Histidine and tryptophan requirement of growing chicks.
Experiments were conducted to determine the His and Trp requirement of broiler chicks during the period 8 to 22 days posthatching. A His- or Trp-deficient diet (.32% total His; .18% total Trp; 25% CP; 3,200 kcal MEn/kg) based upon corn, feather meal, and soybean meal was supplemented with graded increments of either L-His.HCl.H2O or L-Trp to produce growth responses. Growth rate and feed efficiency of birds fed the fully fortified experimental diet were similar to those of birds fed a corn and soybean meal positive control diet (23% CP; 3,200 kcal MEn/kg). True digestibility of the protein blend (corn, feather meal, and soybean meal) used in the basal diet was 81.4% for His and 83.3% for Trp as established in precision-fed, cecectomized adult cockerels. Requirements for digestible His and Trp were determined to be not greater than .31% (1.24% of CP) and .20% (.80% of CP), respectively, for maximal weight gain and feed efficiency. Translating the requirement estimates to practice, wherein a 23% corn and soybean meal diet would be fed, results in a total His requirement of .32% and a total Trp requirement of .22% of the diet during the broiler chick's 2nd and 3rd wk of life.
Han
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YM
Department of Animal Sciences, University of Illinois, Urbana 61801.
Suzuki
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H
Baker
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DH
D000821:Animal Feed / Q000592:standards*; D000818:Animals; D002645:Chickens / Q000254:growth & development* / Q000502:physiology; D004044:Dietary Proteins / Q000008:administration & dosage* / Q000378:metabolism; D004063:Digestion; D004435:Eating; D005241:Feathers; D005260:Female; D006639:Histidine / Q000008:administration & dosage* / Q000378:metabolism; D008297:Male; D013025:Glycine max; D014364:Tryptophan / Q000008:administration & dosage* / Q000378:metabolism; D015430:Weight Gain; D003313:Zea mays
D004044:Dietary Proteins; D006639:Histidine; D014364:Tryptophan