The aim of the study was to investigate the Eimeria spp. and Passalurus ambiguus infections of rabbits by day of life. From 2018 to 2024, pooled faecal samples were collected from 29 Hungarian and 2 Slovakian rabbit farms. Low level of Eimeria oocysts infection was observed during lactation. In the week following the weaning the proportion of positive samples increased. Between day 43 and slaughter age, the proportion of positive samples was consistently high. The average OPG values (number of Eimeria oocysts per gram faeces), never reached 5,000 during the lactation period, but a critical period started at 42 days of age, with average OPG values above 10,000 in several cases. High number of oocysts were observed until the end of fattening period. The exponential smoothing model estimated the onset of Eimeria infection at 38-40 days of age (p=0.023). The proportion of P. ambiguus eggs positive samples reached 50% already in the lactation period. From day 29 to slaughter age, a relatively low rate of infected samples was detected. For P. ambiguus, the model estimated 7 days of age as the increase (p=0.001) of infection. It can be concluded that P. ambiguus eggs and Eimeria oocysts can be detected in the faeces of rabbits during their whole life cycle. During the fattening period (5-11 weeks of age), the Eimeria infection is on high level while the P. ambiguus infection is in low level.

The effect of a dietary butyrate supplementation on the production of fattening rabbits was examined. The control group (n=70 rabbits) was fed with granulated diet whereas the diet of butyrate group (n=70 rabbit) was supplemented with 0.2% of butyrate. The mortality rate was examined on a larger population (n=1050 rabbits/group). Butyrate group had lower weight gain at the ages of 46-52 and 60-66 days (-20 and - 17 %, respectively; P>0.001) but higher weight gain at 53-59 days of age (+13%; P<0.05). Butyrate group consumed less feed than the control group between 38-45, 46-52 and 60-66 days (-2.4%, P<0.001; -5.7%, P<0.01; - 4.9%, P<0.05, respectively). The feed conversion ratio of the butyrate group was worse between 46-52 days of age (+19%; P<0.01) but favourable at the ages of 53-59 and 67-73 days (-15% and -9%, respectively; P<0.05). Concerning the whole fattening period the weight gain, the feed intake and the feed conversion ratio of the groups did not differ. In the larger examined population, 4.0% and 6.3 % mortality was observed in the control and butyrate groups, respectively. The parasitological tests resulted only negative samples independently of groups. It can be concluded that dietary butyrate supplementation has not improved the performance of the growing rabbits.