Effect of plastic foreign body impaction on rumen function and heavy metal concentrations in various body fluids and tissues of buffaloes.

Rumen impaction by plastic waste (PW) is a common condition in the developing countries where ruminants are reared under extensive grazing. As heavy metals (HM) are used in the manufacture of plastic, we hypothesized that buffaloes with PW impaction would have suboptimal rumen function and higher content of HM in the rumen fluid, sera and body tissues. Buffaloes at an abattoir were categorized into impacted with PW or not (Group C and B, respectively; n = 30/group). From the animals of group C and B, rumen fluid and sera were collected ante-mortem, while muscle, liver and kidney were collected after exsanguination. Blood and rumen fluid of stall-fed buffaloes (Group A; n = 15) served as known negative control. Rumen function was assessed by protozoal density, motility, pH, methylene blue reduction time (MBRT) and sedimentation activity time (SAT). Concentration of HM such as mercury (Hg), lead (Pb), cadmium (Cd), chromium (Cr) and copper (Cu) in the body fluids, tissues and impacted PW was estimated by atomic absorption spectrometry (AAS). A significant decrease in the rumen protozoal density, motility and increase (P < 0.05) in the rumen fluid pH, MBRT and SAT were observed in group C as compared to group A and B. Concentration of Pb, Hg and Cd showed a moderate to strong significant negative correlation with rumen function indicators. Quantitatively, Cu content (ppm) was highest in PW with 0.9 ± 0.04. The concentration of HM in the body fluids and tissues was significantly (P < 0.05) elevated in group C, but was below the toxic levels. In stall-fed buffaloes, Hg, Pb and Cd were undetectable in body fluids. Collectively, the results indicate that long term exposure of buffaloes to HM from PW affect the health, productivity and increase the risk of entering the food chain.