Tracing sources of nitrate using water chemistry, land use and nitrogen isotopes in the Ganjiang River, China

<p>In this work, we traced sources of nitrate in the Ganjiang River, a major tributary of Yangtze River, China, by analysing the water chemistry, nitrogen isotopes and land use. Water samples from 20 sites in the main stream and tributaries were collected in the dry and wet seasons. The ranged from 0.97 to 8.60 ‰, and was significantly higher in the wet season than in the dry season, and significantly higher in tributaries than in the main stream. In the dry season, concentrations and were significantly negatively correlated with forest and grassland areas, and positively correlated with paddy field and residential area. However, most of the correlations were not significant in the wet season. The results showed that fertilizer was the main source of nitrate in the Ganjiang River, and domestic sewage was important in the dry season, but its contribution was lower than that in other rivers in the Yangtze Basin. In the wet season, the intensified nitrogen cycle caused by high temperature and the mixing effect caused by rainfall made it difficult to trace nitrate sources using and land use.</p

Data_Sheet_1_Dietary β-hydroxybutyric acid improves the growth performance of young ruminants based on rumen microbiota and volatile fatty acid biosynthesis.docx

IntroductionThe ketone body β-hydroxybutyric acid (BHB) plays critical roles in cellular proliferation and metabolic fuel utilization; however, its effects on the rumen microbiota remain unknown.MethodsHere, three doses of BHB (low, medium, and high) were supplemented to early-weaned goat kids.ResultsCompared with controls, the beneficial effects of BHB on growth and rumen development were observed in goats at 90 days of age (d). The low dose of dietary BHB increased the concentration of rumen acetate, propionate, and butyrate on d90. The sequencing results of the rumen microbiota revealed marked shifts in rumen microbial community structure after early-weaned goat kids consumed BHB for 2 months. The signature bacterial ASVs for each treatment were identified and were the main drivers contributing to microbial interactions in the rumen. The bacteria associated with rumen weight were also correlated with body weight. Some classified bacterial signatures, including Prevotella, Olsenella umbonate, and Roseburia faecis, were related to rumen volatile fatty acids and host development.ConclusionOverall, dietary BHB altered rumen microbiota and environments in young goats, which contributed to rumen development and growth.</p