| A large proportion of grain concentrate is frequently applied in the diet to meet the energy needs of animals for rapid fattening in the production mutton sheep of China duo to the shortage of high-quality roughage resources.However,long-term feeding of high concentrate diets will lead to disorders of rumen metabolism and cause subacute rumen acidosis(SARA).A large number of gram-negative bacteria in the rumen die under low rumen pH and release their cell wall component lipopolysaccharide(endotoxin)into the blood,which induces inflammatory response in the body and adversely affects the health and performance of mutton sheep.Flavonoids have the properties of anti-inflammation,antimicrobial and antioxidation,which can regulate rumen fermentation,inhibit the growth of harmful bacteria such as Escherichia coli and Clostridium perfringens,and optimize the microflora of digestive tract.Citrus is one of the main fruits in China,citrus peel and other by-products contain a large number of citrus flavonoids,citrus flavonoids as one of the natural plant-derived flavonoids,it may be able to reduce the side effects of feeding high concentrate feed by regulating rumen fermentation and microflora of ruminants.Therefore,in this experiment,citrus flavonoids-naringin were added to the high-concentration diet to explore the effects of naringin on rumen fermentation and microbiota,inflammation and growth performance of mutton sheep.The purpose of this paper is to provide experimental basis for the application of naringin in the actual production of mutton sheep.Trial 1.The effect of high concentrate substrate supply with naringin on the in vitro rumen fermentation parameters.In this experiment,batch culture technique was used to explore the effect of naringin on rumen fermentation parameters.Three goats with permanent fistula were selected as rumen fluid donors,and the culture substrate was high concentrate diet(concentrate/forage ratio 70:30).Groups CON,L,M and H were supplemented with 0,0.3,0.5 and 1.0 g/kg naringin(dry matter basis)respectively.The fermentation both pH and rumen fermentation parameters were determined at 6,12 and 24 hours after fermentation.The results showed follows:(1)At 6 h of fermentation,compared with group CON,the pH of fermentation both of group L,M,and H had no significant difference(P>0.05);At 24 h of fermentation,the pH of fermentation both of group L,M,and H was significantly lower than that of group CON(P<0.05).(2)Compared with group CON,the concentration of TVFA,the proportion of acetate increased significantly(P<0.05),and the proportion of Propionate decreased significantly(P<0.05)in group L,M and H;In addition,the proportion of valerate in group L,M and H was significantly lower than that in group CON(P<0.05);At 24 h of fermentation,the proportion of butyrate in the fermentation both of groups M and H was significantly higher than that of group CON(P<0.05);There was no significant difference in the concentration of lactic acid in the test group during the fermentation period(P>0.05).(3)Compared with the CON group,there was no significant difference in the cumulative gas production of L and M groups in vitro at 24 h(P>0.05),but the H group had a tendency to increase compared with the CON group.(4)At 24 h of fermentation,the relative abundance of lactic acid-producing bacteria Streptococcus bovis,lactic acid-utilizing bacteria Selenomonas ruminantium and Megasphaera elsdenii were not significantly different(P>0.05)Trial 2.The effect of naringin supplementation on rumen fermentation parameters,microbial community structure and feces metabolites of goats fed high concentrate diet.Twenty-four Boer goats with initial weight of 29 ± 1.5kg were randomly divided into 3 groups with 8 goats in each group.The experimental treatments was divided into three groups:low concentrate diet group(CON),high concentrate diet group(HC),high concentrate diet plus naringin group(THC).The trial period was 42 days and the pre-trial period was 7 days.The sheep were fed 0700 and 1700 daily,and the sheep were fed and drank freely.At the end of the experiment,the rumen fluid of the goat was collected to detect the pH value,the content of short-chain fatty acid(SCFA),the rumen microflora and the content of endotoxin(LPS)in the rumen fluid;Collect uncontaminated feces of each test sheep to determine fecal parameters and microbiota.The initial body weight and final weight of each sheep were recorded for two consecutive days at the beginning and end of the experiment,and the daily feed intake was recorded to calculate the average daily gain(ADG)and average daily feed intake(ADMI).The results showed follows:(1)Compared with the CON group,the final weight and ADG of the test sheep in the HC and THC groups were significantly increased(P<0.05),and the feed-to-gain ratio was significantly reduced(P<0.05),but there was no significant difference between the HC and THC groups(P>0.05).(2)Compared with CON,the HC and THC groups significantly reduced the pH of the rumen fluid(P<0.01),but compared with the HC group,the addition of naringin significantly increased the pH of the rumen fluid(P<0.05).(3)Compared with CON,HC significantly reduced the proportion of acetate in the rumen fluid(P<0.01)and significantly increased the proportion of valerate(P<0.05);The proportion of butyrate in rumen fluid of THC group was significantly higher than that of HC group(P<0.05),and the proportion of valerate was significantly lower than that of HC group(P<0.05);Compared with CON group,the concentration of lactic acid in rumen fluid of HC group was significantly increased(P<0.05),the concentration of lactic acid in the rumen fluid of the THC group was significantly lower than that of the HC group(P<0.05),but there was no significant difference from the CON group(P>0.05).(4)Compared with the HC group,there was no significant difference in the rumen microbial alpha diversity index between the CON group and the THC group(P>0.05).(5)At the phylum level,Firmicutes has the highest relative abundance in the HC and THC groups,and the relative abundance of Bacteroidetes is the highest in the CON group;Compared with the HC group,THC significantly increased the relative abundance of Bacteroides(P<0.05).(6)At the genus level,Prevotella,Ruminococcus and Rikenellaceae_RC9_gut_group are the dominant genera in the CON group,HC group and THC group,respectively.compared with HC group,THC group significantly increased the relative abundance of Rikenellaceae_RC9_gut_group(P<0.05),and significantly decreased the relative abundance of Lachnospiraceae_ND3007_group(P<0.05).(7)Compared with CON group,HC group significantly increased the proportion of propionate and valerate in feces(P<0.05);Compared with the HC group,the proportion of propionate in the THC group was significantly reduced(P<0.05),and the proportion of butyrate was significantly increased(P<0.05).(8)At the bacterial phyla level,Firmicutes and Bacteroidetes had the highest relative abundance among the three groups of tested sheep fecal microbiota;At the bacterial genus level,Ruminococcaceae-UCG-005 is the dominant genus of the CON and THC group,and Succinivibrio is the dominant genus of the HC group;Compared with the CON group,the HC group significantly reduced the relative abundance of Ruminococcaceae UCG-005(P<0.05),and the relative abundance of Prevotella increased trend.(9)Compared with the CON group,the LPS content in the rumen of the HC group was significantly increased(P<0.05).The LPS content in the rumen of the THC group was significantly reduced after naringin was added to the diet(P<0.05),but there was no significant difference compared with the CON.Trial 3.The effect of naringin supplementation on blood biochemistry,inflammation and antioxidant capacity of goats fed high concentrate diet.Before the end of the test,blood was collected from the jugular vein of the test sheep and centrifuged to determine the blood biochemistry,inflammation and antioxidant capacity of the body.The results showed follows:(1)Compared with the CON group,the concentration of triglyceride in HC group was significantly increased(P<0.05);Compared with HC group,alanine transaminase activity and triglyceride concentration in THC group were significantly decreased(P<0.05),and creatinine content was significantly increased(P<0.05).However,there was no significant difference between CON group and CON group(P>0.05).(2)Compared with CON group,the contents of tumor necrosis factor-α(TNF-α)and interleukin-6(IL-6)in serum of HC group were significantly increased(P<0.05),and compared with HC,HCT significantly decreased the contents of TNF-α and IL-6(P<0.05).(3)The levels of LPS binding protein(LBP),haptoglobin(Hp)and serum amyloid A(SAA)in the HC group were significantly higher than those in the CON group(P<0.05);Compared with HC,THC was significantly lower the content of SAA(P<0.05).(4)Compared with the CON group,the serum malondialdehyde(MDA)content in the HC group was significantly increased(P<0.05),and the glutathione peroxidase activity(GSH-Px)was significantly decreased(P<0.05);Compared with HC group,the content of malondialdehyde(MDA)in THC group was significantly decreased(P<0.05),and the activity of glutathione peroxidase(GSH-Px)was significantly increased(P<0.05),but there was no significant difference compared with CON group(P>0.05);In addition,the CON group and the THC group had higher superoxide dismutase(SOD)activity,but the difference was not significant compared with the HC group(P>0.05). |
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