Evaluation Of Nutritional Value And Prediction Of Available Nutrients Of Fermented Soybean Meals For Weaned Pigs

Soybean meal contains about 45%protein with balanced amino acid composition,which is a commonly protein feed in animal husbandry.However,the anti-nutritional factors of soybean meal have adverse effects on weaned pigs with incomplete intestinal barrier and undeveloped immune function.Soybean meal is fermented in production to decrease anti-nutritional factors,protect intestinal health of weaned pigs and increase the nutritional value of soybean meal,and the nutritional value of fermented soybean meal is related to the fermentation process.At present,the nutritional value data of fermented soybean meal in weaned pigs are incomplete while there are few dynamic prediction models for available nutrient of fermented soybean meal.The study is aimed to evaluate the nutritional value of different fermented soybean meals in weaned pigs,establish the dynamic prediction model of available nutrient of fermented soybean meal and explore the effect of fermented soybean meal for the health of weaned pigs.This study can provide data support for improving database,accurately grasping the nutritional value of fermented soybean meal and realizing the prediction of available nutrient of fermented soybean meal.The study consists of three parts:Experiment 1.Analysis of chemical composition of different fermented soybean mealsThis experiment selected 9 types of fermented soybean meal from different regions and fermentation processes,and used conventional methods to determine the content of nutrients,amino acids,main anti-nutritional factors,and mycotoxins,as well as the variability of chemical components.The results show that:（1）Based on dry matter（DM）,the contents of crude protein（CP）,crude fat（EE）,crude ash（Ash）,crude fiber（CF）,neutral detergent fiber（NDF）,acid detergent fiber（ADF）,calcium（Ca）and phosphorus（P）in different fermented soybean meal were 46.21～58.22%,6.74～10.05%,2.03～3.07%,3.83～6.95%,8.48～16.23%,6.25～8.96%,0.39～1.58%,0.48～0.82%,3.69～4.72Mcal/kg.The contents of lysine,methionine,tryptophan and threonine were 1.94～3.24%,0.29～0.65%,0.33～0.60%and 1.28～2.39%.Except CP and GE,the variable coefficient of other chemical components was more than 10%.（2）On the DM basis,the contents of glycinin,β-conglycinin and trypsin inhibitor in different fermented soybean meals were 145.2～933.7mg/g,262.3～431.0mg/g and 0～8.0mg/g,and the variable coefficients were 56.39%,13.33%and 115.38%,respectively.The contents of aflatoxin,zearalenone and deoxynivalenol were 6.2～16.0 mg/kg,3.2～47.3 mg/kg and1.3～14.0 mg/kg,and the variable coefficients were 36.54%,111.95%and 96.03%,respectively.Except for mycotoxins,the main anti-nutritional factors of fermented soybean meal are lower than those of soybean meal.The above results showed that the chemical composition,the main anti-nutritional factors and mycotoxins of fermented soybean meal from different sources were different,and fermentation was beneficial to reduce the content of anti-nutritional factors in soybean meal.Experiment 2.Ileal amino acid digestibility and antioxidant capacity and immune function effects of different fermented soybean meals in weaned pigsThe purpose of this experiment was to evaluate the ileal protein and amino acid digestibility of eight fermented soybean meals and to compare them with soybean meals in terms of antioxidant and immune function in weaned pigs.Ten castrated boars（Duroc×Landrace×Yorkshire,initial weight of 13.45±0.88 kg）fitted with T-fistulas after terminal ileum operation were allocated to the 10×6 Youden square with 10 diets（one nitrogen free diet,one soybean meal diet and eight fermented soybean meal diets）.All the 10 diets were supplemented with 0.3%chromium trioxide（Cr₂O₃）.The experiment lasted for 6 periods,each of which lasted for 11 d,including 4 d recovery period,4 d pre-feeding period and 3 d collection period.The apparent amino acid digestibility（AID）and standard amino acid digestibility（SID）of ileal terminal of fermented soybean meal were determined.The prediction equation of limiting amino acid SID by amino acid content was established,the effects of fermented soybean meal on health function of weaned pigs were explored.The results show that:（1）There were significant differences in CP and amino acid digestibility of different fermented soybean meals in weaned pigs（P<0.05）.The CP range was 72.61～81.46%and limiting amino acid AID ranges were lysine 70.63～83.75%,methionine 76.49～87.11%,tryptophan 32.07～84.10%,threonine 47.81～80.27%,respectively.SID ranges were CP82.13～88.72%,lysine 79.27～88.81%,methionine 87.74～92.40%,tryptophan 51.87～91.08%,threonine 64.82～88.78%,respectively.Compared with soybean meal,the digestibility of CP and most amino acid of fermented soybean meal was increased.（2）Based on the difference of chemical composition of fermented soybean meal（DM basis）,the prediction equation of limiting amino acid SID of weaned pigs was established as follows:SID Lys（%）=52.22-82.45×Val（%）+160.35×Ile（%）+29.19×Phe（%）-65.20×Arg（%）（R²=0.90,P<0.05）;SID Met（%）=60.87-52.56×His（%）+40.59×Pro（%）（R²=0.73,P<0.05）;SID Trp（%）=30.52+26.97×Asp（%）+49.60×Ile（%）-152.73×His（%）（R²=0.72,P<0.05）;SID Thr（%）=51.97+45.85×Asp（%）-24.67×Glu（%）（R²=0.56,P<0.05）.（3）The amino acid SID of fermented soybean meal was negatively correlated with soybean globulin,trypsin inhibitor,zearalenone,deoxynivalenol and fumonisin.There was a significant negative correlation between amino acid SID such as arginine and tryptophan and main anti-nutritional factors and mycotoxins（P<0.05）.（4）Compared with soybean meal,fermented soybean meal significantly affected serum antioxidant and immune-related indexes of weaned pigs（P<0.05）.Serum total antioxidant capacity（T-AOC）,total superoxide dismutase（T-SOD）,immunoglobulin A（IgA）,immunoglobulin M（IgM）,immunoglobulin G（IgG）and anti-inflammatory cytokine interleukin 4（IL-4）levels were increased.Malondialdehyde（MDA）level and the pro-inflammatory cytokine interleukin-6（IL-6）level were decreased.Correlation analysis showed that SID of CP and amino acid were positively correlated with serum T-AOC,T-SOD,IgA and IgG,while negatively correlated with MDA.These results indicated that the digestibility of CP and amino acid in ileal terminal of fermented soybean meal which from different sources for weaned pigs was different.Compared with soybean meal,fermentation can improve the amino acid terminal ileal digestibility of soybean meal,and the fermented soybean meal can improve the antioxidant and immune capacity of weaned pigs.Experiment 3.Apparent total tract digestibility of nutrients,DE and ME of different fermented soybean mealsThis experiment was conducted to determine total intestinal nutrient digestibility and available energy of eight fermented soybean meals.Nine healthy DLY（Duroc×Landrace×Yorkshire）castrated boars with initial weight of 11.05±1.15 kg was allocated to nine diets according to a 9×6 Youden square design.A total of six periods were conducted,with each period of 9 days,4 days of pre-feeding period and 5 days of fecal urine collection.The total intestinal apparent digestibility（ATTD）and available energy of nutrients in fermented soybean meal were determined by total fecal collection method,and the regression equation for predicting the available energy of nutrients in fermented soybean meal was preliminary established.The results show that:（1）There were significant differences in ATTD of DM,CP,CF,Ash,P and GE on fermented soybean meal（P<0.05）,but no differences in ATTD of EE and Ca（P>0.05）.The ATTD ranges of nutrients in different fermented soybean meal were DM 84.25～89.19%,CP89.48～94.31%,EE 35.81～61.90%,CF 66.58～85.94%,Ash 71.01～85.69%,Ca 58.89～76.28%,P,respectively 50.89～81.08%and GE 69.56～87.67%.（2）Digestible energy（DE）,metabolizable energy（ME）and general energy（GE）digestibility of different fermented soybean meals were significantly different（P<0.05）.On the basis of DM,the DE,ME and GE digestibility varied in the range of 14.92～18.68 MJ/kg,13.55～17.21MJ/kg and 69.56～87.67%.（3）There were significant differences in daily nitrogen balance indices of different fermented soybean meals（P<0.05）.Nitrogen deposition rate and biological value of nitrogen ranged from 52.26～70.66%and 66.60～80.99%.（4）The key factor affecting DE and ME of fermented soybean meal is P content,which is proportional to P content.The more chemical components added to the independent variables,the higher the accuracy of the prediction equation,and the prediction equations of DE and ME were respectively:DE（MJ/Kg）=21.23+6.76×EE（%）-19.07×Ash（%）-5.18×CF（%）+4.30×ADF（%）+127.02×Ca（%）+126.09×P（%）（R²=0.96,P<0.05）.ME（MJ/Kg）=73.70+2.62×EE（%）+4.73×Ash（%）+0.57×CF（%）+59.11×P（%）（R²=0.57,P<0.05）.The results indicated that the nutrient ATTD,available energy and nitrogen balance of fermented soybean meal in weaned pigs were significantly different.Phosphorus content was the key factor affecting DE and ME of fermented soybean meal.In conclusion,the chemical composition and nutritional value of fermented soybean meal from different sources are significantly different in weaned pigs.The chemical composition of fermented soybean meal can be used to predict amino acid ileum digestibility and available energy.The key factor affecting DE and ME of fermented soybean meal is Phosphorus content.The fermented soybean meal can improve the antioxidant and immune functions of weaned pigs by reducing the contents of anti-nutritional factors and mycotoxins to increase the digestion and absorption of nutrients.