| Compound protein feed (CPF) was used to produce fermented compound protein feed (FCPF) through solid state fermentation. The objective of this study was to determine the optimal strain combination and fermentative parameters, and evaluate the nutritional value of FCPF through growing pig's metabolic test. Two experiments were conducted for the study.Experiment 1 Study on strains screening and solid state fermentative parameters of CPFA series trials were conducted to determine the suitable stain combinations and process parameters for CPF through solid state fermentation. CPF was used as fermenting materials, and crude protein content as the indicator for fermentation effect. Combination strains were inoculated into CPF to screen the best stain combination. The influence of sterilisation process was also studied on the content of product's nutrient compositions.A orthogonal trial was taken to determine the optimal fermentative parameters of three factors including culture time, water content, total inoculation dose, and the ratio of strains with each factor being designed at three levels. Four strains used included Candida utilis,Geotrichum candidum,Bacillus subtilis and Lactobacillus. The results showed that the species and combination of strains influenced the CP content of FCPF significantly (P<0.05). Considering the strains characteristic and cultural status, Bacillus subtilis- Candida utilis- Lactobacillus were determined as the best strain combination. Sterilisation process had slight influence on the product's protein content. The suitable fermentative parameters were 2.5d culture time with 1:1:1 ratio of the 3 strains. 10% inoculation dose, and 65% water content. Experiment 2 Study on the preparation of FCPF and its Nutritional Value on growing pigsThis experiment studied on the nutritional value of FCPF prepared according to the results of Exp.1. CPF was fermented with C. utilis,B.subtilis and Lactobacillus for 2.5d, and then dried into FCPF. Using SBM as the reference protein, a digestibility trial to evaluate the nutritional value of CPF and FCPF was conducted on the basis of analyzing nutrients and amino acid contents. Twenty-four DLY growing pigs with 24.36±1.78kg were allocated into 4 groups to feed N-free diet and semi-purified diets with CPF,FCPF or soybean meal(SBM) as only protein source, with 6 replications in each group. The experiment determined the digestibility of CP, energy, and endogenous AA excretion to calculate AA true digestibility. Solid state fermentation can significantly improved the content of routine nutrients and AA of CPF, and digestibility or availability of protein and energy on growing pigs. FCPF contained 47.80% and 41.00% of crude protein(CP) and true protein(TP) respectively. The apparent and true digestibility of the CP were 82.57% and 84.94%. Gross energy and digestible energy were 19.07MJ/kg and 16.80 MJ/kg. Energy digestibility was 88.05%. Total amino acids was 40.46%. The contents of Lys and Met were 1.59% and 0.66%. The apparent and true ileal digestibility of AA varied between 67.78%～85.60% and 85.21 %～102.90%. The content of total true digestible AA was 35.72%. Compared to CPF, CP and TP of FCPF were improved above 11%. The digestibilities and availabilities of protein and energy were improved by 15.90%～22.66% and 11.26%～154.97%. Nutrient profiles and its bioavilability were close to or better than SBM.It is concluded that the nutritive value of CPF can be improved by solid state fermentation established in this study and the nutritive value of FCPF is close to or better than SBM.
|
PDF Full Text Request