Studies On The Effects Of Different Dietary Amylose And Amylopectin Ratio On The Performance And Its Related Mechanism In Yellow Broilers

To investigate the effects of different dietary amylose and amylopectinratio on the performance, nutritive efficiency, two hundred and fifty six29-day-day yellow broilers were selected and allocated to 4 groups, eachgroup had 4 replicates of 16 birds at randomly. The experiment was conductedwith single factor experiment design and the experiment diets weresupplemented with amylase and amylopectin ratio 0.11, 0.23, 0.35 and 0.47respectively, which were based on the same nutrient levels. The performance,the carcass quality, the microbial population in hindgut and bloodbiochemical indices were measured in this experiment, and the nutritiveefficiency were determined by metabolic trial. The results showed that:1,Different amylase and amylopectin ratio had no effect on average dailyweight gain (P＞0.05), but had significant effects on average daily feedintake and the ratio of feed to meat (F/D) (P＜0.05), and the group of amyloseand amylopectin ratio 0.23 had the best performance among all the groups.There exist a certain]y quadratic relationship between the F/D (Y) and theratio of dietary amylase and amylopectin (X) for broilers in the periodof 29-56 day, the quadratic equation was: Y=5.768X~2-3.443X+3.174(P=0.026,r=0.6557). After derivation calculus to this quadratic equation we can get theappropriate ratio of amylase and amylopectin for abtaining minmum F/D of29～56—day—old yellow broilers was 0.30.2,Nutrient availability:②,Different amylase and amylopectin ratio had significant effects onHis, Thr, Set apparent and true digestibility and Gly true digestibility(P＜0.01) as well as Gly and Cys apparent digestibility (P＜0.05), but hadno significant effect on protein availability and other amino acidsdigestibility (P＞0.05). And the group of amylose and amylopectin ratio 0.23was the highest while the amylase and amylopectin ratio 0.47 was the lowestfor all amino acid digestibility.②,The metabolic energy value for the diets of amylase and amylopectinratio 0.23 were the highest among the 4 trial diets. And there exist asignificant quadratic relationship between the dietary energy value (Y)and the ratio of dietary amylase and amylopectin (X) for broilers in theperiod of 29-56 day, the quadratic equations were as follows: AME:Y(KJ/g)=-27.869X~2+16.241X+12.742(p=0.000,r=0.834), AMEn:Y(KJ/g)=-25.651X~2+14.407X+12.520(p=0.000,r=0.851), TME:Y(KJ/g)=-26.776X~2+15.262X+13.275(p=0.000,r=0.850), TMEn:Y(KJ/g)=-24.558X~2+13.428X+13.053(p=0.000,r=0.856).After derivation calculus to above quadratic equations we can get theappropriate ratio of amylase and amylopectin for abtaining maximum AME,AMEn,TME,TMEn for 29～56-day-old yellow broilers were 0.29,0.28,0.29and 0.27 respectively.3,Different amylase and amylopectin ratio had no significant effectson dressing percentage, half and total empty ratio, chest and leg meatpercentage, and the crude protein content of breast and thigh meat (P＞0.05),but had significant effects on abdominal fat percentage (P＜0.01). Thereexist a significant quadratic relationship between abdominal fat percentage (Y) and the ratio of dietary amylase and amylopectin (X) forbroilers in the period of 29～56 day, the quadratic equation was:Y(%)=45.657X~2-28.673X+7.140 (P=0.000, r=0.844). After derivat ion calculus tothis quadratic equation we can get the appropriate ratio of amylase andamylopectin for abtaining minmum abdominal fat percentage for29～56-day-old yellow broiler was 0.30.4,Dietary amylase and amylopectin ratio significantly increased thenumber of Enterococcus (P＜0.05), Lactobacillus and Bifidobacteria (P＜0.01),while reduced the number of Escherichia coli in hindgut of broilers (P＜0.05).There exist a significant quadratic relationship between the microbialpopulations in hindgut (Y) and the dietary amylase and amylopectin ratio(X) for broilers in the period of 29～56 day, the quadratic equations wereas follows: Lactobacillus: Y(log10 CFU/g)=-4.837X~2+3.789X+6.508 (p=0.002,r=0.842), Bifidobacteria: Y(log10 CFU/g)=0.841X~2+0.315X+7.189 (p=0.030,r=0.664), Enterococcus: Y(log10 CFU/g)=12.026X~2-6.573X+8.034 (p=0.005,r=0.784), Escherichia coli: Y(log10 CFU/g)=-7.055X~2+2.331X+8.269(p＜0.000,r=0.959).