Evaluation of Chlorella vulgaris and Laurus nobilis as Feed Additives: Influence on Physiology of Nutrition in New Zealand White Rabbit

Dietary phytogenic additives and microalgae are increasingly investigated as natural alternatives to antibiotic growth promoters in rabbit production due to their potential effects on gut health and nutrient utilisation. This study evaluated the nutraceutical potential of Chlorella vulgaris and Laurus nobilis as plant-based additives for growing New Zealand White rabbits. A 45-day feeding trial was conducted using control and experimental diets enriched with 0.1% Chlorella and 0.1% Laurus. Productive performance, nutrient digestibility, blood biochemistry and faecal composition were monitored, and polyphenolic compounds were analysed in feed, blood, faeces and caecal microbiota using HPLC-DAD. Final body weight (3097 vs. 2909 g) and feed intake (142.7 vs. 145.0 g day−1) did not differ significantly between treatments. However, crude protein digestibility was significantly lower in the supplemented group than in the control group (54.39–47.79% vs. 63.73–62.33%; p < 0.05). Faecal chemical composition differed significantly between groups, particularly for dry matter, which was higher in the supplemented group across sampling times. Polyphenols detected across biological matrices confirmed the bioavailability of selected phytochemicals, with ferulic acid showing the highest stability. Correlation analysis indicated shared metabolic or absorptive pathways among several compounds. Overall, low-dose supplementation with C. vulgaris and L. nobilis appears safe and may support improved digestive physiology and nutrient utilisation without compromising rabbit health. Further research with larger sample sizes and detailed microbiome profiling is needed to clarify metabolic interactions and long-term effects of these nutraceutical strategies.