| Chestnut tannin,as a natural plant polyphenol,not only has healthcare function but also popularized value in animal feed industry.In this study,a total of 90 healthy 3-month-old weaned Hu male lambs were randomly divided into 3 groups(n=30),with 30 replicates in each treatment and one sheep in each replicate.There was no significant difference at initial body weight among three groups.Each sheep was fed in single column,and each group was fed by TMR(total mixed rations)pellet feed with chestnut tannin level,including 0%(CK),0.3%(CT3)and 0.6%(CT6).The experiment was undergone three stages: transitional period(14 d),pre-feeding period(7 d),and formal feeding period(90 d).Finally,the optimal level of chestnut tannin in feed was determined based on growth performance,digestion and metabolism indexes,slaughter indexes and meat quality according to feeding test,the digestion and metabolism test and slaughter experiment.The main findings are as follows:(1)The effects of chestnut tannin on the growth performance,digestive and metabolic indicators of Hu lambs.The additional level of different levels of chestnut tannin had no significant effect on the growth performance,apparent digestibility and nitrogen apparent retention rate of Hu male lambs(P>0.05);the addition of 0.3% chestnut tannins had the highest final body weight(46.48 kg).The final body weight was increased by 7.51%.The study found that the average daily gain of CT3 group at 0~21d and 64~90d feeding stages was significantly higher than the other two groups(P<0.05),which indicated that the addition of 0.3% chestnut tannin was beneficial to the early growth of the Hu lambs.The addition of chestnut tannin has a tendency to reduce the feed intake of DM(Dry matter),OM(Organic matter),ADF(Acid detergent fiber)and NDF(Neutral detergent fiber)(P>0.05).(2)The effects of chestnut tannin level on the slaughter performance and meat quality of Hu lambs.Fifteen sheep with similar body weight from each group were slaughtered to compare slaughter performance among three groups.The results revealed that the body weight before slaughter of CT3 group was significantly higher than CT6 and CK groups(P<0.01),while CT6 group had a larger liver index than CT3 and CK groups(P<0.01),For meat quality,addition of chestnut tannin significantly decreased the b*24h and shearing force values of longissimus dorsi(P<0.05),while no significant effects were observed in cooking loss and drip loss(P>0.05).In addition,the water pressing loss of CT6 group was significantly lower than CK and CT3 groups(P<0.01).(3)The effects of chestnut tannin level on the shelf life and antioxidant index of Hu lambs.The shelf life of CT3 and CT6 was 115.2 h and 111.9 h acrroding to the dection of TVB-N(Total volatile basic nitrogen)content in longissimus dorsi,which was 8.7 h and 5.4 h longer than CK group,respectively.The result indicates chestnut tannin can prolong shelf life of mutton.No significant effect of adding chestnut tannin was found in the TC(Total cholesterol)and TG(Total triglycerides)content of serum at different growth stage of Hu lambs(P>0.05).Addition of chestnut tannin can significantly decrease MDA(malondialdehyde)content in serum and muscle(P<0.01),with that CT3 group is better than CT6,late stage is better than early stage,indicating chestnut tannin can enhance antioxidant ability.The addition of 0.3% chestnut tannin significantly increased the contents of T-AOC(total antioxidant capacity),GSH-PX(Glutathione peroxidase),SOD(Superoxide dismutase)and CAT(Catalase)in the muscle(P<0.01).In summary,the addition of chestnut tannin in the diet can slow down lipid peroxidation,improve endogenous antioxidant defense system,and prolong shelf life of sheep meat.Comprehensively,0.3% is the optimal adding ration in animal feed. |
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