Effects of Different Microbial Culture Supplements on In vitro and In situ Ruminal Fermentation Characteristics of Italian ryegrass Silage

The study was conducted to evaluate the effects of microbial culture supplements on ruminal fermentation and fermentative quality of Italian ryegrass silage (IRGS) both in vitro and in situ. Three species of microbes (Lactobacillus casei (LC), Bacillus subtilis (BS), and Saccharomyces cerevisiae (SC)) were used in this study. They were applied to IRGS at 30 days after silage manufacture. Various items were measured using in vitro and in situ incubation technique after each microbial supplement was inoculated into IRGS at $0.5{\times}10^4CFU/g$. In the first experiment, in vitro ruminal fermentation characteristics of IRGS were evaluated at 0, 12, 24, 48, and 72 hours after microbes were inoculated into IRGS. In the second experiment, in situ fermentation characteristics were investigated at 0, 1, 3, and 5 days after the inoculation of each microbial supplement. In vitro ruminal $NH_3-N$ content was significantly (p<0.05) increased in LC-, BS-, and SC-IRGS at 12 hrs post incubation compared to that in control IRGS. In vitro ruminal total VFA concentration and dry matter digestibility (DMD) of IRGS were not significantly difference among LC-, BS-, and SC-IRGS, although they were numerically increased in LC-IRGS than those of the other IRGS. In addition, this study evaluated the fermentation characteristics and in situ DMD of IRGS with the lapse of incubation time up to 5 days. Throughout the incubation times from 1 day to 5 days, the pH value was significantly (p<0.05) lower in BS-, LC-, and SC-IRGS than that in control IRGS. Lactate was significantly (p<0.05) higher, and significantly (p<0.05) butyrate was lower in LC-IRGS than that in other treatments at 0 day. It was higher (p<0.05) in control IRGS than that of BS-, LC-, and SC-IRGS at 1-5 days. In situ DMD tended to increase in BS-, LC-, and SC-IRGS compared to that in control IRGS. Especially, DMD was higher in SC-IRGS than that in other treatments at 0 day. It tended to be higher in LC-IRGS at all incubation time. Taken together, these results suggest that it might be useful to select a microorganism by considering the feeding time of IRGS to ruminants because organic acids and DMD of IRGS were affected by the incubation time of each microorganism with IRG silage, especially for L. casei decreased the content of acetate and butyrate in IRGS.

미생물제 처리에 의한 이탈리안 라이그라스 사일리지의 In vitro 및 In situ 반추위 발효특성에 미치는 영향

본 연구는 국내산 조사료인 IRG 사일리지의 이용성을 증진하기 위해 다양한 미생물제의 첨가 시 IRG 사일리지의 in vitro 반추위 발효특성 및 소화율에 미치는 영향을 조사하였으며, 미생물제의 접종 후 배양시간이 경과함에 따라 IRG 사일리지의 품질 및 in situ 반추위 소화율에 미치는 영향을 분석하였다. 미생물제로는 LC, BS 및 SC ($2.7{\times}10^7CFU/m{\ell}$)를 사용하였으며, IRG 사일리지에 $0.5{\times}10^4CFU/g$가 되도록 첨가하여 수행하였다. In vitro 실험 결과, 암모니아태 질소 함량은 12시간 배양 시 대조구보다 미생물제 처리구에서 높았고(p<0.05), 총 VFA 농도와 건물 분해율의 경우에도 유의적 차이는 없었지만, 대조구보다 미생물제 처리구에서 증가하였으며, 특히 L. casei에서 높게 나타났다. 미생물제를 접종한 후 5일간 배양한 결과, IRG 사일리지의 pH는 대조구보다 미생물제 처리구에서 낮았으며(p<0.05), 젖산 농도는 배양 1~5일 동안 대조구보다 미생물제 처리구에서 높았으며(p<0.05), 다른 처리구보다 LC-IRGS에서 접종 직후 가장 높았다(p<0.05). In situ 건물 분해율은 대조구보다 모든 처리구에서 증가하는 경향을 나타내었으며, 접종 직후에는 SC-IRGS에서 높았으나 이후 LC-IRGS에서 증가하였다. 본 연구결과를 보면, IRG 사일리지의 이용성을 제고하기 위해 LC, BS 및 SC을 활용한다면 IRG 사일리지의 반추위 내 소화율이 개선될 수 있으며, 특히 IRG 사일리지에 L. casei를 첨가하여 단시간 추가 발효하여 젖소에 급여한다면 IRG 사일리지 내 초산 및 낙산의 감소로 품질 및 소화율 개선에 효과가 있을 것으로 사료된다.