Effects Of Yeast Culture And Ammonia Concentration On Production Performance,Blood Biochemical Parameters And Intestinal Flora Of Laying Hens

The purpose of this experiment was to study the effects of yeast culture and ammonia concentration on the production performance,blood biochemical parameters and intestinal flora of laying hens.The trial used 160 healthy and similar,23-week-old,Hy-Line Brown hens.They were to be randomly divided into 4 groups（A1,A2,B1,and B2）with 4 replicates in each group and 10 chickens in each replicate.The test period is 6weeks.A 2×2 two-factor test design was used with two ammonia levels（3 mg/m³ low ammonia group and 30 mg/m³ high ammonia group）and two addition levels（0.3%yeast culture and blank control group）.Tests A₁ and B₁ were 0.3%yeast culture group,test A₂group and B₂ group were blank control group（tests A₁ and A₂ were kept in the control cabin A,and tests B1 and B2 were kept in the control cabin B）.Starting from week 23,the test A1 group and the B1 group began to add a 0.3%concentration of the yeast culture.At the beginning of the test,the ammonia in the containment tank B remained unchanged at 3 mg/m³,and the ammonia in the control cabin A was increased to 30 mg/m³ and remained basically unchanged.The production performance,egg quality,blood biochemical index and intestinal flora were measured separately.The test results showed that:（1）Production performance:Yeast cultures significantly improve the performance of laying hens.There was no significant difference in the average daily feed intake,egg production rate and feed-to-egg ratio between the high ammonia group and the low ammonia group during the test period（P>0.05）.Compared with the low ammonia group,the high ammonia group showed a significant decrease in egg weight（P<0.05）.The weight of egg in the yeast culture group at 4-6 weeks were significantly higher than those in the blank control group（P<0.05）.（2）Egg quality:High ammonia environment does not significantly affect egg quality,but yeast culture can effectively improve egg quality.There was no significant difference in egg shape index,eggshell thickness,eggshell strength,protein height,hastelloy and eggshell weight between the high ammonia group and the low ammonia group（P>0.05）.The eggshell thickness of the yeast culture group was significantly higher than that of the blank control group（P<0.05）.Furthermore,the yeast culture group had a tendency to be higher than the blank control group in eggshell strength,protein height and hastelloy.（3）Immune performance:High ammonia environment will reduce the immune performance of laying hens,but yeast culture can significantly improve the immunity of laying hens.The levels of IgM and IgA in the serum of high ammonia group decreased significantly at the first week and the sixth week（P<0.05）.The IgG content decreased significantly at the first,third and sixth weeks（P<0.05）.Compared with the blank control group,the IgA content of the serum in the yeast culture group was significantly increased at the first week and the third week（P<0.05）,and the IgM content was significantly increased at the sixth week（P<0.05）.The IgG content showed a significant increase at week 1,3 and 6（P<0.05）.At the first week,the interaction between ammonia and yeast culture had a significant effect on IgM content（P<0.05）.At the third week,the interaction between ammonia and yeast culture had a significant effect on IgG content（P<0.05）.（4）Antioxidant:High ammonia environment will reduce the antioxidant performance of laying hens,and yeast culture can effectively improve the antioxidant performance.Compared with the low ammonia group,the serum SOD activity and T-AOC ability of the high ammonia group of the laying hens were significantly lower at the first,third and sixth weeks（P<0.05）,and the GSH-Px activity at the third week was significantly lower（P<0.05）,and serum MDA levels increased significantly at 1 and 6weeks（P<0.05）.Yeast culture significantly increased GSH-Px activity（P<0.05）and T-AOC ability at week 1 and 3（P<0.05）in the serum,and significantly decreased the MDA content at the third week in the serum（P<0.05）.At the first week,the interaction between ammonia and yeast culture significantly affected the activity of GSH-Px（P<0.05）.At the third week,the interaction between ammonia and yeast culture significantly affected the MDA content（P<0.05）.At 3 and 6 weeks,ammonia and yeast culture interactions significantly affected SOD activity（P<0.05）.（5）Antioxidant:High ammonia and yeast cultures also affect the endocrine function of laying hens.The adrenaline content of the high ammonia group was significantly increased at the first week（P<0.05）.The corticosterone content was significantly increased at the first week and the sixth week（P<0.05）.The T₃ content in the serum in the high ammonia group was significantly decreased at the first week（P<0.05）.The T₄content in the serum in the high ammonia group was significantly decreased at the first week and the sixth week（P<0.05）,but significantly increased at the third week（P<0.05）.At the 3rd and 6th week,the yeast culture group significantly reduced the corticosterone content in the serum of laying hens（P<0.05）.At the 1st,3rd and 6th week of the experiment,the levels of T3 and T4 in the serum of the yeast culture group were significantly higher than those of the blank control group（P<0.05）.（6）Intestinal flora:The high ammonia environment reduced the number of species of the cecal microbial flora.After the yeast culture was added,the number of species of the cecal microbial flora also decreased.From the level of the Phylum,it was found that the Bacteroides and the thick-walled bacteria in the cecum of the laying hen were the most dominant bacteria.The number of Enterobacteriaceae in the high ammonia control group was significantly higher than the other three groups.Studies at the subordinate level found that Bacteroides and Desulfovibrio were the main dominant bacteria.The number of Enterobacteriaceae Escherichia coli in the high ammonia control group was significantly higher than that in the other three groups,indicating that the high ammonia environment can significantly increase the number of E.coli in the cecum,and the addition of yeast culture can effectively reduce the number of cecal E.coli.There was no significant difference in the diversity analysis index between Shannon,Simpson,Chao1and ACE in the yeast culture group and the blank control group（P>0.05）.There was also no significant difference between the high ammonia group and the low ammonia group（P>0.05）.The above test results show that the laying hens are in the 30mg/m³ ammonia environment for a long time,which will reduce the production performance,immune performance,antioxidant performance and number of cecal microbial flora of the laying hens,and disturb the secretion of the body.The yeast culture can effectively improve the production performance,immune performance and antioxidant performance of the laying hen,reduce the number of cecal microbial flora and regulate the secretion function of the body.