| Probiotics are active microorganisms that can have positive effects on the health of the host when given a certain amount,and their safety has been proved.However,probiotics are sensitive to changes in external environment（such as food substrate,p H,temperature and O2）and are easy to lose activity.Microcapsules are a new technology that encapsulates the active ingredients in the wall material,protects the active substances from losing their activity in the process of processing,storage and transportation,and ensures that the active ingredients play a role in the target site.Microcapsules have been widely used in food,medicine and other industries.In this paper,Lactobacillus casei LC2W（LC2W）was encapsulated by double-layer microcapsules,which were prepared by adjusting the amount of sodium alginate and whey protein（1:0,1:1,1:1.5 and 1:2,AWC-1,AWC-2,AWC-3 and AWC-4,w/w）.Cellulose nanocrystalline（CNC）coating was successfully embedded in LC2W through composite coagulation as the outer layer.The effects of microencapsulation encapsulation efficacy（EE）and particle size,temperature and storage time on the viability of encapsulated LC2W were determined,and its survival rate was evaluated after exposure to SGF and SIF.Finally,animal feeding experiment was conducted to add the embedded probiotics to the cat food to explore the effect of adding probiotics to the cat food on the apparent digestibility of nutrients,blood routine and fecal flora of cats.The test was divided into three groups（control group,group A and group B）.The control group was fed with the basic diet.Group A added 0.1%probiotics to the basic diet,and Group B added 0.6%probiotics to the basic diet.The test period was 63 days.The cat growth index,blood routine index,apparent digestibility of nutrients,fecal flora richness and diversity and other indicators were measured to provide more reference and theoretical basis for the application of probiotics in the cat diet.1.Sulfuric acid hydrolyzed microcrystalline cellulose（MCC）was used to prepare CNC,adjust the amount of sodium alginate and whey protein,and CNC coating is used as the outer layer to prepare microcapsules,and EE and particle size of the microcapsules are measured.The results showed that the diameter of dry microcapsules was 0.45-0.57 mm with encapsulation efficiency of 83.25-84.34%.2.The morphology of CNC and single-layer and double-layer microcapsules was observed by scanning electron microscope（SEM）,the effects of temperature and storage time on the viability of encapsulated LC2W were measured,and the survival rate was evaluated after exposure to SGF and SIF.The results showed that the activity of LC2W decreased with the increase of storage temperature.Under the optimal conditions,the viability of LC2W encapsulated by AWC-3 after 90 days storage at 4℃and 25℃reached 6.72 and 5.97 log CFU/g,respectively,showing good storage stability,which was significantly higher than the number of viable bacteria in free and non-CNC-coated LC2W.In SGF,the survival rate of LC2W encapsulated in AWC-3was higher than that of SIF,which maintained 6.56 and 5.96 log CFU/g respectively.This study shows that the prepared microcapsules could enhance the vitality of LC2W,indicating that it has great application potential in functional food and dairy products.3.18 British cats were fed for 63 days,and their food intake,apparent digestibility of nutrients,blood routine indicators and fecal flora were measured.The results showed that the number of white blood cells in the control group increased significantly on the63rd day,indicating that the addition of probiotics in the cat diet could effectively reduce the inflammation in the cat.There was significant difference in average daily feed intake between group A and group B and the control group,but there was no significant difference in body weight;Compared with the control group and group A,the feces of the cats in group B were significantly better;The results showed that adding probiotics in cat diet could effectively reduce diarrhea rate and soft stool rate,and improve stool score.With the increase of addding probiotics,the apparent digestibility of nutrients increased significantly.On the 63rd day of the test,compared with the control group,the Chao1 index,Shannon index,Simpson index and observed sample index of the fecal flora of cats in the control group was lower than Group A and B.In different classification grades,the relative abundance of bacteroides,classes,orders,families and genera in the control group was significantly lower than that in Group A and Group B.Bacteroides was the dominant bacteria in the intestine,indicating that the diet of the experimental group could increase the number of beneficial bacteria,and the abundance and diversity of cat fecal flora in Group B was the highest.4.After feeding 18 Chinese pastoral dogs for 63 days,their food intake,apparent digestibility of nutrients,blood routine indicators,and fecal microbiota were measured.The results showed that the apparent digestibility of dry matter and crude protein in Group B was higher than that in the control group,indicating that probiotics can improve the digestion and absorption rate of nutrients in dogs.On the 63rd day,compared with the control group,the total number of white blood cells in the blood of group A and group B dogs significantly decreased,indicating mild inflammation.Adding probiotics to the diet could alleviate the dog’s own inflammation.The abundance and diversity of fecal microbiota in Group B were the highest,while the control group had the lowest,indicating that the addition of probiotics is beneficial for improving the body’s immunity and regulating the balance of intestinal microbiota.Lactobacillus,as a beneficial genus in the body,can inhibit the proliferation of harmful bacteria and improve the structure of the gut microbiota;With the addition of adding probiotics,the genus Lactobacillus in dog feces significantly increases,increasing the proportion of beneficial bacteria.To sum up,the microcapsules prepared with CNC coating could be used in the processing of companion animal food,which could reduce body inflammation,enrich the abundance and diversity of fecal flora,and improve the health of cats. |
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