title: [The reproductive function in experimentally-produced monozygotic twin bulls].
abstract: Reproductive functions were evaluated in 12 experimentally derived monozygotic cattle twins (6 pairs). In 4 twin pairs GnRH (20 micrograms Receptal i.m.) was administered in monthly intervals from 6 through 12 months of age. LH-secretion was determined by radioimmunoassay up to 6 hours after the GnRH-challenge in hourly collected peripheral blood samples. In 5 twin pairs (age 14 to 20 months) semen was collected 5 times and processed for cryoconservation. In fresh and in frozen-thawed semen samples sperm motility was determined by means of a computerized system. Twins showed a remarkable uniform response to the GnRH-challenge. One set of twins (HF-breed) had a significantly reduced response compared to the other pairs (DFV-breed). Both individuals of this particular pair had a low percentage of progressively motile spermatozoa. In pairs with physiological sperm motility, variance of this parameter within pairs and between pairs was not different. In contrast, twin uniformity concerning the average velocity of motile spermatozoa was high; differences between set of twins explained most of the total variance. According to this study, reproductive parameters in monozygotic cattle twins are strongly influenced by twin uniformity.
authors.affiliation: Gynäkologische und Ambulatorische Tierklinik der Universität München.
authors.forename: J
authors.initials: J
authors.lastname: Braun
authors.forename: D
authors.initials: D
authors.lastname: Schams
authors.forename: G
authors.initials: G
authors.lastname: Brem
mesh_terms: D000818:Animals; D002417:Cattle / Q000502:physiology*; D015925:Cryopreservation; D005298:Fertility; D007986:Luteinizing Hormone / Q000097:blood; D008297:Male; D013081:Sperm Motility; D013094:Spermatozoa / Q000502:physiology; D014430:Twins, Monozygotic
chemical_list: D007986:Luteinizing Hormone
vernacular_title: Zur Fortpflanzungsfunktion bei experimentell erzeugten monozygoten Zwillingsbullen.