| Raffinate generated by the citric acid production process is a kind of high concentration organic wastewater, mainly contain various organic acids, proteins, fermentation residues and other organics. According to this characteristic of citric acid raffinate, it can be changed waste into resource. Bentonite, attapulgite, zeolite or other non-metallic minerals, have good adsorption and ion exchange properties, been widely used as the adsorbent. In this study, non-metallic minerals such as bentonite, attapulgite, zeolite were used for treating the citric acid raffinate.This reseach filtered out the adsorbent which had best adsorption effect of organic acids in the citric acid raffinate and optimized the adsorption process parameters. After the processing, the residue of non-metallic mineral was processed into adsorption products used in animal production. In this study, AA broilers were chosen as the research object to preliminarily investigate the feed efficacy of the product. The research results could provide scientific basis for citric acid raffinate treatment and comprehensive exploitation of feed resources.The experiment included three parts:The first experiment was designed to filter out the adsorbent which had best effect on adsorption of acids and sugars in the wastewater and optimize the adsorption process parameters. The result showed that attapulgite and modified attapulgite had better adsorption effect on acids. Attapulgite was chosen for further study of the optimal adsorption conditions. The parameters were presented as follows:addition of adsorbent5%, the oscillation time of70min, the rotate speed180r/min, temperature30℃, the acid removal rate was about89.48%. Effective adsorbent for sugars in the citric acid raffinate had not yet been found in this study.The second experiment was designed to investigate the effects of basal diets supplemented with adsorption products on growth performance, intestinal tract development, metabolisibilities of feed nutrients and activities of digestive enzymes of small intestine of broilers. In this study, Arbor Acres broiler chicks were randomly allocated to4treatment groups and fed with one of four diets, basal diets (control) or diets supplemented with2%clay,1%adsorption products,2%adsorption products, respectively, for42d.The result showed that:(1) In contrast to the control, Clay and adsorption products enhanced AFDI and ADG in different degrees, and FCR in starter phase was unaffected. In growth phase, a significant decrease was observed for FCR of1%adsorptionproducts supplementation compared with the control.(2) Diets supplemented with clay and products didn’t affect carcass characteristics.(3) Clay and adsorption products diets tended to enhance relative length of jejunum and ileum in starter phase. There was no significant difference between groups in growth phase (P>0.05).(4) Clay and adsorption products diets tended to enhance apparent metabolisibilities of feed nutrients.14-16d, broilers in2%clay group had higher apparent metabolisibilities of crude protein and energy than the other two treatment groups.35-37d, broilers in1%products group had higher apparent metabolisibilities of crude protein and energy than the other two treatment groups in growth phase.(5) Broilers in2%clay group and1%product group-had higher activities of AMS, lipase and trypsin within intestinal contents than that of the other two groups. Broilers in2%clay group elevated activities of maltase and sucrose significantly (P<0.05) on day21. On day42all three treatment groups enhanced maltase activity (P<0.05) but no significant difference in activity of sucrose among all groups(P>0.05).The third experiment was designed to investigate the effects of basal diets supplemented with adsorption products on intestinal antioxidant capacity and activities of serum diamine oxidase (DAO) of broilers. The result showed that:(1) Clay and products diets tended to reduce malondialdehyde (MDA) and elevate catalase (CAT) activity. Broilers fed2%clay diet had highest CAT activity and lowest MDA in starter phase.Broilers fed1%products group diet had highest CAT activity and lowest MDA in growth phase.(2) All three treatment groups reduced DAO activity(P>0.05)on day21.On day42, DAO level of chicken fed1%products diet reduced significantly(P<0.01),2%clay group and2%products group tended to decrease too(P>0.05).In summary, attapulgite was chosen as adsorbent for acids in the citric acid raffinate and optimal adsorption conditions were:addition of adsorbent5%, the oscillation time of70min, the rotate speed180r/min, temperature30℃, the acid removal rate was about10.51%. Supplementation of adsorption products enhanced AFDI and ADG, and FCR of1%adsorption products group was lower than that of the control. Adsorption products had positive effect on growth performance. Adsorption products enhanced development of intestinal tract, activities of digestive enzymes and apparent metabolisibilities of feed nutrients. Adsorption products could improve intestinal antioxidant capacity and decrease serum DAO activity, therefore proved diets supplemented with adsorption products could preliminarily maintain integral intestinal barrier. |
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