title: Effect of vaccination against gonadotropin-releasing factor (GnRF) with Bopriva® in the prepubertal bull calf.
abstract: The aim of this study was to evaluate the effect of immunization against gonadotropin-releasing factor (GnRF) with Bopriva(®) (Pfizer Animal Health, Parkville, Australia) in prepubertal bull calves. For the study, 6 calves were vaccinated at the age of 3 and 6 weeks with 1 mL Bopriva(®), and 6 animals served as matched controls. Concentrations of GnRF antibodies, testosterone and LH were determined in serum samples out to 30 weeks after the first immunization. Body weight and scrotal circumference were measured for 59 weeks. At slaughter, 65 weeks after the first immunization, the quality of epididymal sperm was evaluated. The results showed that vaccination against GnRF influenced (P<0.05) anti-GnRF titer, LH and testosterone concentrations as well as scrotal circumference. Antibody titers significantly (P<0.05) increased after the booster vaccination and reached peak values 2 weeks later. Compared to control animals, inhibition (P<0.05) of the prepubertal LH secretion was observed in vaccinated calves at weeks 10 and 12-14 after the first vaccination. In vaccinated calves testosterone concentrations decreased after the booster injection to values below 0.5 ng/mL serum and remained for at least 22 weeks at this low level. Animals vaccinated with Bopriva(®) showed a delay in testes growth and smaller scrotal circumference. Puberty occurred at the age between 46 and 55 weeks in vaccinated and between 38 and 52 weeks in control animals and body weight gain was similar in both groups. All vaccinated bulls attained spermatogenic capacity at slaughter when they were 68 weeks old.
authors.affiliation: Clinic of Reproductive Medicine, Vetsuisse-Faculty University of Zürich, Switzerland. fjanett@vetclinics.uzh.ch
authors.forename: F
authors.initials: F
authors.lastname: Janett
authors.forename: T
authors.initials: T
authors.lastname: Gerig
authors.forename: A C
authors.initials: AC
authors.lastname: Tschuor
authors.forename: S
authors.initials: S
authors.lastname: Amatayakul-Chantler
authors.forename: J
authors.initials: J
authors.lastname: Walker
authors.forename: R
authors.initials: R
authors.lastname: Howard
authors.forename: M
authors.initials: M
authors.lastname: Piechotta
authors.forename: H
authors.initials: H
authors.lastname: Bollwein
authors.forename: S
authors.initials: S
authors.lastname: Hartnack
authors.forename: R
authors.initials: R
authors.lastname: Thun
mesh_terms: D000818:Animals; D001835:Body Weight; D002417:Cattle / Q000276:immunology*; D007987:Gonadotropin-Releasing Hormone / Q000037:antagonists & inhibitors / Q000276:immunology*; D007986:Luteinizing Hormone / Q000097:blood; D008297:Male; D009929:Organ Size; D011897:Random Allocation; D012611:Scrotum / Q000276:immunology; D012741:Sexual Maturation / Q000502:physiology; D018709:Statistics, Nonparametric; D013737:Testis / Q000276:immunology; D013739:Testosterone / Q000097:blood; D014611:Vaccination / Q000379:methods / Q000662:veterinary*
chemical_list: D007987:Gonadotropin-Releasing Hormone; D013739:Testosterone; D007986:Luteinizing Hormone