초록
Ferritin 유전자 이식 효모 (FRT, Saccharomyces cerevisiae)를 생균제로 급여시에 육계와 산란계의 생산성과 장기 및 난황의 철분 함량에 미치는 영향을 구명하기 위하여 3회의 사양실험을 실시하였다. FRT의 급여효과는 일반 효모 (W0)와 20mM의 구연산 철을 첨가한 배지에서 배양한 효모(W20)의 급여시와 비교하였다. 실험 1에서는 철분을 첨가급여구(75mg/kg; Fe75), 무첨가구 (Fe0) 효모의 급여(무첨가, W0, FRT)가 육계의 생산성과 장기의 철분함량에 미치는 영향을 구명하기 위하여 1일령 육계 수컷 420수를 이용하여 5주간 사양실험을 실시하였다. 매주 증체량과 사료섭취량, 사료요구율을 측정하였다. 실험 2에서는 33주령 이사브라운 산란계 15수를 산란케이지에 개체수용하여 대조구와 W0, FRT 사료를 3주간 급여하였다. 실험 3은 45주령 이사브라운 산란계 24수를 산란케이지에 개체수용하여 1주간 기초사료를 급여한 뒤 시험사료(대조구, W0, W20, FRT)를 3주간 급여하였다. 모든 실험의 종료시 간과 심장, 비장, 경골의 철분함량을 측정하였으며 주간별로 난황의 철분함량을 측정하였으며 주간별로 난황의 철분함량을 측정하였다.(Expt 2, 3) 실험 1과 2에서 효모의 급여량은 사료에 $1{\times}10^8$cfu/kg이었으며 철분함량은 세포 건물기준 500mg/kg이었다. 실험 3에서는 사료에 $2{\times}10^{10}$cfu/kg을 첨가하였으며 철분함량은 1000mg/kg이었다. 실험 1에서 Fe75의 급여는 Fe0에 비해 증체량이 현저히 증가하였다.(P<0.05). 실험 3에서 FRT의 급여는 간과 비장의 철분함량을 증가시키는 경향을 보였으나 경골의 철분함량은 감소하는 경향을 보였다. 이상의 결과에서 FRT의 급여는 생균제로서 육계와 산란계의 생산성과 장기의 철분함량을 개선하지 못하였다.
Three experiments were conducted to investigate the effect of feeding yeast accumulated transgenic ferritin(FRT, Saccharomyces cerevisiae) as a probiotic on the performance, iron contents in the liver, spleen, bone and yolk of laying hens and broiler chicks. Effects of feeding FRT were compared with that of feeding wild-type yeast(W0) and yeast grown on 20 mM ferric citrate-added medium (W20). In Expt 1, to investigate the effect of feeding yeast (control, W0 FRT) on performance and iron content of organs of broiler chicks which were fed basal diet supplemented with 75mg/kg iron(Fe75) or not (Fe0), three hundred sixty one-day-old male broiler chicks were fed a corn-sov based diet for five weeks. Weight gain, feed intake and feed conversion were measured weekly. In Expt 2, fifteen 33-week-old ISA Brown laying hens were placed in individual cages and were fed control, W0 and FRT diets for Four weeks. In Expt 3, twenty four 45-week-old ISA Brown laying hens were placed in individual cages and were fed a basal diet for a week. Then, experimental diets (control, W0, W20, FRT) were fed for three weeks. Iron contents in the liver, heart, spleen and tibia were determined at the end of all experiments. Iron content in yolk was measured weekly (expt 2, 3). The level of yeast added and iron concentration of FRT were $1{\times}10^8$cfu/kg diet and 500 mg/kg cell (DM) respectively in Expt 3, yeast was supplemented at $2{\times}10^{10}$cfu/kg diet and the iron content of FRT was 1000mg/kg cell (DM). In Expt 1. birds fed Fe75 showed significantly higher weight gain compared with Fe0 (P<0.05). However, weight gain and feed intake of birds fed FRT was significantly lower than control (P<0.05). In Expt 2, the iron content of the liver was decreased in the FRT treatment (P<0.05). In Expt 3, iron concentration of the liver and spleen tended to be increased by feeding FRt. However, the iron content of the tibia tended to be decreased in the FRT treatment. These results suggest that feeding FRT as a probiotic cannot improve performance and iron content in organs of broiler chicks and laying hens.
