title: Dietary sulfur amino acid level and energy utilization in laying hens.
abstract: Effects of marginal total sulfur amino acid (TSAA) deficiency and methionine toxicity on energy utilization of laying hens were studied with 7-month-old Single Comb White Leghorn pullets housed in individual cages at constant temperatures of 15.6 and 32.2 C. Diets containing .47, .49, .51, and 3.47% TSAA were fed throughout the 4-week study. Following a 2-week acclimation period, each diet was fed at three levels of intake for 2 weeks. Voluntary feed and metabolizable energy (ME) consumption of nontoxic TSAA diets was significantly reduced at the higher housing temperature, and a further significant reduction was observed with the toxic diet at both temperatures. Energy balance increased from 79.7 to 98.7 kcal/bird per day at 32.2 C and from 117.3 to 142.0 kcal at 15.6 C as dietary TSAA increased from .47 to .51%; energy balance of hens fed 3.47% TSAA was very low at both temperatures. Maintenance ME requirements were unaffected by dietary TSAA up to .51%, ranging from 123.3 to 131.1 and 155.5 to 163.5 kcal/hen per day at 32.2 C and 15.6 C, respectively; the requirement increased about 20 kcal/day at each temperature when the toxic TSAA diet was fed. As the amino acid balance of the diet was improved with methionine supplementation up to .51%, heat increment plus activity decreased from 70.2 to 37.0 kcal/bird per day for hens housed at 32.2 C. Consequently, efficiency of conversion of dietary ME to net energy improved from 52.1% with .47% TSAA to 63.8% with .51% TSAA. Housing temperature did not influence energetic efficiency.(ABSTRACT TRUNCATED AT 250 WORDS)
mesh_terms: D000603:Amino Acids, Sulfur / Q000008:administration & dosage / Q000172:deficiency*; D000821:Animal Feed; D000818:Animals; D001835:Body Weight; D002645:Chickens / Q000378:metabolism*; D004734:Energy Metabolism; D005247:Feeding Behavior; D005260:Female; D008715:Methionine / Q000008:administration & dosage / Q000633:toxicity*; D010058:Oviposition; D013237:Stereoisomerism; D013696:Temperature
chemical_list: D000603:Amino Acids, Sulfur; D008715:Methionine