{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2025,10,12]],"date-time":"2025-10-12T02:10:46Z","timestamp":1760235046299,"version":"build-2065373602"},"reference-count":44,"publisher":"MDPI AG","issue":"7","license":[{"start":{"date-parts":[[2021,7,12]],"date-time":"2021-07-12T00:00:00Z","timestamp":1626048000000},"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>Precocious puberty in beef heifers can result in unwanted pregnancies due to accidental breeding by farm bulls. Inbreeding, premature calving followed by dystocia and a high stillbirth rate or slaughtering of pregnant heifers are the consequences of this behaviour. The aim of the study was to postpone puberty by using Improvac\u00ae, an anti-GnRH vaccine. Therefore, n = 25 calves were twice vaccinated, once at the age of 5 and then at 6.5 months. n = 24 calves served as unvaccinated case controls. The onset of puberty was assigned if progesterone analysis in the blood exceeded 1 ng\/mL. Progesterone values were excluded if the corresponding serum cortisol levels were \u226560 nmol\/L. Our target was met, as in the vaccinated group none of the calves exceeded a progesterone value &gt;1 ng\/mL until the scheduled age of slaughter at 11 months and only 12.5% of the animals exceeded a progesterone value of 1 ng\/mL over the whole measuring period (&gt;400 days) compared with 56.5% of the calves in the control group. In conclusion, the favourable results from our study using the vaccine Improvac\u00ae represent an animal-friendly, non-invasive and reliable way to avoid early pregnancy in heifers as well as the slaughter of pregnant cattle.<\/jats:p>","DOI":"10.3390\/ani11072071","type":"journal-article","created":{"date-parts":[[2021,7,12]],"date-time":"2021-07-12T21:56:37Z","timestamp":1626126997000},"page":"2071","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":4,"title":["Immunization against Gonadotropin-Releasing Hormone in Female Beef Calves to Avoid Pregnancy at Time of Slaughter"],"prefix":"10.3390","volume":"11","author":[{"given":"Julia","family":"Sch\u00fctz","sequence":"first","affiliation":[{"name":"Nutztierpraxis Rudolph AG, CH-6280 Hochdorf, Switzerland"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"J\u00fcrn","family":"Rudolph","sequence":"additional","affiliation":[{"name":"Nutztierpraxis Rudolph AG, CH-6280 Hochdorf, Switzerland"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Adrian","family":"Steiner","sequence":"additional","affiliation":[{"name":"Clinic for Ruminants, Vetsuisse Faculty, University of Bern, Bremgartenstrasse 109 a, CH-3012 Bern, Switzerland"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Esther","family":"Rothenanger","sequence":"additional","affiliation":[{"name":"labor-zentral.ch, Stationsweg 3, CH-6232 Geuensee, Switzerland"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"J\u00fcrg","family":"H\u00fcsler","sequence":"additional","affiliation":[{"name":"Institute of Mathematical Statistics and Actuarial Science, University of Bern, Sidlerstrasse 5, CH-3012 Bern, Switzerland"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0000-0001-5158-8906","authenticated-orcid":false,"given":"Gaby","family":"Hirsbrunner","sequence":"additional","affiliation":[{"name":"Clinic for Ruminants, Vetsuisse Faculty, University of Bern, Bremgartenstrasse 109 a, CH-3012 Bern, Switzerland"}],"role":[{"role":"author","vocabulary":"crossref"}]}],"member":"1968","published-online":{"date-parts":[[2021,7,12]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","unstructured":"Maurer, P., Lucker, E., and Riehn, K. 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