Many β-lactam antimicrobials, including cephalosporins, have been used in both veterinary and human medicine in the treatment of zoonotic and infectious diseases. Especially, third-generation cephalosporins such as ceftiofur have been approved for systemic use in food-producing animals, which has resulted in the emergence of β-lactamase genes. This study aimed to investigate the occurrence of β-lactamase-producing E. coli isolated from commercial layers and characterized their antimicrobial resistance and virulence genes. Among the 85 cefotaxime (CTX)-resistant E. coli, all isolates showed resistance to at least one antimicrobial, and the rates of resistance to nalidixic acid, cephalothin, ampicillin, and cefazolin were more than 50.0%. In particular, 28 isolates were identified as containing b-lactamase genes. The extended-spectrum β-lactamase (ESBL) and plasmid-mediated AmpC genes blaCTX-M-1, blaCTX-M-14, blaCTX-M-15, and blaCMY-2 were detected in 1, 6, 5, and 4 isolates, respectively. The non-ESBL/pAmpC gene blaTEM-1 was detected in 12 isolates. The distribution of antimicrobial resistance genes in 28 β-lactamase-producing E. coli was as follows: aac(3)-II (64.3%), sul2 (32.1%), tetA (28.6%), sul1 (25.0%), cmlA gene (25.0%), and tetB (14.3%). In total, 6 virulence genes (astA, eaeA, escV, fimH, iucC, and papC) were also identified and the rates in virulence gene were as below: fimH (92.9%), iucC (25.0%), astA (21.4%), papC (10.7%), eaeA (7.1%) and escV (7.1%). Our findings suggest that antimicrobials used in commercial layer must be regulated in Korea, and comprehensive surveillance is necessary to prevent the dissemination of resistant isolates.

Although winter rye is now widely grown as a silage crop in Korea, but silage quality of the winter rye produced from farmer's fields have not been published. Therefore, this experiment was conducted to evaluate forage quality of winter rye which was participated in Forage Quality Contest in 2008. These data were classified by resign, forage production, added inoculants, planting date, and harvest date. Difference on lactic acid of rye silage was detected in forage production (p＜0.01), however, there were no significant differences among the rye silage tested. The moisture and lactic acid were significant differences in dry matter yield of rye silage. There is all the difference between silage added inoculants and control. The pH, ash, CP, NDF and ADF of rye added with inoculants were higher t㏊n those of control silage, however, the TDN and lactic acid were increased in silage added with inoculants. The ash and CP were significant differences in planting date, but lactic acid was significant differences in harvest date. This experiment indicates t㏊t lactic acid of silage was good indicator for evaluation of rye silage. Differences in forage quality were also observed among winter rye silage. Therefore, nutritional quality as well as lactic acid is important in silage quality contest of winter rye silage.

刈取가 알팔파根瘤의 着生 및 發達과 室素固定活性에 미치는 影響을 檢討하기 위하여 圃場實驗에서는 刈取區와 非刈取區로 구분하여 時期別로 Acetylene還元法에 의하여 根瘤의 室素固定活性을 測定하였다. 養液栽培實驗에서는 地上部의 50%와 90%刈取, 花芽의 除法, 根瘤의 50%와 100% 除法등을 組合處理後 알팔파 再生과 根瘤의 着生과 發達에 미치는 影響을 檢討하였다. 1. 圃場實驗에서 根瘤의 무게는 1回刈取後 30%, 2 回刈取後 25%의 減少가 있었고

The main nutritional problem of sorghumxsudangrass hybrid (Sorghum bicolorxSorghum sudanese) silage is low quality and palatability. This experiment was conducted to evaluate whether organic com grain and crushed rice addition of sorghumxsudangrass hybrid silage increases forage quality of the silage. The sorghumxsudangrass hybrid silages with added com grain and crushed rice were similar to conventional corn silage in moisture content. However organic sorghumxsudangrass hybrid silage had low pH values. Silage added with gain and byproduct had higher crude ash, acid detergent fiber (ADF) and neutral detergent fiber (NDF) contents than control corn silages, while its non-fiber carbohydrate (NFC) and total digestible nutrients (TDN) showed the opposite results. Lactic acid, butyric acid and lactic percentage oftotal organic acid (UT) of sorghumxsudangrass hybrid silages were higher than those of com silage, but acetic acid was higher than control. In vitro dry matter digestibi/ity (IVDMD) of com silage was higher than other sorghum silages. Feed intake of sorghumxsudangrass hybrid silage added with crushed rice was highest among silages. Therefore, these data indicate that crushed rice and com grain added sorghumxsudangrass hybrid silage could be recommended as the most effective treatment for increasing silage quality and palatability.