1, nr 79 (11.05.2022): 7. http://dx.doi.org/10.15835/10.15835/buasvmcn-asb:2021.0020.

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Farm profitability is heavily influenced by reproductive capacity. Fertility, prolificacy, and fecundity are all indicators of reproductive efficiency. In sheep with high economic value, prolificacy is a key reproduction parameter (Notter, 2008). Because most sheep breeds are monotocous, similar to Mouflon wild sheep (Garel et al., 2005), improving fecundity is a serious concern (Tang et al., 2019). This review aims to study genes and the genetic means of improving sheep reproduction parameters. Numerous mutations in the transforming growth factor (TGF) superfamily have been reported to influence sheep reproductive parameters. As a result, molecular genetics and marker-assisted selection (MAS) are essential in improving reproduction efficiency. If these mutations are not present in the population, introgression of the beneficial mutations to indigenous breeds is possible. Because within-breed selection has been considered relatively inefficient, due to the low heritability of the trait, crossbreeding of native breeds with prolific breeds has been the major means of genetically improving prolificacy. Studying fecundity genes is important in order to increase production efficiency and stabilizing optimal litter sizes. Different studies based on whole-genome sequencing (WGS), which are called genome-wide association studies (GWAS), and also proteomic studies, transcriptome analysis, and mitochondrial DNA analysis have revealed further genetic variation with medium or minor effects on reproduction.

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Rosa, H. J. D., i M. J. Bryant. "Seasonality of reproduction in sheep". Small Ruminant Research 48, nr 3 (czerwiec 2003): 155–71. http://dx.doi.org/10.1016/s0921-4488(03)00038-5.

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Matoušek, J. "Genetics of reproduction in sheep". Animal Reproduction Science 11 (styczeń 1986): 235–36. http://dx.doi.org/10.1016/0378-4320(86)90125-9.

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HE, MINGFENG, QIU-HUI PAN i SHUANG WANG. "FINAL STATE OF ECOSYSTEM CONTAINING GRASS, SHEEP AND WOLVES WITH AGING". International Journal of Modern Physics C 16, nr 01 (styczeń 2005): 177–90. http://dx.doi.org/10.1142/s0129183105007017.

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This paper describes a cellular automata model containing movable wolves, sheep and reproducible grass. Each wolf or sheep is characterized by Penna bitstrings. In addition, we introduce the energy rule and the predator–prey mechanism for wolf and sheep. With considering age-structured, genetic strings, minimum reproduction age, cycle of the reproduction, number of offspring, we get three possible states of a predator–prey system: the coexisting one with predators and prey, the absorbing one with prey only, and the empty one where no animal survived. In this paper, we mainly discuss the effect of the number of poor genes, the energy supply (food), the minimum reproduction age, the reproductive cycle and the birth rate on the above three possible final states.

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Qiu, Xiaoyan, Xiong Xiao, Nan Li, Wenhui Ling, Mingyu Wang i Yuemin Li. "Association of steroid 17-alpha-hydroxylase/17,20 lyase (CYP17) single nucleotide polymorphism (SNP) 628 and dopamine receptor D2 (DRD2) SNP939 genotypes with sheep reproductive performance". Reproduction, Fertility and Development 31, nr 4 (2019): 743. http://dx.doi.org/10.1071/rd18069.

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In a previous study we investigated the association between two single nucleotide polymorphism (SNP) genotypes, namely steroid 17-alpha-hydroxylase/17,20 lyase (CYP17) SNP628 and dopamine receptor D2 (DRD2) SNP939, with two temperaments (calm and nervous) in Australian Merino sheep and concluded that the DRD2 SNP939 T/T genotype combined with the CYP17 SNP628 G/G genotype is associated with a calm temperament and could be used as a potential marker for calm sheep, whereas the DRD2 SNP939C allele combined with the CYP17 SNP628 A/A genotype is associated with a nervous temperament and could be used as a potential marker for nervous sheep. In sheep, the association between temperament and reproductive performance has been determined, but the association of these two SNP genotypes with sheep reproduction has not been investigated. Therefore, using Chinese Sinkiang Merino sheep, the present study investigated the association of the two CYP17 SNP628 and DRD2 SNP939 genotypes with sheep reproductive performance. Sheep with the DRD2 SNP939 T/T genotype combined with the CYP17 SNP628 G/G genotype had a higher ovulation rate, multiple gestation rate, better maternal behaviour and lower lamb mortality. Thus, the results of this study contribute to our knowledge of the association between genotypes and reproduction in sheep, which is beneficial for sheep genetics and breeding.

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Lahlou-Kassi, A., S. Benlamlih i R. Boukliq. "Reproduction and adaptation characteristics in D’man sheep". Agricultural and Food Science 60, nr 6 (1.10.1988): 566–75. http://dx.doi.org/10.23986/afsci.72314.

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D’man breed (D) is found in the oasis of the subsaharian regions of Morocco and reared usually in sedentary type of management with small flocks (< 10 ewes). Preliminary field surveys showed that D is early maturing, prolific and aseasonal. Hence, a multidisciplinary research programme on D was started in 1974. This paper reports the findings of these studies and describes the approach used to (1) characterize and evaluate the performances of D in field and station, (2) study the physiological mechanism involved in its peculiar reproduction and production, (3) study the genetic basis of reproduction parameters, and (4) evaluate use of D in crossbreeding schemes to improve the productivity of other Moroccoan breeds. Results show that D is one of the rare breeds that is simultaneously early maturing, highly prolific and completely aseasonal. However, studies on water turnover and nitrogen recycling show that D is not well adapted to hot climate and poor nutrition. Its reproduction parameters are relatively independent of photoperiod and related to a low sensitivity to negative oestrogen feedback. D male is characterized by high libido and can be used for synchronizing oestruses through the »ram effect». Crossbreeding experiments with non-prolific sheep confirm the heritability of reproductive parameters. However, the genetic basis for these is not yet well known.

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Richards, J. S., M. A. Sladek i G. J. Lee. "Cumulative reproductive performance effect on overall lifetime productivity in Merino sheep". Animal Production Science 58, nr 8 (2018): 1470. http://dx.doi.org/10.1071/an17794.

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Reproduction is an important driver of profitability in commercial sheep flocks. Historically, Merino flocks have been run with a fixed age structure, ignoring individual merit and casting for age at a specific age. More recently, research has focussed on utilising the variation within age groups by keeping productive older ewes longer and culling less productive ewes earlier. Previous studies have also examined the effect of age on reproduction and the impact of reproduction status on productivity, but little research has been conducted on cumulative effects of reproductive performance on later productivity, reproduction and health. The present study examined the impact of higher lifetime reproduction on other key production and fitness traits in older ewes run under commercial conditions. Data were collected from two commercial wool-producing properties in the South West Slopes and the Central West Plains of New South Wales during 2009–2011. Reproduction, fleece measurements, bodyweight and condition and dental health were recorded during the study. The results showed that age had a bigger effect on productivity and dental health than did cumulative lifetime reproduction. Environment and genetics determined the level of impact, with minimal loss in productivity from increased age of animals occurring in the South West Slopes flock, whereas the Central West Plains flock would appear to require closer monitoring of productivity as ewes aged. The data collected did not allow separation of the genetic and environmental influences within the study. Retaining animals with a higher reproductive performance past normal culling age does not necessarily result in reduction of productivity or ewe health, but this must be monitored.

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Blache, Dominique, i Samantha L. Bickell. "Temperament and reproductive biology: emotional reactivity and reproduction in sheep". Revista Brasileira de Zootecnia 39, suppl spe (lipiec 2010): 401–8. http://dx.doi.org/10.1590/s1516-35982010001300044.

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Reproductive capacity is controlled by a large number of factors such as season, social interactions and metabolic status. However, the influence of emotional reactivity on reproductive success has not been intensively investigated in farm animals. In this review, we define emotion reactivity and the expression of its inter individual variability named temperament. We briefly describe our protocol to measure temperament in sheep and discuss the heritability of temperament traits. Using the results obtained from our flock of sheep selected for calm or nervous temperament, we illustrate how this selection affects the reproductive biology from changing the inexperienced ewe's response to the male effect to improving lamb survival and ovulation rate. We conclude that the mechanisms by which selection for temperament affects the different steps of the reproductive cycle are not yet understood but nevertheless this type of selection could have a great impact on reproduction efficiency of sheep and other domestic ruminants.

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Lianou, Daphne T., Natalia G. C. Vasileiou, Charalambia K. Michael, Irene Valasi, Vasia S. Mavrogianni, Mariangela Caroprese i George C. Fthenakis. "Patterns of Reproductive Management in Sheep and Goat Farms in Greece". Animals 12, nr 24 (7.12.2022): 3455. http://dx.doi.org/10.3390/ani12243455.

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This paper reports findings regarding patterns of reproductive management in 325 sheep flocks and 119 goat herds throughout Greece. The objectives were to describe the patterns of reproductive management in sheep and goat farms, to highlight factors that were associated with these management patterns and the clinical application of the various reproductive management approaches in the farms and to establish potential associations with production outcomes. The median months of the start of the mating period for adult sheep and goats were May and June, respectively and for ewe lambs and replacement goats these were August and September, respectively. The median duration of the mating period was 2 months for adults and 1 month for replacements. The median ratio of female to male animals was 22:1 and 25:1 in sheep and goat farms, respectively. Control of reproduction was applied in 33.2% and 16.8% of sheep and goat farms, respectively, mostly by intravaginal progestagen sponges and less often by melatonin implants; multivariable analysis indicated five (availability of milking parlour, number of ewes in a farm, number of daily milkings, daily period spent by farmers at the farm, farming tradition in the family) and two (number of daily milkings, availability of milking parlour) predictors in sheep and goat farms, respectively. Pregnancy diagnosis ultrasonographically was performed in 36.6% and 16.8% of sheep and goat farms, respectively; multivariable analysis indicated as significant three (management system applied in farms, age of farmer, farming tradition in the family) and two (management system applied in farms, availability of milking parlour) predictors in sheep and goat farms, respectively. The control of reproduction and pregnancy diagnosis were associated with a higher number of vaccinations during pregnancy: 2.6 and 2.7, respectively, versus 2.2 and 2.1 in farms where they were not performed. The average per farm number of lambs/kids born per female animal was 1.33 ± 0.01 and 1.30 ± 0.02 for sheep and goat farms, respectively; five (control of reproduction, location of the farm, presence of working staff, collaboration with veterinary practice, breed of ewes) and two (control of reproduction, breed of female goats) predictors were identified in sheep and goat farms, respectively, for high numbers of lambs/kids. Lambs/kids were taken away from their dams at the age of 50 and 65 days, respectively. The average culling age (females, males) was 5.9 and 4.4 years and 6.9 and 4.9 years for sheep and goats, respectively. Farmers sourced animals to be used as replacements for those removed from the farm, mostly from the animals in their own farms, considering criteria related to milk production. Finally, the application of the control of reproduction was associated with increased milk production and the number of newborns, whilst an inverse correlation between the culling age of animals and milk production was seen.

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Dolebo, Asrat Tera, Negar Khayatzadeh, Aberra Melesse, David Wragg, Mourad Rekik, Aynalem Haile, Barbara Rischkowsky, Max F. Rothschild i Joram M. Mwacharo. "Genome-wide scans identify known and novel regions associated with prolificacy and reproduction traits in a sub-Saharan African indigenous sheep (Ovis aries)". Mammalian Genome 30, nr 11-12 (22.11.2019): 339–52. http://dx.doi.org/10.1007/s00335-019-09820-5.

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Abstract Maximizing the number of offspring born per female is a key functionality trait in commercial- and/or subsistence-oriented livestock enterprises. Although the number of offspring born is closely associated with female fertility and reproductive success, the genetic control of these traits remains poorly understood in sub-Saharan Africa livestock. Using selection signature analysis performed on Ovine HD BeadChip data from the prolific Bonga sheep in Ethiopia, 41 candidate regions under selection were identified. The analysis revealed one strong selection signature on a candidate region on chromosome X spanning BMP15, suggesting this to be the primary candidate prolificacy gene in the breed. The analysis also identified several candidate regions spanning genes not reported before in prolific sheep but underlying fertility and reproduction in other species. The genes associated with female reproduction traits included SPOCK1 (age at first oestrus), GPR173 (mediator of ovarian cyclicity), HB-EGF (signalling early pregnancy success) and SMARCAL1 and HMGN3a (regulate gene expression during embryogenesis). The genes involved in male reproduction were FOXJ1 (sperm function and successful fertilization) and NME5 (spermatogenesis). We also observed genes such as PKD2L2, MAGED1 and KDM3B, which have been associated with diverse fertility traits in both sexes of other species. The results confirm the complexity of the genetic mechanisms underlying reproduction while suggesting that prolificacy in the Bonga sheep, and possibly African indigenous sheep is partly under the control of BMP15 while other genes that enhance male and female fertility are essential for reproductive fitness.

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Brien, Forbes. "Foreword to ‘Sheep Reproduction: Part 2’". Animal Production Science 56, nr 4 (2016): iii. http://dx.doi.org/10.1071/anv56n4_fo.

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Rasmusen, B. A., i Elizabeth M. Tucker. "Transferrin types and reproduction in sheep". Animal Blood Groups and Biochemical Genetics 4, nr 4 (24.04.2009): 207–20. http://dx.doi.org/10.1111/j.1365-2052.1973.tb01301.x.

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Fahmy, M. H. "Major genes for reproduction in sheep". Small Ruminant Research 8, nr 4 (wrzesień 1992): 361–62. http://dx.doi.org/10.1016/0921-4488(92)90219-t.

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Notter, DR. "Genetic Aspects of Reproduction in Sheep". Reproduction in Domestic Animals 43 (lipiec 2008): 122–28. http://dx.doi.org/10.1111/j.1439-0531.2008.01151.x.

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Novotniné Dankó, Gabriella. "Some Practical and Biotechnological Methods for Improving Reproduction Traits in Sheep". Acta Agraria Debreceniensis, nr 11 (15.09.2003): 15–20. http://dx.doi.org/10.34101/actaagrar/11/3437.

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However, reproduction in sheep is seasonal, many breeds of sheep are able to mate not only in autumn, but out-of-season as well. The main factor determining seasonality is the photoperiod, but other factors can influence reproductive pattern, such as genetics, management practices and social cues. The fertility of spring and early summer breeding is usually lower; this imposes the need for alternative methods (e.g. hormonal treatments, biotechnological practice), to increase the conception rate.The author summarize the main practical techniques and biotechnological methods for controlling reproduction completed with some own experimental results in connection with different topics.

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Carrick, MJ. "Sheep Reproduction Modelled as a Markov Series. I. The Model". Australian Journal of Biological Sciences 41, nr 1 (1988): 133. http://dx.doi.org/10.1071/bi9880133.

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Sheep reproduction from ovulation to weaning was modelled as a Markov series of multiple binomial distributions, which required a minimum of assumptions and a small number of parameters for the entire reproductive process. Methods of constructing the model and of estimating the parameters are described, and results from simulated example flocks with different ovulatory potentials are presented. A variety of potential applications, for example as an adjunct to economic modelling and methods of validation and use in the analysis of reproductive experiments, are discussed.

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Petrovic, Milan, V. Caro-Petrovic, D. Ruzic-Muslic, N. Maksimovic, Z. Ilic, B. Milosevic i J. Stojkovic. "Some important factors affecting fertility in sheep". Biotehnologija u stocarstvu 28, nr 3 (2012): 517–28. http://dx.doi.org/10.2298/bah1203517p.

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Efficiency of sheep production is conditioned by fertility. According to some authors number of offspring obtained per lambing is more important than gain of weight. Genetic relationships involving reproductive traits were seldom studied. Reproductive traits have low heritabilities, a discrete phenotypic expression, and are expressed only in sexually mature ewes leading to low selection intensities and long generation intervals. Documentation of realized selection response is also often complicated by the low heritabilities of fertility traits. Existence of a major gene affecting prolificacy had been suggested and at that time there were many sceptics who strongly doubted that a trait as complex as reproduction could be profoundly influenced by a single gene. Major genes affecting prolificacy in sheep was founded. A mutation in the bone morphogenetic protein 15 gene (BMP15, also known as GDF9B) responsible for high prolificacy in Inverdale sheep had been discovered and evidence of segregating major genes was being reported from flocks around the world. Development of gene mapping techniques, and locating alleles that are responsible for the fertility of sheep began a new chapter in predicting and controlling the fertility of sheep. The beneficial effects of nutrition on reproduction in sheep are well known. This procedure is known as flushing. The effect of Body Condition Score (BCS), before mating, during mating and after mating period, on reproductive efficiency of different breeds of sheep in the different rearing systems were studied. The farm manager has the ability to control or at least to manipulate the factors that have an impact on fertility.

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AIBAZOV, А. М. М. "RESULTS AND PROSPECTS OF THE USE OF ASSISTED REPRODUCTIVE TECHNOLOGIES IN REPRODUCTION OF SMALL RUMINANTS’S ANIMAL". Sheep, goats, woolen business, nr 2 (2022): 8–14. http://dx.doi.org/10.26897/2074-0840-2022-2-8-14.

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The article discusses the most common ART (artificial insemination, cryopreservation of sperm and creation of storage facilities, induction and synchronization of sexual reproduction), as well as ART used in rare cases (technology of superovulation induction and embryo transfer, in-vitro embryo production, embryo cryopreservation, transgenesis). The author presents the results of own long-term research on the development of biotechnological methods and methods of increasing the reproductive qualities of sheep and goats. The reasons for the rare use of multiple ovulation and embryotransplantation programs (MOET) in domestic sheep and goat breeding practice are given. Recommendations on using MOET to preserve the gene pool and to increase the efficiency of using genetic resources of high-value animals, increasing their participation in the sheep and goat reproduction process, are given.

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He, Xiaoyun, Qiuyue Liu, Xiaoyu Li, Xiaofei Guo, Xiangyu Wang, Wenping Hu, Ran Di i Mingxing Chu. "Molecular cloning and epigenetic change detection of Kiss1 during seasonal reproduction in Chinese indigenous sheep". Reproduction, Fertility and Development 30, nr 5 (2018): 734. http://dx.doi.org/10.1071/rd17028.

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Like most seasonal domesticated species, sheep are short-day breeders, which means that the reproduction axis is activated by short days. The annual photoperiodic cycle affects the amount of daylength information that is transmitted to the hypothalamic–pituitary–gonadal (HPG) axis by regulating pulsatile secretion of gonadotrophin-releasing hormone from the hypothalamus. Kisspeptin, which is encoded by Kiss1, plays a major role in reproductive seasonality. Based on results from our previous Solexa sequencing data obtained from Tan (T) and Small Tail Han (STH) sheep during anoestrus and the breeding season, full-length mRNA information for ovine Kiss1 was obtained; 894 bp in T sheep and 1145 bp in STH sheep. Both encode 135 amino acids. Additionally, T and STH sheep have different transcription start sites of Kiss1. Kiss1 expression during oestrus was significantly higher than that during dioestrus, both in T and STH sheep (P < 0.01). We also found a strong relationship between Kiss1 mRNA levels and histone H3 acetylation status in the 5′ promoter region of ovine Kiss1. These data indicated that epigenetic modification occurs during reproduction in sheep, and this is the first report that histone H3 deacetylation occurs in the hypothalamus of seasonal sheep breeders during the transition from dioestrus to oestrus.

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Chang, Cheng, Xiaoyun He, Ran Di, Xiangyu Wang, Miaoceng Han, Chen Liang i Mingxing Chu. "Thyroid Transcriptomic Profiling Reveals the Follicular Phase Differential Regulation of lncRNA and mRNA Related to Prolificacy in Small Tail Han Sheep with Two FecB Genotypes". Genes 13, nr 5 (10.05.2022): 849. http://dx.doi.org/10.3390/genes13050849.

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Long non-coding RNA (lncRNA) accounts for a large proportion of RNA in animals. The thyroid gland has been established as an important gland involved in animal reproduction, however, little is known of its gene expression patterns and potential roles in the sheep. Herein, RNA-Seq was used to detect reproduction-related differentially expressed lncRNAs (DELs) and mRNAs (DEGs) in the follicular phase (FT) FecBBB (MM) and FecB++ (ww) genotypes of Small Tail Han (STH) sheep thyroids. Overall, 29 DELs and 448 DEGs in thyroid between MM and ww sheep were screened. Moreover, GO and KEGG enrichment analysis showed that targets of DELs and DEGs were annotated in biological transitions, such as cell cycle, oocyte meiosis and methylation, which in turn affect reproductive performance in sheep. In addition, we constructed co-expression and networks of lncRNAs-mRNAs. Specifically, XLOC_075176 targeted MYB, XLOC_014695 targeted VCAN, 106991527 targeted CASR, XLOC_075176 targeted KIFC1, XLOC_360232 targeted BRCA2. All these differential lncRNAs and mRNAs expression profiles in the thyroid provide a new resource for elucidating the regulatory mechanism underlying STH sheep prolificacy.

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Wang, Wei, Xiaoyun He, Ran Di, Xiangyu Wang i Mingxing Chu. "Transcriptome Analysis Revealed Long Non-Coding RNAs Associated with mRNAs in Sheep Thyroid Gland under Different Photoperiods". Genes 13, nr 4 (28.03.2022): 606. http://dx.doi.org/10.3390/genes13040606.

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The thyroid gland is a vital endocrine organ involved in the reproduction of animals via the regulation of hormone synthesis and secretion. LncRNAs have been proven to play important roles in reproductive regulation; however, the associated mechanism in the thyroid gland has not been clarified. In this study, we investigated to identify photoperiod-induced lncRNAs and mRNAs in the thyroid gland in Sunite ewes by comparing the expression profiles of short photoperiod (SP) and long photoperiods (LP). A total of 41,088 lncRNAs were identified in the thyroid gland through RNA-Seq. Functional analysis of differentially expressed lncRNAs using the R package revealed that reproductive hormone- and photoperiod response-related pathways, including the prolactin signaling, cAMP signaling, and circadian rhythm pathways, were significantly enriched. An mRNA-lncRNA interaction analysis suggested that the lncRNA LOC1056153S88 trans targets ARG2 and CCNB3, and the lncRNA LOC105607004 trans targets DMXL2, both of these might be involved in seasonal sheep breeding reproduction. Together, these results will provide resources for further studies on seasonal reproduction in sheep.

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Fu, Xiaoyu, Yanan Yang, Zunqiang Yan, Miaomiao Liu i Xinrong Wang. "Transcriptomic Study of Spermatogenesis in the Testis of Hu Sheep and Tibetan Sheep". Genes 13, nr 12 (25.11.2022): 2212. http://dx.doi.org/10.3390/genes13122212.

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Numerous genes involved in male reproduction regulate testis development and spermatogenesis. In this study, the testis tissue transcriptome was used to identify candidate genes and key pathways associated with fecundity in sheep. Histological analysis of testis tissue using hematoxylin–eosin (HE) routine staining was performed for two sheep breeds. Overall, 466 differentially expressed genes (DEGs) were identified between Hu sheep (HS) and Tibetan sheep (TS) through RNA sequencing technology (RNA-Seq), including 226 upregulated and 240 downregulated genes. Functional analysis showed that several terms and pathways, such as “protein digestion and absorption”, “cAMP signaling pathway”, “focal adhesion”, and “p53 signaling pathway” were closely related to testis development and spermatogenesis. Several genes (including COL1A1, COL1A2, COL3A1, SOX9, BCL2, HDC, and GGT5) were significantly enriched in these terms and pathways and might affect the reproduction of sheep by regulating the migration of spermatogenic cells, apoptosis of spermatogenic cells, and secretion of sterol hormones via testicular interstitial cells. Our results provide a theoretical basis for better understanding the molecular mechanisms of reproduction in sheep.

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Kennedy, Karen J., Nathan S. Boyd, Vilis O. Nams i A. Randall Olson. "The Impacts of Fertilizer and Hexazinone on Sheep Sorrel (Rumex acetosella) Growth Patterns in Lowbush Blueberry Fields". Weed Science 59, nr 3 (wrzesień 2011): 335–40. http://dx.doi.org/10.1614/ws-d-10-00088.1.

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Sheep sorrel is an invasive, creeping perennial weed of lowbush blueberry fields that decreases yields and hinders harvest. Much of the basic phenology of sheep sorrel in blueberry fields is unknown and not documented in peer-reviewed journals. Three levels of fertilizer (0, 20, and 40 kg N ha−1) and two levels of hexazinone (0 and 1.92 kg ai ha−1) were applied to three vegetative-year blueberry fields to determine their effects on root and shoot growth, biomass allocation, and seed production of sheep sorrel plants. Hexazinone efficacy varied widely between sites, but suppressed shoot biomass, achene number and weight, and reproductive biomass, as well as the reproductive : shoot biomass ratio. Fertilizer tended to increase achene number and increased sheep sorrel shoot biomass in the absence of hexazinone, but had no effect on achene weight, root biomass, or reproductive biomass. When fertilizer was applied, sheep sorrel allocated resources to sexual reproduction at the expense of vegetative growth.

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Sodiq, Akhmad. "Identifikasi Sistim Produksi dan Keragaan Produktivitas Domba Ekor Gemuk di Kabupaten Brebes Propinsi Jawa-Tengah". Jurnal Agripet 10, nr 1 (1.04.2010): 25–31. http://dx.doi.org/10.17969/agripet.v10i1.634.

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Identification of production system and productivity level of fat tailed sheep in brebes regency of central javaABSTRACT. Reproductive performance is one of the main determinants of productivity of the sheep. This applies to the breeding of animal for meat production. High reproduction rates are essential for profit in meat sheep production and determined by the number of progeny delivered in a given period of time. The level of reproductive performance is dependent on the interaction of genetic and environmental factors. The evaluation of reproductive performance of a local and adapted breed of sheep such as Fat Tailed Sheep can provide important information to understand its productive potential under local production system. The study was designed to identify characteristic of production system and to find out the level productivity of Fat Tailed Sheep in Brebes areas of Central Java. Livestock On-Farm Trials (LOFT) using multistage sampling was implemented in this study. Descriptive and variance analysis using procedure of General Linear Model (GLM) was applied in this study. This study revealed that (1) In general, production system in Brebes is based on integration scheme of crop livestock in the form of traditional smallholders. In low land area, mostly extensive and tethering model were implemented. Intensive and semi intensive model was found in landless area. (2) Average litter size at birth was 1.54 head and dominated by double litter, followed by single and triplets (46.8, 47.88 and 4.29%). The highest preweaning lamb mortality was 15% with the average 8.9%. Ewe productivity ranges from 1.76-5.24 with average of 2.14 lamb/ewe/year. Least squares analysis of variance reveals that ewe reproduction rate was significantly affected by type of birth.

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Maclachlan, N. J., J. E. Crafford, W. Vernau, I. A. Gardner, A. Goddard, A. J. Guthrie i E. H. Venter. "Experimental Reproduction of Severe Bluetongue in Sheep". Veterinary Pathology 45, nr 3 (maj 2008): 310–15. http://dx.doi.org/10.1354/vp.45-3-310.

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Lehman, Michael N., Zamin Ladha, Lique M. Coolen, Stanley M. Hileman, John M. Connors i Robert L. Goodman. "Neuronal plasticity and seasonal reproduction in sheep". European Journal of Neuroscience 32, nr 12 (grudzień 2010): 2152–64. http://dx.doi.org/10.1111/j.1460-9568.2010.07530.x.

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32

Talafha, Abdelsalam Q., i Mohammed M. Ababneh. "Awassi sheep reproduction and milk production: review". Tropical Animal Health and Production 43, nr 7 (21.04.2011): 1319–26. http://dx.doi.org/10.1007/s11250-011-9858-5.

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33

Zhang, Zhuangbiao, Jishun Tang, Ran Di, Qiuyue Liu, Xiangyu Wang, Shangquan Gan, Xiaosheng Zhang, Jinlong Zhang, Wenping Hu i Mingxing Chu. "Comparative Transcriptomics Reveal Key Sheep (Ovis aries) Hypothalamus LncRNAs that Affect Reproduction". Animals 9, nr 4 (8.04.2019): 152. http://dx.doi.org/10.3390/ani9040152.

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The diverse functions of long noncoding RNAs (lncRNAs), which execute their functions mainly through modulating the activities of their target genes, have been have been widely studied for many years (including a number of studies involving lncRNAs in the ovary and uterus). Herein, for the first time, we detect lncRNAs in sheep hypothalami with FecB++ through RNA Sequencing (RNA-Seq) and identify a number of known and novel lncRNAs, with 622 and 809 found to be differentially expressed in polytocous sheep in the follicular phase (PF) vs. monotocous sheep in the follicular phase (MF) and polytocous sheep in the luteal phase (PL) vs. monotocous sheep in the luteal phase (ML), respectively. Then, Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) analyses were performed based on the predicted target genes. The most highly enriched GO terms (at the molecular function level) included carbonyl reductase (NADPH), 15-hydroxyprostaglandin dehydrogenase (NADP+), and prostaglandin-E2 9-reductase activity in PF vs. MF, and phosphatidylinositol-3,5-bisphosphate binding in PL vs. ML was associated with sheep fecundity. Interestingly, the phenomena of valine, leucine, and isoleucine degradation in PL vs. ML, and valine, leucine, and isoleucine biosynthesis in PF vs. MF, were present. In addition, the interactome of lncRNA and its targets showed that MSTRG.26777 and its cis-targets ENSOARG00000013744, ENSOARG00000013700, and ENSOARG00000013777, and MSTRG.105228 and its target WNT7A may participate in the sheep reproductive process at the hypothalamus level. Significantly, MSTRG.95128 and its cis-target Forkhead box L1 (FOXG1) were shown to be upregulated in PF vs. MF but downregulated in PL vs. ML. All of these results may be attributed to discoveries of new candidate genes and pathways related to sheep reproduction, and they may provide new views for understanding sheep reproduction without the effects of the FecB mutation.

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Barr, A. Catherine, Bruce Abbitt, Robert A. Fiske, John T. Jaques, Heather R. Maynard i John C. Reagor. "Reproductive Effects of Fenoxycarb on Sheep". Journal of Veterinary Diagnostic Investigation 9, nr 4 (październik 1997): 401–6. http://dx.doi.org/10.1177/104063879700900410.

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Fenoxycarb (ethyl [2-(4-phenoxyphenoxy)-ethyl] carbamate) is an insect growth regulator used for long-term fire ant control. Because of its effects on insect reproduction and its potential use on pasturage consumed by food animals, a reproductive study was conducted using Rambouillet sheep. The sheep were dosed daily with a placebo or with fenoxycarb at 0.69 or 1.38 mg/kg/day, representing ten (10X) and 20 times (20X) the maximum amounts of fenoxycarb in forage or hay treated at recommended levels for fire ant control. Parameters that were measured included rates of weight gain of adults, serum clinical chemistry profiles of adults, spermatozoal morphology and motility, estrus cycling, pregnancy rates, maintenance of pregnancies to term, numbers of live births, and rates of weight gain of lambs to 28 days. There were no statistically significant ( P ≤ 0.05) differences between the exposed and control groups of sheep in any of these facets of the study. No clinical signs associated with exposure to fenoxycarb were observed in any animal at any time, and no exposure-related pattern of pathologic lesions or reproductive organ histology was observed. Means of hepatic fenoxycarb residues in the rams followed a statistically significant ( P ≤ 0.05) dose-related pattern. No fenoxycarb was detected (detection limit of 5 ppb) in any neonatal liver, despite the presence of hepatic fenoxycarb residues in the treated ewes, indicating that transplacental transport of fenoxycarb was minimal. No fenoxycarb was detected in any lamb liver at 28 days, although both the colostrum and the milk of exposed ewes were found to contain fenoxycarb at levels proportional to the treatments. Based on the lack of significant findings in this study, it is unlikely that use of fenoxycarb, according to label instructions (currently applicable to homeowner and registered agricultural usage) for fire ant control in pasturage or hay fields, will affect ruminant reproduction.

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Rakib, Md, Nure Desha, Md Rahman, Md Kabir, Farzana Yasmin, Md Alam, Sonia Akther i Nasrin Sultana. "Environmental adaptability, morphometric features with reproductive and productive potentialities of indigenous sheep in Bangladesh". Journal of Advanced Veterinary and Animal Research 9, nr 4 (2022): 649. http://dx.doi.org/10.5455/javar.2022.i634.

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Indigenous sheep are highly adaptable and widely distributed in different regions of Bangladesh. They are famous for their tolerance to harsh environmental conditions, low demand for feed, and disease resistance with minimum or no housing and management facilities. Ample indiscrimi¬nate research reports and case studies on the native sheep of Bangladesh have been published. Nonetheless, a comprehensive review of reproductive and productive performances, as well as their various morphometric physiognomies and climate resilience capabilities, is lacking. This review was designed to explore and summarize the available research reports on indigenous sheep to highlight the gaps and provide an updated database for the future research plan for sustainable native sheep production in Bangladesh. It covers studies on sheep biodiversity, their adaptabil¬ity to the local environment, morphometric features, feeding and nutrition, reproduction and production performances, diseases and health management, and the problems and prospects of sheep farming in Bangladesh. Due to the increased demand for animal protein, especially red meat, the scope of sheep farming increases along with that of other large and small ruminants. The vital constraints of sheep production in Bangladesh include insufficient feed and fodder sup¬ply with its high prices, higher disease occurrence with low or no management practices, kid mortality, and a poor marketing channel with the lower popularity of sheep meat than goat meat. Future research would be a prerequisite to measuring the impact of native sheep on household economies and food security during the year, evaluating the other challenges, and finding out the possible interventions in the fields of nutrition, reproduction, and health management.

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Merkley, Christina M., Allison N. Renwick, Sydney L. Shuping, KaLynn Harlow, Jeffrey R. Sommer i Casey C. Nestor. "Undernutrition reduces kisspeptin and neurokinin B expression in castrated male sheep". Reproduction and Fertility 1, nr 1 (31.10.2020): 21–33. http://dx.doi.org/10.1530/raf-20-0025.

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Undernutrition impairs reproductive success through suppression of gonadotropin-releasing hormone (GnRH), and subsequently luteinizing hormone (LH), secretion. Given that kisspeptin and neurokinin B (NKB) neurons in the arcuate nucleus (ARC) of the hypothalamus are thought to play key stimulatory roles in the generation of GnRH/LH pulses, we hypothesized that feed restriction would reduce the ARC mRNA abundance and protein expression of kisspeptin and NKB in young, male sheep. Fourteen wethers (castrated male sheep five months of age) were either fed to maintain (FM; n = 6) pre-study body weight or feed-restricted (FR; n = 8) to lose 20% of pre-study body weight over 13 weeks. Throughout the study, weekly blood samples were collected and assessed for LH concentration using RIA. At Week 13 of the experiment, animals were killed, heads were perfused with 4% paraformaldehyde, and brain tissue containing the hypothalamus was collected, sectioned, and processed for detection of mRNA (RNAscope) and protein (immunohistochemistry) for kisspeptin and NKB. Mean LH was significantly lower and LH inter-pulse interval was significantly higher in FR wethers compared to FM wethers at the end of the experiment (Week 13). RNAscope analysis revealed significantly fewer cells expressing mRNA for kisspeptin and NKB in FR wethers compared to FM controls, and immunohistochemical analysis revealed significantly fewer immunopositive kisspeptin and NKB cells in FR wethers compared to FM wethers. Taken together, this data supports the idea that long-term feed restriction regulates GnRH/LH secretion through central suppression of kisspeptin and NKB in male sheep. Lay summary While undernutrition is known to impair reproduction at the level of the brain, the components responsible for this in the brain remain to be fully understood. Using male sheep we examined the effect of undernutrition on two stimulatory molecules in the brain critical for reproduction: kisspeptin and neurokinin B. Feed restriction for several weeks resulted in decreased luteinizing hormone in the blood indicating reproductive function was suppressed. In addition, undernutrition also reduced both kisspeptin and neurokinin B levels within a region of the brain involved in reproduction, the hypothalamus. Given that they have stimulatory roles in reproduction, we believe that undernutrition acts in the brain to reduce kisspeptin and neurokinin B levels leading to the reduction in luteinizing hormone secretion. In summary, long-term undernutrition inhibits reproductive function in sheep through suppression of kisspeptin and neurokinin B within the brain.

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Zhang, Zhuangbiao, Jishun Tang, Xiaoyun He, Mingxia Zhu, Shangquan Gan, Xiaofei Guo, Xiaosheng Zhang, Jinlong Zhang, Wenping Hu i Mingxing Chu. "Comparative Transcriptomics Identify Key Hypothalamic Circular RNAs that Participate in Sheep (Ovis aries) Reproduction". Animals 9, nr 8 (14.08.2019): 557. http://dx.doi.org/10.3390/ani9080557.

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Circular RNA (circRNA), as an emerging class of noncoding RNA, has been found to play key roles in many biological processes. However, its expression profile in the hypothalamus, a powerful organ initiating the reproductive process, has not yet been explored. Therefore, we used RNA sequencing to explore the expression of circRNAs in the hypothalamus of sheep with the FecB ++ genotype. We totally identified 41,863 circRNAs from sheep hypothalamus, in which 333 (162 were upregulated, while 171 were downregulated) were differentially expressed in polytocous sheep in the follicular phase versus monotocous sheep in the follicular phase (PF vs. MF), moreover, 340 circRNAs (163 were upregulated, while 177 were downregulated) were differentially expressed in polytocous sheep in the luteal phase versus monotocous sheep in the luteal sheep (PL vs. ML). We also identified several key circRNAs including oar_circ_0018794, oar_circ_0008291, oar_circ_0015119, oar_circ_0012801, oar_circ_0010234, and oar_circ_0013788 through functional enrichment analysis and oar_circ_0012110 through a competing endogenous RNA network, most of which may participate in reproduction by influencing gonadotropin-releasing hormone (GnRH) activities or affecting key gene expression, indirectly or directly. Our study explored the overall expression profile of circRNAs in sheep hypothalamus, which potentially provides an alternative insight into the mechanism of sheep prolificacy without the effects of FecB mutation.

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Sultan, Ahammad, Md Rashedul Islam, Rakesh Kumer Yadav, Rupaly Akhter i Jalal Uddin Ahmed. "Prevalence of different reproductive disorders of small ruminants in five upazillas of Mymensingh district". Asian Journal of Medical and Biological Research 1, nr 1 (4.11.2015): 74–79. http://dx.doi.org/10.3329/ajmbr.v1i1.25501.

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Small ruminants (goat and sheep) are economically important and promising animal resource in Bangladesh. Reproductive disorders of goat and sheep cause the great economic problems. Therefore, the aim of the study was to investigate the prevalence of reproductive disorders in goat and sheep in five upazillas of Mymensingh district. Records of reproductive disorders were collected from official stock book of different Upazillas veterinary hospitals of Mymensingh district during April 2010 to March 2011. Seasonal occurrences of reproductive disorders were also recorded. Descriptive statistical analysis was done to study the prevalence of different reproductive disorders of goat and sheep in five upazillas of Mymensingh district. Out of 4804 clinical cases, a total of 147 reproductive disorders of goat and sheep were screened out from datasheet of official stock book. Among the five upazila, the prevalence of reproductive disorders was higher in Muktagacha (3.35%) and lower in Fulbaria (2.38%). Prevalence of reproductive disorders in all upazila was higher in sheep (4.12%) than goat (2.88%). Prevalence of reproductive disorders of goat was higher in Tarakanda (3.26%) and lower in Fulbaria (2.03%) and the prevalence of reproductive disorders of sheep was higher in Gaforgaon (5.22%) and lower in Haluaghat (3.15%). The major reproductive disorders recorded in goats were dystocia (41.2%), abortion (21.8%), mastitis (21.8%), retained placenta (11.8%) and pyometra (3.4%). Similarly, major reproductive disorders in sheep were dystocia (53.7%), abortion (25%), pyometra (7.1%), mastitis (7.1%) and retained placenta (7.1%). Moreover, seasonal prevalence of reproductive disorders was higher in summer than winter in the species, goat (57.14%) and sheep (12.25%). It was concluded that the most pressing constraint on goat and sheep reproduction in Bangladesh is dystocia, abortion and mastitis. Strategies should be taken to minimize their occurrence.Asian J. Med. Biol. Res. June 2015, 1(1): 74-79

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39

Huisman, A. E., D. J. Brown, A. J. Ball i H. U. Graser. "Genetic parameters for bodyweight, wool, and disease resistance and reproduction traits in Merino sheep. 1. Description of traits, model comparison, variance components and their ratios". Australian Journal of Experimental Agriculture 48, nr 9 (2008): 1177. http://dx.doi.org/10.1071/ea08119.

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Both wool and sheep meat industries are interested in sheep that have a high reproduction performance and are resistant to internal parasites, in addition to the traditional traits. There is considerable interest in breeding sheep for wool, carcass, reproductive and internal parasite resistance traits simultaneously. The objective of this study was to estimate single trait genetic parameters for 40 traits recorded in Merino sheep, covering bodyweight, carcass, wool, reproduction and internal parasite resistance traits. This also involved determining the appropriate models. The results from this study will be used to review the genetic parameters used in the routine genetic evaluations conducted by Sheep Genetics. The most appropriate models included a maternal genetic effect and covariance between direct and maternal genetic effects for most of the bodyweight traits, greasy and clean fleece weight, fibre diameter and coefficient of variation of fibre diameter. The permanent environment due to the dam was not included for any trait. There was considerable genetic variation in most traits analysed; lowest heritabilities (0.09–0.10) were found for number of lambs born and weaned per lambing opportunity, and highest heritabilities (0.62–0.77) for fibre diameter. The estimated heritabilities and genetic variances, in combination with the estimated correlations, indicate that there is potential to make genetic improvement in most traits currently recorded in Australian Merino sheep.

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Ralph, C. R., M. N. Lehman, R. L. Goodman i A. J. Tilbrook. "Impact of psychosocial stress on gonadotrophins and sexual behaviour in females: role for cortisol?" Reproduction 152, nr 1 (lipiec 2016): R1—R14. http://dx.doi.org/10.1530/rep-15-0604.

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This review focuses on the importance of cortisol in mediating the inhibitory effects of psychosocial stress on reproduction in females. In particular, we have summarized our research in sheep where we have systematically established whether cortisol is both sufficient and necessary to suppress reproductive hormone secretion and inhibit sexual behaviour. Our findings are put into context with previous work and are used to develop important concepts as well as to identify productive further lines of investigation. It is clear that cortisol is necessary to inhibit some, but not all, aspects of reproduction in female sheep. These actions vary with reproductive state, and there are important interactions with gonadal steroids. The impact of cortisol on the tonic secretion of gonadotrophin-releasing hormone and luteinizing hormone has been investigated extensively, but less is known about the surge secretion of these hormones and their effects on sexual behaviour. Furthermore, there are separate effects of cortisol in the brain (hypothalamus) and at the anterior pituitary, illustrating that there are different mechanisms of action. Thus, although cortisol is important in mediating some of the effects of stress on reproduction, we need to look beyond cortisol and investigate some of the other mechanisms and mediators that relay the effects of stress on reproduction. In this regard, we propose that a group of neurons in the hypothalamus that co-synthesize kisspeptin, neurokinin B and dynorphin, termed KNDy cells, play important roles in mediating the effects of cortisol on reproduction. This hypothesis needs to be rigorously tested.

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41

Walkom, S. F., i D. J. Brown. "Impact of liveweight, fat and muscle sire breeding values on ewe reproduction is minimal but variable across Australian grazing systems". Animal Production Science 57, nr 9 (2017): 1952. http://dx.doi.org/10.1071/an15574.

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Australian sheep producers have the potential to improve reproductive rates through optimising ewe body condition across the production cycle. Managing ewe body condition can become costly when supplementary feeding is required due to poor pasture growth or rainfall and by using appropriate genetics, producers can theoretically reduce the flock’s dependency on supplementary feed and improve reproductive rates. Reproductive records from the Information Nucleus Flock and Sheep Genetics Merino and maternal breed datasets were analysed to examine the influence of sire breeding values for liveweight (post-weaning, yearling and adult assessments), fat and eye muscle depths (post-weaning and yearling assessments) and number of lambs weaned on reproductive performance (fertility, litter size and number of lambs born) across a variety of production environments. To determine the impact of environmental conditions on the relationship between weight, ultrasound body composition, and reproduction traits the daughters’ adjusted reproductive performances were regressed on the sire’s breeding value across flocks, within flocks and within flock × year. Irrespective of age at assessment, sire breeding values for liveweight, fat and eye muscle depths had very little association with the reproductive performance of their daughters, on average. The regressions of reproduction on weight, and fat and eye muscle depth traits varied across flocks from unfavourable to favourable estimates. The very small overall impact of weight, and fat and eye muscle depth traits, on average suggests that using sire breeding values for number of lambs weaned, which had a large impact on reproduction, will provide the most viable method to genetically improve reproductive performance within the production system in question.

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42

Li, Zhifeng, Xiaoyun He, Xiaosheng Zhang, Jinlong Zhang, Xiaofei Guo, Wei Sun i Mingxing Chu. "Analysis of Expression Profiles of CircRNA and MiRNA in Oviduct during the Follicular and Luteal Phases of Sheep with Two Fecundity (FecB Gene) Genotypes". Animals 11, nr 10 (28.09.2021): 2826. http://dx.doi.org/10.3390/ani11102826.

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CircRNA and miRNA, as classes of non-coding RNA, have been found to play pivotal roles in sheep reproduction. There are many reports of circRNA and miRNA in the ovary and uterus, but few in the oviduct. In this study, RNA-Seq was performed to analyze the expression profile of circRNA and miRNA in the oviduct during the follicular phase and luteal phase of sheep with FecBBB and FecB++ genotypes. The results showed that a total of 3223 circRNAs and 148 miRNAs were identified. A total of 15 DE circRNAs and 40 DE miRNAs were found in the comparison between the follicular phase and luteal phase, and 1 DE circRNA and 18 DE miRNAs were found in the comparison between the FecBBB genotype and FecB++ genotype. GO and KEGG analyses showed that the host genes of DE circRNAs were mainly enriched in the Rap1 signaling pathway, PI3K–Akt signaling pathway and neuroactive ligand–receptor interactions. Novel_circ_0004065, novel_circ_0005109, novel_circ_0012086, novel_circ_0014274 and novel_circ_0001794 were found to be possibly involved in the oviductal reproduction process. GO and KEGG analyses showed that the target genes of DE miRNAs were mainly enriched in insulin secretion, the cAMP signaling pathway, the cGMP–PKG signaling pathway, the Rap1 signaling pathway and the TGF-β signaling pathway, and the target genes LPAR1, LPAR2, FGF18, TACR3, BMP6, SMAD4, INHBB, SKP1 and TGFBR2 were found to be associated with the reproductive process. Miranda software was used to identify 27 miRNAs that may bind to 13 DE circRNAs, including miR-22-3p (target to novel_circ_0004065), miR-127, miR-136 (target to novel_circ_0000417), miR-27a (target to novel_circ_0014274) and oar-miR-181a (target to novel_circ_ 0017815). The results of this study will help to elucidate the regulatory mechanisms of circRNAs and miRNAs in sheep reproduction. Our study, although not establishing direct causal relationships of the circRNA and miRNA changes, enriches the sheep circRNA and miRNA database and provides a basis for further studies on sheep reproduction.

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de Vries, F., H. Hamann, C. Drögemüller, M. Ganter i O. Distl. "Analysis of associations between the prion protein genotype and reproduction traits in meat sheep breeds". Animal Science 79, nr 3 (grudzień 2004): 397–404. http://dx.doi.org/10.1017/s1357729800090263.

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AbstractThe objective of this study was to analyse the associations between ovine prion protein (PrP) genotypes and reproduction traits in three German meat sheep breeds. Reproduction traits were age at first early lambing, age at first late lambing, first lambing interval, second lambing interval and total number of lambs born. The data set included 595 genotyped German Texel sheep among 5225 recorded sheep, 351 genotyped German Black-Headed Mutton among 10 177 sheep and 282 genotyped Suffolk sheep among 2849 sheep. Linear animal models were employed for the analysis of the PrP-genotype effect. The PrP-genotype effect was analysed by comparing the most frequent PrP genotypes ARR/ARR, ARR/ARQ, and ARQ/ARQ. In a more general analysis three PrP genotype classes of animals with two, one or no copy of the ARR allele were compared.In most cases, no significant associations were found between the PrP genotypes and the reproduction traits investigated. Only for the traits age at first early lambing in German Texel and second lambing interval in German Black-Headed Mutton and Suffolk could a significant association with the PrP genotype be observed.

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44

Z, Hernández-Russo. "Effect of Gastrointestinal Nematodes on Reproduction and Lamb Growth in Australian Merino Sheep". Open Access Journal of Veterinary Science & Research 5, nr 2 (2020): 1–5. http://dx.doi.org/10.23880/oajvsr-16000204.

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Environmental conditions in Uruguay favour the development of gastrointestinal nematodes (GIN) throughout the year, with clinical or subclinical manifestations that cause significant economic losses. The aim of this study was to evaluate the effect of the GIN on fertility, fecundity, reproductive rate and lamb growth in Australian Merino sheep grazing on basalt fields. The study was carried out in a farm located in north of Uruguay. Sixty-eight Merino ewes facing a natural parasite challenge were divided into two groups. Control group was doused with active anthelmintic that have proven efficacy to minimize the effects of parasitic and the parasitized group that did not receive anthelmintic, except rescue dosages. Stool sample of each sheep was collected monthly for egg counts (EPG) of GIN using McMaster technique and nematode genders were identified from infective larvae obtained in cultures by Roberts O’ Sullivan technique. Artificial insemination and ewes were mated for new service, and pregnancy condition was diagnosed by ultrasound. Lambing control was made and lambs were weighed at birth and marking. The evolution of EPG values showed significant differences between groups at the end of gestation and lactation. Haemonchus spp. was the main gender of nematodes found, followed by Trichostrongylus spp. Fertility was 95 % versus 90 %; fecundity 87 % versus 63 % and reproductive rate 73 % versus 47 % for the control group and the parasitized one respectively. No significant differences were recorded in birth-weight. However market-weight and lamb daily gain were lower in the parasitized group. The effect of natural infection GIN was evident in lower reproductive performance of Australian Merino sheep.

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45

Gruszecki, Tomasz M., Monika Greguła-Kania, Roman Niżnikowski, Mirosław Pięta, Krzysztof Kostro, Anna Szymanowska, Anna Miduch i Ewa Strzelec. "Effect of PRNP Gene Polymorphism on Reproductive Performance of Mother Sheep and their Offspring Growth". Bulletin of the Veterinary Institute in Pulawy 56, nr 3 (1.09.2012): 279–82. http://dx.doi.org/10.2478/v10213-012-0050-0.

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Abstract The polymorphism of prion protein (PrP) amino acids in codons 136 (A/V), 154 (R/H); and 171 (Q/R/H) was established. Reproductive performance of mother sheep was evaluated analysing the fertility coefficient and litter size, i.e. the number of born and reared lambs. The studies included mothers of synthetic lines BCP - 111 sheep and SCP - 104 sheep born in 2001-2007. In the examined ovine PRNP gene, the following four alleles were identified: ARR, AHQ, ARQ, and VRQ, with the absence of the ARH allele. The highest frequency was determined for the ARR (49.8%) and ARQ (45.8%) alleles. In the studied sheep population, the occurrence of seven different genotypes was reported. It was found that 71.6% of the animals had the genotypes ARR/ARR, ARR/ARQ, and ARR/AHQ, which are regarded as the most resistant to scrapie, while 7.9% of the population had ARR/VRQ-bearing genotypes (low resistance) or ARQ/VRQ ones (high susceptibility to scrapie). The analysis of the obtained results indicates that the PRNP genotype does not affect reproduction efficiency of mothers, or their offspring growth. It was concluded that flock elimination of ewes of genotypes with high and very high susceptibility to scrapie will not reduce the reproduction parameters of ewes or growth of their lambs.

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Khan, N. N., N. Assad, Nishant Kumar, D. Chakraborty, Aadil Ayaz, Mashooq Ahmad Dar, Aarif Ali i Suheel Yousuf Wani. "Genetic Parameters of Reproduction Traits in Rambouillet Sheep". International Journal of Current Microbiology and Applied Sciences 6, nr 8 (10.08.2017): 2090–94. http://dx.doi.org/10.20546/ijcmas.2017.608.248.

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47

Loi, Pasqualino, Grazyna Ptak, Maria Dattena, Sergio Ledda, Salvatore Naitana i Pietro Cappai. "Embryo transfer and related technologies in sheep reproduction". Reproduction Nutrition Development 38, nr 6 (1998): 615–28. http://dx.doi.org/10.1051/rnd:19980604.

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48

Abecia, José A., Fernando Forcada i Antonio González-Bulnes. "Pharmaceutical Control of Reproduction in Sheep and Goats". Veterinary Clinics of North America: Food Animal Practice 27, nr 1 (marzec 2011): 67–79. http://dx.doi.org/10.1016/j.cvfa.2010.10.001.

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49

Zhulinska, O. S., S. L. Drozd i S. V. Mohylnytska. "ANALYSIS OF REPRODUCTION OF SHEEP OF ASKANIAN SELECTION". Animal Biology 18, nr 3 (wrzesień 2016): 36–45. http://dx.doi.org/10.15407/animbiol18.03.036.

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50

OHUCHI, Nozomu, Kuniji YAMAKI, Toshihiro YAMAGISHI, Masami SUZUKI, Masaaki TADA i Tomoo KONNNO. "Reproduction in the Three Different Breeds of Sheep". Japanese Journal of Sheep Science 1993, nr 30 (1993): 43–47. http://dx.doi.org/10.11595/jpnjsheepsci1964.1993.43.

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