Repeatability of the plasma luteinizing-hormone response to two consecutive injections of gonadotropin-releasing hormone to prepubertal ewe-lambs reared in individual pens

E. Gur-Arie, Miriam Rosenberg, J. Hillel, Y. Folman, E. Eyal

Research output: Contribution to journalArticlepeer-review

Abstract

Thirty Finn X German-Mutton Merino ewe-lambs (6 born in May, 10 in November and 14 in February) were artificially reared in individual pens. Uniformity of growth was attempted by limiting dietary intake to predetermined ratios of body weight. At the age of 35, 56, 77 and 90 days each lamb was given two i.v. injections of 30 μg of synthetic analog of the gonadotropin-releasing hormone (GnRH) each at an 80-min interval. Blood samples were collected consecutively for 200 min. Differences between individual prepubertal lambs accounted for 69.4%, 46.8%, and 37.5% of the variability of the LH response to GnRH in the May-, November- and February-born lambs, respectively. There were no significant differences in mean plasma LH concentration between lambs born in different months. However, at the ages of 77 and 90 days there was an age X season interaction and the November-born lambs had significantly lower mean plasma LH concentration at 90 days than did those born in May or February. Repeatabilities of the plasma LH response within the age range of 70-90 days were 0.86, 0.90 and 0.94 in the May, November and February lambs, respectively. Furthermore, coefficients of concordance for the ranking of the lambs between the age of 77 and 90 days were 1.00, 0.98 and 0.97. Indications obtained to show that prepubertal LH level correlated with post-pubertal reproduction traits suggest that they could eventually become useful in the future as an aid to selection.

Original languageEnglish
Pages (from-to)85-97
Number of pages13
JournalAnimal Reproduction Science
Volume12
Issue number2
DOIs
StatePublished - Oct 1986

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