Study On The Preventive Of Walnut Green Husk Extract On Subacute Ruminal Acidosis

The experiment was conducted to study the effects of walnut green husk extract on apparent digestibility Index,ruminal fermentation index,histamine,lipopolysaccharide and microbial diversity and function in sheep fed with high concentrate diet induced subacute ruminal acidosis.In this experiment,walnut green husk was extracted with ethyl acetate as solvent,and then the walnut green husk extract was obtained by rotary evaporation.Four healthy male sheep with an average weight of43.3 kg and a permanent rumen fistula were selected as experimental animals.Sara model was induced with 65:35 ratio of concentrate to roughage by 4 × 4 latin square design.0(control),0.125%,0.25% and0.5% walnut green husk extract were added into the basal diet.The 4-phase trial included pre-trial period of 9 days and sampling period of 8 days(5 days before sampling was for fecal collection,and 3 days after sampling was for rumen fluid).The results showed that:(1)The results showed that the addition of 0.125%,0.25% and 0.5% walnut green husk extract had no significant effect on the apparent digestibility of nutrients(P>0.05).(2)The results showed that the rumen p H was significantly increased by adding 0.125%,0.25% and0.5% walnut green husk extract(P<0.05),the number of protozoa and the concentration of ammonia nitrogen in rumen fluid were significantly decreased(P<0.05).Adding 0.125%,0.25% and 0.5% walnut green husk extract in diet significantly decreased the concentration of total volatile fatty acid,acetic acid,propionic acid,isobutyric acid,butyric acid and isovaleric acid in rumen fluid(P<0.05),and the ratio of acetate to propionate tended to be decreased(P=0.07).However,supplementation of 0.125%,0.250%and 0.500% extracts from walnut green husk significantly decreased the concentration of lactic acid and the activity of hexokinase,Lactate dehydrogenase and pyruvate kinase in rumen fluid(P<0.05),there was a tendency to decrease the activity of fructokinase 6-phosphate(P=0.098),but no significant effect on the activity of Amylase(P>0.05).When 0.125%,0.25% or 0.5% walnut green husk extracts were added to the diet,the abundance of microbial communities at Phyla and genus levels did not change significantly(P>0.05),the number of rumen bacteria and amylophilus were significantly increased(P<0.05),flbrinpgen succinate significantly decreased(P<0.05),but there was no significant change in vibrio ding,streptococcus bovis and anaerobic fungi(P>0.05).(3)The contents of histamine and lipopolysaccharide in blood and rumen fluid were significantly decreased by adding 0.125%,0.25% and 0.5% walnut green husk extract(P<0.05),the content of lipopolysaccharide in rumen fluid was significantly decreased(P<0.05),but there was no significant change in blood lipopolysaccharide(P>0.05).The results showed that walnut green husk extract could reduce the production of lactic acid,volatile fatty acid and ammoniacal nitrogen by regulating the rumen microflora,decreasing the activity of key enzymes in lactic acid synthesis and inhibiting the proliferation of Protozoa,it can improve the p H of rumen fluid,improve rumen fermentation,and alleviate the sheep SARA induced by high-concentrate diet by reducing the contents of histamine and lipopolysaccharide in rumen fluid and histamine in blood.The addition of 0.125% walnut green husk extract to the diet was helpful to alleviate SARA in sheep.