Role of luteinizing hormone in primiparous sow responses to split weaning

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dc.contributor.authorZak, L.
dc.contributor.authorFoxcroft, G.
dc.contributor.authorAherne, F.
dc.contributor.authorKirkwood, R.
dc.date.issued2008
dc.description.abstractIn 45 primiparous sows, we examined endocrine, ovarian and reproductive responses to split-weaning or five injections per day of 800 ng GnRH from 18 to 21 days of lactation. There was no effect of treatment on absolute or changes in sow weight or backfat depth during lactation. Average piglet growth rates were similar among treatments except that piglets suckling split-weaned sows grew faster (p < 0.05) during days 18-21. On day 18, mean plasma LH concentrations and LH pulse frequency remained relatively stable in conventionally weaned sows but increased (p < 0.01) in response to split-weaning and GnRH. Prior to weaning on day 21, mean plasma LH concentrations remained elevated in GnRH-treated sows but had returned to control levels in split weaned sows. There was no treatment effect on preweaning LH pulse frequency noted on day 21. Weaning was associated with an increase in plasma LH concentrations in all the treatment groups. Mean plasma IGF-I remained relatively constant in conventionally weaned and GnRH sows, decreased in response to split weaning on day 18 (p < 0.02), but were elevated (p < 0.03) in split wean sows on day 21. On the day after weaning, split wean sows had more (p < 0.04) ovarian follicles >or=3 mm than conventionally weaned sows, with GnRH sows being intermediate. The wean-to-oestrus interval was reduced in split-wean sows compared with those conventionally weaned (p < 0.01), with GnRH sows being intermediate. There was no effect of treatment on ovulation rates, numbers of embryos, or embryonic survival rates. These data indicate that split-weaning of litters results in a more rapid return to oestrus after weaning and that this effect is associated with a transient acute increase in circulating gonadotrophins and earlier resumption of ovarian follicular development.
dc.description.statementofresponsibilityL Zak, GR Foxcroft, FX Aherne and RN Kirkwood
dc.identifier.citationReproduction in Domestic Animals, 2008; 43(4):445-450
dc.identifier.doi10.1111/j.1439-0531.2007.00932.x
dc.identifier.issn0936-6768
dc.identifier.issn1439-0531
dc.identifier.orcidKirkwood, R. [0000-0002-3294-8301]
dc.identifier.urihttp://hdl.handle.net/2440/88658
dc.language.isoen
dc.publisherWiley
dc.rights© 2007 The Authors. Journal compilation © 2007 Blackwell Verlag
dc.source.urihttps://doi.org/10.1111/j.1439-0531.2007.00932.x
dc.subjectOvarian Follicle
dc.subjectAnimals
dc.subjectAnimals, Newborn
dc.subjectAnimals, Suckling
dc.subjectSwine
dc.subjectLuteinizing Hormone
dc.subjectInsulin-Like Growth Factor I
dc.subjectRandom Allocation
dc.subjectParity
dc.subjectWeaning
dc.subjectReproduction
dc.subjectLactation
dc.subjectPregnancy
dc.subjectFemale
dc.subjectGonadotropin-Releasing Hormone
dc.titleRole of luteinizing hormone in primiparous sow responses to split weaning
dc.typeJournal article
pubs.publication-statusPublished

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