Abstract
Copper (Cu) is an important trace element with a two-sided effect on the growth performance of animals, which depends on the timing and dosage of Cu addition, etc. The purpose of this study was to determine the effects of oral copper sulfate (CuSO4, 350 ppm) on growth performance, cecal morphology, and its microflora of chickens (n = 60) after 30, 60, and 90 days. The results showed that after 90 days of copper exposure, the chickens lost weight, the cecum mucosa was detached, and vacuolation and inflammatory infiltration occurred at the base of the lamina propria. In addition, using the 16S rDNA sequencing method, we observed that copper exposure changed the richness and diversity of intestinal microorganisms. At the phylum level, Proteobacteria and Actinobacteria both significantly increased, while Bacteroidetes significantly decreased in the Cu group compared with control check (CK) group. At the genus level, the relative abundance of Rikenellaceae_RC9_gut_group decreased significantly, while Ruminococcaceae_UCG-014, Lachnoclostridium, and [Eubacterium]_coprostanoligenes_group increased significantly after copper exposure, and the change in microflora was most significant at 90 days. Moreover, the relevance of genus-level bacteria was altered. PICRUST analysis revealed potential metabolic changes associated with copper exposure, such as Staphylococcus aureus infection and metabolic disorders of nutrients. To sum up, these data show that subchronic copper exposure not only affects the growth and development of chickens but also causes the imbalance of intestinal microflora, which may further induce metabolic disorders in chickens.
Highlights
Copper (Cu) is an essential trace element, which plays a key role in maintaining the normal growth and development of animals (Frieden, 1986)
The results showed that compared with the CK group, the weight of the copper group decreased at all-time points, with significant difference at 60 days (p = 0.013) and 90 days (p = 0.000) (Figure 1A)
The results showed that copper exposure destroyed the normal structure of chicken cecum, mucosa fell off, vacuoles appeared in the lamina propria, and inflammatory infiltration occurred in a time-dependent manner
Summary
Copper (Cu) is an essential trace element, which plays a key role in maintaining the normal growth and development of animals (Frieden, 1986). It has been shown that Cu has the ability to inhibit immune response and increase the susceptibility of the host to pathogens (Zhao et al, 2018; Ruan et al, 2019). Early studies have shown that excessive copper intake may lead to the accumulation of copper in tissues, leading to organ and cytotoxic damage in animals and even humans, as well as intestinal damage (Pal, 2014). In order to improve production efficiency, copper is still being abused because it is often used as a promoter to inhibit fungal growth, bacterial and parasitic infections. With the development of industry, surface water and soil are polluted by copper, which increases the risk of subchronic copper poisoning (Shahzad et al, 2012; Bui et al, 2016)
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