Effects Of Plant Extracts On Performance,Meat Quality And Disease Resistance Of White-feather Broiler

This experiment was designed to study the effects of adding different levels of plant extracts on the production performance,meat quality and disease resistance of white-feather broilers.The study aims to explore the appropriate amount of plant extracts as poultry feed additives,to provide a basis for the development and utilization of plant feed additives,and to make them used as natural,green and healthy feed additives in actual production.In experiment one,240 one-day-old white-feather broilers were randomly divided into 4 groups:A、B、C、D,with 6 repetion in each group and in each replicate.Group Awas fed basic diet.Group B,C and D were fed with 0.01%,0.02% and 0.04% plant extracts respectively.Slaughtering experment were conducted on 21 and 42 days respectively.Experiment result are as follows: 1.Dietary supplementation with plant extracts can significantly decreased the feed-gain ratio of whole-stage white-feather broilers by about 4.7%(P < 0.05),with no significant effect on daily weight gain(P > 0.05).It can significantly increased the slaughter rate of 42-day-old white-feather broilers(P < 0.05),but the eviscerating percentage and semi-eviscerated weight,breast muscle rate and leg muscle rate were not significantly affected(P > 0.05).Adding 0.02% plant extract(group C)can significantly reduce the abdominal fat rate of broilers(P < 0.05).2.Dietary supplementation with plant extracts had no significant effect on the apparent metabolic rate of crude protein in white-feather broilers at 21 and 42 days of age(P > 0.05),but the apparent digestibility of dry matter of white-feather broilers at the age of 21 days could be significantly improved(P < 0.05).The apparent digestibility of crude fat in 21-day and 42-day white-feather broilers in group C with 0.02% plant extract was also significantly increased(P < 0.05).3.The study found that the thymus index and spleen index of 21-day old white feather broilers were significantly increased by different levels of addition(P < 0.05),while there was no significant difference in bursa index between groups(P > 0.05).The thymus index of 42-day-old white-feather broilers was significantly increased(P < 0.05),but there was no significant changes in spleen index and bursa index(P > 0.05)when plant extracts were added to the level of 0.02%.The contents of IgM and IgG in plasma of chickens in group C and group D were significantly increased(P < 0.05).In addition,the contents of IgA in plasma of 21-day old white-feathered broiler chickens in group C were significantly higher than those in group A,B and D.4.The study found that after the addition of plant extracts,the serum MDA of 21-day old and 42-day old chickens was significantly decreased(P < 0.05),while the content of GSH-PX increased significantly(P < 0.05).And the level of T-SOD in serum of 21-day-old chickens increased significantly(P < 0.05)when plant extracts are added to 0.02%.The addition of 0.04% plant extract in the diet significantly increased the serum T-SOD content in 42-day-old chickens(P < 0.05).5.Research show that the addition of plant extracts to the diet had no significant effect on the pH value,shear force,moisture,protein,ash content and moisture,fat and ash content of the chest muscles of 42-day-old white-feather broilers(P >0.05);but the pH value of chicken leg muscle in group C and D was significantly higher than that in group A and group B(P < 0.05).At the same time,the fat content of the chest muscle of 42-day old broilers was significantly reduced(P < 0.05),and the protein content of the leg muscle of group C was significantly increased(P < 0.05).The content of essential amino acids,flavor amino acids and total amino acids in chest muscle and leg muscle were significantly increased after the addition of plant extracts(P < 0.05).In experiment two,120 healthy white-feather broilers aged 1 day were randomly divided into groups A,B,C,D,E and F,with 20 replicates in each group and 1 in each replicate.Group A and D was fed basal diet,Group B and E was fed basal diet with apple extract(According to the results of test one),and C、F was fed basal diet with antibiotics(forage grade aureomycin,50mg/kg).The challenge of pathogenic escherichia coli was carried out after 21 days of routine feeding.According to the challenge model,the optimal challenge dose was determined to be 0.5ml.In group A,B and C,0.5ml salime was injected into breast muscle of each chicken,and in group D,E and F t,0.5ml Escherichia coli solution was injected into the breast muscle of each chicken(bacteria content in 1.12 x 109 cfu/ml).Observe and record the state of chicken,as well as morbidity and mortality of chickens in each group within 72 hours.After challenge,all test chickens were slaughtered 72 hours later.The results showed that adding plant extracts to daily food can significantly increase the resistance of the white-feather chicken to e.coli,reducing morbidity and mortality.The plasma IgG and IgM levels of white-feather broilers in the challenge group were significantly increased(P < 0.05),while the plasma IgA levels of white-feather broilers in the challenge group were not significantly affected(P > 0.05).It can significantly improve the conversion rate of lymphocytes in peripheral blood and spleen of white-feather broilers in the challenge group(P < 0.05),and improve the disease resistance of white-feather broilers.