Influence of dietary arginine concentration on lymphoid organ growth in chickens

In vivo effects of graded dietary levels of arginine on the body and lympho id organs were investigated using Cornell. K strain chickens of the B-15/B- 15 haplotype. Two-week-old birds were fed an arginine-deficient: basal diet (0.53% arginine) supplemented with. additional arginine (up to 1.0% L-argi nine to the diet). At four weeks of age, body weight, lymphoid organ weight , and concentrations of amino acids in plasma were measured. Arginine suppl ementation produced significant increases in plasma arginine (from 200 nM i n chicks fed the basal diet to 2,000 nM in chicks receiving the 1.5% argini ne diet) and ornithine concentrations (from 17 nM in chicks fed the basal d iet to 500 nM in chicks receiving the 1.5% arginine diet). The arginine-def icient diet reduced body weight gain (P < 0.0001) and thymus, spleen, and b ursa of Fabricius weights (P < 0.05). In contrast to the bursa weight, the thymus and spleen weights, as percentages of body weight, were also decreas ed (P < 0.05). This study suggests that arginine markedly influences lympho id organ development, with a more pronounced effect on the thymus and splee n than on the bursa of Fabricius.