Effects Of Chinese Herbal Medicine On The Production Performance,Apparent Digestibility And Rumen Fermentation Of Fattening Sheep In Hot Season

Aiming at the current situation of sheep suffering from heat stress in summer,The objective of present study was to investigate the effects of compound Chinese medicine herb（CMH）alleviating heat stress on production performance,apparent digestibility,blood biochemical parameter,and rumen fermentation,and to evaluate the safety of CMH.The main contents are as follows:Experiment 1 Evaluation of acute toxicity on compound Chinese medicineThe purpose of the study was to verify the CMH safety.The lethal dose（LD50）of mice was measured when CMH was administrated orally,and the acute toxicity was also demonstrated at a maximum tolerance dose of CMH.The results showed that the LD50 on 14 d was over 21500 mg/kg.When mice were provided with maximum tolerance dose of CMH for 7 d,no poisonation was observed,and the feed intake and body weight of mice were not affected（P>0.05）.The hematological parameter（e.g.red blood cell,white blood cell,platelet,and so on）and serum physicochemical parameter（e.g.alanine aminotransferase,urea nitrogen,glucose,and so on）demonstrated no difference（P>0.05）.In addition,all organ coefficient(（e.g.heart,liver,spleen）had no difference（P>0.05）between the two groups.From microscopic observation of organ,no drug-related pathological change from organs was found.In summary,the CMH would be no toxic and side effect,and used safely and reliably in husbandry.Experiment 2 Effects of Chinese Herbal Medicine on the Production Performance,Apparent Digestibility and Rumen Fermentation of Fattening Sheep in Hot SeasonFour herbs,including Elsholtzia,Rhubarb,and Magnolia officinalis,were used and formulated.The 240 hybrid and late-fattening sheep（Small Tail Han Sheep × Inner Mongolia Fine Wool Sheep）with weight（36.61 ± 0.73 kg）were used and randomly divided into 4 groups,with 60 sheep each group,which were fed with 0%（control group）,0.5%,1.0%,or 1.5%of the CMH（dry matter basis）,respectively.The expermental period was 35 days.At the end of experiment,the performance,apparent nutrient digestibility,antioxidant enzyme activity and its conventional physibiological parameters in serum were measured.Moreover,the abundance and diversity of rumen microflora were analized by high-throughput sequencing technology（16S rRNA）.During entire experiment,the temperature and humidity index in sheep shed averaged 79.68,which indicated that the sheep were suffering from heat stress.The results showed that:（1）For physiological parameter,the various doses of CMH reduced respiratory rate of sheep（P<0.05）,and increased its lying rate;particularly during the period from 12:00 to 16:00,the lying rate increased by 13.38%to 19.15%,compared with the control.（2）For production performance,Among three CMH-fed groups,the ADG and feed-to-weight ratio（F/G）in 0.5%group was the highest,demonstrating an increase by 12.12%in ADG（P<0.05）and a decrease by 14.68%in F/G（P<0.05）,compared with the control.（3）For apparent digestibility,the 0.5%and 1.5%CMH increased apparent digestibility of crude fat by 3.19%and 4.07%,respectively,compared with the control（P<0.05）,and the digestibility of acid detergent fiber increased by 15.54%in 0.5%group（P<0.05）.（4）From blood physibiological paremeters,the serum thyroxine（T4）and cortisol（COR）levels in CMH-fed sheep showed increasing and decreasing trends,respectively（P<0.05）.Particularly in 0.5%group,the T4 content increased by 13.97%compared with the control（P<0.05）,while the COR content decreased by 33.15%（P<0.05）.There was also a difference in urea nitrogen or glucose（GLU）content among all groups（P<0.05）,suggesting that the GLU in 0.5%group was higher than that in the control（P<0.01）.From analysis of heat stress protein（HSP）,the HSP90 content in serum for three CMH-fed groups was lower than that for the control（P<0.05）,and the level in 0.5%group was the lowest（254.20 pg/mL）among all groups.Also,the HSP70 or HSP60 content in 0.5%group was lower than that in the control（P<0.05）.In addition,the antioxidant enzyme content involving superoxide dismutase（SOD）,catalase（CAT）,total antioxidant capacity（T-AOC）,and glutathione peroxidase（GSH-PX）increased（P<0.05）.（5）For rumen fermentation parameter,the CMH of 0.5%increased total volatile fatty acid,acetic acid and butyric acid content in rumen（P<0.05）,and reduced isobutyric acid content（P<0.05）.Though there was no difference in ethylene-to-propylene ratio among all groups（P>005）,the ratio showed a downward trend when sheep were fed CMH.（6）From rumen bacterial flora,the relative abundance and diversity of bacterial flora were changed by CMH on the basis on alpha diversity index（P>0.05）.From phylum level,Firmicutes and Bacteroidetes were the dominant flora in rumen.The Firmicutes abundance in 0.5%or 1.0%group was higher than that in the control（P<0.05）,while the Bacteroidetes abundance in 0.5%group was lower than that in the control（P<0.05）.From subordinate level,Prevotella in all groups showed an absolute advantage in rumen bacteria,and the Prevotella abundance in 0.5%or 1.0%group increased compared with the control（P<0.05）,while the abundance in 1.5%group showed a downward trend.Also,the abundance of NK4A214_genus in CMH-given groups increased（P<0.01）,and the abundance of Riyan bacteria_RC9_intestinal bacterium was enhanced by 0.5%or 1.5%CMH（P<0.05）.（7）From rumen archaeal flora,the dominant phyla in each group was Euryarchaeota,and methanobrevibacter accounted for the highest proportion among all genus,followed by Methanosphaera Methanosphaera.The abundance of Methanobrevibacter was decreased by the addition of CMH,demonstrating that the Methanobrevibacter in 1.0%group was lower with 6.88%than the control（P<0.05）;the abundance of Methanosphaera in three CMH group was higher than that in the control（P<0.05）.In summary,the CMH would effectively alleviate heat stress in fattening sheep,and the appropriate dose of CMH is suggested for 0.5%in diet（DM basis）.