Comparative effects of individual amino acid excesses when added to a corn-soybean meal diet: effects on growth and dietary choice in the chick.
Six experiments were conducted with 8-d-old crossbred chicks to evaluate the effects of 4% excesses of DL-methionine (Met), L-phenylalanine (Phe), L-tryptophan (Trp), L-lysine (Lys), L-histidine (His), L-threonine (Thr), L-isoleucine (Ile), L-arginine (Arg), L-valine (Val) or L-leucine (Leu) on growth or dietary "choice" (i.e., self-selection) when added to 23% protein corn-soybean meal (C-SBM) diets. Arginine and His were supplied as the free base and Lys as Lys X acetate to avoid acid-base problems. In the growth studies, weight gain was reduced 92, 79, 53, 50, 47, 31, 29, 15, 9, 4 and 0% by additions of 4% Met, Phe, Trp, His, Lys, Tyr, Thr, Ile, Arg, Val and Leu, respectively. Improvements (P less than .05) in weight gain, feed intake and gain/feed occurred by addition of 1% Arg to the C-SBM diet supplemented with 4% excess Phe or Tyr. Addition of 1% Arg to the C-SBM diet supplemented with 4% excesses of most of the other amino acids also tended to improve performance, although diets imbalanced with Lys, Val or Leu did not respond to supplemental Arg. Self-selection studies revealed that chicks preferred the C-SBM diet containing 4% excess Lys over diets containing 4% excesses of Met, Thr, Arg or Trp. Moreover, chicks preferred diets with 4% excess Met, Thr or Arg over those containing an equal excess of Trp. When given a choice between the C-SBM diet and this diet supplemented with 4% Leu, chicks consumed similar quantities of both diets.
Edmonds
M S
MS
Dept. of Anim. Sci., University of Illinois, Urbana 61801.
Baker
D H
DH
D000596:Amino Acids / Q000494:pharmacology*; D000821:Animal Feed; D000818:Animals; D001835:Body Weight / Q000187:drug effects*; D002645:Chickens / Q000254:growth & development*; D002755:Choice Behavior; D004032:Diet; D005260:Female; D005518:Food Preferences; D008297:Male
D000596:Amino Acids