应用PCR-DGGE技术对发酵全混合日粮中可培养乳酸菌的调查

为了了解发酵全混合日粮(TMR silage)发酵过程中的乳酸菌的菌种变化,应用MRS琼脂培养基对新鲜啤酒糟和豆腐渣以及它们的发酵TMR(贮存0、14和56 d)的乳酸菌进行培养,所得的可培养乳酸菌应用PCR-DGGE进行筛选,对菌体DNA的碱基序列进行测定,在GenBank上检索相近的16S rDNA序列对其鉴定.结果表明:2种原料中的乳酸菌种类完全不同;加入相同的其他材料变成TMR后,优势乳酸菌发生改变;发酵初期(14 d)的2种发酵TMR中都有2种乳酸菌,并且有1种乳酸菌相同;发酵后期(56 d)的2种发酵TMR中都有5种乳酸菌,而且有4种乳酸菌相同.由此可知,采用不同食品废弃物所制作的发酵TMR,在发酵后期所含菌种趋于相同、种类增加.     

Differentially methylated CpG sites related to fertility in Japanese Black bull spermatozoa: epigenetic biomarker candidates to predict sire conception rate

For semen suppliers, predicting the low fertility of service bull candidates before artificial insemination would help prevent economic loss; however, predicting bull fertility through in vitro assessment of semen is yet to be established. In the present study, we focused on the methylated CpG sites of sperm nuclear DNA and examined methylation levels to screen new biomarkers for predicting bull fertility. In frozen-thawed semen samples collected from Japanese Black bulls, for which the sire conception rate (SCR) was recorded, the methylation level of each CpG site was analyzed using human methylation microarray. According to regression analysis, 143 CpG sites related to SCR were significantly differentially methylated. Whole genome bisulfite sequence data were obtained from three semen samples and the differentially methylated regions (DMRs) that included the target CpG sites selected by human methylation microarray were confirmed. Using combined bisulfite restriction analysis, fertility-related methylation changes were detected in 10 DMRs. With the exception of one DMR, the methylation levels of these DMRs were significantly different between groups with high fertility (> 50%) and low fertility (< 40%). From multiple regression analysis of methylation levels and SCR, three DMRs were selected that could effectively predict bull fertility. We suggest that these fertility-related differences in spermatozoal methylation levels could be new epigenetic biomarkers for predicting bull fertility.     

普通与发酵全混合日粮的好气安定性比较

本试验旨在比较普通与发酵全混合日粮(TMR)的好气安定性的优劣。选用3～6种不同材料与啤酒糟调制成的4种TMR、含50%的啤酒糟和豆腐渣与其他材料调制的2种TMR、啤酒糟和豆腐渣的单独贮存及与其他材料调制的TMR等进行了3个试验,对普通TMR(贮存0 d)与发酵TMR(贮存14和56 d)的好气安定性进行了比较。结果显示:发酵TMR的好气安定性高于普通TMR,而且贮存时间长(56 d)的发酵TMR的好气安定性高于贮存时间短(14 d)的发酵TMR。提示发酵TMR的好气安定性较好,尤其发酵56 d以上的发酵TMR,开封后不易变坏,为实际生产中解决TMR变败问题提供了依据。