육계 사료에 허브와 식물체의 추출물의 첨가가 생산능력, 영양소 소화율, 장내 미생물, IgG, 혈액의 조성에 미치는 영향을 구명하고자 2차례의 실험을 수행하였다. 시험 1은 대조구, 항생제(<TEX>$Aviilamix^{(R)}premix-avilliamycin$</TEX> 0.02 %) 0.03%구, Herb M (Herb <TEX>$mix^{(R)}$</TEX>-지황 10%, 산약 10%, 당귀 20 %, 오미자 5%, 감초 5%, 천궁 10%) 0.2%구, Plant extract B(BIOSTONG <TEX>$510^{(R)}-Anise$</TEX> Extract 20%, Thyme Extract 17%, Quillaja 30%) 0.02%구, Plant Extract A(<TEX>$APEX^{(R)}$</TEX> - garlic, anise, cinnamon rosemary, thyme, Talin등 50%) 0.02%구 등 5개 처리구를 두었다. 시험 2는 대조구, 항생제(<TEX>$Aviilamix^{(R)}$</TEX>premix- avilliamycin 0.02%) 0.03% 구, Plant Extract D(<TEX>$Digestarom^{(R)}$</TEX>-peppermint oil, gentian, horse-tail herb, saponins, oak bark 50 %) 0.02 %구, Plant extract P(<TEX>$Phellozyme^{(R)}$</TEX> -Kilmora lavan extract, bromelain extract, bioflavonoid, propolis 15%) 0.1%구, Plant Extract G(<TEX>$Galicin^{(R)}$</TEX>-allicin 10%) 0.05%구, Plant Extract C(CRINA <TEX>$POULTRY^{(R)}$</TEX>-cinnamon, lemongrase, savory, rosewood, spearmint, tea) 0.05%구 등 6개 처리구를 두었다. 시험 1은 1일령 육계(<TEX>$Ross^{(R)}$</TEX>종) 1,000수(암 수 각각 500수)를 공시하여 5처리 4반복 반복당 50수(암 수 동수) 씩을 floor pen(가로: 2.0 m, 세로: 2.4 m)에 완전 임의 배치하였다. 시험 2는 1일령 육계(<TEX>$Ross^{(R)}$</TEX>종) 240수(암 수 각각 120수)를 공시하여 6처리 4반복, 반복당 10수(암 수 동수) 씩을 케이지(가로: 35.5 cm, 세로: 45 cm, 높이: 55 cm)에 완전 임의배치하여 각각 35일간사양 시험을 실시하였다. 시험 1에서 생산지수는 대조구에 비해 첨가구들이 높은 경향이 있었고 herbs M구가 가장 높았다. 시험 2에서 <TEX>$4{\sim}5$</TEX>주 사료 섭취량은 대조구에 비해 첨가구들이 유의적으로 높았다(P<0.05) 사료 요구율은 항생제 처리구가 다른 처리구보다 낮았다. 시험 1의 RBC와 적혈구 용적 (HCT 또는 PCV), Hb는 첨가구들이 대조구보다 유의적으로 높았다(P<0.05). 시험 2의 BA는 대조구보다 첨가구들이 유의적으로 낮았다(P<0.05). 시험 1과 시험 2의 혈청 IgG 농도는 대조구에 비해 첨가구들이 유의적으로 높았다(P<0.05). 시험 1과 시험 2의 장내 미생물 균총과 영양소 이용율은 처리간에 통계적 차이가 없었다. 결론적으로 일부 한방제와 생약제제는 육계에서 항생제를 대체하여 사용이 가능하며 특히 혈액의 성분에 유의한 영향을 미치는 것으로 사료된다. Experiments were conducted to investigate the effects of dietary botanicals (herbs and plant extracts) on the performance, nutrient metabolizability, small intestinal microflora, IgG level and blood parameters in broiler chickens. In Exp. 1, 1,000 (500 each sex) broiler chicks(<TEX>$Ross^{(R)}$</TEX>) were divided into 20 groups of 50 chickens each(25 birds each sex). Four groups were assigned to each of five dietary treatments:control and diets containing antibiotics(<TEX>$Avillamix^{(R)}$</TEX>, avillamycin-premix), Herb M(Herb <TEX>$mix^{(R)}$</TEX>), Plant extract B(BIOSTRONG <TEX>$510^{(R)}$</TEX>) and Plant extract A(<TEX>$APEX^{(R)}$</TEX>). In Exp. 2, 240(120 each sex) broiler chicks(<TEX>$Ross^{(R)}$</TEX>) were devided into six treatment groups:control and diets containing antibiotics(<TEX>$Avillamix^{(R)}$</TEX>, avillamycin-premix), Plant extract D(<TEX>$Digestarom^{(R)}$</TEX>), Plant extract P(<TEX>$Phellozyme^{(R)}$</TEX>), Plant extract G(<TEX>$Galicin^{(R)}$</TEX>) and Plant extract C(CRINA <TEX>$POULTRY^{(R)}$</TEX>). Each treatment consisted of four replicates of 10 birds each. In both experiments, birds had free access to diets and water for 5 wk on floor pens(Exp. 1) and cages(Exp. 2). In Exp.1, production index of groups fed diets supplemented with herbs and plant extracts was slightly higher than the control and those fed Herb M was highest. In Exp. 2, groups fed diets supplemented with herbs and plant extracts consumed more feed than the control during the period between 4 and 5 wk(P<0.05). Feed conversion(feed/gain) was lower in antibiotics group than other groups. The values of RBC, Hb and HCT were higher(P<0.05) in chicken fed diets supplemented with the additives than in the control in Exp. 1. BA value was lower(P<0.05) in groups fed diets supplemented with the additives than in the control in Exp. 2. Serum IgG were higher(P<0.05) in groups fed diets supplemented with the additives than in the control in both experiments. The cfu of intestinal microflora and metabolizability of nutrients were not significantly different among treatments in both experiments. It was concluded that the botanical supplements can be used as an alternative to antibiotics in broiler diets.