LAYING HEN PRODUCTION RESPONSES TO LEAST-COST RATIONS FORMULATED WITHSTOCHASTIC-PROGRAMMING OR LINEAR-PROGRAMMING WITH A MARGIN OF SAFETY

An experiment with 480 DeKalb DK laying hens was conducted to study th e effect of rations formulated with stochastic programming (STCH) or l inear programming with a margin of safety (LPMS) over 12, 28-d periods . Rations were formulated to guarantee the requirement of methionine a nd lysine greater-than-or-equal-to 69%, in all rations, and Ca and P g reater-than-or-equal-to either 69 or 90%. The four rations were: LPMS6 9 with Ca and P greater-than-or-equal-to 69%, LPMS90 with Ca and P gre ater-than-or-equal-to 90%, STCH69 with Ca and P greater-than-or-equal- to 69%, and STCH90 with Ca and P greater-than-or-equal-to 90%. Rations formulated with STCH were lower in cost than LPMS rations for respect ive probability levels. Costs per metric ton for LPMS69, LPMS90, STCH6 9, and STCH90 were $155.70, $157.71, $155.00, and $156.30, respectivel y. Compared to STCH rations, LPMS rations were overformulated in nutri ents. There was no difference (P > .05) in performance for hen-housed egg production, hen-day egg production, feed er dozen eggs, mortality, egg weight, or eggshell percentage.