| In this study,the model animals SD rats(Sprague-Dawley Rats)were subjected to orally acute toxicity and sub-acute toxicity test.The toxicological changes of general behavior,state,hematology,serum biochemical and pathological indicators in all test animals were observed.To evaluate the initial safety of mulberry leaves,the no-observed-adverse-effect-level(NOAEL)was determined,and the dose-response relationship was investigated.The rumen fistula test was performed to make clear the ruminal degradation of mulberry leaves in beef cattle.At the same time,the mulberry leaf feeding beef cattle test was carried out.And the slaughter performance and organ by-products of the beef cattle at the end of the feeding test were studied.The quality of the mulberry leaf fed test beef was analyzed and compared to comprehensively evaluate the feeding value.In this study,the toxicity evaluation,ruminal degradation of mulberry leaf,silage treatment and feeding effects of mulberry leaves were determined in order to ensure the feeding safety of mulberry leaves.It provides theoretical basis for safety and feeding value for mulberry leaves as an animal feed,and offers technical support for the transformation of mulberry industry,the development of grass and animal husbandry,and the cross-coupling of related industries.(1)The results of the acute toxicity test showed that no-observed-adverse-effect-level of the mulberry leaf test substance in the mouse was 12 g/kg·BW.Under these conditions,no death or abnormal toxicity of the mice occurred.so it can be determined actually non-toxic substances.(2)Sub-acute toxicity test results indicated that there were no significance in the general behavior,state,body weight,feed intake,hematological index,coagulation index,blood biochemical index and histopathological index in all treatment SD rats.Although there were some abnormal indicators,it has not toxicological significance(P>0.05).It was initially verified that mulberry leaves have certain safety.And under the test conditions,the non-toxic reaction dose(NOAEL)was up to 2.00 g/kg.(3)The results of ruminal degradation test showed that OM,CP,DM,NDF and ADF tend to degrade stably within 36 h,then slowly degrade;And the degradation rate of all these indexes increased with the prolongation of mulberry leaves in beef cattle.The maximum degradation rate were reached at 72 h.The effective degradation rates were 68.45%,74.42%,68.14%,54.20%,and 14.94%,respectively.(4)The slaughter performance test results showed that Yunling cattles fed with mulberry leaves had no adverse effect on the growth performance and slaughter performance.And it could be used to replace the protein source in some concentrates.Mulberry leaves can produce lipid-lowering effects on beef cattle organs,but the reduction is limited.The by-products of organs still have good high-fat performance,and the palatability and edibleness are strong,and the development potential is huge.(5)The meat quality test showed that the beef cattle fed with mulberry leaves were rich in beef,minerals and amino acids.The performance of the color of the beef showed that L *and a * is higher,the flesh is bright.And the color of meat is dark red,which means it is good.The meat protein content is high,the acidity and alkalinity are moderate.In addition,the water content of the beef is low,and the meat loss rate is low.Moreover,the shearing force of the beef is low,and the tenderness is good.Compared with the control group,the beef from cattle fed with the mulberry leaves,had more intramuscular fat content and better fat deposition.The mulberry leaves did not affect the intermuscular fat deposition and had the potential to develop high-grade meat. |
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