The effects of soil intake on the growth performance, rumen microbial community and tissue mineral deposition of German Mutton Merino sheep

• Published in: Ecotoxicology and environmental safety Vol. 263; p. 115368
• Main Authors: Wang, Yingjie, Jiang, Mengyu, Tang, Yunmeng, Qiu, Shengnan, Sun, Youran, Sun, Haixia
• Format: Journal Article
• Language: English
• Published: Elsevier Inc 15.09.2023; Elsevier
• Subjects: Minerals deposition; Nutrient digestibility; Rumen fermentation; Rumen microorganisms; Sheep; Soil ingestion; Rumen microorganisms; Sheep; Minerals deposition; Soil ingestion; Rumen fermentation; Nutrient digestibility
• ISSN: 0147-6513; 1090-2414
• DOI: 10.1016/j.ecoenv.2023.115368

Soil ingestion by livestock is common in grazing ecosystems, but few studies have been conducted to assess its effect on the animal organism. The topic is worthy of attention because these potential effects are likely to be enriched in the food chain and interfere with animal and human health. In this study, we present an indoor feeding trial conducted based on a completely randomized design to comprehensively evaluate the effects of simulated soil ingestion during grazing on nutrient digestibility, rumen fermentation, and microflora, and mineral deposition in the organs and tissues of sheep. Eighteen Mutton Merino crossbred sheep (42.7 ± 2.34 kg) were randomly allotted to three treatments and fed diets containing 0% (Control), 5% (SOIL5), and 10% (SOIL10) for 62 d, including a 7-d metabolism trial. It was found that soil intake altered the rumen fermentation in sheep, as evidenced by a decrease in total volatile fatty acids (VFA) and acetate concentrations in rumen fluid of 50.6% and 51.3%, respectively (p < 0.01), with soil proportion in the diet increased from 0% to 10%. Soil ingestion also reduced the species richness of rumen bacteria, with the relative abundance of Bacteroidetes decreasing significantly (p < 0.01), while that of Firmicutes and Proteobacteria increased considerably (p < 0.05). In terms of mineral elements deposition, higher levels of iron (Fe) were detected in the spleen and liver, and a higher concentration of copper (Cu) and zinc (Zn) in the liver were found in sheep fed a diet containing 5% soil compared to the other two groups (p < 0.05). Moreover, the concentrations of lead (Pb) in the liver and kidney, and arsenic (As) in the heart were also clearly increased after ingestion of soil (p < 0.05). Our findings indicate that although soil intake had no significant effect on the growth performance of sheep, it altered ruminal fermentation and increased the risk of excessive Fe, Pb, and As in their organism. This study supplies a theoretical basis for risk assessment of soil ingestion in grazing livestock. •The intake of soil had no adverse effect on growth performance and nutrient digestibility of sheep.•Soil ingestion caused a decrease in rumen total volatile fatty acids.•Soil ingestion reduced the rumen bacterial richness.•The ingestion of soil posed a risk of excessive Fe, Cu, Pb and As deposition.