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Cadmium (Cd) is an environmental pollutant, widely existing in soil, and can be absorbed and accumulated by plants. Hunan Province exhibits the worst cadmium contamination of farmland in China. Ruminants possess an abundant microbial population in the rumen, which enables them to tolerate various poisonous plants. To investigate whether the rumen microbiota could respond to Cd and mitigate the toxicity of Cd-accumulated maize to ruminants, 6-month-old cattle were fed with 85.82% (fresh basis) normal whole-plant maize silage diet (CON, n = 10) or Cd-accumulated whole-plant maize silage diet (CAM, n = 10) for 107 days. When compared to the CON cattle, CAM cattle showed significantly higher gain-to-feed ratio and an increased total bacterial population in the rumen, but a decreased total bacterial population in the colon. CAM cattle had higher relative abundance of Prevotella and Lachnospiraceae ND3007 group in the rumen, and Lachnospiraceae NK4A136 group and Clostridia vadinBB60 group in the colon. Notably, microbial correlations were enhanced in all segments of CAM cattle, especially Peptostreptococcaceae in the jejunum. Transcriptome analysis revealed down-regulation of several immune-related genes in the rumen of CAM cattle, and differentially expressed genes in the rumen were mostly involved in immune regulation. These findings indicated that feeding Cd-accumulated maize diet with a Cd concentration of 6.74 mg/kg dry matter (DM) could stimulate SCFA-related bacteria in the rumen, induce hormesis to promote weight gain, and improve energy utilization of cattle.

Reproductive efficiency of a heifer is directly dependent on the health of reproductive system especially ovary and uterus. Current experiment was carried out to screen candidate genes related to reproductive traits and detect molecular mechanisms of DEGs by using RNA-sequencing (RNAseq) and Gene Set Enrichment Analysis (GSEA) to understand the environmental adaptability, molecular breeding and analyze the reproductive performance. Furthermore, Illumina II high throughput sequncing technology was utilized in the current experiment to sequence transcriptomes and analysis related to pathway of different genes between uterus and ovary in Xiangxi cattle. The total number of ovary assembled was compared to the reference genome sequence, DEGs analysis, GO and KEGG enrichment analysis and candidate gene screening were performed. Based on the transcriptome data, seven cDNA libraries were constructed by utilizing total RNA. Out of seven contracted cDNA libraries, in every sequencing library, raw reads reached >133 Mb, and >94% clean reads remained. After comparing the Xiangxi cattle ovaries with the uterus, a total of 3635 mRNAs were found, in which 1608 were significantly up-regulated expressed and 2027 were down-regulated expression mRNAs. The mRNA expression of ADCY3, ADCY4, ADCY9, FSHR, BMP15, LHCGR, INSR, CYP11A1, CYP17A1, CYP19A1, STAR and SCARB1 in ovary of Xiangxi Cattle were significant different in ovarian and uterus tissues. Through GSEA and PPI network, we found the ovarian steroidogenesis pathway played significant role in signal regulation during the development of the ovarian tissue of the Xiangxi cattle. [ABSTRACT FROM AUTHOR]

Current study was conducted to evaluate the effects of age on production performance and meat quality of Xiangxi cattle. A total of 12 male weaning Xiangxi cattle (similar age and weight) were used in the current experiment. Animals were slaughtered at the age of six, eight and thirty months. Results showed that animals slaughtered at 30 months of age had the highest production performance and carcass traits (p < 0.05). The longissimus dorsi (LD) of the animals slaughtered at 6-month-age had a lower cooking loss and higher water content (p < 0.05). The LD of the animals slaughtered at 30-month-had significantly higher nutrient composition, total essential amino acid (EAA) composition and EAA/total amino acid percentage, C16 and saturated fatty acid (SFA) contents (p < 0.05). Moreover, higher C20, C17:1, monounsaturated FA, C18:3n-3, polyunsaturated FA, total FA contents and unsaturated fatty acid to saturated fatty acid ratio (p < 0.05) was observed in the LD muscle of cattle slaughtered at 18 months of age. Based on results, it is concluded that age significantly influenced the production performance, carcass traits, meat quality, and meat nutrient composition in Xiangxi cattle. [ABSTRACT FROM AUTHOR]