VTechWorks staff will be away for the winter holidays starting Tuesday, December 24, 2024, through Wednesday, January 1, 2025, and will not be replying to requests during this time. Thank you for your patience, and happy holidays!
 

Hormonal regulation of the onset of puberty in purebred and crossbred Holstein and Jersey heifers

Simple item page
dc.contributor.authorGetzewich, Karen Elizabethen
dc.contributor.committeechairNebel, Raymond L.en
dc.contributor.committeememberAkers, Robert Michaelen
dc.contributor.committeememberCassell, Bennet G.en
dc.contributor.departmentDairy Scienceen
dc.date.accessioned2014-03-14T20:42:11Zen
dc.date.adate2005-08-09en
dc.date.available2014-03-14T20:42:11Zen
dc.date.issued2005-07-19en
dc.date.rdate2005-08-09en
dc.date.sdate2005-07-29en
dc.description.abstractThe objective of this study was to determine the onset of puberty by using progesterone profiles and anterior pituitary gonadotropin releasing hormone (GnRH) challenges in purebred and crossbred Holstein and Jersey heifers. In experiment 1, fifty prepubertal heifers by four sire - dam classifications (18 HH, 11 JJ, 10 JH, and 11 HJ) were used. The HH heifers attained puberty at an older age than the HJ, JH or JJ heifers, and these three classifications were not different from each other. There were significant differences in weight and wither height at puberty and average daily weight gain (ADWG) between all four sire - dam classifications. Season of birth had a significant effect on age and weight at puberty. In experiment 2, four prepubertal heifers from each sire - dam classification in experiment 1 were used at 3, 6, 9 and 12 mo of age to determine the effects of administering 200 μg GnRH on LH secretion. The effects of breed, age at challenge, and their interaction were only significant for time to LH peak. In conclusion, age at puberty in crossbred Holstein X Jersey heifers is regulated by breed and season of birth, and further research with larger sample sizes is needed to establish the relationship of pituitary maturation and the capacity to secrete LH in response to GnRH stimulation as related to onset of puberty in purebred and crossbred dairy heifers.en
dc.description.degreeMaster of Scienceen
dc.identifier.otheretd-07292005-151652en
dc.identifier.sourceurlhttp://scholar.lib.vt.edu/theses/available/etd-07292005-151652/en
dc.identifier.urihttp://hdl.handle.net/10919/34239en
dc.publisherVirginia Techen
dc.relation.haspartkgthesis.pdfen
dc.rightsIn Copyrighten
dc.rights.urihttp://rightsstatements.org/vocab/InC/1.0/en
dc.subjectGnRHen
dc.subjectCrossbreedingen
dc.subjectHolstein X Jerseyen
dc.subjectPubertyen
dc.titleHormonal regulation of the onset of puberty in purebred and crossbred Holstein and Jersey heifersen
dc.typeThesisen
thesis.degree.disciplineDairy Scienceen
thesis.degree.grantorVirginia Polytechnic Institute and State Universityen
thesis.degree.levelmastersen
thesis.degree.nameMaster of Scienceen

Files

Original bundle
Now showing 1 - 1 of 1
Thumbnail Image
Name:
kgthesis.pdf
Size:
215 KB
Format:
Adobe Portable Document Format
Download

Collections

Masters Theses