| Zearalenone(ZEA) is a nonsteroidal oestrogenic mycotoxin, and has an adverse effect on animal reproductive development.A strain of Bacillus licheniformisisolated from soil has the ability to degrade ZEA in the culture medium. The aim of the research was to determine the ability of Bacillus licheniformis CK1 to degrade ZEA in feed during fermentation and to explore the alleviation of adverse effect caused by ZEA in pigletsin an animal trial. For the fermentation step, use fermentation tank to detoxify ZEA in diets with Bacillus licheniformis CK1, and the fermentation conditions were inoculum 1%, rotation speed 250 rpm,temperature 37℃natural p H and incubation 36 h.In the animal experiment,eighteen weaned female crossbred piglets(21±1 days) were randomly allocated in 3 treatments on the basis of body weight, with 6 piglets in each treatment.The experiment lasted 22 days, with pre-feeding of 7 days and a trial period of 15 days.The treatments included control group(basal diet), ZEA group(basal diet+ZEA) and ZEA+Strains group(ZEA-contaminated diet degraded by srain CK1 fermentation). At the end of the experiment, the growth performance, vulva size, organ indexes, levelsof sex hormones in serum and levesls of m RNA expression of estrogen receptors were determined. The main results are as follows:1.The concentrations of ZEA in basal diets, ZEA-contaminated diets and detoxified diets were not detected, 1.20 mg/kg and 0.47 mg/kg, respectively. The strain degraded ZEA in feed by 60.8%.2. The animal experiment showed alleviation by CK1 fermentation to the adverse effect of ZEA in piglets to ensure their normal growth, especially the develpoment of reproductive organ. There were no differences among treatments regarding average daily feed intake(ADFI), average daily gain(ADG) and feed conversion rate(FCR) during 15 days of the trial(P>0.05). Liver index(Liver weight/body weight) in the ZEA group was significantly higher than that in the control group(P<0.05),but the ZEA+Strains group was not different from the control and ZEA groups(P>0.05).The ZEA+Strains group had a higher kidney index(kidney weight / body weight) than the control group and the ZEA group(P<0.05).Thelatter two groups were similar in terms of the kidney index(P>0.05). The reproductive organs were significantly higher in the ZEA group and the ZEA+Strains group than that in the control group(P<0.05). For the sex hormones, the ZEA group significantly decreased the luteinizing hormone(LH) level in serum compared to control group and ZEA+Strains group, while LH in the ZEA+Strains group was similar to the control group.Expression of estrogen receptors(ERα and ERβare two types of receptors) was determined at the m RNA level.The ZEA group significantly increased the expression of ERβin reproductive organs and gonad(uterus,vagina and ovary)(P<0.05), while the ZEA+Strains group reduced ERβexpression compared to the ZEA group.The reduction was most obvious in vagina, because ERβ expression inthe ZEA+Strains group was significantly lower than the ZEA group(P <0.05). For expression of ERα, no significant difference among 3 treatments was found except that the ZEA+Strains significantly reduced ERα expression in vagina compared with the control and ZEA groups(P<0.05).This reseach revealed that Bacillus licheniformis CK1 had a good ability to degrade the ZEA in feed with a degradation rate of 60.8%. ZEA-contaminated diet detoxifed by the straincould alleviate ZEA toxicosis in piglets, including abnormal organ index, vulva swelling, abnormal sex hormones secretion, increased expression of estrogen receptor ERβ and other estrogen-like systoms and Bacillus licheniformis CK1 could alleviate zearalenone-induced toxicosis in weaning female piglets. |
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