{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,1,21]],"date-time":"2026-01-21T17:51:00Z","timestamp":1769017860050,"version":"3.49.0"},"reference-count":45,"publisher":"CSIRO Publishing","issue":"8","license":[{"start":{"date-parts":[[2025,5,27]],"date-time":"2025-05-27T00:00:00Z","timestamp":1748304000000},"content-version":"vor","delay-in-days":4225,"URL":"https:\/\/doi.org\/10.1071\/journalslicense"}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":[],"published-print":{"date-parts":[[2014,10,8]]},"abstract":"<jats:p>The objective of this study was to determine the effects of vehicle and route of administration of letrozole on ovarian function in sexually mature beef heifers. On Day 3 (Day 0 = ovulation), heifers were assigned randomly to four treatment groups and given 1 mg kg\u20131 letrozole intravenously (iv, n = 10) or intramuscularly (im, n = 10) or given a placebo iv (control iv, n = 5) or im (control im, n = 5). The interwave interval was longer in heifers treated with letrozole im than in im and iv controls (11.7 \u00b1 0.30 vs 9.5 \u00b1 0.50 and 10 \u00b1 0.43, respectively; P &amp;lt; 0.05). Corpus luteum diameter profiles and plasma progesterone concentrations were greater (P &amp;lt; 0.03 and P &amp;lt; 0.05, respectively) in heifers treated with letrozole im compared with control im. Plasma oestradiol concentrations were lower in both letrozole-treated groups compared with controls (P = 0.03). Plasma LH concentrations tended to be elevated at the time of wave emergence in heifers treated with letrozole im compared with other groups (group-by-day interaction, P = 0.06) and plasma FSH concentrations tended to be greater (P &amp;lt; 0.09) in heifers treated with letrozole by either route compared with a single control group. We conclude that intramuscular administration of letrozole in oil is a feasible route and vehicle for the development of a letrozole-based treatment protocol for herd synchronisation in cattle.<\/jats:p>","DOI":"10.1071\/rd13100","type":"journal-article","created":{"date-parts":[[2013,11,1]],"date-time":"2013-11-01T02:44:31Z","timestamp":1383273871000},"page":"1198-1205","source":"Crossref","is-referenced-by-count":11,"title":["Effect of vehicle and route of administration of letrozole on ovarian function in a bovine model"],"prefix":"10.1071","volume":"26","author":[{"given":"M. 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A.","family":"Pierson","sequence":"additional","affiliation":[{"name":"CDepartment of Obstetrics, Gynecology and Reproductive Sciences, College of Medicine, University of Saskatchewan, Saskatoon, Saskatchewan S7N 0W8, Canada."}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"J.","family":"Singh","sequence":"additional","affiliation":[{"name":"ADepartment of Veterinary Biomedical Sciences, Western College of Veterinary Medicine, University of Saskatchewan, Saskatoon, Saskatchewan S7N 5B4, Canada."}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"G. P.","family":"Adams","sequence":"additional","affiliation":[{"name":"ADepartment of Veterinary Biomedical Sciences, Western College of Veterinary Medicine, University of Saskatchewan, Saskatoon, Saskatchewan S7N 5B4, Canada."},{"name":"DCorresponding author. 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