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Bruno-Galarraga MM, Fernandez J, Lacau-Mengido IM, Gonzalez-Bulnes A, Gibbons A, Cueto M. A simple method to select high superovulatory responder goats. Theriogenology 2023; 195:187-191. [DOI: 10.1016/j.theriogenology.2022.10.032] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2022] [Revised: 10/24/2022] [Accepted: 10/25/2022] [Indexed: 11/06/2022]
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2
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Comparison of superovulatory responses to a standardized hormonal superstimulation protocol among three indigenous breeds of sheep in Brazil. Small Rumin Res 2022. [DOI: 10.1016/j.smallrumres.2022.106703] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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3
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Lagares MDA, Varago FC, Moustacas VS, Gheller VA, Nicolino RR, Borges I, Henry M. Effect of season and frequency of embryo collections on superovulatory response and embryo recovery in Santa Inês hair sheep. Small Rumin Res 2021. [DOI: 10.1016/j.smallrumres.2021.106441] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
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4
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Pinto PHN, Balaro MFA, Saraiva HFRDA, Brair VL, Alfradique VAP, Côrtes LR, Cosentino IO, Souza-Fabjan JMG, Fonseca JFD, Brandão FZ. Successive in vivo embryo production in Santa Inês sheep. ANIMAL PRODUCTION SCIENCE 2020. [DOI: 10.1071/an18740] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
Context
In vivo embryo production, also called multiple ovulation and embryo transfer, can accelerate genetic gain, and thus improve animal production. However, there are issues limiting a wider use of this biotechnology in sheep livestock.
Aims
This study aimed to determine (1) whether a previous response to superovulation (SOV) can be used as a criterion to select ewes for in vivo embryo production, (2) whether the intensity of the SOV response (number of corpora lutea, CL) can affect the embryo recovery rate, and (3) whether the number of CL quantified by colour Doppler ultrasonography can be used to calculate the recovery rate.
Methods
Twenty-five Santa Inês ewes underwent SOV three times (SOV1, SOV2 and SOV3), with 200 mg FSH and natural mating. The number of CL after each SOV was determined by laparoscopy and by colour Doppler ultrasonography.
Key results
The number of CL significantly decreased (P < 0.05) after SOV1 (7.5 ± 4.8) to 3.0 ± 5.0 at SOV 2 and 2.2 ± 3.5 at SOV3. Strong correlations were observed between SOV2 and SOV3 in terms of numbers of CL (r = 0.86, r2 = 0.74; P < 0.0001) and viable embryos (r = 0.79, r2 = 0.63; P < 00001). However, no correlations were observed between SOV1 and SOV2 or between SOV1 and SOV3. Recovery rate did not differ with the intensity of the SOV response (≤6, 7–10, >10 CL) or between the methods used to quantify CL.
Conclusions
Ewes did not show the same pattern of response when submitted to successive FSH-based SOV. The intensity of the SOV response did not affect the recovery rate, and the number of CL estimated by colour Doppler ultrasonography can be used to calculate the recovery rate.
Implications
Selecting sheep embryo donors by a previous SOV response is not always feasible. The recovery rate is homogeneous and it is not affected by the intensity of the SOV response. A nonsurgical technique can be used to assess the recovery rate, improving animal welfare in MOET programs.
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Fonseca J, Zambrini F, Guimarães J, Silva M, Oliveira M, Bartlewski P, Souza-Fabjan J. Cervical penetration rates and efficiency of non-surgical embryo recovery in estrous-synchronized Santa Inês ewes after administration of estradiol ester (benzoate or cypionate) in combination with d-cloprostenol and oxytocin. Anim Reprod Sci 2019; 203:25-32. [DOI: 10.1016/j.anireprosci.2019.02.004] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2018] [Revised: 01/30/2019] [Accepted: 02/08/2019] [Indexed: 11/15/2022]
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6
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Santos JDR, Arashiro EKN, Balaro MFA, Souza-Fabjan JMG, Pinto PHN, de Souza CV, Leite CR, Fonseca JFD, Brandão FZ. Cervical transposition test using Hegar dilator at oestrus as a tool to select ewes for transcervical embryo collection. Reprod Domest Anim 2018; 54:126-128. [DOI: 10.1111/rda.13306] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2018] [Accepted: 08/02/2018] [Indexed: 11/30/2022]
Affiliation(s)
| | | | | | | | | | | | - Ceci Ribeiro Leite
- Faculdade de Veterinária; Universidade Federal Fluminense (UFF); Niterói Brazil
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Tur İ, Dínç DA, Semacan A. Protein based flushing related blood urea nitrogen effects on ovarian response, embryo recovery and embryo quality in superovulated ewes. Theriogenology 2017; 98:62-67. [PMID: 28601157 DOI: 10.1016/j.theriogenology.2017.05.002] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2016] [Revised: 04/27/2017] [Accepted: 05/02/2017] [Indexed: 12/01/2022]
Abstract
The present study is the first report that evaluates effects of nutritional effects of flushing with differing diet crude protein ratios on blood urea nitrogen (BUN) levels, related some reproductive parameters and embryo quality in ewe. During mating season, before synchronization protocol ewes were fed on alfalfa hay and additive concentrate feeding as flushing. Intra vaginal FGA containing sponges applied for 12 days for the purpose of synchronization and pFSH was administered by 8 declining doses for the purpose of superovulation. Uterus was flushed in the morning of the seventh day of mating and embryos were collected surgically. Collected embryos were qualified according to IETS criterion. There is no dependency found between BUN values measured at different days and at different diet crude protein concentrations. An increase in uterine pH levels due to increasing protein amounts was observed but this increase was not significant among groups. Ovarian function was evaluated by ovarian responses (CL + large follicle) showed difference between groups (p < 0.05) and the lowest protein intake group gave highest ovarian response. In addition, embryo recovery rates revealed difference between groups (p < 0.05) and it was observed that the lowest ovarian response group showed the highest rates of embryo recovery. It is concluded that, in some Anatolian native sheep breeds, the application of diet flushing with different crude protein concentrates influence ovarian responses and embryo recovery rates but has no effect on BUN levels; uterus physiology or embryonic quality.
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Affiliation(s)
- İrfan Tur
- Department of Molecular Biology and Genetics, İzmir Institute of Technology, Gülbahçe Campus, Urla, İzmir, 35430, Turkey.
| | - Dursun Ali Dínç
- Department of Obstetrics and Gynecology, Faculty of Veterinary Medicine, Selçuk University, Alaaddin Keykubat Campus, Selçuklu, Konya, 42003, Turkey.
| | - Ahmet Semacan
- Department of Obstetrics and Gynecology, Faculty of Veterinary Medicine, Selçuk University, Alaaddin Keykubat Campus, Selçuklu, Konya, 42003, Turkey.
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8
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Bruno-Galarraga M, Cueto M, Gibbons A, Pereyra-Bonnet F, Subiabre M, González-Bulnes A. Preselection of high and low ovulatory responders in sheep multiple ovulation and embryo transfer programs. Theriogenology 2015; 84:784-90. [DOI: 10.1016/j.theriogenology.2015.05.011] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2014] [Revised: 05/01/2015] [Accepted: 05/12/2015] [Indexed: 11/30/2022]
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9
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10
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Comparison of different cryoprotectant regimes for vitrification of ovine embryos produced in vivo. Small Rumin Res 2014. [DOI: 10.1016/j.smallrumres.2014.02.013] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
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11
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Follicular Stimulation and Laparoscopic Ovum Pick-up (LOPU) in Repeatedly Superovulated Korean Black Goats. JOURNAL OF ANIMAL REPRODUCTION AND BIOTECHNOLOGY 2014. [DOI: 10.12750/jet.2014.29.1.35] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022] Open
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12
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Chalhoub M, Portela APM, Feitosa LMDC, Araujo EAB, Oliveira SND, Rodrigues AS, Loiola MVG, Andrade BHDA, Ferraz PA, Ribeiro Filho ADL. Resposta superovulatória de caprinos da raça Boer submetidos a produtos com diferentes relações FSH:LH. REVISTA BRASILEIRA DE SAÚDE E PRODUÇÃO ANIMAL 2012. [DOI: 10.1590/s1519-99402012000400025] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Objetivou-se averiguar a eficiência e padrões na resposta superovulatória de caprinos da raça Boer submetidos a produtos com diferentes relações FSH:LH. Foram utilizadas 43 fêmeas caprinas da raça Boer. Em um dia aleatório do ciclo estral, os animais receberam metade de um implante de progesterona (Crestar®). No dia 11, iniciou-se o estímulo à superovulação por meio da utilização do FSH fracionado em seis doses decrescentes administradas a cada 12 horas e os animais foram separados em dois grupos: o grupo I (GI, n=22) recebeu 200mg de FSH (Folltropin®) por via intramuscular (i.m.) nos dias D11 (62,5mg), D12 (35,0mg) e D13 (2,5mg), enquanto o grupo II (GII, n=21) recebeu 300UI de FSH (Pluset®) por via i.m. nos dias D11 (75UI), D12 (50UI) e D13 (25UI). Nas 60 e 72h após o início da superovulação foram retirados os implantes, e aplicaram-se duas doses de 125µg de Cloprostenol (Ciosin®) por via intravulvosubmucosa em todos os animais. Doze, 24 e 36 horas após a remoção dos implantes, as fêmeas foram colocadas com quatro reprodutores para serem cobertas. No D16, os implantes foram reinseridos e, nas 24h antes da coleta dos embriões, retiraram-se os implantes, e administrou-se 125µg de Cloprostenol i.m. a cada animal. Os embriões foram coletados no D21, selecionados e classificados. Os resultados obtidos nesse estudo mostraram que não houve diferença estatística entre os grupos, quanto ao número de estruturas recuperadas, embriões viáveis, embriões degenerados e estruturas não fertilizadas. Portanto, as diferentes relações FSH:LH avaliadas não afetaram a produção e a qualidade de embriões.
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Amiridis GS, Cseh S. Assisted reproductive technologies in the reproductive management of small ruminants. Anim Reprod Sci 2012; 130:152-61. [PMID: 22381207 DOI: 10.1016/j.anireprosci.2012.01.009] [Citation(s) in RCA: 58] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/14/2022]
Abstract
In modern agriculture, assisted reproductive technologies are being used for out of season oestrus induction, enhancement of reproductive performance and genetic improvement. In addition, they can have substantial contribution in preservation of endangered species or breeds, as well as in eradication programs of various diseases. While their applications are widespread in cattle, in small ruminants it is almost restricted to artificial insemination. The main limitations of a wider application in small ruminants are the naturally occurring anoestrus period, the variability of response to superovulatory treatments, the fertilisation failure and the need of surgery for collection and transfer of gametes and embryos. Nonetheless, during the last 30 years, considerable progress has been made in sheep and goat embryo technologies, especially in the fields of oestrus synchronisation, superovulation and in vitro embryo production. This paper reviews the status of assisted reproductive technologies in sheep, analysing the prospects offered by recent advances in in vivo and in vitro embryo production from mature and juvenile lambs.
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Affiliation(s)
- G S Amiridis
- Department of Obstetrics and Reproduction, Veterinary Faculty, University of Thessaly, Karditsa, Greece.
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14
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Quan F, Zhang Z, An Z, Hua S, Zhao X, Zhang Y. Multiple Factors Affecting Superovulation in Poll Dorset in China. Reprod Domest Anim 2011; 46:39-44. [DOI: 10.1111/j.1439-0531.2009.01551.x] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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15
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Toosi B, Seekallu S, Barrett D, Davies K, Duggavathi R, Bagu E, Rawlings N. Characteristics of peaks in serum concentrations of follicle-stimulating hormone and estradiol, and follicular wave dynamics during the interovulatory interval in cyclic ewes. Theriogenology 2010; 73:1192-201. [DOI: 10.1016/j.theriogenology.2009.11.005] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2009] [Revised: 11/03/2009] [Accepted: 11/04/2009] [Indexed: 11/29/2022]
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16
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Menchaca A, Vilariño M, Pinczak A, Kmaid S, Saldaña JM. Progesterone treatment, FSH plus eCG, GnRH administration, and Day 0 Protocol for MOET programs in sheep. Theriogenology 2009; 72:477-83. [PMID: 19515409 DOI: 10.1016/j.theriogenology.2009.04.002] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2009] [Revised: 03/28/2009] [Accepted: 04/14/2009] [Indexed: 11/18/2022]
Abstract
The effect of various superstimulatory treatments on the number of corpora lutea, fertilization rate, and embryo yield was studied in sheep. Overall, data from 708 Merino donors and 4262 embryos were analyzed in four experiments. In Experiment 1, varying intervals of progesterone treatment (5 to 14 d) before follicle-stimulating hormone (FSH) administration did not significantly affect the proportion of responding donors, the mean number of corpora lutea, or the mean number of recovered and transferable embryos per donor. In Experiment 2, a single dose of equine chorionic gonadotropin (eCG, 200 or 300 IU) combined with the FSH treatment (i.e., given at CIDR removal) reduced the number and the quality of embryos compared with that for not giving eCG (P<0.05). In Experiment 3, one dose of gonadotropin-releasing hormone (GnRH) given 24h after CIDR removal improved the number of transferable embryos compared with that for not giving GnRH (P<0.05). In Experiment 4, the new superstimulatory Day 0 Protocol, which includes starting FSH treatment at the emergence of Wave 1 (i.e., soon after ovulation, in the absence of a large follicle), improved ovarian response, with a tendency to produce more embryos compared with that for the Traditional Protocol. In summary, this study, analyzing data from various pharmacologic treatments, allows an improvement from four to eight transferable embryos per treated donor in multiple ovulation and embryo transfer programs in sheep.
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Affiliation(s)
- A Menchaca
- Instituto de Reproducción Animal Uruguay, Montevideo, Uruguay.
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Green RE, Santos BFS, Sicherle CC, Landim-Alvarenga FC, Bicudo SD. Viability of OPS Vitrified Sheep Embryos After Direct Transfer. Reprod Domest Anim 2009; 44:406-10. [DOI: 10.1111/j.1439-0531.2008.01088.x] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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18
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Jacob JC, Gastal EL, Gastal MO, Carvalho GR, Beg MA, Ginther OJ. Temporal Relationships and Repeatability of Follicle Diameters and Hormone Concentrations within Individuals in Mares. Reprod Domest Anim 2009; 44:92-9. [DOI: 10.1111/j.1439-0531.2007.01003.x] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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19
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Malhi PS, Adams GP, Mapletoft RJ, Singh J. Superovulatory response in a bovine model of reproductive aging. Anim Reprod Sci 2007; 109:100-9. [PMID: 18374524 DOI: 10.1016/j.anireprosci.2007.12.002] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2006] [Revised: 12/03/2007] [Accepted: 12/13/2007] [Indexed: 11/16/2022]
Abstract
Two experiments were done to test the hypotheses that aging in cattle is associated with a reduced number of follicles recruited into an ovarian follicular wave, and a reduction in the ovarian response to gonadotropin treatment. Older cows (13-16 years of age) and their daughters (3-6 years of age) were treated with FSH for ovarian superstimulation four times over two consecutive years (31 and 33 superstimulations in old and young cows, respectively, experiments and years combined). In Experiment 1, ovulation was induced using LH. In Experiment 2, cumulus-oocyte complexes were collected by ultrasonographic-guided follicle aspirations before expected ovulations. The ovarian follicular and ovulatory responses were monitored daily by ultrasonography. Fewer 2-5mm follicles (P<0.01) were detected at the expected time of follicular wave emergence in older cows than in their daughters. After superstimulation, older cows had fewer follicles >or=6mm (P<0.01), and tended (P=0.1) to have fewer ovulations than their daughters (32+/-4 versus 40+/-3, respectively). There was a positive correlation in the response of individual cows to successive superstimulatory treatments (r>0.8; P<0.0001) and the number of detected ovulations from one year to the next (r=0.6; P=0.04). In conclusion, aging was associated with fewer 2-5mm follicles at follicular wave emergence and a lesser follicular and ovulatory response after superstimulatory treatment. The follicular and ovulatory response after superstimulation was repeatable within individuals, regardless of age.
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Affiliation(s)
- Pritpal S Malhi
- Department of Veterinary Biomedical Sciences, Western College of Veterinary Medicine, University of Saskatchewan, Saskatoon, Canada
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20
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Ehling C, Wirth P, Schindler L, Hadeler KG, Döpke HH, Lemme E, Herrmann D, Niemann H. Laparoscopical intrauterine insemination with different doses of fresh, conserved, and frozen semen for the production of ovine zygotes. Theriogenology 2003; 60:777-87. [PMID: 12832025 DOI: 10.1016/s0093-691x(03)00049-9] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The objective of the present study was to increase the efficiency in the production of ovine zygotes suitable for microinjection via laparoscopical intrauterine insemination. In the first part of the study, 71 ewes of three different breeds were inseminated with one of two different insemination doses (50 x 10(6) or 300 x 10(6) sperm per inseminate) and semen was either freshly diluted, liquid conserved, or frozen/thawed, or females were mated by a fertile ram (controls). In the second part, a total of 46 ewes was inseminated with 300 x 10(6) freshly diluted sperm to verify the findings from part 1 and to unravel effects of breed and age of donor ewe. The oviducts were flushed 24-26 h after insemination and the success of insemination was assessed by microscopical examination. Recovery rates were 78.0+/-26.4 and 72.1+/-24.6% in parts 1 and 2 of the study, respectively. Of these oocytes 62.3 and 62.8% (parts 1 and 2, respectively) were fertilized. In part 1, the highest proportion (64.7%) of pronuclear stages was observed in the group inseminated with 300 x 10(6) freshly diluted semen and was significantly higher compared to the groups inseminated with 50 x 10(6) freshly diluted semen (25.5%, P<0.001), 300 x 10(6) liquid conserved semen (49.0%, P<0.001), or 50 x 10(6) frozen/thawed semen (39.6%, P<0.05). In the control group, the proportion of pronuclear stages amounted to 60.2%. Irrespective of the type of sperm conservation, the overall fertilization rate (zygotes plus 2-cell stages) was higher (P<0.05) following insemination with 300 x 10(6) sperm (68.2%) compared to 50 x 10(6) sperm (56.8%). In part 2, the proportion of pronuclear stages reached 54.2% with an overall fertilization rate of 62.9%. These results were affected by breed and age of the donor as crossbred and younger (<3 years) animals yielded the highest proportion of pronuclear stages. The present study shows that freshly diluted semen at a dosage of 300 x 10(6) sperm yields the highest fertilization rates, the greatest proportion of pronuclear stages and the lowest proportion of mature unfertilized oocytes. Further increases in yields of pronuclear stages can possibly be achieved by selection of sheep from the best suited breed and younger than 3 years of age.
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Affiliation(s)
- Christine Ehling
- Department of Biotechnology, Institute for Animal Science, Mariensee, Hoeltystr. 10, Neustadt 31535, Germany
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Ptak G, Tischner M, Bernabo N, Loi P. Donor-dependent developmental competence of oocytes from lambs subjected to repeated hormonal stimulation. Biol Reprod 2003; 69:278-85. [PMID: 12606346 DOI: 10.1095/biolreprod.102.011312] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/01/2022] Open
Abstract
An unpredictability of ovarian response still remains the major problem concerning ovine reproductive programs. The influence of several environmental, genetic, and ovarian cycle effects on oocyte/embryo yield from donor females has been previously reported. The present research has been designed to exclude aforementioned causes of variability, thus to verify embryogenic competence in homogenous groups of animals. For this purpose we used prepubertal ewes kept under identical conditions. Initially, we stimulated three groups of prepubertal ewes at various ages and used a number of gonadotropin treatments to assess differences in oocyte competence between individuals. The results revealed the repeatability of response within individual donor lambs throughout the study. Moreover, once the variability in both oocyte and embryo yield between homogenous groups of donors was revealed alongside the influence of age and type of gonadotropin treatment (P < 0.001), we investigated whether the individual donor effect persisted among genetically similar animals. Therefore, we compared oocyte and subsequent embryo output of sibling lambs derived from the most efficient donor. Here the genetic homogeneity of sisters kept under identical conditions substantially improved the uniformity of either follicular response or embryo production, suggesting that the genotype plays a primary role in establishing follicular recruitment and developmental capability of oocytes. This observation consents to predict the ovarian performance from a single ewe already in early prepuberty (i.e., to qualify the female to breeding programs).
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Affiliation(s)
- Grazyna Ptak
- Dipartimento di Scienze Biomediche Comparate, Università di Teramo, 64100 Teramo, Italy.
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Abstract
This review presents an overview of the technical bases of in vivo and in vitro embryo production in sheep and goat. The current limitations of in vivo production, such as variability of response to the hormonal treatment, fertilization failure in females showing a high ovulatory response, and the importance of premature regressed CL in the goat, are described along with possibilities for improvement. The new prospects offered by in vitro embryo production, by repeated ovum pick-up from live females and by juvenile breeding, are presented along with their limiting steps and research priorities. The recent improvements of embryo production and freezing technologies could be used for constitution of flocks without risks of disease transmission and will allow wider propagation of valuable genes in small ruminants populations in the future.
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Affiliation(s)
- Y Cognié
- INRA, Physiologie de la Reproduction et des Comportements, 37380 Nouzilly, France.
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