Studies On Solid-state Fermentation Parameters Of Rapeseed Meal And Evaluation Of Diets Containing Fermented Rapeseed Meal On Growing Pigs

The optimal fermentation parameters in rapeseed meal (RSM) fermentation were determined by orthogonal design, in which four levels, three factors, and 16{Li6(45)}. treatments were employed. The factors and levels were fermentation time (FT,26 h,48 h, 60 h,72 h), material-water ratio (MWR,1:0,1:0.4,1:0.5,1:0.6,1:0.7) and strain addition(SA,0.2%,0.4%,0.6%,0.8%).The solid-state fermentation(SSF)was carried out, and 500g RSM was packaged and 3% wheat bran was added as bulking agent. Fermentation was performed in an electro-heating standing-temperature cultivator at 38℃.The results indicated that FT was more important to improve fermented rapeseed meal (FRSM) quality than other factors, and the optimal parameters were 36h FT,0.4% SA,1: 0.7 MWR. The contents of crude protein (CP) and trichloroacetic acid-nitrogen solution index (TCA-NSI) were 44.27 and 24.74%, whereas glucosinolate declined by 49.42μmol/g, respectively. According to the results, a pilot-test with two treatments was conducted-fermentation with present parameters (control group,1:0.5,0.2%,48h) and the optimal parameters (experimental group), and 200 kg RSM were fermented. The results indicated that CP and TCA-NSI increased 3.08% and 93.36%, and glucosinolate content delined by 63.27% in control group, whereas indexes in experimental group were 7.23%,88.93% and 58.59%, respectively. FRSM quality in experimental group was the same with control group without more time, and we found a trend of increasing of substrait temperature but decreasing of humidity.An animal trail was conducted to evaluate the nutritional value of FRSM fermented with the optimal parameters in grower pigs' diets.One huandred and forty-four crossbred grower pigs (LandracexYorkshire) (38.00±0.10 kg), were randomly allotted to 6 diets: Negative control group (NC)---basal diet with 10% RSM to replace soybean meal (SBM); Positive control group (PC)---basal corn-soybean meal diet; GroupⅠ,Ⅱ,ⅢandⅣwere diets with 25%,50%,75% and 100% FRSM to replace SBM by equal nitrogen. The pigs were raised for 35 days including 7 days of preliminary trial period to determine the growth performances.Another animal trial was conducted to evaluate the digestibility of nutrients and AA in diets with different level of FRSM using 6 male pigs.The results indicated that:(1)There were no significant differences between the average daily feed intake (ADFI) in FRSM diet groups and PC,however, the increasing FRSM resulted in a trend toward decease of ADFI.Diet in group IV decreased average daily gain (ADG) of grower pigs (P <0.05) except pigs in group I,which was 13 g/d higher than that of PC (P>0.05), and feed gain ratio (F/G) of pigs in groupⅣwas also significantly improved (P<0.001).(2) The fecal apparent digestibility (FAD) of nutrients and AA for pigs in NC was not significantly affected (P>0.05), but FAD for pig in groupⅠwas significantly higher than that of PC (P<0.05).The FAD of CP, DM, TP and methionine of grower pigs in groupⅡwere 8.67%,4.11%,28.90% and 7.73%higher than pigs in PC,respectively, and only FAD of methionine of pigs in groupⅢwas significantly improved (P<0.05).However, high level of FRSM addition(100% replacement of SBM by equal nitrogen) significantly decreased the FAD of most nutrients and AA in groupⅣ(P<0.05). Moreover, the FAD of TP of grower pigs given all diets containing FRSM was significantly higher than that of pigs given SBM diet (P<0.05).(3)The relative cost of NC increased 0.29 yuan, and the economic benefit declined by 3.46%. The increasing level of FRSM resulted in a higher economic benefit, and pigs fed diet with 25% FRSM to replace SBM (group I)had the best performances, whose relative cost was decreased by 0.44 yuan and economic benefit was increased by 5.25%. However, pigs fed diets with more than 50% FRSM to replace SBM had bad performances and the economic benefits were decreased.In conclusion, RSM quality and TP digestibility improved possibly through SSF by increasing protein and small peptide content and reducing glucosinolate. Diets with Low level of FRSM addition(≤50% to replace SBM by equal nitrogen) improved the growth performaces,FAD of nutrients and AA and economic benefits for grower pigs, however, diets with high level of FRSM addition(>50% to replace SBM by equal nitrogen) might result in the adverse effect. It was feasible to replace 50% of SBM by equal nitrogen in diets of grower pigs through the addition of FRSM.