| At present, the livestock husbandry of our country is suffering the serious grain shortage and the defectiveness of grassland agriculture system. Therefore, it is so urgent to develop available feed resources comprehensively. Since the crop stalk in our country is great in quantity, utilizing the crop stalk effectively not only can alleviate the food crisis but also can protect ecological environment and promote the sustainable development in animal husbandry. However, crop stalk as fodder directly has a low utilization ratio and bad palatability, especially fed to the monogastric animals. In this research topic, compound agent, which contains Trichoderma koningii, white rot fungi and saccharomycetes three microbial bateria, was used to ferment corn stalk to select the best fermentation condition by sensory evaluation to the fermented fodder, chemical component analysis and so on. After the fermentation, the fermented corn stalk substituted part of the unleavened corn of the test pigs’basic ration to conduct feeding test and slaughter test, then there was a comparison between the effect of the stalk fodder fermented by commercial enzyme agent and commercial bacteria agent. A further evaluation to the nutritional value of the fermented stalk fodder was conducted. At last, the effect of the three bacteria fermented stalk fodder on the development of pigs’digestive tract was studied. The microbial flora in pigs’intestinal tract in different groups was analyzed with the technique of DGGE, which provided an overall data support and scientific basis for the application of the stalk processing technique.Part 1 Tri-fungus fermented stalk feed fermentation experiment and optimization of fermentation processIn the test, the fermentation principle is that using T. koningii and white rot fungi to degrade the lignocellulose in the corn stalk and using the saccharomycetes to proliferate organic product from fermentation to make the microbial protein increase in the fermented feed, by which the content of available nutrition can be improved. The test was designed as a orthogonal experiment. By sensory evaluation and nutritional determination to fermented feed, the best fermentation condition was set as:corn stalk:bran 7:3, nutrient liquid 60%, normal saline (NS) 140%, the best proportion of Trichoderma koningii, white rot fungi and saccharomycetes in compound microbial additives as 2:2:1, inoculation quantity 10%, time of fermentation 30d. After fermentation, the degradation ratio reached over 20%, crude protein increased by 59.67%. Meanwhile the fermented stalk feed had sweet fruit fragrance and its feeding value was improved drastically. In the verification of preparing the fermented feed on a large scale according to the above conditions, the similar result was realized.Part 2 Application effect evaluation of straw fermented feed on growing-finishing pigThis test aimed to prove the application effect of three bacteria fermented stalk fodder on fattening up finishing pigs and on study its effects to fattening pigs’production performance, digestion rate of nutrients, blood relative index, carcass quality and so on as substitute of part of the corn in daily food. By comparing the above result with the stalk fodder fermented by commercial enzyme agent and commercial bacteria agent and with the group without stalk fodder, the most efficient stalk fermentation way would be found. The study result shows:(1)72 pigs (Large White×Landrace×Duroc three-way cross commercial), with an average initial body weight of 30.79±0.98kg, were divided into four groups,3 repetitions in each group,6 pigs of every repetition with the same sexual ratio. The overall test time was 98days, which was divided into two periods, growth period (before 55kg) and fattening period (55kg-sold). The control group (group C) was fed with complete feed. Test group 1, group 2 and group 3(T1、T2、T3) used the stalk fodder fermented by three bacteria compound agent and the stalk fodder was fermented by commercial enzyme agent and commercial bacteria agent to substitute 10% and 15% corn of basic ration respectively in growth period and fattening period. The result shows:the fermented stalk fodder replacing part of corn had little effect on finishing pigs’ADG and average feed intake (P>0.05). However, through the whole period, the feed to gain ratio of T1 (2.81:1) was significantly smaller than T3 (P<0.05) and slightly smaller than the other two groups with an unobvious difference (P>0.05). At the end of the feeding, two test pigs was selected in every group to slaughter according to the principles of half male and half female and the similar body condition. There are little differences about the slaughter indexes (P>0.05) such as carcass weight, slaughter rate, lean meat percentage, bone percentage, leaf fat rate, eye muscle area, thickness of backfat and so on. In terms of economic benefit, the average gross profit of T1 is the biggest compared with the contrast groups. The profits of every pig in T1, T2 and T3 increase by 68.26yuan,43.6yuan and 22.6yuan.(2) The digestive test was conducted a week before the end of growth period and fattening period respectively. The result showed that in two periods the dry matter digestion ratios in Tl, T2, T3 were all less than the control group, T1 was the least with an obvious difference to control group (P< 0.05). However, there was no significant difference in the digestive utilization ratios of crude protein, crude fat and crude fibre among each group (P>0.05). In growth period, the digestibility of calcium was slightly lower than the control group. The digestibility of three test groups in growth period was slightly lower than the control group. Then in fattening period the digestibility to phosphorus in T1 was a little higher than the control group. At the end of digestive test physiological and biochemical indexes were determined by blood sampling. In two periods, the content of total protein (TP), albumin, globulin and blood glucose had no change. The content of glutamic-pyruvic transaminase (GPT) in T1 was markedly higher than control group (P<0.05). In growth period, the content of glutamic oxalacetic transaminase in T3 was considerably higher than the other three groups (P<0.05). The content of serium inorganic phosphorus and triglyderide was more than the control group. In fattening period, the content of alkaline phosphatase in T1 was obviously less than the other three groups (P <0.05) while the content of urea greatly exceeded the other three groups (P<0.05). The number of leukocyte, lymphocyte and granulocyte in T3 was larger than the other three groups and T2 had the maximum amount of erythrocyte and blood platelet.(3) In the slaughter experiment, the meat quality in different groups was compared by collecting the longissimus dorsi at the same position and examining the muscle shear force, TPA, drip loss, pH, the meat color(L*、a*、b*)and the content of fatty acid. The result indicated that the muscle shear force, hardness, chewiness, tackiness, cohesiveness and drip loss of T1 were all remarkably smaller than the control group(P<0.05). There were not significant difference in the pH(45min),pH(24h),cooked meat percentage and the color(45min and 24h) among all of the four groups(P>0.05). Then the nutritional components of meat were studied:the content of crude protein and crude fat of T1 was significant larger than the control group(P>0.05). In addition, the content of linoleic acid, proline, glycine, alanine and valine of T1 was the highest in the four groups.Part 3 Effect of straw fermented feed on growing-finishing pig’s digestive system development and intestinal microfloraIn the slaughter experiment, there was a comparison by weighing spleen, pancreas and stomach, calculating purtenance index and sample observation to the form of intestine mucosa. The result manifested that the tri-fungus fermented stalk feed influenced the development of enteron and increased the index of pancreas distinctly(P<0.05) and the index of stomach slightly in T1. Compared with the control group, the villus height, crypt depth and the ratio of villus height to crypt depth increased, especially in the part of the ileum. Finally, the different fermented feed’s influence to intestinal micro-flora was studied by collecting the chyme samples in cecum with the help of DGGE technique and 16S rDNA’s clone and sequence. The sequence was entrusted to the consultant department of Harbin Rurizhongtian biotechnology to examine, Feeding straw fermented feed can inhibit some pathogens and increase the number and variety of intestinal probiotics, It has great significance to maintain intestinal micro ecological balance and improve the production performance of animal.Considering every study in the experiment comprehensively, tri-fungus fermented stalk feed not only hasn’t harmful effect on pigs’ growth performance, blood physiological and biochemical index and apparent digestibility of nutrients but also can facilitate the development of pigs’ digestive system, optimize the intestinal microflora, improve carcass quality and decrease feeding cost. |
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