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Paitoon P, Sartsook A, Thongkham M, Sathanawongs A, Lumsangkul C, Pattanawong W, Hongsibsong S, Sringarm K. Sperm quality variables of sex-sorted bull semen produced by magnetic-activated cell sorting coupled with recombinant antibodies targeting Y-chromosome-bearing sperm. Theriogenology 2024; 219:11-21. [PMID: 38377714 DOI: 10.1016/j.theriogenology.2024.02.016] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2023] [Revised: 02/07/2024] [Accepted: 02/13/2024] [Indexed: 02/22/2024]
Abstract
The immunological sexing method using antibodies offers cost-effective, high-volume production but faces challenges in terms of X-sperm purity in sexed semen. This research aimed to produce sexed bull semen using highly specific recombinant antibodies in magnetic-activated cell sorting (MACS), evaluate sperm quality and kinematic parameters, and verify the sex ratio of sperm, embryos, and live calves. Fresh semen from two Angus bulls was separated into two equal groups: conventional (CONV) semen and semen sexed using MACS with Y-scFv antibody conjugation to separate two fractions, i.e., the X-enriched and Y-enriched fractions. Then, computer assisted semen analysis and imaging flow cytometry were used to evaluate sperm motility and kinematic variables, acrosomal integrity, sperm viability, and sperm sex ratios. The results showed that sperm motility and quality did not differ between X-enriched and CONV semen. However, the Y-enriched fraction showed significantly lower sperm quality than the X-enriched fraction and CONV semen. The sperm ratio revealed that X-sperm accounted for up to 79.50% of the X-enriched fraction, while Y-sperm accounted for up to 78.56% of the Y-enriched fraction. The sex ratio of embryos was examined using in vitro fertilization. The cleavage rates using CONV and X-enriched semen were significantly higher than that using Y-enriched semen. Accordingly, 88.26% female blastocysts were obtained by using X-enriched semen, and 83.58% male blastocysts were obtained by using Y-enriched semen. In farm trials, 304 cows were subjected to AI using X-enriched and CONV semen. The pregnancy rate did not differ between the X-enriched and CONV semen groups. On the other hand, X-enriched semen generated significantly more live female calves (83.64%) than CONV semen (47.00%). The MACS sexing method significantly enhanced the X-sperm purity in sexed semen, producing high-quality sperm, a high percentage of female blastocytes, and a high percentage of live female calves.
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Affiliation(s)
- Phanuwit Paitoon
- Department of Animal and Aquatic Sciences, Faculty of Agriculture, Chiang Mai University, Chiang Mai, 50200, Thailand
| | - Apinya Sartsook
- Department of Animal and Aquatic Sciences, Faculty of Agriculture, Chiang Mai University, Chiang Mai, 50200, Thailand
| | - Marninphan Thongkham
- Department of Animal and Aquatic Sciences, Faculty of Agriculture, Chiang Mai University, Chiang Mai, 50200, Thailand
| | - Anucha Sathanawongs
- Department of Veterinary Biosciences and Veterinary Public Health, Faculty of Veterinary Medicine, Chiang Mai University, Chiang Mai, 50100, Thailand
| | - Chompunut Lumsangkul
- Department of Animal and Aquatic Sciences, Faculty of Agriculture, Chiang Mai University, Chiang Mai, 50200, Thailand
| | - Wiwat Pattanawong
- Faculty of Animal Science and Technology, Maejo University, Chiang Mai, 50290, Thailand
| | - Surat Hongsibsong
- School of Health Sciences Research, Research Institute for Health Sciences, Chiang Mai University, Chiang Mai, 50200, Thailand
| | - Korawan Sringarm
- Department of Animal and Aquatic Sciences, Faculty of Agriculture, Chiang Mai University, Chiang Mai, 50200, Thailand.
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2
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Ngcobo JN, Nedambale TL, Sithole SM, Mtileni B, Mpofu TJ, Ramukhithi FV, Chokoe TC, Nephawe KA. A systematic review on the prospects of X- and Y-sexed semen in ruminant livestock: implications for conservation, a South African perspective. Front Vet Sci 2024; 11:1384768. [PMID: 38655533 PMCID: PMC11037082 DOI: 10.3389/fvets.2024.1384768] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2024] [Accepted: 03/12/2024] [Indexed: 04/26/2024] Open
Abstract
South Africa is home to numerous indigenous and locally developed sheep (Nguni Pedi, Zulu, and Namaqua Afrikaner, Afrino, Africander, Bezuidenhout Africander, Damara, Dorper, Döhne Merino, Meat Master, South African Merino, South African Mutton Merino, Van Rooy, and Dorper), goat (SA veld, Tankwa, Imbuzi, Bantu, Boer, and Savanna) and cattle (Afrigus, Afrikaner, Bolowana, Bonsmara, Bovelder, Drakensberger, South African Angus, South African Dairy Swiss, South African Friesland, South African Red, and Veld Master) animals. These breeds require less veterinary service, feed, management efforts, provide income to rural and or poor owners. However, most of them are under extinction risks and some with unknown status hence, require immediate conservation intervention. To allow faster genetic progress on the endangered animals, it is important to generate productive animals while reducing wastages and this can be achieved through sex-sorted semen. Therefore, this systematic review is aimed to evaluate the prospects of X and Y-sexed semen in ruminant livestock and some solutions that can be used to address poor sex-sorted semen and its fertility. This review was incorporated through gathering and assessing relevant articles and through the data from the DAD-IS database. The keywords that were used to search articles online were pre-gender selection, indigenous ecotypes, fertility, flow cytometry, artificial insemination, conservation, and improving sexed semen. Following a careful review of all articles, PRISMA guidelines were used to find the articles that are suitable to address the aim of this review. Sex-sorted semen is a recently introduced technology gaining more attention from researchers particularly, in the conservation programs. Preselection of semen based on the sex chromosomes (X- and or Y-bearing chromosomes) is of paramount importance to obtain desired sex of the offspring and avoid animal wastage as much as possible. However, diverse factors can affect quality of semen of different animal species especially after sex-sorting. Flow cytometry is a common method used to select male and female sperm cells and discard dead and abnormal sperm cells during the process. Thus, sperm sexing is a good advanced reproductive technology (ART) however, it is associated with the production of oxidative stress (OS) and DNA fragmentation (SDF). These findings, therefore, necessitates more innovation studies to come up with a sexing technology that will protect sperm cell injuries during sorting in frozen-thawed.
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Affiliation(s)
| | | | - Sindisiwe Mbali Sithole
- Germplasm, Conservation, Reproductive Biotechnologies, Agricultural Research Council, Pretoria, South Africa
| | - Bohani Mtileni
- Department of Animal Sciences, Tshwane University of Technology, Pretoria, South Africa
| | - Takalani Judas Mpofu
- Department of Animal Sciences, Tshwane University of Technology, Pretoria, South Africa
| | | | - Tlou Caswel Chokoe
- Department of Agriculture, Land Reform, and Rural Development, Directorate Farm Animal Genetic Resource, Pretoria, South Africa
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Quelhas J, Pinto-Pinho P, Lopes G, Rocha A, Pinto-Leite R, Fardilha M, Colaço B. Sustainable animal production: exploring the benefits of sperm sexing technologies in addressing critical industry challenges. Front Vet Sci 2023; 10. [PMID: 38076548 PMCID: PMC10704908 DOI: 10.3389/fvets.2023.1181659] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/10/2024] Open
Abstract
The sex of the animals is of paramount importance in many animal production systems. This is particularly evident in the production of milk or in breeding programs focused on the production of female animals. In some cases, slaughter or euthanasia of animals of the unwanted sex becomes the only solution, highlighting ethical and economic concerns. As global demand for food continues to rise, the importance of addressing these issues becomes more evident. Reproductive technologies, such as sperm sexing techniques, may hold the key to addressing both animal welfare and the sustainability of animal production. The use of semen enriched with sperm capable of producing offspring of the desired sex can serve as a valuable tool for producers to exert greater control over production outcomes, not only helping to mitigate welfare issues related to the unnecessary premature death of unwanted offspring but also providing a possible ally in the face of stricter animal welfare guidelines. In addition, sexed semen can also contribute to financial gains and reduce greenhouse gas emissions and food waste associated with the less profitable part of the herd. This paper explores the positive impacts that sperm sexing can have on animal welfare, economy, and environment. It also discusses currently available options and strategies for more successful implementation of sexed semen. Partnerships between companies and scientists will be essential to find innovative ways to adapt current production systems and develop sperm sexing technologies that apply to most livestock industries.
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4
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Tao D, Liu J, Li Q, Jiang Y, Xu B, Khazalwa EM, Gong P, Xu J, Ma Y, Ruan J, Niu L, Xie S. A Simple, Affordable, and Rapid Visual CRISPR-Based Field Test for Sex Determination of Earlier Porcine Embryos and Pork Products. Mol Biotechnol 2023; 65:263-272. [PMID: 35840848 DOI: 10.1007/s12033-022-00532-x] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2022] [Accepted: 06/29/2022] [Indexed: 01/18/2023]
Abstract
Sex selection technologies have immensely impacted swine production globally. Conventional earlier embryo sex identification methods require professional technicians and sophisticated laboratory instruments. Rapid on-site gender identification of porcine embryos and pork products remains challenging. In this study, we developed a CRISPR/Cas12a-based fluorescence visualization point-of-care sex determination test that is rapid, accurate and easy to implement on-site. The CRISPR/Cas12a assay coupled with either the polymerase chain reaction (PCR) or loop-mediated isothermal amplification (LAMP) employs precisely designed primers and single-guide RNAs targeting the sex-determining region Y (SRY) and the zinc finger protein X-linked (ZFX) genes. PCR and LAMP amplicons were cleaved with the subsequent generation of fluorescing products detectable with portable blue and ultraviolet light transilluminators. Approximately two copies per microliter of the ZFX and SRY genes were detected using the RApid VIsual CRISPR (RAVI-CRISPR) assay. This method is a sensitive, inexpensive, versatile, and point-of-care test. The technology has other potential applications like determining the sex of diverse livestock species, detecting livestock disease-causing pathogens and evaluating the quality of meat products.
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Affiliation(s)
- Dagang Tao
- Key Laboratory of Agricultural Animal Genetics, Breeding and Reproduction of Ministry of Education & Key Lab of Swine Genetics and Breeding of Ministry of Agriculture and Rural Affairs, Huazhong Agricultural University, Wuhan, 430070, People's Republic of China
| | - Jiajia Liu
- College of Animal Science and Technology, Sichuan Agricultural University, Chengdu, 611130, People's Republic of China
| | - Qiushi Li
- College of Biological Engineering and Food Science, Hubei University of Technology, Wuhan, 430070, People's Republic of China
| | - Yu Jiang
- Yangshan Customs, Shanghai, 201306, People's Republic of China
| | - Bingrong Xu
- Key Laboratory of Agricultural Animal Genetics, Breeding and Reproduction of Ministry of Education & Key Lab of Swine Genetics and Breeding of Ministry of Agriculture and Rural Affairs, Huazhong Agricultural University, Wuhan, 430070, People's Republic of China
| | | | - Ping Gong
- Institute of Animal Husbandry and Veterinary, Wuhan Academy of Agricultural Science, Wuhan, 430208, People's Republic of China
| | - Jing Xu
- Key Laboratory of Agricultural Animal Genetics, Breeding and Reproduction of Ministry of Education & Key Lab of Swine Genetics and Breeding of Ministry of Agriculture and Rural Affairs, Huazhong Agricultural University, Wuhan, 430070, People's Republic of China
| | - Yunlong Ma
- Key Laboratory of Agricultural Animal Genetics, Breeding and Reproduction of Ministry of Education & Key Lab of Swine Genetics and Breeding of Ministry of Agriculture and Rural Affairs, Huazhong Agricultural University, Wuhan, 430070, People's Republic of China
| | - Jinxue Ruan
- Key Laboratory of Agricultural Animal Genetics, Breeding and Reproduction of Ministry of Education & Key Lab of Swine Genetics and Breeding of Ministry of Agriculture and Rural Affairs, Huazhong Agricultural University, Wuhan, 430070, People's Republic of China.,Hubei Hongshan Laboratory, Frontiers Science Center for Animal Breeding and Sustainable Production, Wuhan, 430070, People's Republic of China
| | - Lili Niu
- College of Animal Science and Technology, Sichuan Agricultural University, Chengdu, 611130, People's Republic of China.
| | - Shengsong Xie
- Key Laboratory of Agricultural Animal Genetics, Breeding and Reproduction of Ministry of Education & Key Lab of Swine Genetics and Breeding of Ministry of Agriculture and Rural Affairs, Huazhong Agricultural University, Wuhan, 430070, People's Republic of China. .,Hubei Hongshan Laboratory, Frontiers Science Center for Animal Breeding and Sustainable Production, Wuhan, 430070, People's Republic of China.
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5
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Development of CRISPR-Mediated Nucleic Acid Detection Technologies and Their Applications in the Livestock Industry. Genes (Basel) 2022; 13:genes13112007. [PMID: 36360244 PMCID: PMC9690124 DOI: 10.3390/genes13112007] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2022] [Revised: 10/26/2022] [Accepted: 10/31/2022] [Indexed: 11/06/2022] Open
Abstract
The rapid rate of virus transmission and pathogen mutation and evolution highlight the necessity for innovative approaches to the diagnosis and prevention of infectious diseases. Traditional technologies for pathogen detection, mostly PCR-based, involve costly/advanced equipment and skilled personnel and are therefore not feasible in resource-limited areas. Over the years, many promising methods based on clustered regularly interspaced short palindromic repeats and the associated protein systems (CRISPR/Cas), i.e., orthologues of Cas9, Cas12, Cas13 and Cas14, have been reported for nucleic acid detection. CRISPR/Cas effectors can provide one-tube reaction systems, amplification-free strategies, simultaneous multiplex pathogen detection, visual colorimetric detection, and quantitative identification as alternatives to quantitative PCR (qPCR). This review summarizes the current development of CRISPR/Cas-mediated molecular diagnostics, as well as their design software and readout methods, highlighting technical improvements for integrating CRISPR/Cas technologies into on-site applications. It further highlights recent applications of CRISPR/Cas-based nucleic acid detection in livestock industry, including emerging infectious diseases, authenticity and composition of meat/milk products, as well as sex determination of early embryos.
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Hedonic pricing analysis for semen of dairy bulls in Brazil. PLoS One 2022; 17:e0267109. [PMID: 35439267 PMCID: PMC9017886 DOI: 10.1371/journal.pone.0267109] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2021] [Accepted: 04/01/2022] [Indexed: 11/19/2022] Open
Abstract
Dairy farming is an important aspect of the Brazilian agricultural sector. The presence of numerous producers has created a large number of jobs in this field, contributing significantly to the rural economy. Artificial insemination (AI), used as one of the main means of reproduction, is increasingly gaining importance in the genetic improvement of animals. Given this scenario, the semen of bulls has become extremely marketable and an important aspect of the animal industry. This study aims to develop a hedonic model for the price of semen doses of dairy bulls based on the information from the main sellers of the product in the Brazilian market. The main findings reveal that there is an additional premium for proven bulls. Semen doses from Gir bulls proved to be more expensive, and the AI firm ALTA has a discount compared to the other firms. From the characteristics obtained in the tests, there is a premium only for the Predicted Transmitting Ability–Milk (volume). The most valued feature found is the dose being sexed, that is, the dose that guarantees the gestation of a female from its use. Semen doses from dead bulls has proved to be more expensive.
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Neculai-Valeanu AS, Ariton AM. Game-Changing Approaches in Sperm Sex-Sorting: Microfluidics and Nanotechnology. Animals (Basel) 2021; 11:ani11041182. [PMID: 33924241 PMCID: PMC8074747 DOI: 10.3390/ani11041182] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/19/2021] [Revised: 04/07/2021] [Accepted: 04/17/2021] [Indexed: 12/16/2022] Open
Abstract
Simple Summary Sexing of sperm cells, including the capacity to preselect the sex of offspring prior to reproduction, has been a major target of reproductive biotechnology for a very long time. The advances in molecular biology, biophysics, and computer science over the past few decades, as well as the groundbreaking new methods introduced by scientists, have contributed to some major breakthroughs in a variety of branches of medicine. In particular, assisted reproduction is one of the areas in which emerging technologies such as nanotechnology and microfluidics may enhance the fertility potential of samples of sex-sorted semen, thus improving the reproductive management of farm animals and conservation programs. In human medicine, embryo sex-selection using in vitro fertilization (IVF) and preimplantation genetic testing (PGT) is accepted only for medical reasons. Using sex-sorting before IVF would enable specialists to prevent sex-linked genetic diseases and prevent the discharge of embryos which are not suitable for transfer due to their sex. Abstract The utilization of sex-sorted sperm for artificial insemination and in-vitro fertilization is considered a valuable tool for improving production efficiency and optimizing reproductive management in farm animals, subsequently ensuring sufficient food resource for the growing human population. Despite the fact that sperm sex-sorting is one of the most intense studied technologies and notable progress have been made in the past three decades to optimize it, the conception rates when using sex-sorted semen are still under expectations. Assisted reproduction programs may benefit from the use of emergent nano and microfluidic-based technologies. This article addresses the currently used methods for sperm sex-sorting, as well as the emerging ones, based on nanotechnology and microfluidics emphasizing on their practical and economic applicability.
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Affiliation(s)
- Andra-Sabina Neculai-Valeanu
- Research and Development Station for Cattle Breeding Dancu, 707252 Iasi, Romania;
- Department of Fundamental Sciences in Animal Husbandry, Faculty of Food and Animal Sciences, University of Applied Life Sciences and Environment “Ion Ionescu de la Brad”, 700490 Iasi, Romania
- Correspondence:
| | - Adina Mirela Ariton
- Research and Development Station for Cattle Breeding Dancu, 707252 Iasi, Romania;
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Keles E, Malama E, Bozukova S, Siuda M, Wyck S, Witschi U, Bauersachs S, Bollwein H. The micro-RNA content of unsorted cryopreserved bovine sperm and its relation to the fertility of sperm after sex-sorting. BMC Genomics 2021; 22:30. [PMID: 33413071 PMCID: PMC7792310 DOI: 10.1186/s12864-020-07280-9] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2020] [Accepted: 11/24/2020] [Indexed: 02/06/2023] Open
Abstract
BACKGROUND The use of sex-sorted sperm in cattle assisted reproduction is constantly increasing. However, sperm fertility can substantially differ between unsorted (conventional) and sex-sorted semen batches of the same sire. Sperm microRNAs (miRNA) have been suggested as promising biomarkers of bull fertility the last years. In this study, we hypothesized that the miRNA profile of cryopreserved conventional sperm is related to bull fertility after artificial insemination with X-bearing sperm. For this purpose, we analyzed the miRNA profile of 18 conventional sperm samples obtained from nine high- (HF) and nine low-fertility (LF) bulls that were contemporaneously used to produce conventional and sex-sorted semen batches. The annual 56-day non-return rate for each semen type (NRRconv and NRRss, respectively) was recorded for each bull. RESULTS In total, 85 miRNAs were detected. MiR-34b-3p and miR-100-5p were the two most highly expressed miRNAs with their relative abundance reaching 30% in total. MiR-10a-5p and miR-9-5p were differentially expressed in LF and HF samples (false discovery rate < 10%). The expression levels of miR-9-5p, miR-34c, miR-423-5p, miR-449a, miR-5193-5p, miR-1246, miR-2483-5p, miR-92a, miR-21-5p were significantly correlated to NRRss but not to NRRconv. Based on robust regression analysis, miR-34c, miR-7859 and miR-342 showed the highest contribution to the prediction of NRRss. CONCLUSIONS A set of miRNAs detected in conventionally produced semen batches were linked to the fertilizing potential of bovine sperm after sex-sorting. These miRNAs should be further evaluated as potential biomarkers of a sire's suitability for the production of sex-sorted sperm.
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Affiliation(s)
- Esin Keles
- Clinic of Reproductive Medicine, Vetsuisse Faculty, University of Zurich, CH-8057, Zurich, Switzerland
| | - Eleni Malama
- Clinic of Reproductive Medicine, Vetsuisse Faculty, University of Zurich, CH-8057, Zurich, Switzerland.
- Veterinary Research Institute, Hellenic Agricultural Organization Demeter, 57001, Thermi, Thessaloniki, Greece.
| | - Siyka Bozukova
- Institute of Veterinary Anatomy, Vetsuisse Faculty, University of Zurich, CH-8057, Zurich, Switzerland
| | - Mathias Siuda
- Clinic of Reproductive Medicine, Vetsuisse Faculty, University of Zurich, CH-8057, Zurich, Switzerland
| | - Sarah Wyck
- Swissgenetics, CH-3052, Zollikofen, Switzerland
| | | | - Stefan Bauersachs
- Institute of Veterinary Anatomy, Vetsuisse Faculty, University of Zurich, CH-8057, Zurich, Switzerland
| | - Heinrich Bollwein
- Clinic of Reproductive Medicine, Vetsuisse Faculty, University of Zurich, CH-8057, Zurich, Switzerland
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Osada M, Iwabuchi H, Aoki T, Sasaki K, Ushijima H, Ozawa T. Economic evaluation of artificial insemination of sex-sorted semen on a Brown Swiss dairy farm-A case study. Anim Sci J 2019; 90:597-603. [PMID: 30739361 PMCID: PMC6594040 DOI: 10.1111/asj.13156] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2018] [Revised: 11/21/2018] [Accepted: 11/21/2018] [Indexed: 12/04/2022]
Abstract
Artificial insemination using sex‐sorted semen is employed to efficiently increase the number of female dairy calves born. Previous studies have determined that using sex‐sorted semen is beneficial to improve the management, but the mechanism by which it increases cattle numbers through objective indices of breeding remains unclear. This study focused on a Brown Swiss cattle herd in which frozen female sex‐sorted semen was systematically employed to increase the number of cattle. We analyzed the correlation between the increase in the number of cattle and the screening accuracy of sex‐sorted semen, measuring indices such as pregnancy rate and birth rate of female calves. Study revealed that: (1) production cost for female calves is influenced by the pregnancy rate, rate of female calves, and using sex‐sorted semen is less expensive than using nonsorted semen; (2) improvements in screening accuracy nearly doubled the number of cows and tripled the number of heifers in 5 years; and (3) use of sex‐sorted semen improved milk quality. The pregnancy rate was lower when sex‐sorted semen was used, but the birth rate of heifers was improved. Results suggest that artificial insemination using sex‐sorted semen is beneficial because it economically produces offspring to increase the herd.
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Affiliation(s)
- Masahiro Osada
- Nippon Veterinary and Life Science University, Musashino, Tokyo, Japan
| | - Hitomi Iwabuchi
- Nippon Veterinary and Life Science University, Musashino, Tokyo, Japan
| | - Toru Aoki
- Tochigi Prefecture Ozasa Farm, Tochigi Dairy Farmers Cooperative, Nikko, Tochigi, Japan
| | - Kika Sasaki
- Tochigi Prefecture Ozasa Farm, Tochigi Dairy Farmers Cooperative, Nikko, Tochigi, Japan
| | - Hitoshi Ushijima
- Nippon Veterinary and Life Science University, Musashino, Tokyo, Japan
| | - Takeyuki Ozawa
- Nippon Veterinary and Life Science University, Musashino, Tokyo, Japan
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