title: Efficacy of cysteine in replacing methionine in the immune responses of broiler chicks.
abstract: Two trials were conducted to compare the effects of supplements of methionine and cysteine on the growth and immune responses of broiler chicks fed corn-soy diets. The basal diet contained 21% crude protein, 3,255 kcal metabolizable energy/kg diet, .35% methionine, .37% cysteine, and .13% choline. Additions to the basal diet were methionine (.063, .25, .85, and 1.45%), or cysteine (.203%), or a combination of methionine (.063%) and cysteine (.153%). Total antibody and 2-mercaptoethanol-resistant antibodies, immunoglobulin G (IgG), were determined in chicks inoculated intraperitoneally at 14 days of age and serially bled at 4, 7, and 10 days postinoculation. Thymus-derived (T)-cell-dependent in vivo mitogen response to phytohemagglutinin-P (PHA-P) was assessed via wing web swelling. The methionine requirement for growth (0 to 3 wk of age) was found to be no more than .413% of the diet (.35% in the basal diet plus .063% added). Addition of 1.45% methionine to the basal diet resulted in significant depression (P less than .05) in growth. The antibody responses generally peaked at 7 days postprimary inoculation. Both methionine and cystine supplementation at low levels resulted in improvement in the cell mediated PHA-P responses as well as in the IgG (T-cell-dependent) responses. High supplemental methionine (1.45%), however, caused significant (P less than .05) depressions in both responses. Equimolar additions of methionine and cysteine (16.8 mmol/kg diet) showed that cysteine was about 84 and 70% as efficacious as methionine in the IgG and the PHA-P stimulation (PHA-I), respectively, in healthy chicks.(ABSTRACT TRUNCATED AT 250 WORDS)
authors: Department of Poultry, University of Wisconsin, Madison 53706.
authors: V K
authors: VK
authors: Tsiagbe
authors: M E
authors: ME
authors: Cook
authors: A E
authors: AE
authors: Harper
authors: M L
authors: ML
authors: Sunde
mesh_terms: D000818:Animals; D000917:Antibody Formation / Q000187:drug effects*; D001835:Body Weight / Q000187:drug effects; D002645:Chickens / Q000276:immunology*; D003545:Cysteine / Q000008:administration & dosage / Q000494:pharmacology*; D006386:Hemagglutination Tests / Q000662:veterinary; D007074:Immunoglobulin G / Q000032:analysis; D007075:Immunoglobulin M / Q000032:analysis; D008715:Methionine / Q000008:administration & dosage / Q000494:pharmacology*; D010835:Phytohemagglutinins / Q000494:pharmacology
chemical_list: D007074:Immunoglobulin G; D007075:Immunoglobulin M; D010835:Phytohemagglutinins; D008715:Methionine; D003545:Cysteine