Effect Of Different Feed Additives On The Growth Performance And Immune Function Of Corolla Oil Chickens

In the field of livestock and poultry breeding,the level of production performance determines its economic value.The emergence of antibiotics has greatly improved the breeding efficiency.However,scientific research has found that antibiotics have residues and can make bacteria resistant to them,so it is urgent to find other types of feed additives to replace antibiotics.Objective: in the context of the prohibition of antibiotics in feed,by adding compound probiotics,antimicrobial peptides,compound vitamins and Chinese herbal medicine preparations to the feed,and measuring the changes of chicken growth performance,slaughter performance,immune function and intestinal tissue morphology,to analyze the differences of various indexes in different test groups,so as to provide a theoretical basis for the application of different kinds of feed additives in broiler production.Methods: the experiment was divided into three continuous growth stages: the first stage(8d-55d),the second stage(56d-103d)and the third stage(104d-151d).Each stage consisted of 200 corolla oil chickens.They were randomly divided into 5 groups with 40 birds in each group(half male and half female).The five groups of chickens in each stage were fed with five different diets: the control group was fed with the basic diet,and the remaining four groups were added to the basic diet successively in the experimental stage: compound probiotics(1000mg / kg),antimicrobial peptides(1000mg / kg),compound vitamins(500mg / kg)and Chinese herbal medicine(4000mg / kg).There were 15 groups in three stages,including600 corolla oil chickens.After the test,the following performance indexes shall be measured: 1 For the determination of growth performance,the feeding amount,residual feed amount,initial weight,final weight and death number of test chickens will be recorded in each group during the test,so as to calculate the average daily feed intake,average daily gain,feed weight ratio and survival rate of test chickens.2.Determination of slaughtering performance: six chickens(half male and half female)will be randomly selected from each group.They will be fasted for 12 hours.Before and after slaughtering,they will be depilated,bled and weighed,and their live weight,half clean bore rate,full clean bore rate,slaughtering rate,chest muscle rate and leg muscle rate will be calculated.3.Determination of immune function: six chickens(half male and half female)will be randomly selected from each group.Blood was collected from pterygoid vein and serum was separated.Chickens were detected with enzyme-linked immunosorbent assay kit.The contents of Ig G,Ig A and Ig M in serum were determined by double antibody one-step sandwich method.The absorbance(OD value)was measured at 450 nm wavelength by enzyme labeling instrument,and the concentration was calculated through standard curve.The immune organs taken after slaughter:thymus,spleen and bursa of Fabricius were weighed,and the index of immune organs was measured with the live weight before slaughter as the denominator.4.Determination of intestinal tissue morphology: six chickens(half male and half female)in each group will be randomly selected for slaughter.The intestinal segment about 1cm long in the middle of duodenum,the intestinal segment about 1cm long around the yolk pedicle of jejunum and the intestinal segment about 1cm long around the ileocecal orifice of ileum will be paraffin sectioned and observed under 40 times of optical microscope.4 ～ 5 visual fields will be selected to measure the villus length,recess depth and the ratio of villus length to recess depth,Intestinal wall thickness.Results: in the three growth stages of corolla oil chicken,different kinds of feed additives had significant effects on the indexes of average daily gain,average live weight before slaughter,average daily feed intake and feed weight ratio(P < 0.5).Among them,the antibacterial peptide group has the greatest improvement effect.In the slaughter performance,different kinds of feed additives had no significant difference in the slaughter rate of three stages of corolla oil chicken(P > 0.5),but had limited effect on the improvement of half clean bore rate,full clean bore rate,chest muscle rate and leg muscle rate.In terms of immune performance,different kinds of feed additives had the effect of improving the contents of Ig G,Ig M,Ig A and immune organ index in the three stages of corolla oil chicken,among which the Chinese herbal medicine group had the most significant effect(P < 0.5)and had the greatest effect on the third stage of corolla oil chicken.In the intestinal morphology,different kinds of feed additives increased the villus height and recess depth of duodenum,jejunum and ileum,but had no significant effect on the thickness of intestinal wall.Among them,the Chinese herbal medicine group had the greatest effect on the height and recess depth of small intestinal villi in the first and second stages of corolla oil chicken,and the compound vitamin group had the greatest effect on the height and recess depth of small intestinal villi in the third stage.Conclusion: from the perspective of economic value,because different kinds of feed additives used in the experiment are commercialized and the use cost is almost the same,adding commercialized cecropin antibacterial peptide to the feed has the best feed utilization rate for corolla oil chicken,which can effectively improve the breeding efficiency,reduce the feed cost and increase the economic income.Adding Chinese herbal medicine preparation-Eucommia ulmoides in the feed can maximize the survival rate of corolla oil chickens and effectively reduce the economic losses caused by dead chickens in the process of breeding.