Abstract
This study was conducted to investigate the effects of supplementation with transgenic Bacillus subtilis secreting chitinase on the growth performance, nutrient digestibility, blood characteristics and carcass traits in finishing pigs. A total of sixty-four pigs ($50.82{\pm}0.82kg$, average initial body weight) were assessed over a period of 84 days. Dietary treatments included: 1) CON (basal diet without antibiotics), 2) AD (basal diet + 0.1% Virginiamycin), 3) CD0.5 (basal diet + 0.5% transgenic B. subtilis), 4) CD1.0 (basal diet + 1.0% transgenic B. subtilis). Each dietary treatment had 4 replicates of 4 pigs per pen in a randomized complete block design. In terms of growth performance, the ADG (average daily gain) and gain/feed ratio were significantly increased with the CD1.0 diet compared to the AD diet during weeks 0-4 (p<0.05). During weeks 4-8, the ADG was significantly increased with the AD diet compared to the CON and CD0.5 diets (p<0.05). The ADFI was also significantly increased with the AD diet compared to the other diets (p<0.05). During weeks $8{\sim}12$, the ADFI was significantly increased with the CON diet compared to the other diets (p<0.05), and the gain/feed ratio was significantly increased with the CD0.5 and CD1.0 diets compared to the AD diet (p<0.05). Over the entire 84 day test period, the ADFI was significantly increased with the AD diet compared to the CD0.5 and CD1.0 diets (p<0.05). The gain/feed ratio was significantly increased with the CD0.5 and CD1.0 diets compared to the CON diet (p<0.05). In terms of meat color, the L value was significantly increased with the CD0.5 diet compared to the CON and AD diets (p<0.05), and the a value was significantly increased with the CON diet compared to the other diets (p<0.05). In terms of sensory evaluation, meat color was significantly improved with the CON, CD0.5 and CD1.0 diets compared to the AD diet (p<0.05). Marbling was significantly increased with the CON diet compared to the other diets (p<0.05). Firmness was significantly increased with the CD0.5 diet compared to the AD diet (p<0.05). In conclusion, supplementation with transformed B. subtilis secreting chitinase improved gain/feed ratios and influenced meat color. Thus, we suggest that transformed B. subtilis secreting chitinase can partially substitute for antibiotics.
본 시험은 키틴분해효소를 분비하는 형질전환 B. subtilis의 사료내 첨가가 비육돈의 성장, 영양소 소화율, 혈액성상 및 육질에 미치는 영향을 알아보기 위하여 실시하였다. 3원교잡종(Landrace${\times}$Yorkshire${\times}$Duroc) 비육돈 64두를 공시하였으며 시험 개시시 체중은 $50.82{\pm}0.82kg$이었고 84일간 사양시험을 실시하였다. 처리구는 1) CON(basal diet without antibiotics), 2) AD(basal diet + 0.1% Virginiamycin), 3) CD0.5(basal diet + 0.5% transformed B. subtilis) 및 4) CD1.0(basal diet + 1.0% transformed B. subtilis)로 4 처리로 하였으며 처리당 4반복, 반복당 4두씩 완전임의 배치하였다. 본 사양시험에 사용한 B. subtilis 농도는 $3{\times}10^8cfu/g$이었다. 성장에 있어서 0-4주 동안에는 일당증체량과 사료효율에서 CD1.0 처리구가 AD 처리구보다 유의적으로 증가하였으며(p<0.05), 4-8주 동안에는 일당증체량과 사료섭취량에서 있어 AD 처리구가 CON 처리구와 형질전환 B. subtilis 첨가구에 비해 향상되었다(p<0.05). 8-12주 동안의 일당사료섭취량에서 CON 처리구가 형질전환 B. subtilis 첨가구와 비교하여 유의적으로 증가하였으며(p<0.05) 사료효율에서는 형질전환 B. subtilis 첨가구가 AD 처리구 보다 유의적으로 증가하였다(p<0.05). 전체 사양기간 동안에는 일당사료섭취량에서 AD 처리구가 형질전환 B. subtilis 첨가구와 비교하여 유의적으로 증가하였으며(p<0.05)사료 효율에서는 형질전환 B. subtilis 첨가구가 CON 처리구와 비교하여 유의적으로 증가하였다(p<0.05). 육색에 있어서 명도를 나타내는 L 값은 CD0.5 처리구가 CON 처리구 및 AD 처리구에 비해 개선되었으며(p<0.05), 적색도를 나타내는 a 값은 CON 처리구가 AD 및 CD0.5 처리구와 비교하여 유의적으로 증가하였다(p<0.05). 관능검사에서 육색은 CON 처리구, 형질전환 B. subtilis 첨가구가 AD 처리구와 비교하여 유의적으로 증가하였으며(p<0.05) 근내지방도는 CON 처리구가 다른 처리구들과 비교하여 유의적으로 증가하였다(p<0.05). 경도에서는 CD0.5 처리구가 AD 처리구와 비교하여 유의적으로 증가하였다(p<0.05). 본 시험결과, 사료효율, 육색에서 키틴분해효소를 분비하는 형질전환 B. subtilis의 첨가급여로 항생제의 부분적 대체가 가능하다고 사료된다.
