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Letteratura scientifica selezionata sul tema "Sheep Reproduction"

Autore: Grafiati

Pubblicato: 4 giugno 2021

Ultima modifica: 31 gennaio 2023

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Articoli di riviste sul tema "Sheep Reproduction"

1

Joshi, Purushotam. "NUTRITION AND REPRODUCTION IN SHEEP". FOOD & AGRIBUSINESS MANAGEMENT 3, n. 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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2

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

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3

Dzakuma, J. M., e D. L. Harris. "Computer Modeling of Sheep Reproduction: II. Accelerated Reproduction in Sheep". Journal of Animal Science 67, n. 9 (1 settembre 1989): 2212–21. http://dx.doi.org/10.2527/jas1989.6792212x.

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4

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

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5

Haresign, W. "Controlling reproduction in sheep". BSAP Occasional Publication 14 (gennaio 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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6

DEAC, Alexandru Marius, Adriana Sebastiana MUSCĂ, Marius Gavril AIPĂTIOAIE, Viorica COŞIER e 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, n. 79 (11 maggio 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., e M. J. Bryant. "Seasonality of reproduction in sheep". Small Ruminant Research 48, n. 3 (giugno 2003): 155–71. http://dx.doi.org/10.1016/s0921-4488(03)00038-5.

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8

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

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9

HE, MINGFENG, QIU-HUI PAN e SHUANG WANG. "FINAL STATE OF ECOSYSTEM CONTAINING GRASS, SHEEP AND WOLVES WITH AGING". International Journal of Modern Physics C 16, n. 01 (gennaio 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 e 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, n. 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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Più fonti

Tesi sul tema "Sheep Reproduction"

1

Nassiri, Mohammad Taghi Beigi. "Aspects of prolificacy in Cambridge sheep". Thesis, Bangor University, 1996. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.321435.

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2

Ibraheem, Majid. "The manipulation of seasonality of reproduction in sheep". Thesis, University of Aberdeen, 1991. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.332379.

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The phenomenon of seasonability of reproduction restricts the ewe to only one lambing around the same time every year, which in turn prevents an even supply of lamb meat to the market. The long term objective of the current study was to develop two systems of early and summer lambing using alternative techniques for the manipulation of sheep production in an attempt to produce high quality lamb throughout the year. In recent years, major advances in our knowledge of seasonality of reproduction have been the recognition of the integral role of the pineal gland and its indoleamine melatonin in the timing of reproductive activity and the use of the pattern of reproductive behaviour in sheep in the manipulation of reproductive processes. Therefore, the current study aimed at examining the use of melatonin and/or the 'ram effect' in early and summer lambing systems in order to report on their effectiveness in advancing the breeding season and/or enhancing fecundity. Also, the concern over the seasonal variation in libido and semen quality in the ram made it necessary to examine ways of eliminating the seasonal depression in the mating performance and capcity of the ram. Experiments 1, 2 and 3 examined the effectiveness of the intraruminal device of melatonin administration and/or the 'ram effect' in advancing the breeding season of the ewes. Also the effects of duration and methods of 'teasing' were assessed.

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3

Archer, Zoe Anne. "Neuroendocrine control of appetite and reproduction in sheep". Thesis, University of Aberdeen, 2001. http://digitool.abdn.ac.uk/R?func=search-advanced-go&find_code1=WSN&request1=AAIU602029.

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Reproductive neuroendocrine activity and appetite are modulated at the hypothalamus by both nutritional status and photoperiod in the seasonal animal. The objectives of this work were (1) to measure circulating hormones and/or metabolites that relay information about peripheral nutritional status to the hypothalamus, (2) to identify which hypothalamic neuropeptides and receptors that are responsive to photoperiodic and nutritional feedback and (3) to establish which changes in peripheral signals and/or hypothalamic neuropeptides are associated with alterations in the activity of the reproductive neuroendocrine axis. Three main experiments were carried out. The first experiment (Chapter 1) utilised a 2 x 2 design to examine the separate and interactive effects of photoperiod and food restriction on hypothalamic neuropeptide and receptor mRNA expression and on GnRH/LH secretion. In the second experiment (Chapter 2), two components of nutritional status, BC and increased food intake were investigated since both are positively related to reproductive performance in sheep. In the final experiment (Chapter 3) the approach was to use an exogenous treatment to artificially raise plasma insulin in an attempt to "drive" some of the foregoing effects. Collectively these studies have lead to the first localisation AgRp, MCH, orexin, Mc3R, Mc4R gene expression in the ovine hypothalamus. They indicate that circulating insulin and leptin are major factors relaying information about nutritional status to the hypothalamus. In addition, they have dissociated BC and food intake as signals to the hypothalamus. Moreover these studies have provided no evidence that NPY, AgRp, POMC, MCH and ObRb play a role in driving seasonal changes in appetite and gonadotrophin secretion. However they do suggest NPY-ergic and melanocortin pathways are important in maintaining appetite/bodyweight/energy homeostasis or restoring energy balance following perturbation. Furthermore the results show that changes in nutrient-sensitive hypothalamic neuropeptide and receptor gene expression may not necessarily lead to alterations in the activity of the reproductive neuroendocrine axis. However, they do indicate that increased NPY biosynthesis during food restriction may be involved in the inhibition of pulsatile GnRH/LH release.

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Singh, Inderjeet. "Embryonic survival in adrenal hyperactivity in sheep". Thesis, University of Liverpool, 1994. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.386839.

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5

Ferasyi, Teuku Reza. "Mathematical model of the reproductive endocrine system in male sheep". University of Western Australia. School of Animal Biology, 2008. http://theses.library.uwa.edu.au/adt-WU2008.0080.

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[Truncated abstract] The activity of the reproductive endocrine axis is the result of interactions among many organs and tissues, particularly the hypothalamus, pituitary gland and gonad. However, it depends on more than the communication between anatomical structures because it is also affected by genotype, internal factors (e.g., metabolic inputs) and external factors (e.g., photoperiod, socio-sexual cues, stress, nutrition). This multifactorial complexity makes it difficult to use animal experimentation to investigate the pathways and mechanisms involved. Therefore, in this study, I have turned to mathematical modelling. The general hypothesis was that, by modelling the hormonal feedback loop that links the hypothalamus, pituitary gland and gonad, I would be able to discover the critical control points in this homeostatic system. This would allow me to inform and direct research into the processes that control reproduction, including inputs from environmental factors. My studies began with the development of a model of the negative feedback loop through which testosterone controls the secretion of pulses of gonadotrophin-releasing hormone (GnRH) by the hypothalamus. The model incorporated two critical factors: testosterone concentration and a time delay in the inhibition of the activity of the GnRH 'pulse generator' by testosterone. The general assumptions were: i) there are two positive feedforward processes (GnRH pulses stimulate LH pulses, and, in turn, LH pulses stimulate testosterone secretion); ii) testosterone exerts negative feedback that reduces the frequency of GnRH pulses. The model incorporated a group of equations that represent the GnRH pulse generator, through which the inhibitory effect of testosterone acted to reduce GnRH pulse frequency. Simulations were run with various values for the time delay in feedback and, as model development progressed, the simulations were extended to include combinations of time delays and levels of sensitivity of the GnRH pulse generator to inhibition by testosterone. The output of the simulations showed clearly that a time delay in negative feedback, as well as the concentration of testosterone, can greatly affect the frequency of GnRH pulses and the shape of the GnRH secretory profile. Importantly, the effect of the time delay depends on the sensitivity of the pulse generator to testosterone. In addition, the simulations suggested two additional components that might be involved in the control of the GnRH pulse generator: i) a delay in the rate of adaptation to a change in steroid feedback; and ii) a minimum pulse interval (maximum frequency). These studies iii therefore suggest that the regulation of the activity of the GnRH pulse generator, and thus the frequency and profile of GnRH and LH pulses, requires interactions among these four components. These interactions should be tested in animal experimentation. In the next stage, I extended the model so I could test whether the feedback delay might involve the process of aromatization in which testosterone is converted to oestradiol at brain level. ... This information can be used to direct future experimental studies that will help us to understand the factors that underlie the dynamic behaviour of the hypothalamic and pituitary systems that control reproduction.

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Holmberg, Bradford J. "Influence of the vagus nerve and urocortin on the nutrition-reproduction axis of the ovine /". free to MU campus, to others for purchase, 2002. http://wwwlib.umi.com/cr/mo/fullcit?p3074407.

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7

Tempest, Louisa-Jayne. "Parasites and the costs of reproduction in Soay sheep". Thesis, University of Stirling, 2005. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.720356.

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8

Hawken, Penelope Alison Rhian. "The role of socio-sexual cues in sheep reproduction". Thesis, University of Newcastle Upon Tyne, 2006. http://hdl.handle.net/10443/1660.

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Exposure of previously isolated anoestrous ewes to a ram induces an almost instantaneous rise in luteinising hormone (LH) pulse frequency. This physiological response, a phenomenon coined 'the ram effect' is commonly sufficient to override the seasonal suppression of the hypothalamic-pituitary axis and induce a synchronous first ovulation. The objective of the first series of experiments in this thesis was to develop a nonpharmacological method of oestrus synchronisation, using socio-sexual cues, for natural mating of mule ewes during the breeding season. Initially two experiments were conducted to investigate the effect of short-term fence line and vasectomised ram exposure repeated every 17 days on three occasions during the transition into the breeding season. Ewes repeatedly exposed to the ram had a significantly compacted mating period compared to ewes maintained in isolation from rams prior to mating. This compaction persisted through to lambing with no significant negative effect on litter size. Artificially inseminated ewes synchronised using the above method of ram synchronisation had higher conception rates than progestagen synchronised ewes. The second objective was to compare the efficacy of different durations and frequencies of ram exposures as methods of oestrus synchronisation. Ewes maintained continuously with rams over the pre-mating period had a more compacted mating and lambing period than ewes exposed intermittently to rams. Maiden ewes typically show a poorer level of reproductive competence than adult ewes. Similarly maiden ewes induced to ovulate using the ram effect have been found to have a lower ovulatory response. The next objective of this thesis was to determine if pre-exposure to the ram during anoestrus or the breeding season would modulate the hormonal and behavioural responses of maiden ewes when re-introduced to rams during the breeding season or anoestrus. There was no major effect of prior experience of the ram on any parameters of the LH response to ram introduction. However ewes with prior ram experience did have more positive interactions with the rams and demonstrated more ram seeking behaviour. Incorporation of socio-sexual cues with artificial methods of reproductive control has to date been restricted to ram exposure post progestagen sponge withdrawal. Therefore the final objective of this thesis was to investigate the effect of ram exposure towards the end of a progestagen synchronisation protocol on ewe fertility. There was no significant difference in conception rates between ram exposed and control ewes, however ram exposed ewes had a significant depression in mean litter size due to a greater number of ewes having single lambs. The studies in this thesis show a robust and repeatable endocrine response to ram introduction in mule ewes exposed to the ram during the transition between anoestrus and the breeding season. The potency of the socio-sexual cues from the ram permits modification of the distribution of oestrus within randomly cycling ewes. The findings in this thesis highlight the potential for application and development of pre-mating strategies using socio-sexual cues within seasonal breeds of sheep.

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Bancroft, David. "Genetic variation and fitness in Soay sheep". Thesis, University of Cambridge, 1993. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.338112.

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Fray, Martin Dennerley. "Gonadotrophin release in post parturient cattle and sheep". Thesis, University of Nottingham, 1992. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.314751.

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Più fonti

Libri sul tema "Sheep Reproduction"

1

Gordon, Ian R. Controlled reproduction in sheep and goats. Wallingford, Oxon, UK: CAB International, 1997.

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2

Clariget, Raquel Perez. Studies on seasonal variation in testicular function in Corriedale rams with special emphasis on nutritional effects. Uppsala: Sveriges Lantbruksuniversitet, 1998.

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3

Kelly, John P. Factors affecting superovulation in cattle and sheep. Dublin: University College Dublin, 1995.

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4

Knights, Marlon. Reproductive management in the ewe flock by induction or synchronization of estrus. Morgantown, WV: West Virginia University, Davis College of Agricultural, Forestry and Consumer Sciences, WV Agriculture and Forestry Experiment Station, 2004.

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Lawson, Laura. Managing your ewe and her newborn lambs. Culpeper, Va: LDF Publications, 1993.

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O'Neill, Daniel J. Studies related to the cryopreservation of ram spermatozoa. Dublin: University College Dublin, 1998.

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Carlsson, Ulla. Pestivirus infections in pregnant sheep and cattle: Studies on epidemiology, reproduction, and prospects for control. Uppsala: Sveriges Lantbruksuniversitet, 1994.

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8

Byrne, William. An evaluation of nutritional strategies and sire breed for mid-season lamb production. Dublin: University College Dublin, 1999.

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9

Roldán, Jorge Cassinello. El arrui sahariano: Un caprino ancestral en Almería. [Almería]: Instituto de Estudios Almerienses, Diputación de Almería, 1998.

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Byrne, Garret P. Effects of freezing rate of ram semen on subsequent fertility in vivo and in vitro. Dublin: University College Dublin, 1998.

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Capitoli di libri sul tema "Sheep Reproduction"

1

Jainudeen, M. R., H. Wahid e E. S. E. Hafez. "Sheep and Goats". In Reproduction in Farm Animals, 172–81. Baltimore, Maryland, USA: Lippincott Williams & Wilkins, 2016. http://dx.doi.org/10.1002/9781119265306.ch12.

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Kumar, Davendra, Kalyan De, Veerasamy Sejian e S. M. K. Naqvi. "Impact of Climate Change on Sheep Reproduction". In Sheep Production Adapting to Climate Change, 71–93. Singapore: Springer Singapore, 2017. http://dx.doi.org/10.1007/978-981-10-4714-5_3.

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3

Loi, Pasqualino, e Grazyna Ptak. "Gene Expression/Phenotypic Abnormalities in Placental Tissues of Sheep Clones: Insurmountable Block in Cloning Progress?" In Epigenetics and Human Reproduction, 85–96. Berlin, Heidelberg: Springer Berlin Heidelberg, 2010. http://dx.doi.org/10.1007/978-3-642-14773-9_4.

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4

Dufourny, Laurence, e Isabelle Franceschini. "Plasticity of Neuroendocrine Mechanisms Regulating Seasonal Reproduction in Sheep". In Neuroendocrine Clocks and Calendars, 103–18. Cham: Springer International Publishing, 2020. http://dx.doi.org/10.1007/978-3-030-55643-3_5.

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Robertson, Susan, e Michael Friend. "Strategies to Ameliorate Heat Stress Effects on Sheep Reproduction". In Climate Change and Livestock Production: Recent Advances and Future Perspectives, 175–83. Singapore: Springer Singapore, 2021. http://dx.doi.org/10.1007/978-981-16-9836-1_15.

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Dattena, M., I. Mayorga, L. Mara, M. Gallus, G. Meloni, A. Cabiddu e S. Salaris. "An example of reproduction management in organic sheep farming". In Animal farming and environmental interactions in the Mediterranean region, 223–27. Wageningen: Wageningen Academic Publishers, 2012. http://dx.doi.org/10.3920/978-90-8686-741-7_27.

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Sheldrick, E. L., e A. P. F. Flint. "Secretion of Oxytocin by the Corpus Luteum and its Role in Luteolysis in the Sheep". In Endocrinology and Physiology of Reproduction, 211–19. Boston, MA: Springer US, 1987. http://dx.doi.org/10.1007/978-1-4899-1971-7_17.

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Russel, A. J. F. "The Application of Real-Time Ultrasonic Scanning in Commercial Sheep, Goats and Cattle Production Enterprises". In Diagnostic Ultrasound and Animal Reproduction, 73–87. Dordrecht: Springer Netherlands, 1989. http://dx.doi.org/10.1007/978-94-017-1249-1_7.

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Viñoles-Gil, Carolina, Antonio Gonzalez-Bulnes, Graeme B. Martin, Francisco Sales Zlatar e Sebastiano Sale. "Sheep and Goats". In Practical Atlas of Ruminant and Camelid Reproductive Ultrasonography, 181–210. Ames, Iowa, USA: John Wiley & Sons, 2016. http://dx.doi.org/10.1002/9781119265818.ch11.

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Dunlap, Kathrin A. "Sheep". In Encyclopedia of Reproduction, 656–66. Elsevier, 2018. http://dx.doi.org/10.1016/b978-0-12-809633-8.20523-2.

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Atti di convegni sul tema "Sheep Reproduction"

1

Lobachova, I. V., e S. L. Drozd. "The influence of taking into account the ewes age to the sheep flocks reproduction indicators calculating". In Current problems of modern animal husbandry. �� "��-��" - �� -�� , 2021. http://dx.doi.org/10.33694/978-966-1550-33-8-2021-0-0-91-93.

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Lawson, Peter J., Bihe Hu, Brittany T. Fasy, Carola Wenk e J. Quincy Brown. "Quantifying prostate cancer morphology in 3D using light sheet microscopy and persistent homology (Conference Presentation)". In Diseases in the Breast and Reproductive System IV, a cura di Melissa C. Skala e Paul J. Campagnola. SPIE, 2018. http://dx.doi.org/10.1117/12.2290994.

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Devia, P., Carlos A. Alvarez M, N. Alejandro, L. Hurtado e A. Jairo. "Reproduction of the music contained in a music sheet using MATLAB®". In 2015 20th Symposium on Signal Processing, Images and Computer Vision (STSIVA). IEEE, 2015. http://dx.doi.org/10.1109/stsiva.2015.7330404.

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4

Ali Tribaldos, Jicmat, e Chiradeep Sen. "Evolutionary Grasp Planning for Sheet Metal Parts With Multi-Type Grippers". In ASME 2021 International Design Engineering Technical Conferences and Computers and Information in Engineering Conference. American Society of Mechanical Engineers, 2021. http://dx.doi.org/10.1115/detc2021-71632.

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Abstract Grasping sheet metal objects for manufacturing operations requires custom-made robot-mounted end-effectors to grip the parts. Modern end-effectors use multi-type grasp where a combination of gripper types such as suction cups, magnets, and fingers may be used. This paper presents a genetic algorithm-based approach of grasp design automation. The algorithm first generates an option space of possible grasping locations by analyzing the geometry of the sheet metal part and then uses a genetic algorithm to optimize the grasp using up to five magnets and suction cups. The algorithm includes as fitness criteria the factor of safety of the total gripping force against part weight, the unbalanced moment created by the gripping forces and part weight, the cost of the grasp, and three combinations of these parameters. The GA features asexual reproduction, mutation, and elitism. The algorithm is implemented in the Siemens NX™ Knowledge Fusion language and on Microsoft VBA code. The paper presents detailed test results and sensitivity analyses that indicate that genetic algorithms can produce viable solutions for multi-type grasp configurations and that the algorithm behaves in response to varying its control parameters in ways that are logically anticipated.

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5

Pukhova, Ekaterina, e Vladislav Vereshchagin. "Compensation of defects in printing process with histogram methods". In 10th International Symposium on Graphic Engineering and Design. University of Novi Sad, Faculty of technical sciences, Department of graphic engineering and design,, 2020. http://dx.doi.org/10.24867/grid-2020-p41.

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Abstract (sommario):

A method of image preparation for printing reproduction is suggested. This method allows to automatically compensate transformations that occur during reproduction, by analyzing a histogram of test chart image and based on it, creating a compensation pre-correction function. It also takes into consideration the visual perception of images. Pre-correction function is applied to images at the prepress stage after all other corrections. It is aimed to compensate defects, occurring at the printing stage, caused by the process of tone value increase and restriction of tonal range reproduction. It is suggested to use a test chart, which is a gradient with an even increase of lightness in the range from 0 to 255. After printing the test chart its digital image is created by scanning. Then Gaussian filter is applied to the image with parameters according to the visual perception, and lightness distribution histogram is calculated. This histogram will have changes in lightness distribution in comparison with the original digital image. These changes will correspond to the influence of tone value increasing process during printing. The cumulative sum is calculated from the received histogram, and the pre-correction is being formed. And this precorrection applies to an image, prepared for printing in similar conditions as test chart. The algorithm was written on Python and allows to create a pre-correction using a press sheet with the test chart. It is shown that the use of the suggested method gives a positive result and doesn’t require expensive measurement equipment. Having a scanner calibrated for linear transmission of lightness and developed programming module is enough. This method was tested on electrographic printing equipment on three different types of paper. Statistic parameters of a histogram, such as mean, standard deviation and the Skewness, were used for evaluation. It is shown that the suggested method can be used as part of an automatized system based on histogram methods for image preparation before printing.

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Cassilly, Ryan T., Haley A. Bunting, Brian Jin, Christopher S. Ahmad, Louis U. Bigliani, William N. Levine e Thomas R. Gardner. "Failure Properties of the Simian Inferior Glenohumeral Ligament". In ASME 2011 Summer Bioengineering Conference. American Society of Mechanical Engineers, 2011. http://dx.doi.org/10.1115/sbc2011-53520.

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Several animal models of the shoulder are currently in use, including the rat, sheep and goat, as a means to model shoulder pathology[1]. Cynomolgus monkeys have served as nonhuman primate models in several studies including monkey models of menopause [2], reproductive support structures [3] and the knee joint[4]. Anatomical comparisons of simian and human shoulders have demonstrated that the simian shoulder is similar to that of the human in both musculature and bony structures[5]. A preliminary study concluded that there exists a high degree of similarity between the simian and human glenohumeral joint (GHJ)[6]. Biomechanical studies have been performed on the human IGHL to determine its tensile properties [7] yet there are few comparative studies of the biomechanical properties of the simian and human GHJ. The objective of this study was to determine the geometric and tensile properties of the simian IGHL as compared to those of the human IGHL.

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Tabata, Soichiro, Yasuhiro Sasao e Kiyoshi Segawa. "Experimental and Numerical Investigations of the Effects of Real Shape Modeling and Non-Equilibrium Condensation Modeling on the Flow Pattern in Steam Turbine". In ASME Turbo Expo 2021: Turbomachinery Technical Conference and Exposition. American Society of Mechanical Engineers, 2021. http://dx.doi.org/10.1115/gt2021-01754.

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Abstract This study presents the results of measurements in a scaled model turbine test rig operated at Mitsubishi Hitachi Power Systems, Ltd. In this paper, the flow pattern obtained by traverse measurements is compared with the results of CFD. In order to investigate the flow field in the low pressure steam turbine, the tests are carried out using a test turbine (4 stages) of × 0.33 scale. The velocity and pressure fields are evaluated by traverse measurements. The corresponding CFD are performed by ANSYS CFX. Generally, shroud and stub are used in last stage rotating blades of industrial steam turbine to provide high structural stability by increasing stiffness and damping. In this study, the shroud and stub are modeled in CFD to evaluate the effect on flow pattern. Besides, in order to evaluate the effects of super cooling in blade rows, non-equilibrium condensation is modeled in CFD by ANSYS CFX. The computation model is constructed as accurate reproduction of the scaled model test steam turbine including some steam pipes, supporting sheet metal and the measurement equipment such as traverse pipes and instruments. However, the simple computation model which consists of blade rows with cavities (multi stages) and short diffuser is applied for non-equilibrium condensation calculation due to convergence problems. Comparative evaluation of the test results with the corresponding CFD results showed that the flow patterns predicted by CFD are good. In order to capture the flow pattern characteristics by CFD, it is necessary to consider both real shape modeling and non-equilibrium condensation modeling.

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Lutfiasari, Dessy, e Galuh Pradian Yanuaringsih. "The Effect of Soybean-Palm Date Milk Consumption on Hemoglobin Level among Adolescent". In The 7th International Conference on Public Health 2020. Masters Program in Public Health, Universitas Sebelas Maret, 2020. http://dx.doi.org/10.26911/the7thicph.05.61.

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Background: Anemia is a problem that affects reproductive health among adolescent. High incidence of anemia among adolescents still needs an attention. One of which is the consumption of foods containing iron (Fe). The purpose of this study was to examine the effect of soybean-date palm (kurma) milk consumption on hemoglobin (Hb) levels among adolescent girls. Subjects and Method: A quasi experiment was conducted at the Al Ma’ruf Islamic Boarding School in Kediri, East Java, from March to July 2020. The samples obtained were 28 people who had Hb below 12 g% and were not menstruating. The sample was divided into 4 treatment groups i.e. A group (100 g soybean and 100 g date palm), B group (100 g soybean and 50 gr date palm), C group (100 g soybean and 60 g date palm), D group (50 g soybean and 60 gr date palm). The dependent variable was hemoglobin level. The independent variable was the consumption of soy- date palm milk. Data of hemoglobin levels were taken before and after the consumption of soybean- date palm milk with a ratio data scale. The other data were collected using observational sheet. The data were analyzed using t-test. Results: Hemoglobin levels was increased from 10.24 to 12.03 (p= 0.021) in A group, and it was statistically significant. While groups B, C, and D had no effect on the consumption of soybean-date palm milk on hemoglobin levels among adolescent girls. Conclusion: Soybean-date palm milk consumption with ratio of 1:1 increasing hemoglobin level among adolescent girls. Keywords: hemoglobin levels, soybean, date palm, adolescent girl Correspondence: Dessy Lutfiasari. Kadiri University, East Java, Indonesia. Email: dessylutfiasari@unik-kediri.ac.id. Mobile: +62 813-3622-9675 DOI: https://doi.org/10.26911/the7thicph.05.61

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Rapporti di organizzazioni sul tema "Sheep Reproduction"

1

Bazer, Fuller W., Arieh Gertler e Elisha Gootwine. Role of Placental Lactogen in Sheep. United States Department of Agriculture, gennaio 2001. http://dx.doi.org/10.32747/2001.7574339.bard.

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Abstract (sommario):

Central problems in sheep and dairy cattle production are reproductive failure due to embryonic/fetal mortality and low birth weights, especially in prolific breeds, and reduced milk yields which adversely affect neonatal survival and economy of production. The sheep placenta expresses lactogenic (ovine placental lactogen, oPL) and somatogenic (ovine placental growth hormone, oGH) hormones. Our research has focused on the biological roles of oPL and oGH in function of the uterine endometrium during gestation and the mammary gland during pregnancy and lactation. Major conclusions were that: ( 1 ) immunization of prepubertal ewes against oPL resulted in increased birth weights of their lambs and their milk production during lactation; (2) neither oPL nor oGH had an antiluteolytic effect on uterine endometrium to affect lifespan of the corpus luteum; (3) only sequential exposure of the progesterone stimulated uterus to oIFNt and oPL or oGH increased endometrial gland proliferation and secretory protein gene expression; (4) oPL signals through a homodimer of ovine prolactin receptor (PRL-R) and heterodimer of oPRL-R and growth hormone receptor (GH-R); (5) exogenous recombinant oPL and oGH stimulated mammogenesis and milk yield during lactation; and (6) mutation of oPL and oGH was used to define specific biological effects and a rational basis for design of a specific receptor agonists or antagonists. This project was very productive in elucidating basic biological effects of oPL and oGH on intracellular signal transduction pathways, uterine development and secretory function, as well as mammogenesis and lactogenesis. We determined that immunization of prepubertal ewes against roPL increased birth weights of their lambs, especially those born as twins and triplets, as well as enhanced lactational performance. These studies significantly extended our knowledge of uterine and fetal-placental physiology and provided a foundation for new strategies to enhance reproductive and lactation efficiency. Based on these results, the major achievements were: 1) creation of a practical and cost effective management tool for producers to increase reproductive performance, neonatal survival, and milk yield of ewes in commercial flocks; and 2) define, for the first time, biological effects of oPL on endometrial functions and gene expression by uterine gland epithelium.

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Spencer, Thomas E., Elisha Gootwine, Arieh Gertler e Fuller W. Bazer. Placental lactogen enhances production efficiency in sheep. United States Department of Agriculture, dicembre 2005. http://dx.doi.org/10.32747/2005.7586543.bard.

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Abstract (sommario):

The key objectives of this BARD project were to: (1) study long-term effects of immunization of prepubertal ewes against recombinant ovine placental lactogen (roPL) on subsequent birth weights of their lambs and their milk production; (2) optimize the anti-roPL immunization protocol using adjuvant preparations acceptable to producers and regulatory agencies; and (3) determine the physiological mechanism(s) whereby immunization against oPL increases fetal growth and development and mammogenesis. These objectives were based on key findings from a previous BARD project that: (a) immunization of ewes against roPL increased lamb birth weight and ewe milk production during lactation; (b) roPL and recombinant ovine growth hormone (roGH) increased the proliferation and differentiated function of endometrial glands that, in turn, would enhance uterine secretions necessary for fetal and placental growth; and (c) exogenous roPL and roGH stimulated mammogenesis and milk production during lactation. The BARD projects address central problems in sheep production, including reproductive failure due to embryonic/fetal mortality, low birth weight of lambs especially in prolific breeds, and reduced milk yields which affect neonatal survival. The sheep placenta secretes both lactogenic (oPL) and somatogenic (oGH) hormones. The receptors for those hormones are present in the fetus and placenta as well as maternal uterus, and mammary gland. Our research has focused on determining the biological role of these placental hormones in development and differentiation of the uterus during gestation and the mammary gland during pregnancy and lactation. Studies conducted in the current BARD project indicated that the effects of anti-roPL immunization were variable in ewes and that commercially available and widely acceptable adjuvant preparations were not effective to produce high anti-roPL titers in pre-pubertal ewes. In the non-prolific Rambouillet ewe in Texas and in the Awassi and the Assaf in Israel, anti-roPL immunization increased lamb birth weight; however, the magnitude of this effect and the inherent variability precluded our ability to determine the physiological mechanism of how the immunization increases fetal growth. Collectively, our findings suggest that anti-roPL immunization is not currently feasible as an easy and efficacious tool for the producer to increase flock reproductive and production efficiency. The variability in response of individual ewes to anti-roPL immunization likely includes modifying the recombinant hormone and the type of adjuvant used for the immunization. In particular, the oPL may need to be modified to ensure maximum antigenicity in a broad range of breed types. Nonetheless, the investigators continue to collaborate on identifying fundamental mechanisms that can be improved by genetics or management to enhance the efficiency of uteroplacental function and, in turn, fetal growth and development. High prolificacy is a desirable trait in intensive sheep production systems. One of the main limitations of using prolific breeds of sheep is that increased litter size is associated with low birth weights and increased mortality of lambs. Further, low birth weight is associated with an increased propensity for adult diseases and decreased production efficiency. Indeed, our recent studies find that the birth weights of lambs born in large litters can be improved by both genetics and management. Future cooperative research will continue to focus on reproductive efficiency of sheep that have broader implications for improving production efficiency in all types of ruminant livestock.

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Brosh, Arieh, David Robertshaw, Yoav Aharoni, Zvi Holzer, Mario Gutman e Amichai Arieli. Estimation of Energy Expenditure of Free Living and Growing Domesticated Ruminants by Heart Rate Measurement. United States Department of Agriculture, aprile 2002. http://dx.doi.org/10.32747/2002.7580685.bard.

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Abstract (sommario):

Research objectives were: 1) To study the effect of diet energy density, level of exercise, thermal conditions and reproductive state on cardiovascular function as it relates to oxygen (O2) mobilization. 2) To validate the use of heart rate (HR) to predict energy expenditure (EE) of ruminants, by measuring and calculating the energy balance components at different productive and reproductive states. 3) To validate the use of HR to identify changes in the metabolizable energy (ME) and ME intake (MEI) of grazing ruminants. Background: The development of an effective method for the measurement of EE is essential for understanding the management of both grazing and confined feedlot animals. The use of HR as a method of estimating EE in free-ranging large ruminants has been limited by the availability of suitable field monitoring equipment and by the absence of empirical understanding of the relationship between cardiac function and metabolic rate. Recent developments in microelectronics provide a good opportunity to use small HR devices to monitor free-range animals. The estimation of O2 uptake (VO2) of animals from their HR has to be based upon a consistent relationship between HR and VO2. The question as to whether, or to what extent, feeding level, environmental conditions and reproductive state affect such a relationship is still unanswered. Studies on the basic physiology of O2 mobilization (in USA) and field and feedlot-based investigations (in Israel) covered a , variety of conditions in order to investigate the possibilities of using HR to estimate EE. In USA the physiological studies conducted using animals with implanted flow probes, show that: I) although stroke volume decreases during intense exercise, VO2 per one heart beat per kgBW0.75 (O2 Pulse, O2P) actually increases and measurement of EE by HR and constant O2P may underestimate VO2unless the slope of the regression relating to heart rate and VO2 is also determined, 2) alterations in VO2 associated with the level of feeding and the effects of feeding itself have no effect on O2P, 3) both pregnancy and lactation may increase blood volume, especially lactation; but they have no effect on O2P, 4) ambient temperature in the range of 15 to 25°C in the resting animal has no effect on O2P, and 5) severe heat stress, induced by exercise, elevates body temperature to a sufficient extent that 14% of cardiac output may be required to dissipate the heat generated by exercise rather than for O2 transport. However, this is an unusual situation and its affect on EE estimation in a freely grazing animal, especially when heart rate is monitored over several days, is minor. In Israel three experiments were carried out in the hot summer to define changes in O2P attributable to changes in the time of day or In the heat load. The animals used were lambs and young calves in the growing phase and highly yielding dairy cows. In the growing animals the time of day, or the heat load, affected HR and VO2, but had no effect on O2P. On the other hand, the O2P measured in lactating cows was affected by the heat load; this is similar to the finding in the USA study of sheep. Energy balance trials were conducted to compare MEI recovery by the retained energy (RE) and by EE as measured by HR and O2P. The trial hypothesis was that if HR reliably estimated EE, the MEI proportion to (EE+RE) would not be significantly different from 1.0. Beef cows along a year of their reproductive cycle and growing lambs were used. The MEI recoveries of both trials were not significantly different from 1.0, 1.062+0.026 and 0.957+0.024 respectively. The cows' reproductive state did not affect the O2P, which is similar to the finding in the USA study. Pasture ME content and animal variables such as HR, VO2, O2P and EE of cows on grazing and in confinement were measured throughout three years under twenty-nine combinations of herbage quality and cows' reproductive state. In twelve grazing states, individual faecal output (FO) was measured and MEI was calculated. Regression analyses of the EE and RE dependent on MEI were highly significant (P<0.001). The predicted values of EE at zero intake (78 kcal/kgBW0.75), were similar to those estimated by NRC (1984). The EE at maintenance condition of the grazing cows (EE=MEI, 125 kcal/kgBW0.75) which are in the range of 96.1 to 125.5 as presented by NRC (1996 pp 6-7) for beef cows. Average daily HR and EE were significantly increased by lactation, P<0.001 and P<0.02 respectively. Grazing ME significantly increased HR and EE, P<0.001 and P<0.00l respectively. In contradiction to the finding in confined ewes and cows, the O2P of the grazing cows was significantly affected by the combined treatments (P<0.00l ); this effect was significantly related to the diet ME (P<0.00l ) and consequently to the MEI (P<0.03). Grazing significantly increased O2P compared to confinement. So, when EE of grazing animals during a certain season of the year is estimated using the HR method, the O2P must be re measured whenever grazing ME changes. A high correlation (R2>0.96) of group average EE and of HR dependency on MEI was also found in confined cows, which were fed six different diets and in growing lambs on three diets. In conclusion, the studies conducted in USA and in Israel investigated in depth the physiological mechanisms of cardiovascular and O2 mobilization, and went on to investigate a wide variety of ruminant species, ages, reproductive states, diets ME, time of intake and time of day, and compared these variables under grazing and confinement conditions. From these combined studies we can conclude that EE can be determined from HR measurements during several days, multiplied by O2P measured over a short period of time (10-15 min). The study showed that RE could be determined during the growing phase without slaughtering. In the near future the development microelectronic devices will enable wide use of the HR method to determine EE and energy balance. It will open new scopes of physiological and agricultural research with minimizes strain on animals. The method also has a high potential as a tool for herd management.

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4

Egypt: Encourage journalists to cover reproductive health. Population Council, 2000. http://dx.doi.org/10.31899/rh2000.1029.

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Abstract (sommario):

To raise public awareness of reproductive health (RH) issues, the Population Council’s Frontiers project and the Futures Group’s Policy project jointly organized four press briefings and provided background materials to key journalists from Arabic newspapers and magazines. From May 1999 to June 2000, project staff worked closely with 20 Egyptian journalists, including editors of women’s pages and senior editors. The press briefings covered youth, marriage patterns, contraceptive technology, and menopause. The press kit prepared for each briefing contained fact sheets, reference materials, a contact list of key experts, and an evaluation sheet. To assess RH reporting and track coverage resulting from the intervention, project staff monitored eight major Arabic newspapers and nine magazines daily. All articles on RH were coded according to their topic, length, and use of research findings. As noted in this brief, after Egyptian print journalists attended briefings on RH issues, their reporting of these issues improved. Health agencies can improve coverage of RH issues by providing a regular flow of accurate information to a broad range of journalists.

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