Using phosphorylated mannan oligosaccharide and fibrolytic enzyme as natural feed additive substitutes for growth-enhancing technologies in sustainable beef production [Sürdürülebilir si{dotless}ǧi{dotless}r eti üretiminde büyümeyi arti{dotless}ri{dotless}ci{dotless} teknolojilere İkame olarak doǧal yem katki{dotless} maddesi fosforile mannan oligosakkarit ve fibrolitik enzim kullani{dotless}mi{dotless}]

The study objective was to determine the effect on beef production sustainability when growth-enhancing technologies (get) were substituted with the natural feed additives (nfa) phosphorylated mannan oligosaccharide (bio-mos®-(mos)) and fibrolytic enzyme (fibrozyme®-(fib)). angus × hereford × gelbvieh steers,after weaning (n=80; bw=279.6±3 kg),were used in an 84-day backgrounding study (4 treatments; 4 pen replicates/treatment) that was followed by a 122-day finishing study. a control (c) treatment with get (revelor-is® and rumensin®) was compared to nfa (10 mg/head/day): mos,fib,and mos+fib. data were analyzed using mixed procedure of sas. the backgrounding c steers end weight,weight gain,and average daily gain (adg) were greater (p<0.01) compared to mos,fib,and mos+fib. feed efficiency ratio did not differ (p=0.198). feed cost/kg of gain was lower for the c treatment (p<0.01). the c treatment net return was 45.9% greater than the average of mos,fib,and mos+fib treatments. for finishing,the c treatment adg was greater (p<0.05) compared to mos,fib,and mos+fib. in addition,the c treatment harvest weight and hot carcass weight were greater (p<0.01) and were harvested 5 days earlier. however,other carcass measurements did not differ (p>0.10). ending net return was $54.22,-$33.62,-$20.65,and -48.69 for the c,mos,fib,and mos+fib,respectively. the nfa were less profitable during backgrounding,but not profitable for finishing.