{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,10,7]],"date-time":"2026-10-07T16:12:01Z","timestamp":1791389521180,"version":"4.3.3"},"reference-count":15,"publisher":"MDPI AG","issue":"2","license":[{"start":{"date-parts":[[2020,2,14]],"date-time":"2020-02-14T00:00:00Z","timestamp":1581638400000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Animals"],"abstract":"<jats:p>In order to efficiently have a consistent supply of service-ready gilts available to incorporate into each batch of breeding sows, it is necessary to manipulate the timing of estrus and possibly the timing of ovulation of gilts. Estrus can be synchronized by the withdrawal of altrenogest after at least 14 days of treatment. It is possible that protocols developed to induce ovulation, and therefore allow fixed-time artificial insemination (FTAI), can improve the predictability of gilt breeding. This study investigated the effect of two FTAI protocols in gilts on reproductive performance and timing of farrowing and piglet weaning weight compared to gilts bred based on signs of estrus after cessation of altrenogest. Puberty was induced in gilts, followed by treatment with altrenogest. Following altrenogest withdrawal, 180 gilts were assigned to one of three treatment groups. Group 1 gilts (LUT, n = 62) were treated with 600 IU equine chorionic gonadotropin 24 h after altrenogest withdrawal and 5 mg porcine luteinizing hormone (pLH) 80 h later, followed by a single FTAI 36 h after pLH. Group 2 gilts (TRI, n= 61) received 2 mL of a gonadotropin-releasing hormone agonist, triptorelin acetate, intravaginally 6 d after altrenogest withdrawal and were bred by a single FTAI 24 h later. Group 3 gilts (CON, n = 57) were observed for estrus and bred twice by AI, 24 h apart. LUT and TRI gilts farrowed closer together (2.4 \u00b1 1.6 and 2.9 \u00b1 1.2 d(days), respectively) compared to CON gilts (4.5 \u00b1 3.3 d). Piglets in LUT were 80 g (p &lt; 0.001) heavier and piglets in TRI were 64 g (p &lt; 0.05) heavier at weaning than CON piglets, when controlling for birth weight. Results indicate that FTAI might be useful as a means of minimizing the time from the first to the last gilt farrowing in a breeding batch of gilts. However, modifications of the protocols may be required to ensure optimum farrowing rates and litter size.<\/jats:p>","DOI":"10.3390\/ani10020306","type":"journal-article","created":{"date-parts":[[2020,2,21]],"date-time":"2020-02-21T10:49:16Z","timestamp":1582282156000},"page":"306","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":10,"title":["Comparison of Single, Fixed-Time Artificial Insemination in Gilts Using Two Different Protocols to Synchronize Ovulation"],"prefix":"10.3390","volume":"10","author":[{"given":"Lima","family":"Rodrigues","sequence":"first","affiliation":[{"name":"Department of Population Medicine, University of Guelph, Guelph, ON N1G2W1, Canada"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Rocio","family":"Amezcua","sequence":"additional","affiliation":[{"name":"Department of Population Medicine, University of Guelph, Guelph, ON N1G2W1, Canada"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0001-8788-6999","authenticated-orcid":false,"given":"Glen","family":"Cassar","sequence":"additional","affiliation":[{"name":"Department of Population Medicine, University of Guelph, Guelph, ON N1G2W1, Canada"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0001-5687-0185","authenticated-orcid":false,"given":"Terri L","family":"O\u2019Sullivan","sequence":"additional","affiliation":[{"name":"Department of Population Medicine, University of Guelph, Guelph, ON N1G2W1, Canada"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Robert","family":"Friendship","sequence":"additional","affiliation":[{"name":"Department of Population Medicine, University of Guelph, Guelph, ON N1G2W1, Canada"}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"1968","published-online":{"date-parts":[[2020,2,14]]},"reference":[{"key":"ref_1","first-page":"210","article-title":"Effect of additional human chorionic gonadotrophin (hCG) on follicular growth and ovulation in gonadotrophin-treated gilts","volume":"79","author":"Cassar","year":"2015","journal-title":"Can. J. Vet. Res."},{"key":"ref_2","doi-asserted-by":"crossref","first-page":"84","DOI":"10.1016\/j.anireprosci.2006.01.004","article-title":"Synchronization of estrus and ovulation in sows not conceiving in a scheduled fixed-time insemination program","volume":"97","author":"Kauffold","year":"2007","journal-title":"Anim. Reprod. Sci."},{"key":"ref_3","doi-asserted-by":"crossref","first-page":"2757","DOI":"10.2527\/2001.79112757x","article-title":"Effects of PG 600 on the onset of estrus and ovulation rate in gilts treated with Regu-Mate","volume":"79","author":"Estienne","year":"2001","journal-title":"J. Anim. Sci."},{"key":"ref_4","doi-asserted-by":"crossref","first-page":"1460","DOI":"10.1016\/j.theriogenology.2016.04.089","article-title":"Review: Control of estrus and ovulation: Fertility to timed insemination of gilts and sows","volume":"86","author":"Kirkwood","year":"2016","journal-title":"Theriogenology"},{"key":"ref_5","doi-asserted-by":"crossref","first-page":"1072","DOI":"10.1016\/j.theriogenology.2016.03.039","article-title":"Single fixed-time artificial insemination in gilts and weaned sows using pLH at estrus onset administered through vulvar submucosal route","volume":"86","author":"Ulguim","year":"2016","journal-title":"Theriogenology"},{"key":"ref_6","doi-asserted-by":"crossref","first-page":"391","DOI":"10.1016\/j.theriogenology.2013.05.002","article-title":"Induction of an LH surge and ovulation by buserelin (as receptal) allows breeding of weaned sows with a single fixed-time insemination","volume":"80","author":"Driancourt","year":"2013","journal-title":"Theriogenology"},{"key":"ref_7","doi-asserted-by":"crossref","first-page":"1","DOI":"10.1186\/2049-1891-6-3","article-title":"Review: Current strategies for reproductive management of gilts and sows in North America","volume":"6","author":"Kraeling","year":"2015","journal-title":"J. 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Swine Health Prod."},{"key":"ref_11","first-page":"182","article-title":"Effect of eCG dose on the estrus response of gilts and weaned sows and effect of the interval between eCG and pLH injections on sow performance","volume":"18","author":"Cassar","year":"2010","journal-title":"J. Swine Health Prod."},{"key":"ref_12","doi-asserted-by":"crossref","first-page":"444","DOI":"10.1262\/jrd.09-220T","article-title":"Use of B-mode ultrasound and grey-scale analysis to study uterine echogenicity in the pig","volume":"56","author":"Kauffold","year":"2010","journal-title":"J. Reprod. Dev."},{"key":"ref_13","doi-asserted-by":"crossref","first-page":"2265","DOI":"10.2527\/jas.2009-2121","article-title":"Impact of lactation length and piglet weaning weight on long-term growth and viability of progeny","volume":"88","author":"Cabrera","year":"2010","journal-title":"J. Anim. 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