| dc.description.abstract | This experiment was conducted to investigate the effects of different doses of cadmium on fermentation characterization and nutrient digestibility using dual flow continuous culture system. Eight dual-flow, continuous culture fermenters were used in 2 replicated periods of 10 d (7 d of adaptation and 3 d of sampling). Fermenters were inoculated with a composited ruminal fluid from 3 beef steers fed a high concentrate diet for at least 2 mo before the beginning of the trial. Anaerobic conditions were maintained by the infusion of N2 at a rate of 40 mL/min. Temperature (38.5°C) and liquid (10%/h) and solid (5%/h) dilution rates were kept constant. Fermenters were fed daily with 120 g dry matter in three equal portions. Treatments arranged as complete randomized block design with control and addition three levels of cadmium (0.1, 1 and 10 mg/l) to the high concentrate diet (15:85 forage to concentrate ratio). Organic matter, dry matter, NDF and ADF digestibility significantly decreased with the addition of 1 and 10 mg/l cadmium to the culture media compered to control treatment (P<0.05). Cadmium significantly decreased total volatile fatty acids concentration, acetate proportion and acetate to propionate ratio. Propionate and butyrate proportion increased significantly in response to cadmium addition (P<0.05). Concentration of NH3-N was significantly decreased in 1 and 10 mg/l cadmium treatments compared with control treatment. The results of this study suggest that cadmium in doses of 1 mg/l or more had strong inhibitory effect on mixed rumen microorganisms. | en |
