Abstract
An experiment was conducted to investigate the dietary effects of a transgenic Aspergillus oryzae(AO) culture on the performance, egg quality and intestinal microflora of layers. A total of 840 Hy-line Brown layers of 39wks old were assigned to one of the following 7 dietary treatments: control(C), C+0.2% AO culture, C+0.5% AO culture, C+0.2% transgenic AO culture, C+0.5% transgenic AO culture, C+0.2% transgenic mutant AO culture, and C+0.5% transgenic mutant AO culture. The transgenic AO was made by inserting Salmonella gallinarum gene to AO. And the transgenic mutant AO was made by inserting Salmonella gallinarum gene to mutant AO which was mutated by UV irradiation. Each treatment was replicated six times with 20 birds housed in 2 bird cage. Twenty birds units were arranged according to completely randomized block design. Feeding trial lasted for 8wks under 16 hour lighting regimen. Laying performance and egg quality were significantly(P<0.05) affected by the treatments. Transgenic AO culture supplementation at the level of 0.2% significantly increased egg production, while its egg weight was significantly decreased compared to that of the control. Feed intake and feed conversion ratio(FCR) were not significantly different among the AO treatments and the control. The eggshell strength of the AO treatments was significantly higher than that of the control. Transgenic mutant AO culture supplemented at the level of 0.5% significantly increased egg yolk color. Intestinal microflora were significantly(P<0.05) affected by the treatments. The cfu of Lactobacilli spp. significantly increased and those of Salmonella species and E. coli decreased in the AO treatments. The transgenic AO and transgenic mutant AO culture were more effective than the AO culture in reducing the cfu of Salmonella species and E. coli. It is concluded that supplementation of the transgenic AO culture at the level of 0.2% could be recommended for the improvement of egg production. Supplementation of transgenic AO or transgenic mutant AO culture at 0.2% level effectively controlled intestinal Salmonella species population.
본 연구는 메주에서 순수 분리된 메주곰팡이의 대표적 균종인 황국균(Aspergillus oryzae; AO)으로 만든 AO culture와 Salmonella 병원특이 유전자를 삽입한 형질전환 AO(TAO) culture가 산란계의 생산성, 계란 품질 및 장내 미생물 균총에 미치는 영향을 규명하고자 실시하였다. 39주령 산란계 Hy-line Brown 840수를 공시하여 대조구, AO culture 0.2%와 0.5%, TAO culture 0.2%와 0.5%, UV를 조사하여 단백질 분해효소를 감소시킨 mutant에 Salmonella 병원 특이 유전자를 삽입한 형질전환 AO(TMAO) culture 0.2%와 0.5% 첨가구들을 비교하였다. 각 첨가구는 6반복, 반복당 20수씩, 한 케이지 당 2수씩 배치하여 8주간 사양시험을 실시하였다. 사양시험 결과 모든 산란 생산성 및 계란 품질 관련 조사항목에서 처리간에 유의한(P<0.05) 차이가 있었다. TAO culture 0.2% 첨가구가 산란 생산성에 있어서 유의적으로 가장 높았으며, 난중은 모든 AO 첨가구들이 대조구에 비해 유의적으로 낮거나 낮아지는 경향을 나타내었다. 연파란율은 TMAO culture 0.5% 첨가구가 가장 낮았다. 사료섭취량과 사료요구율은 대조구와 모든 AO 첨가구들간에 유의적 차이가 나타나지 않았다. 난각 강도는 대조구 보다 모든 AO 첨가구들에서 유의적으로 높게 나타났으며, 난황 색도는 TMAO culture 0.5% 첨가구에서 가장 높았다. 난각 색도와 Haugh unit은 대조구와 모든 AO 첨가구들간에 유의적 차이가 나타나지 않았다. 장내 미생물 균총(Salmo- nella spp., E. coli. Lactobacilli spp.)에서는 유의적(P<0.05) 차이가 있었다. AO culture 첨가에 의해서 Lactobacilli spp.의 수는 증가되고, E. coli 및 Salmonella spp.의 수는 감소되었다. 특히 TAO와 TMAO culture 첨가구에서는 AO culture 첨가구보다 Salmonella spp. 및 E. coli 억제효과가 컸으며 첨가수준(0.5% vs 0.2%) 간에는 유의한 차이가 없었다. 결론적으로 TAO culture 0.2% 첨가는 산란 생산성 증가에 효과가 있었으며 TAO 및 TMAO culture 0.2% 첨가는 장내 E. coli 및 Salmonella spp.의 감소에 유의한 효과가 있었다.
