407 VETERINARSKA STANICA 50 (5), 2019. ORIGINAL SCIENTIFIC ARTICLE / IZVORNI ZNANSTVENI ČLANAK Effect of buserelin acetate and gonadorelin treatments on reproductive performance in Croatian Big Silver Marten rabbits after natural mating D. Đuričić*, I. Žura Žaja, H. Valpotić, M. Kovačić, N. Maćešić and M. Samardžija Dražen ĐURIČIĆ*, DVM, PhD, Scientific Advisor, Assistant Professor, (Corresponding author: e-mail: djuricic@vet.hr), Veterinary Practice d.o.o. Đurđevac, Đurđevac, Croatia; Ivona ŽURA ŽAJA, DVM, PhD, Assistant Professor, Hrvoje VALPOTIĆ, DVM, PhD, Associate Professor, Nino MAĆEŠIĆ, DVM, PhD, Associate Professor, Marko SAMARDŽIJA, DVM, PhD, Full Professor, Faculty of Veterinary Medicine, University of Zagreb, Croatia; Mislav KOVAČIĆ, DVM, PhD, Mountrade d.d. Garešnica, Croatia Abstract The goal of this study was to determine the effects of GnRH analogue treatments on reproductive performance of naturally mated Croatian Big Silver Marten (CBSM), an indigenous rabbit breed. A total of six fertile bucks and 36 sexually mature CBSM rabbit does (8-10 months of age) were divided into three groups for this study. Two groups were treated after natural mating: the first group (n=12) received 0.25 mL Receptal ® (RPL) intramuscularly, containing 0.84 μg buserelin acetate, while the second group (n=12) received 0.25 mL Fertagyl ® (FGL) containing 20 μg gonadorelin. The third group (n=12) was comprised of untreated does as the control (CON) group. Each group of does mated with a male from another group after the next lactation. After 35 days of lactation, kits were weaned. All females (n=36) had three liers with an average lier size of 8.01 newborns (dead or alive), or 865 in total following 108 successful matings. Total neonatal losses until weaning at 35 days of age were 30.52% (n=263): stillbirth 9.71% (n=84), 8.79% died within first 7 days of life (n=76), 6.24% died from 8 to 21 days (n=54), and 5.78% died from 22 days until weaning at 35 days (n=50). Nulliparous does had a lower lier size than primiparous and secundiparous does (7.78 vs. 8.06 and 8.19, respectively). Reproductive performance, including kindling rate and lier size at birth and weaning (at 35 days of age), was significantly beer in the RPL and FGL groups than in the CON group. Key words: Buserelin; Gonadorelin; Preweaning mortality; Rabbit; Reproduction