Studying the effects of two polychlorinated residues on water buffalo rumen fluid in vitro fermentation.

The world wide contamination of foods and feeds by emission of Persistent Organic Pollutants (POPs) is a significant problem in the food chain. One of the major family of POPs is the Poly Chloro Biphenyls (PCBs). Dairy ruminants are exposed to these POPs by oral ingestion (water, feedstuffs) (Sanders and Chandler 1972; Breyl et al. 1990). The transfer rate for PCBs in milk varies widely from 5% to 90% (S. Jurianz et al. 2008) becoming a serious risk for human health. Two different PCBs (2,2',5,5'- tetrachlorobiphenyl and 2,4'- dichlorobiphenyl) were tested by using the in vitro Reading Pressure Technique [RPT] according to Mauricio et al. (1999). This feed evaluation system is designed to estimate the rate and extent of both fermentation [gas release] and substrate degradation simultaneously. The objective of this study is to check if there is an effect on fermentation and degradation processes on some commercial feeds (alfalfa hay and barley) by adding two different PCBs at two different concentrations (low = 0,1 ppm and high = 1 ppm) in water buffalo rumen liquor. The feeds were chosen with different degradable ability, in fact alfalfa hay is the least degradable while barley is the fasten (highly degradable). We know that PCB and dioxin levels in milk should not be more than 6 pg/g of fat. The concentrations of the two PCBs were chosen much more higher than the allowed level to find out the possible effects on rumen bacteria. Standard parameters were evaluated: Volatile Fatty Acid (VFA), dry matter (DMD), Organic Matter Degradation (OMD) and fermentation gas release over a 48 h incubation period. No significant effects on rumen fermentation were observed from the inclusion of the two PCBs examined at 0.1 and 1.0 ppm.