Effect of dietary mannan-oligosaccharides on some blood biochemical, haematological parameters and carcass traits in purebred New Zealand White and crossbred rabbits

This study examined the effect of dietary treatments containing mannan-oligosaccharides (MOS) on some blood biochemical, haematological parameters and carcass traits of 60 weaned purebred New Zealand White (NZW) and New Zealand White x Rex (NZW x RX) crossbred rabbits. They were assigned to a 2 x 3 factorial arrangement (two genetic groups; and three dietary treatments of zero, 0.5 or 1.0 g MOS/kg of diet). Blood samples have been collected at slaughter at 10 weeks of age. Significant differences were observed among dietary treatments for all biochemical and haematological parameters with the exception of triglycerides. There was a genetic group and dietary treatment interaction for albumen (P < 0.001), cholesterol (P = 0.002), red blood cell count (RBC) (P = 0.007), haemoglobin (Hb) concentration (P = 0.009) and haematocrit % (P < 0.001) observed. Rabbits from the NZW x RX genetic group fed a diet with 1.0 g/kg MOS had the highest plasma cholesterol level (0.97 +/- 0.012 mmol/L), whereas the lowest level (0.89 +/- 0.012 mmol/L) was detected in rabbits from the NZW x RX genetic group fed the Control diet. Rabbits from the NZW genetic group fed the diet with 1.0 g/kg MOS had the highest RBC (4.27 +/- 0.083 x 10(6)/mm(3)) whereas rabbits from the same genetic group fed the diet with 0.5 g/kgMOShad the highest Hb concentration (11.43 +/- 0.097 g/dL) and haematocrit (30.29 +/- 0.163%). Some carcass traits such as liveweight, hot and reference carcass weight (P < 0.001), percentage of periscapular, and perirenal fat relative to reference carcass weight (P < 0.05) were significantly affected by the dietary MOS supplementation. In conclusion, MOS supplementation in the diet, especially 1.0 g/kg, improved immunity, health indicators in the blood, liveweights and carcass weights of rabbits without any harmful effects on the other carcass traits. Furthermore, purebred NZW and NZW x RX crossbred rabbits showed relatively similar performance for all traits of interest. A significant interaction between genetic group and dietary supplementation of MOS was shown for albumen, cholesterol, RBC and haematocrit %.