三黄鸡是中国的优质地方鸡品种，因黄羽、黄爪和黄喙得名。然而，三黄鸡黄胫变“青胫”的异常现象一直是人们关注的问题，它严重降低了黄羽肉鸡的胴体质量和经济效益。在本研究中，首先系统地调查了鸡小腿异常肤色的原因。生理学解剖显示，鸡胫部皮肤异常主要是由于真皮下的黑色素沉积引起的。通过分析遗传（谱系和遗传标记）、环境（水质监测）和饲料成分（真菌毒素检测）等多种潜在原因，发现饲料中黄曲霉毒素B1(AFB1)严重超标，会伴随较高的L-2羟基苯丙氨酸（L-DOPA）（P<0.05）和黑色素含量（P<0.01）。因此推测过量的AFB1可能是导致小腿皮肤异常绿色的主要原因。

随后，进一步的结果表明，与正常的AFB1含量（<10μg kg^-1）相比，高浓度的AFB1（>170μg kg^-1）确实诱导了小腿胫部的异常皮肤颜色，且与黑色素沉积相关的MC1R和EDN3基因显著上调（P<0.01），酪氨酸酶（TyR）的含量和活性也显著增加（P<0.05）。同时，L-DOPA的含量和黑色素沉积也显著增加（P<0.01）。这也证实了过量AFB1对小腿皮肤黑色素沉积的影响。进一步的实验结果表明，AFB1对小腿皮肤黑色素沉积的负面影响可能会持续更长时间，不易消除。总之，本研究的结果解释了鸡小腿中异常AFB1相关青胫的发生及其可能机制。饲粮中过量的AFB1可能通过促进TyR含量和活性以及黑色素合成相关基因的表达，增加了鸡小腿中的L-DOPA含量和黑色素异常沉积。我们的研究结果有助于再次预警肉鸡生产中黄曲霉毒素B1危害。

    D-Lactate-utilizing bacteria play important roles in maintaining the balance of gut lactate; however, studies on gut D-lactate-utilizing bacteria have been limited. This study aimed to isolate and identify D-lactate-utilizing bacteria from pig gut using the Hungate roll-tube method, and to investigate their metabolic characteristics in vitro. Six different anaerobes were isolated from pig feces, which were identified as related to Bacteroides fragilis, Bacteroides acidifaciens, Veillonella denticariosi, Veillonella caviae, Bacteroides uniformis, and Megasphaera elsdenii based on the 16S rRNA gene sequences. All strains had a significant ability to utilize D-lactate, which was concluded after in vitro fermentation with 25 mmol L–1 D-lactate as the primary carbon source. Of all 6 strains, M. elsdenii J6 showed the highest efficiency of D-lactate utilization and produced a higher ratio of butyrate in total short chain fatty acids (SCFAs). Thus, the in vitro fermentation characteristics of this strain in D-, L-, and DL-lactate mixtures (D-lactate:L-lactate=1:1 or 1:2) were further studied. The results showed that M. elsdenii J6 preferred utilizing D-lactate, and produced more SCFA when using D-lactate as the primary carbon source. The findings suggest that the administration of D-lactate-utilizing bacteria such as M. elsdenii J6 may have a potential advantage in the alleviation of D-lactic acidosis in the animal gut.

Increased food demand from the rapidly growing human population has caused intensive land transition from desert to farmland in arid regions of northwest China. In this developing ecosystem, the optimized fertilization strategies are becoming an urgent need for sustainable crop productivity, efficient resources use, together with the delivery of ecosystems services including soil carbon (C) and nitrogen (N) accumulation. Through a 7-year field experiment with 9 fertilization treatments in a newly cultivated farmland, we tested whether different fertilizations had significant influences on soil C and N accumulation in this developing ecosystem, and also investigated possible mechanisms for this influence. The results showed that applying organic manure in cultivated farmland significantly increased the soil C and N accumulation rates; this influence was greater when it was combined with chemical fertilizer, accumulating 2.01 t C and 0.11 t N ha–1 yr–1 in the most successful fertilization treatment. These high rates of C and N accumulation were found associated with increased input of C and N, although the relationship between the N accumulation rate and N input was not significant. The improved soil physical properties was observed under only organic manure and integrated fertilization treatments, and the significant relationship between soil C or N and soil physical properties were also found in this study. The results suggest that in newly cultivated farmland, long term organic manure and integrated fertilization can yield significant benefits for soil C and N accumulation, and deliver additional influence on physical properties.

Erhualian and Landrace breeds are typical genetically obese and lean pigs, respectively. To compare the fecal methanogenic Archaeal community between these two pig breeds, fecal samples from different growth phase pigs were collected and used for PCR-denaturing gradient gel electrophoresis (DGGE) with two primer pairs (344fGC/519r and 519f/915rGC) and real-time PCR analysis. Results showed that a better separation and higher quality of bands pattern were obtained in DGGE profiles using primers 344fGC/519r as compared with primers 519f/915rGC. Sequencing of DGGE bands showed that the predominant methanogens in the feces of Erhualian and Landrace pigs belonged to Methanobrevibacter spp. and Methanosphaera spp. Real-time PCR analysis revealed that there was no significant difference in the numbers of fecal total methanogens between Erhualian and Landrace pigs; however, pig growth phase affected the numbers of 16S rRNA genes of total methanogens and Methanobrevibacter smithii. Dissociation curves of methyl coenzyme-M reductase subunit A (mcrA) gene fragments amplified with real-time PCR showed all samples possessed a single peak at 82°C, which might be associated with M. smithii. Samples from the same growth phase of each breed showed good replicative dissociation curves. The results suggest that the growth phase (including diet factor) other than genotype of pig may affect the fecal methanogenic Archaeal community of pigs.