An experiment was conducted to investigate the influence of repeated ingestion of ochratoxin A (OTA) on milk production of lactating Holstein cows over 28 days, and the carry-over of OTA from the diets into the milk and tissues of the cows. Nine cows were divided into three groups, labeled OTA5, OTA50 and OTA100, and fed a diet containing 5, 50 and 100 µg OTA/kg of dry matter, respectively. Body weight, feed intake and daily milk yield in cows were not different among the three groups during the OTA-intake period. OTA residues were neither detected in the tissues, such as liver, kidney, muscles, fat and jejunoileum, nor in the milk of any cows in the OTA intake groups. In contrast, a small amount of OTA (0.1 µg/kg) was detected in the blood plasma of one sample in the OTA50 group and multiple samples in the OTA100 group. The results of this study show that the ingestion of diets containing up to 100 µg/kg of OTA over 28 days does not affect feed intake or milk production of cows, and the dietary OTA is not carried over into milk and edible tissues such as the liver, muscles and fat.

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Influence of Yucca shidigera extract and saponins on the growth of bacteria isolated from the animal intestinal tract was investigated in in vitro. Among a total of 20 strains examined, seven strains classified into 7 species of Lactobacillus plantarum, Lactobacillus rhamnosus, Enterococcus hirae, Escherichia coli, Bifidobacterium thermophilum, Bifidobacterium longum and Streptococcus bovis grew well on the media containing 10% Yucca shidigera extract. In addition, the minimum inhibitory concentration (MIC) of Y, shidigera saponins prepared from Y. shidigera extract against these 7 strains exceeded 28mg/ml.Meanwhile, the other 13 strains which include Bacteroides fragilis, Fusobacterium varium, Fusobacterium necrophorum, Clostridium perfringens, Clostridium innocuum, Clostridium sporogenes, Veillonella parvula, Propionibacterium acnes, Eubacterium aerofaciens, Selenomonas ruminantium, Peptococcus asaccharolyticus, Ruminococcus productus and Megasphaera elsdenii did not grow on the media containing 10% Y. shidigera extract. And, the MICs of the Y. shidigera saponins against these 13 strains was in the range of 14 to 0.7mg/ml.The results obtained in this investigation provide useful and basic information for analyzing the effects of Y shidigera extract and saponins on the constitution of microflora in the animal intestinal tract.The Yucca shidigera plant belongs to the family, Agavaceae, and grows in the southwestern deserts of the United States and in the Baja California region of Mexico. The native populations of the arid deserts of the Americas have used extracts and preparations of the flowers, seed pods and stalks of the plant as therapeutic agents for arthritis, rheumatism, diabetes, hypertension and gastroenteric disorders, and con-Corresponding: Hajime MINATO (

Aims:  To investigate the influence of avilamycin (AVM) administration and its subsequent withdrawal on the emergence and disappearance of AVM‐resistant enterococci in the intestine of broiler chickens. Methods and Results:  Five chicks each of C, L and H groups were given the basal diet, the basal diet supplemented with 5 g AVM/ton and the basal diet supplemented with 50 g AVM/ton, respectively. The AVM‐resistant Enterococcus faecalis population did not emerge during 30 days of the AVM administration period, whereas the AVM‐resistant Enterococcus faecium with a minimum inhibitory concentration of >512 μg ml−1 in the faeces of chicks of the L and H groups emerged on 3 and 1 days after the AVM administration, respectively. Thereafter, the AVM‐resistant Ent. faecium population density in both L and H groups maintained high levels during the AVM administration period. Twenty days after the AVM withdrawal, the AVM‐resistant Ent. faecium population disappeared from the intestines of both four of five chicks of L group and three of five chicks of H group. The AVM‐resistant Ent. faecium population density in one chick from each of the groups, L and H, did not change before and after the AVM removal. Conclusions:  The AVM‐resistant Ent. faecium emerged during the AVM administration, and disappeared from the intestine of most chicks after the AVM withdrawal. However, the AVM‐resistant Ent. faecium persisted in some chicks 20 days after AVM withdrawal. Significance and Impact of the Study:  Our results suggest that introducing an AVM withdrawal period could minimize the risk of AVM‐resistant Ent. faecium becoming carcass contaminants, and that prudent antibiotic use alone is not sufficient to stem emergence of the AVM‐resistant Ent. faecium.

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