Study On The Requirements Of Lysine And Other Essential Amino Acids For 1~18d Medium-speed Yellow Broilers

The aim of this experiment was to study the requirement of digestible lysine,methionine,threonine and tryptophan for medium-speed yellow broilers aged from 1 to 18 days.810 male 1-day-old medium-speed yellow broilers were randomly divided into 9 treatment groups,each treatment group consisted of 6 replicates,each replicate consisted of 15 broilers,and were fed with 9 different amino acid levels of diets.The experiment was conducted in 3×3 factor.(three lysine levels and three other amino acids(methionine,threonine and tryptophan)were used in the experiment.The digestible lysine levels were 0.89%,1.05% and 1.20%.The Digestible Methionine levels were 0.66%,0.78% and 0.90%.The digestible threonine levels were 0.58%,0.68%,0.78%,and the digestible tryptophan levels were 0.16%,0.19% and 0.22%.The experimental period was 18 days.The growth performance of yellow feather broilers was measured by repetition at the beginning and end of the experiment.Two broilers were randomly selected from each repetition and slaughtered.Serum parameters,slaughter performance,meat quality,slaughter appearance,immune organ index,intestinal development and structure were determined.The experiment results show that:(1)Lysine had significant effects on ADG and FCR of Broilers(P <0.05).The ADG and FCR of medium-level Lysine diet group were significantly higher than those of other diets group(P<0.05);other essential amino acids had significant effects on AFDI(P<0.05)and decreased FCR(0.05<P<0.1);the interaction between amino acids had no significant effect on growth performance of Broilers(P>0.05).Lysine had significant effect on serum TP(P<0.05),UA(P<0.05),HDL decreased first and then increased(0.05<P<0.1),but had no significant effect on CHO and TG;other essential amino acids had significant effect on CHO,TG and HDL(P<0.05),but had no significant effect on serum TP and UA(P>0.05);the interaction of amino acids had significant effect on serum TP and UA(P>0.05).The effect was(P<0.05).Lysine had a significant effect on serum IGF-1(P<0.01),but had no significant effect on other hormone indexes(P>0.05);other essential amino acids had no significant effect on serum hormone indexes(P>0.05);the interaction between amino acids had a significant effect on corticosterone and IGF-1(P < 0.05),and had a significant effect on serum testosterone(P<0.01).The digestible amino acid requirements of yellow feather broilers aged 1 to 18 days were digestible lysine 1.05%,digestible methionine 0.90%,digestible threonine 0.78% and digestible tryptophan 0.22%.With testosterone and IGF-1 as evaluation indexes,digestible lysine requirement of broilers was 1.20%,digestible methionine 0.60%,digestible threonine 0.58%,digestible tryptophan 0.16%.(2)Lysine had a significant effect on the abdominal fat weight of Broilers(P < 0.05).The lowest abdominal fat weight was found in the medium-level Lysine diet group.Other essential amino acids had a significant effect on the abdominal fat weight of Broilers(P<0.01).The abdominal fat rate of the medium-level and high-level amino acid diet group was lower than that of the low-level diet group,and there was no significant difference in the other slaughter performance(P>0.05).The weight of pectoralis major muscle and chicken wing was significantly affected by the application of the drug(P<0.05).Lysine level had significant effect on meat quality pH(P<0.01),shear stress(P<0.05),other meat quality had no significant difference(P>0.05);other essential amino acids had significant effect on meat yellowness(b*)and meat quality pH(P<0.01),and there was no significant difference among other meat quality indicators(P>0.05);the interaction between amino acids had significant effect on pH.The effect was(P<0.01).Lysine had a significant effect on the water content of meat quality components(P<0.05),but the interaction between Lysine and other essential amino acids had no significant effect on other meat quality components(P>0.05).There was no significant effect of amino acid level on pore density of Broilers(P>0.05).Lysine had significant effect on the length and weight of chicken crown(P<0.05),but had no significant effect on the thickness and height of chicken crown(P>0.05);other essential amino acids had no significant effect on the development of chicken crown(P>0.05).The digestible amino acid requirements of broilers were as follows: lysine 1.20%,methionine 0.90%,threonine 0.78% and tryptophan 0.22%,respectively.The optimum pH was obtained for broilers.The digestible lysine requirement of broilers was 1.05% by shear stress evaluation index,and the crown development of broilers was the best.(3)Lysine level had no significant effect on immune organ index of yellow feather broilers(P>0.05);other essential amino acids had significant effect on thymus index(P<0.01),and the thymus index of medium level diet group was the highest;the interaction of amino acids had significant effect on bursa index(P<0.05),but had no significant effect on other immune organ index(P>0.05).Lysine level had a significant effect on the weight of duodenum,jejunum,ileum and the length of jejunum(P<0.01),and had a significant effect on the length of duodenum and ileum(P < 0.05);other essential amino acids had a significant effect on the length of jejunum(P<0.05),while other intestinal indicators had no significant difference(P> 0.05).The interaction between acids had no significant effect on intestinal development of Broilers(P>0.05).Lysine had a significant effect on the villus height of jejunum(P<0.05),but had no significant effect on the recess depth and V/C of jejunum(P>0.05);other essential amino acids had no significant effect on the villus height of jejunum(P>0.05),but had a significant effect on the recess depth and V/C of jejunum(P<0.01).The depth of crypt had a significant effect(P<0.01)on the villus height of jejunum,but the difference was not significant(0.05<P<0.1),and the difference between V/C was not significant(P>0.05).The digestible amino acid requirements of broilers were lysine 0.89%,methionine 0.78%,threonine 0.68% and tryptophan 0.19%.The digestible amino acid requirements of broilers were lysine 1.20%,methionine 0.78%,threonine 0.68% and tryptophan 0.19%.The digestible lysine,methionine,threonine and tryptophan were 0.89%,0.90%,0.78% and 0.22%.The digestible lysine requirement of broilers was 0.89% based on the jejunal villus height.The digestible amino acid requirements of broilers were lysine 1.05%,methionine 0.66%,threonine 0.58% and tryptophan 0.16%.