{"id":{"repo_id":"uiuc","oai_identifier":"oai:www.ideals.illinois.edu:2142/115411"},"canonical_url":"https://search.dev.ndltd.org/etd/uiuc/oai:www.ideals.illinois.edu:2142/115411","repository":{"repo_id":"uiuc","name":"University of Illinois - Urbana-Champaign","base_url":"https://www.ideals.illinois.edu/oai-pmh"},"display":{"title":"External and internal factors influencing ovarian follicle development in weaned sows and the use of hormonal technology to improve subsequent fertility","abstract":"The student, Lidia Sbaraini Arend, accepted the attached license on 2022-04-20 at 14:45.","abstract_html":"The student, Lidia Sbaraini Arend, accepted the attached license on 2022-04-20 at 14:45.","abstract_has_math":false,"creators":["Sbaraini Arend, Lidia"],"institution":"University of Illinois at Urbana-Champaign","degree_name":"Ph.D.","degree_level":"Dissertation","degree_discipline":"Animal Sciences","degree_department":null,"school":null,"contributors":["Knox, Robert V","Miller, David J","Wheeler, Matthew B","Ellis, Michael"],"advisors":[],"committee_chairs":[],"committee_members":[],"year":2022,"date_issued":"2022-05","date_published":"2022-05","updated_at":"2026-07-22T22:24:54Z","subjects":["Primiparous sows","fertility","follicle","ovulation induction","litter size"],"languages":["en","eng"],"rights":["Copyright 2022 Lidia Sbaraini Arend"],"rights_urls":[],"identifier_entries":[]},"links":{"outbound_url":"https://hdl.handle.net/2142/115411","outbound_label":"Handle","outbound_source":"dc:identifier"},"metadata_groups":[{"id":"people","label":"People","entries":[{"key":"dc:contributor","label":"Contributor","values":["Knox, Robert V","Miller, David J","Wheeler, Matthew B","Ellis, Michael"]},{"key":"dc:creator","label":"Author","values":["Sbaraini Arend, Lidia"]}]},{"id":"academic_context","label":"Academic Context","entries":[{"key":"dc:date","label":"Dc Date","values":["2022-05","2022-04-21"]},{"key":"dc:type","label":"Dc Type","values":["text","Thesis"]},{"key":"thesis:degree_discipline","label":"Discipline","values":["Animal Sciences"]},{"key":"thesis:degree_level","label":"Degree Level","values":["Dissertation"]},{"key":"thesis:degree_name","label":"Degree Name","values":["Ph.D."]},{"key":"thesis:institution_name","label":"Thesis Institution Name","values":["University of Illinois at Urbana-Champaign"]}]},{"id":"subjects_keywords","label":"Subjects and Keywords","entries":[{"key":"dc:subject","label":"Dc Subject","values":["Primiparous sows","fertility","follicle","ovulation induction","litter size"]}]},{"id":"language_rights","label":"Language and Rights","entries":[{"key":"dc:language","label":"Dc Language","values":["en","eng"]},{"key":"dc:rights","label":"Dc Rights","values":["Copyright 2022 Lidia Sbaraini Arend"]}]},{"id":"identifiers","label":"Identifiers","entries":[{"key":"dc:identifier","label":"Identifier","values":["https://hdl.handle.net/2142/115411"]}]},{"id":"additional","label":"Additional Metadata","entries":[{"key":"dc:description","label":"Description","values":["The student, Lidia Sbaraini Arend, accepted the attached license on 2022-04-20 at 14:45.","The student, Lidia Sbaraini Arend, submitted this Dissertation for approval on 2022-04-20 at 15:11.","This Dissertation was approved for publication on 2022-04-21 at 15:14.","DSpace SAF Submission Ingestion Package generated from Vireo submission #17854 on 2022-11-11 at 13:42:36","Submission original under an indefinite embargo labeled 'Open Access'. The submission was exported from vireo on 2022-11-11 without embargo terms","The expectation of 90% of sows exhibiting estrus within 6 to 7 d following weaning is an important target for sow productivity. But concerns about the proportion of sows that are delayed in the breeding group remain, with a particular interest in primiparous sows and the internal and external factors affecting their ability to be fertile after weaning. The first experiment was designed to determine whether induced ovulation (OvuGel, a GnRH agonist) and single fixed-time artificial insemination (SFTAI) could be successful for fertility responses in different parities (P1, P2, P3 to 4, P≥7) and seasons (summer and fall) of the year. Results indicated that ovulation induction increased the proportion of sows ovulating by 10.8%, but with no enhancement in fertility outcomes and no substantial improvement with parity or season. Ovulation induction with SFTAI was associated with smaller follicle size at estrus in P1 sows, and these females displayed a reduced proportion of sows ovulating within 6 days of weaning and lower farrowing rates compared to the older parities. The second experiment was a preliminary study conducted to characterize follicles on the ovaries of a small population of P1 sows during lactation and post-weaning and to determine whether these might associate with estrus and subsequent fertility after weaning. In this group of sows, fertility was lower than expected, and results indicated variation in follicle populations during lactation and after weaning, with heterogeneous follicle sizes observed throughout lactation. The average size of the largest follicles during lactation and Day 1 post-weaning tended to be smaller than the largest follicles on Days 5 to 7 after weaning. Only 64.7% of sows were in estrus within 7 days, and of those inseminated, 76.9% became pregnant and farrowed with a mean litter size of 11.7 ± 1.5. Despite the variation in follicle populations during lactation, this did not explain the estrus and fertility responses after weaning. The third experiment tested the hypothesis that body condition loss occurs more frequently in P1 sows nursing a high number of piglets and would impair ovarian follicle development during lactation and post-weaning, and reduce subsequent fertility. This study assigned P1 sows during lactation to receive a high number (HN, 15 to 16 pigs) or low number (LN, 12 pigs) of nursing piglets. At weaning, to evaluate whether the fertility issue occurred at the pituitary or the ovary, half of each treatment received PG600 or none. Results showed that HN sows lost more piglets due to mortality or removal for poor growth than their littermates, and females lost more body condition than P1 sows nursing a low number of piglets (LN, 12). Still, HN sows weaned more pigs without negative effects on reproductive performance. We conclude that there is variation in fertility in the modern P1 sow and a sub-population of these females develop smaller follicles after weaning but without any significant link to differential follicle development during lactation. The same P1 females are also less likely to ovulate within the optimal time following GnRH, are more predisposed to lose body condition during lactation, and show reduced fertility within certain seasons. The majority of modern P1 sows have the potential for high fertility, but a subpopulation is still susceptible to fertility failures, which seems to be highly related to genetics and management. So, there is still an opportunity for management improvement to achieve high fertility in P1 sows."]},{"key":"dc:format","label":"Dc Format","values":["application/pdf"]},{"key":"dc:title","label":"Title","values":["External and internal factors influencing ovarian follicle development in weaned sows and the use of hormonal technology to improve subsequent fertility"]}]}],"canonical_facts":{"dc:contributor":["Knox, Robert V","Miller, David J","Wheeler, Matthew B","Ellis, Michael"],"dc:creator":["Sbaraini Arend, Lidia"],"dc:date":["2022-05","2022-04-21"],"dc:description":["The student, Lidia Sbaraini Arend, accepted the attached license on 2022-04-20 at 14:45.","The student, Lidia Sbaraini Arend, submitted this Dissertation for approval on 2022-04-20 at 15:11.","This Dissertation was approved for publication on 2022-04-21 at 15:14.","DSpace SAF Submission Ingestion Package generated from Vireo submission #17854 on 2022-11-11 at 13:42:36","Submission original under an indefinite embargo labeled 'Open Access'. The submission was exported from vireo on 2022-11-11 without embargo terms","The expectation of 90% of sows exhibiting estrus within 6 to 7 d following weaning is an important target for sow productivity. But concerns about the proportion of sows that are delayed in the breeding group remain, with a particular interest in primiparous sows and the internal and external factors affecting their ability to be fertile after weaning. The first experiment was designed to determine whether induced ovulation (OvuGel, a GnRH agonist) and single fixed-time artificial insemination (SFTAI) could be successful for fertility responses in different parities (P1, P2, P3 to 4, P≥7) and seasons (summer and fall) of the year. Results indicated that ovulation induction increased the proportion of sows ovulating by 10.8%, but with no enhancement in fertility outcomes and no substantial improvement with parity or season. Ovulation induction with SFTAI was associated with smaller follicle size at estrus in P1 sows, and these females displayed a reduced proportion of sows ovulating within 6 days of weaning and lower farrowing rates compared to the older parities. The second experiment was a preliminary study conducted to characterize follicles on the ovaries of a small population of P1 sows during lactation and post-weaning and to determine whether these might associate with estrus and subsequent fertility after weaning. In this group of sows, fertility was lower than expected, and results indicated variation in follicle populations during lactation and after weaning, with heterogeneous follicle sizes observed throughout lactation. The average size of the largest follicles during lactation and Day 1 post-weaning tended to be smaller than the largest follicles on Days 5 to 7 after weaning. Only 64.7% of sows were in estrus within 7 days, and of those inseminated, 76.9% became pregnant and farrowed with a mean litter size of 11.7 ± 1.5. Despite the variation in follicle populations during lactation, this did not explain the estrus and fertility responses after weaning. The third experiment tested the hypothesis that body condition loss occurs more frequently in P1 sows nursing a high number of piglets and would impair ovarian follicle development during lactation and post-weaning, and reduce subsequent fertility. This study assigned P1 sows during lactation to receive a high number (HN, 15 to 16 pigs) or low number (LN, 12 pigs) of nursing piglets. At weaning, to evaluate whether the fertility issue occurred at the pituitary or the ovary, half of each treatment received PG600 or none. Results showed that HN sows lost more piglets due to mortality or removal for poor growth than their littermates, and females lost more body condition than P1 sows nursing a low number of piglets (LN, 12). Still, HN sows weaned more pigs without negative effects on reproductive performance. We conclude that there is variation in fertility in the modern P1 sow and a sub-population of these females develop smaller follicles after weaning but without any significant link to differential follicle development during lactation. The same P1 females are also less likely to ovulate within the optimal time following GnRH, are more predisposed to lose body condition during lactation, and show reduced fertility within certain seasons. The majority of modern P1 sows have the potential for high fertility, but a subpopulation is still susceptible to fertility failures, which seems to be highly related to genetics and management. So, there is still an opportunity for management improvement to achieve high fertility in P1 sows."],"dc:format":["application/pdf"],"dc:identifier":["https://hdl.handle.net/2142/115411"],"dc:language":["en","eng"],"dc:rights":["Copyright 2022 Lidia Sbaraini Arend"],"dc:subject":["Primiparous sows","fertility","follicle","ovulation induction","litter size"],"dc:title":["External and internal factors influencing ovarian follicle development in weaned sows and the use of hormonal technology to improve subsequent fertility"],"dc:type":["text","Thesis"],"thesis:degree_discipline":["Animal Sciences"],"thesis:degree_level":["Dissertation"],"thesis:degree_name":["Ph.D."],"thesis:institution_name":["University of Illinois at Urbana-Champaign"]},"updated_at":"2026-07-22T22:24:54Z"}