Research On The Process Of Co-fermentation Of Wheat Bran And Corn Distiller’s Grains To Produce Monogastric Animal Feed

With the increase in population and the development of animal husbandry in China,the problem of food shortage is becoming increasingly serious.Therefore,we reuse wheat bran and corn WDG from agro-industrial waste to reduce food pressure and environmental pollution.Wheat bran and corn WDG have high annual production as roughage raw materials,but there are limiting factors such as high lignocellulose content,low crude protein content,unbalanced amino acid composition,and a certain amount of anti-nutritional factors,which are not conducive to digestion and absorption by monogastric animals.To this end,we compared the changes in conventional nutrient composition,microstructure and digestibility of fermentation products under optimal conditions by using single bacteria and mixed bacteria to ferment wheat bran and corn WDG mixed substrates,so as to provide some basis for the development of non-conventional monogastric animal feed.The main results are as follows:（1）In the solid-state fermentation of wheat bran and corn WDG by Trichoderma reesei,the degradation rate of cellulose was used as the main index,and the degradation rate of hemicellulose and variation content of reducing sugar were used as auxiliary indexes.On the basis of the single-factor test,the proportion of substrate,material to water ratio and the quantity of inoculation of Trichoderma reesei were optimized,and the optimal conditions were obtained:wheat bran:corn WDG was 2:1,material to water ratio was 1:3.5 and inoculum of 12%（v/w）.Under these optimal conditions,the degradation rate of cellulose was46.24±0.18%,the degradation rate of hemicellulose was 18.07±0.08%,and the crude protein content increased by 13.84±0.44%.（2）In the solid-state fermentation of wheat bran and corn WDG by Trichoderma reesei and Candida utilis,the proportion of strain mixing,the addition of（NH₄）₂SO₄ and the fermentation time were optimized by single-factor test with the degradation rate of cellulose and the growth rate of crude protein as the indexes.On this basis,the optimal conditions for the degradation rate of cellulose were further optimized by orthogonal test and obtained respectively:the proportion of strain mixing（Trichoderma reesei:Candida utilis）was 2:1,the addition of（NH₄）₂SO₄ was 4%,and the fermentation time was 8 days,and the degradation rate of cellulose was 39.10±0.12%,the degradation rate of hemicellulose was 13.19±0.13%,under this condition,the crude protein content increased by 29.60±1.67%.The optimal conditions for the growth rate of crude protein:the proportion of strain mixing（Trichoderma reesei:Candida utilis）was 2:1,the addition of（NH₄）₂SO₄ was 5%,and the fermentation time was 7 days,under which the degradation rate of cellulose was 37.68±0.15%and the degradation rate of hemicellulose is 10.06±0.12%,and the crude protein content increased by31.15±0.38%.（3）According to the optimized conditions,we analyzed the nutrients,the cellulose decreased from 25.26%to 15.38%,hemicellulose decreased from 18.25%to 15.86%,phytic acid decreased from 0.421%to 0.397%,crude protein increased from 19.60%to 25.41%,and amino acid increased from 16.58%to 22.85%in fermentation product.At the same time,the lignocellulose structure in the microstructure of the product was destroyed after fermentation.In the vitro digestion experiment,The dry matter digestibility increased from 55.30%to62.78%,the crude protein digestibility increased from 55.30%to 62.78%,the cellulose digestibility increased from 47.54%to 53.67%,and the hemicellulose digestibility increased from 18.39%to 33.08%in fermentation product.The test results show that after mixed bacteria solid-state fermentation by the mixture of wheat bran and corn WDG,the content of cellulose decreased,the content of crude protein increased,the distribution of amino acid was balanced,and the digestibility increased,which is more suitable for monogastric animal feed.