Abstract:

The aim of this experiment was to investigate the effects of dietary fucoidan at different levels on the growth performance， slaughter performance， internal organ indexes， serum biochemical indexes， and the apparent digestibility of nutrients in meat rabbits. The ultimate aim of this research was to provide a theoretical basis for the use of fucoidan as an antibiotic substitute in the diet of meat rabbits. Thirty-six healthy rabbits with similar body weight were selected from 200 weanling Fujian yellow rabbits at 35 days of age， and were randomly assigned to four groups （three replicates of three rabbits per group）. Rabbits in the control group were fed with a basal diet while those in experimental groups I， II， and III， were fed diets supplemented with 100， 200， and 300 mg·kg^-1 fucoidan， respectively. The pre-trial period was 5 days and the experimental period was 22 days. The main findings were as follows： 1） The final body weight， average daily feed intake （ADFI）， and average daily gain （ADG） were significantly higher in group III than in the control group （P<0.05） and the feed to gain ratio （F/G） was significantly lower in group III than in the control group （P<0.05）. 2） The live weight before slaughter was significantly higher in group III than in the control group （P<0.05）； But the other indexes were not significantly different among the treatment groups and the control （P>0.05）. 3） The thymus index was higher in all of the experimental groups than in the control group （P<0.05）. The spleen index and round cyst index did not differ significantly among the treatment groups and the control （P>0.05）. The protrusion index was significantly higher in groups II and III than in the control group （P<0.05）； But the other indexes showed no significant differences among the treatment groups and the control （P>0.05）. 4） The levels of alanine aminotransferase were significantly lower in group III than in the other groups （P<0.05）. The levels of low-density lipoprotein cholesterol and cholesterol were significantly lower in groups I and II than in the control group （P<0.05）. The activity of superoxide dismutase was significantly higher in group III than in the control group （P<0.05）. The levels of malondialdehyde were significantly lower all in all the experimental groups than in the control group （P<0.05）. The activity of glutathione peroxidase was significantly higher in the treatment groups than in the control group （P<0.05） and significantly higher in group III than in group I （P<0.05）； No significant differences were detected for the other antioxidant indices （P>0.05）. 5） The apparent digestibility of dry matter （DM）， neutral detergent fiber （NDF）， and crude ash （Ash） were significantly higher in the experimental groups than in the control group （P<0.05）. The apparent digestibility of acid detergent fiber （ADF） was significantly higher in group III than in the control group （P<0.05）. The apparent digestibility of crude protein （CP） did not differ significantly among the treatment groups and the control. Together， these results show that dietary supplementation with fucoidan can significantly increase the ADFI and ADG， significantly decrease the F/G， improve internal organ indices and antioxidant capacity， and significantly improve the apparent digestibility of ADF， NDF， Ash， and DM in meat rabbits. On the basis of these results， the optimum dietary supplementation level of fucoidan for meat rabbits is 300 mg·kg^-1.

Key words: meat rabbits, fucoidan, growth performance, serum biochemical indexes, nutrient apparent digestibility