Growth Performance and Health Responses of Growing New Zealand White Rabbits Fed Different Levels of Dietary Synbiotic Supply

Countering the antibiotics excessive use by the exploitation of promising immunostimulants alternatives is a trending strategy in modern animal husbandry. This research assessed the impact of novel dietary symbiotic supply at different levels on growing rabbits’ performance. Forty-five New Zealand White rabbits (aged seven weeks, weighing 1075 ± 9.78 g) were randomly allotted to five groups. Rabbits were fed the basal diet as control and the other groups supplemented with synbiotic (Saccharomyces cerevisiae along with β-glucan and mannan-oligosaccharide) at an inclusion level of 0.5, 1.0, 1.5, and 2.0 g/kg diet for 6 weeks. Results indicated that synbiotic addition increased the feed intake (p=0.01), enhanced the growth performance and feed conversion ratio (linear, p≤0.001; quadratic, p≤0.002) with the 0.5 g/kg diet level being the most effective. The synbiotic supply increased the serum total protein and albumin (quadratic, p≤0.024) as well as lipase and amylase (linear, p<0.001; quadratic, p=0.001), while decreased alanine-aminotransferase, urea, triglycerides, and glucose (quadratic, p≤0.023) as well as cortisol (linear, p<0.001; quadratic, p≤0.001). The concentrations of immunoglobulin-G, immunoglobulin-M, red blood cells, hemoglobin, hematocrit, and platelet count increased (linear, p≤0.001) and white blood cells decreased (linear, p<0.001) by the synbiotic inclusion. The hot carcass weight and the percentages of dressing, and carcass cuts were increased (quadratic, p≤0.02) in which the 0.5 g/kg diet level was better. Taken together, the current dietary synbiotic supplementation of 0.5 g/kg diet could pave the way for promoting the rabbits’ growth and health status, thus, it is advisable to utilize these findings in the husbandry of rabbits under commercial production conditions.