| Soybean protein,as the main protein source in livestock and poultry production,is widely used in animal feed because of its better amino acid balance than other plant protein.However,there are many anti-nutritional factors in soy protein,including Trypsin inhibitor,soy agglutinin,soy antigen protein,lipoxygenase,etc.,how to remove and use it reasonably and effectively plays a very important role in intensive livestock production.Therefore,this experiment was conducted to study the effects of soybean active peptides produced by enzymatic hydrolysis of soybean meal on growth performance,immune function and antioxidant capacity of Holstein calves,the aim of this study is to use soy active peptides as a routine anti-inflammatory feed to alleviate the inflammatory reaction in intensive farming and to improve feeding efficiency.Trial 1:Effect of soybean active peptides on rumen fermentation parameters of calves in vitroIn this experiment,batch culture technique was used to investigate the effect of adding soybean active peptides on rumen fermentation parameters and microbial community structure in vitro.Three fistula cattle were selected as the donors of rumen fluid.The fermentation substrate was 1 g(60:40).The treatments was set as control group(CON),molecular weight less than 3000 Da(L group),molecular weight 30005000 Da(M group)and molecular weight more than 5000 Da(H group),respectively,soybean peptides were added 5 g/kg on the basis of dry matter.At 0,6,12,24 h determination of fermented liquid pH and rumen fermentation parameters,the results showed that:(1)With the progress of fermentation,the pH of the fermentation broth in the treatment group after adding soybean active peptide was significantly lower than that in the CON group(P<0.05),however,the pH of fermentation broth in all treatment groups was within the normal range during the whole stage.In addition,the concentration of NH3-N and the content of microbial protein in the fermentation broth of M and H groups were significantly higher than those of CON group at 24h(P<0.05),the content of microbial protein in L group was significantly higher than that in CON group(P<0.05),but the concentration of NH3-N in L group was not significantly different from that in CON group.(2)compared with CON group,the concentration of TVFA,the concentration of propionic acid and butyric acid were significantly increased in the treatment group(P<0.05)the valeric acid content in the fermentation broth of each treatment group was significantly lower than that of the CON group(P<0.05).(3)In fermentation for 24 h,the relative abundance of S.bovis in the fermentation broth of L group and M group was significantly decreased(P<0.05).At the same time,the relative abundance of B.fibrisolvens and R.flavefaciens in the fermentation broth increased significantly(P<0.05).(4)In addition,there was no significant difference in cumulative gas production at 24 h in vitro in the treatment group supplemented with soybean active peptides.The results showed that adding soybean active peptides could improve the rumen fermentation.In addition,the addition of soy peptides can also regulate the relative abundance of rumen microorganisms,mainly in the addition of low molecular weight soy peptides can increase the number of cellulose-degrading bacteria in the rumen.Trial 2:Effects of soybean active peptides addition in diets on growth performance,microbial community structure and metabolites of calvesIn this experiment,24 Holstein bull calves with initial body weight of 192±5.16 kg were randomly divided into 4 groups with 6 calves in each group.The experimental treatments were divided into:do not add soy active peptide group(CON),add a small molecular weight of soybean active peptide group(L),add medium molecular weight(M),The trial period was lasted 42 days,feed at 6:00 and 18:00 daily,free access to food and water.The first and last weights of each calf were recorded and recorded during the body size data and the everage daily bodyweight gain(ADG).Three days before the end of the experiment,the faeces of each experimental cow were collected from rectum before morning feed to determine the structure of faecal flora and apparent digestibility.The results show that;(1)Compared with CON group,the ADG in group L was significantly increased(P<0.05),and there was no significant difference between M group and CON group.In addition,the feed-weight ratio of calves fed with soybean active peptide below 5000Da was significantly lower than that of CON group(P<0.05).(2)Compared with CON group,there was no significant difference in body length,body height and cruciate height of calves fed with soybean active peptide.(3)The apparent digestibility of nutrients in the diet could be significantly increased by feeding low molecular weight soy peptides(P<0.05).(4)There was no significant difference in alpha diversity index of calf faeces microbes when feeding soybean active peptides.In addition,the relative abundance of Firmicutes in the posterior intestinal tract could be significantly increased by feeding soybean active peptides at the phyla level(P<0.05),and significantly reduces the relative abundance of Bacteroidetes(P<0.05).At the genus level,the relative abundance of Ruminococcaceae UCG-005 could be increased by feeding small molecular weight soybean active peptides(P<0.05).At the same time,the relative abundance of Rikenellaceae_RC9_gut_group was decreased(P<0.05).The results showed that the addition of low molecular weight soy peptides could improve the growth performance,reduce the feed-weight ratio and improve the apparent digestibility of calves.In addition,small molecular weight soy peptides can also change the intestinal microflora of calves.This indicated that the low molecular weight soybean active peptide as a feed additive can improve the efficiency of aquaculture.Trial 3:Effects of soybean active peptides addition in diets on blood biochemical,inflammatory and antioxidant properties of calvesBefore the morning feeding,blood was collected from jugular vein and serum was separated by centrifugation to determine blood biochemistry,inflammation and anti-oxidation ability of calves.The results showed that:(1)compared with CON group,the content of Alanine transaminase in blood of L and M groups decreased significantly(P<0.05),but there was no significant difference in globulin,creatinine and glucose between L and M groups(P<0.05).(2)compared with CON group,the levels of serum acute phase proteins such as LBP,HP and SAA were significantly decreased in L and M groups(P<0.05).In addition,the contents of TLR-4,IL-6 and TNF-α in calf serum were also significantly decreased(P<0.05),the levels of IL-4 and I1-10 in calf serum were significantly increased(P<0.05).(3)compared with CON group,the content of malondialdehyde(MDA)in serum of L and M groups decreased significantly(P<0.05),but the activities of GSH-Px and SOD increased significantly(P<0.05),the total antioxidant capacity(T-AOC)of calves fed with soybean active peptide increased significantly(P<0.05),but there was no significant difference among the three groups(P>0.05).In conclusion,the addition of small molecular weight(3000 Da)soy peptides can significantly reduce the levels of proinflammatory factors in calf serum and increase the activity of antioxidant enzymes in calf serum.It can alleviate the inflammatory reaction and oxidative stress of calves in intensive breeding. |
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