Effects Of Dietary Different Cystine Levels On Production Performance And Intestinal Microorganisms In Angora Rabbits

In this study,the effects of different levels of dietary cystine on hair production performance,serum biochemical indexes and intestinal microorganisms of Angora rabbits were investigated to select the optimal cystine content.A total of 180 five-month-old Angora rabbits with two cut hair and good health were selected and grouped according to no significant difference in the yield of two cut hair.A total of 180 Angora rabbits were divided into five groups with 36 rabbits in each group.The control group was fed corn-soybean meal basal diet,and the experimental groups were fed the basal diet supplemented with 0.1%,0.2%,0.3% and0.4%,respectively.Feeding arrangement adopts single cage,free feeding and drinking,feeding twice in the morning and evening every day.Pre-feeding lasted for 3 days,formal experiment lasted for 73 days and metabolic experiment lasted for 3 days.Results:(1)Effects of dietary different cystine levels on production performance.Diets supplemented with cystine in the diet and feed/wool ratio(P < 0.05).When the cystine supplemental level was 0.1%,the feed intake was significantly increased,the feed/wool ratio was significantly decreased,and the feed conversion rate was the highest.The fiber fineness and fracture strength of Angora rabbit hair were significantly different with cystine addition(P< 0.05),and showed an increasing trend.Cystine supplementation had a significant effect on the back hair length of Angora rabbits(P < 0.05).When cystine supplementation was 0.1%,the back hair length was significantly increased compared with the control group.The secondary hair follicle density of Angora rabbits was significantly affected by cystine supplementation(P< 0.05),and was significantly increased when cystine supplementation was 0.3% compared with control group.The primary hair follicle density was significantly increased when cystine supplementation was 0.1% and 0.4% compared with the control group(P < 0.05).Supplementation of cystine had significant effects on keratin related protein(KAP6.1)in hair follicle gene expression of Angora rabbits(P < 0.05).(2)Effects of dietary different cystine levels on digestion and metabolism.Dietary supplementation of 0.1% cystine significantly increased the apparent digestibility of serine,glycine,glutamate and cystine(P < 0.05).And the apparent digestibility of serine,glycine,glutamate and cystine showed an increasing trend.(3)Effects of dietary different cystine levels on serum biochemistry.Dietary cystine supplementation significantly decreased the content of triglyceride(TG)in serum of Angora rabbits(P < 0.05);The supplementation of cystine had no significant effects on immunoglobulin A(Ig A),immunoglobulin G(Ig G)and immunoglobulin M(Ig M)in serum of Angora rabbits(P > 0.05).The supplementation of cystine had significant effects on the activity of glutathione peroxidase(GSH-Px)in serum of Angora rabbits(P < 0.05),and showed an increasing trend with the increase of cystine supplemental level.(4)Effects of dietary different cystine levels on intestinal microbiome.Dietary 0.1% cystine can improve intestinal microbiome of Angora rabbits,and the proportion of verrucobacteria is significantly increased,which is beneficial to improve intestinal health of Angora rabbits.In conclusion,dietary cystine supplementation can improve the wool production performance,decrease the content of triglyceride in serum and increase the activity of glutathione peroxidase of Angora rabbits.When the cystine supplemental level was 0.1%,the wool production performance,the serum immunoglobulin content and intestinal microorganisms were improved and reached the optimal value.Therefore,the results of this experiment suggest that 0.1% cystine is the optimal supplemental level in the diet of Angora rabbits.