Background: Probiotics are direct-fed microbial feed supplements which can modulate the gut microflora by competing intestinal pathogens through a competitive process. The present study was conducted to investigate the effect of feeding Saccharomyces cerevisiae, Bacillus subtilis or their mixture on blood biochemical constituents, intestinal pathogenic load and intestinal histological changes of growing New Zealand White (NZW) rabbits. Results: Serum total protein, albumin, and globulin were (P ≤ 0.05) increased for rabbits fed supplemented diets. Microbial pathogenic load of small intestinal and caecal contents (E. coli and C. perfringens) showed reduction (P ≤ 0.05) for rabbits fed supplemented diets, while, lactobacillus spp. recorded higher counts (P ≤ 0.05) in intestinal and caecal contents of rabbits fed probiotics supplemented diets than control group. Small intestine length, villus height and crypt depth were higher (P ≤ 0.05) with probiotic diets than control. Musculosa depth was depressed (P ≤ 0.05) with probiotic diets. Conclusions: It could be concluded that the addition of Bacillus subtilis or Saccharomyces cerevisiae to diets of growing NZW rabbits by 0.1% is recommended to minimize the pathogenic intestinal load and increasing of beneficial lactobacillus strains as well as improving the intestinal barriers integrity.

Forty-five growing New Zealand White (NZW) male rabbits weighed 750.0 ± 5.8 g aged 6 weeks were used in a feeding experiment lasting 56 days. Rabbits were housed in a semi-climatic chamber at a mean ambient temperature of 33.1°C and relative humidity of 43%. The rabbits were placed in three equal groups of five replicates. The first group was fed on free moringa diet (control, R1), while R2 and R3 groups were fed diets supplemented with 0.5% and 1.0% moringa dry leaves respectively. Daily feeds and water were offered ad libitum. At the end of the feeding period, three random animals of each group were slaughtered to investigate intestinal and caecal contents of pathogens and changes of intestinal and caecal tissues. The results indicated that there were no statistical differences among groups concerning daily feed intake, average daily gain and feed conversion ratio; however, slight improvement was noticed with rabbits fed R3. Intestinal microbial load, namely total plate count of Salmonella, Escherichia coli, Staphylococcus aureus, Clostridium perfringens and mould, was reduced (P < 0.01) with R2 and R3 diets compared with the control (R1). A similar trend was also noticed on caecal microbial load. Histological examination of jejunum tissues showed clear increases in villus height, villus : crypt ratio and obvious depth of caecal tunica mucosa, which might reveal better absorption of nutrients and microbial metabolites. It could be concluded that rabbits fed moringa-supplemented diets showed better feed conversion and intestinal and caecal histological structure, with clear reduction of gastro-intestinal pathogenic bacterial load under the hot climatic conditions.

The present study was conducted to investigate the effects of feeding corn silk, orange peel, and pomegranate peel extracts on semen quality, blood biochemical constituents, antioxidants capacity of male New Zealand White rabbits under heat stress conditions. In an experiment that lasted 8 weeks, thirty male rabbits aged twenty-four weeks with an average body weight of 2.85±0.1kg were randomly distributed into five equal groups (6 rabbits/ group). Each rabbit was kept in an individual cage. The first group (control) was fed a basal diet. The second group (positive control) was fed the basal diet supplemented with vit E. at a level of 250 ppm. The third, fourth, and fifth groups were fed the basal diet supplemented with corn silk, orange peel, and pomegranate peel extracts at a level of 150 ppm, respectively. Experimental diets were offered ad-libitum and clean drinking water was freely available. The overall average of ambient temperatures and relative humidity were 31.1°C and 62.5%, respectively. Overall temperature-humidity index (THI) through the experimental period was 29.14 indicating severe heat stress conditions. According to the results of the HPLC screening for the different extracts: ferulic acid, cinnamic acid and coumaric acid were the most abundant polyphenols in orange peel extract, while gallic acid was the most abundant polyphenol in pomegranate peel extract. Semen quality parameters improved in rabbits of orange peel and corn silk groups, opposite to rabbits fed pomegranate peel extract. The activity of seminal catalase and glutathione peroxidase increased in rabbits fed orange peel and corn silk extracts. Blood total proteins, albumin, globulins and creatinine were not affected by different antioxidants supplements. Serum total antioxidants capacity, catalase and superoxide dismutase were significantly increased in all experimental groups compared with the control. In conclusion, the current results showed that using orange peel or corn silk extracts as feed supplements at a level of 150ppm could improve semen quality as well as antioxidants capacity of male rabbits reared under heat stress conditions.