caa a22 4500 397569009 CHVBK 20180308164836.0 cr unu---uuuuu 161202e199606 xx s 000 0 eng 10.3382/ps.0750737 doi (NATIONALLICENCE)oxford-10.3382/ps.0750737 Sulfur Amino Acid Requirement and Cystine Replacement Value of Broiler Chicks During the Period Three to Six Weeks Posthatching [Elektronische Daten] [DAVID H. BAKER, SERGIO R. FERNANDEZ, DOUGLAS M. WEBEL, CARL M. PARSONS] Three experiments were conducted with commercial broiler chicks to determine the SAA requirement during the growth period 3 to 6 wk posthatching. A 20% CP corn-peanut meal basal diet (3,200 kcal MEn/kg) was analyzed to contain 0.23% Met and 0.28% cystine. True digestibility assessment in cecectomized cockerels revealed that Met and cystine in the basal diet were 81 and 75% digestible, respectively. Therefore, the basal diet contained 0.19% digestible Met and 0.21% digestible cystine. When fully fortified with DL-Met, growth rate and feed efficiency of chicks fed the corn-peanut meal diet were equal to that of chicks fed a 20% CP Met-fortified corn-soybean meal diet. In the SAA requirement assay, Ross × Hubbard male chicks were fed graded increments of DL-Met (0.03%) and L-cystine (0.03%) to achieve digestible SAA concentrations of 0.40, 0.46, 0.52, 0.58, 0.64, and 0.70%. Weight gain and feed efficiency responded quadratically (P < 0.01) to increasing doses of SAA. The estimated requirement for maximal feed efficiency was higher than that for maximal weight gain. Both visual appraisal and curve fitting procedures suggested a requirement of close to 0.61% digestible SAA. When extrapolated to a corn-soybean meal diet where SAA true digestibility is 87.5%, the total SAA requirement calculates to be 0.70% of the diet. However, because commercial corn-soybean meal diets typically contain supplemental Met, which is only 81% efficient (wt:wt) in furnishing cystine, the estimated total SAA requirement for chicks fed 20% CP Met-fortified corn-soybean meal diets with 3,200 kcal of ME/kg would probably approximate 0.72% of the diet. A DL-Met vs L-cystine supplementation assay suggested that digestible cystine can supply no more than 52% of the total requirement for digestible SAA of chicks during the 3- to 6-wk growth period. © 1996 Poultry Science Association, Inc. Metabolism and Nutrition nationallicence broiler chick nationallicence methionine nationallicence cystine nationallicence requirement nationallicence BAKER DAVID H. 2To whom correspondence should be addressed at 290 Animal Sciences Laboratory, 1207 W. Gregory Dr., University of Illinois, Urbana, IL 61801. aut FERNANDEZ SERGIO R. aut WEBEL DOUGLAS M. aut PARSONS CARL M. aut Poultry Science Oxford University Press 75/6(1996-06), 737-742 0032-5791 75:6<737 1996 75 ps https://doi.org/10.3382/ps.0750737 text/html Onlinezugriff via DOI 1 research-article jats NATIONALLICENCE 856 40 https://doi.org/10.3382/ps.0750737 text/html Onlinezugriff via DOI NATIONALLICENCE 700 1- BAKER DAVID H. 2To whom correspondence should be addressed at 290 Animal Sciences Laboratory, 1207 W. Gregory Dr., University of Illinois, Urbana, IL 61801 aut NATIONALLICENCE 700 1- FERNANDEZ SERGIO R. aut NATIONALLICENCE 700 1- WEBEL DOUGLAS M. aut NATIONALLICENCE 700 1- PARSONS CARL M. aut NATIONALLICENCE 773 0- Poultry Science Oxford University Press 75/6(1996-06), 737-742 0032-5791 75:6<737 1996 75 ps Metadata rights reserved CC BY-NC-4.0 http://creativecommons.org/licenses/by-nc/4.0 nationallicence BK010053 XK010053 XK010000 NATIONALLICENCE NATIONALLICENCE NL-oxford