Effect And Mechanism Of Curcumin On Growth Performance,Intestinal Environ-Ment And Antioxidant Capacity Of Meat Rabbit

Rabbit is a small herbivore,which has the characteristics of strong reproduction and rough feeding tolerance.China is the largest country in raising rabbits in the world,and rabbit meat production accounts for more than half of the world.Rabbit meat is a kind of healthy and nutritious animal product with the characteristics of high protein,low fat and low cholesterol.Since antibiotics were banned in feed,it has become a hot spot in rabbit nutrition research to screen the suitable feed additives for meat rabbits.Curcumin is a kind of natural plant extract.A large number of applications in livestock have proved that curcumin has the effects of antibacterial,antioxidant and anti-inflammatory,which can improve the health level and production performance of livestock and poultry.The purpose of this study was to investigate the effects of different levels of curcumin on growth performance,nutrient digestibility,intestinal structure,digestive enzyme activities,flora balance,and antioxidant capacity of meat rabbits.(Methods)One hundred and sixty 35-day-old healthy Ira meat rabbits with similar body weight were randomly divided into four groups,40 replicates in each group,one rabbit in each replicate.The control group was fed with the basic diet,and the experimental group was fed with the experimental diet supplemented with 50 g/t,100 g/t and 150g/t curcumin,respectively.The pre-trial period was 7d and the positive trial period was 21 d.The results showed that:1.Compared with the control group,the weight gain of the experimental group was increased by 3.26%–11.67%(P<0.05),the feed intake was increased by0.71%–6.38%(P<0.05),and the specific gravity reduction was reduced by2.17%–3.22%(P<0.05).2.Compared with the control group,the energy utilization rate and the ap-parent protein digestibility of the experimental group were increased by 0.48%-9.49%(P<0.05),2.19%-7.22%(P<0.05),respectively.The apparent digestibility of crude fat was increased by 3.79%-5.25%(P<0.05).The apparent digestibility of crude fiber was increased by 27.32%-68.50%(P<0.05).The apparent digestibility of NDF and ADF were increased by 28.41%–35.87%(P<0.05)and 28.93%–97.38%(P<0.05).3.Compared with the control group,the length of jejunal villus in the ex-perimental group was increased by 4.36%–16.61%(P<0.05),the depth of crypt was decreased by 5.89%–15.06%(P<0.05),the ratio of villus to crypt was increased by12.71%–25.67%(P<0.05),the thickness of intestinal wall was Decreased by8.84%–11.83%(P<0.05),and the thickness of cecal mucosa was increased by8.98%–18.39%(P<0.05).The intestinal wall thickness was increased by11.86%–38.97%(P<0.05).4.Compared with the control group,the SOD activity of the experimental group was increased by 6.36%-7.85%,the CAT activity was increased by 14.42%-27.67%,and the MDA content was decreased by 4.80%-12.98%.The expressions of Nrf2 m RNA,Keap1 m RNA,Mapk1 m RNA and NQO1 m RNA in the liver and jejunum were significantly increased(P<0.05).The relative abundance of O＿Lactobacilles,F＿Lactobacillae and G＿Lactobacillus in cecum was increased remarkably and the microecological balance was improved.In conclusion,the optimal dosage of curcumin in meat rabbit diet was 100 g/t.