PSVI-42 Effect of increasing concentrations of aflatoxins (AFB1) on rumen gas production (GP), dry matter (DM) disappearance and fermentation parameters using the in vitro ANKOM gas technique

Abstract

Abstract Aflatoxins are secondary metabolites produced by Aspergillus species known to be the most prevalent contaminants in feedstuffs. In ruminants, contaminated AFB1 feeds usually exhibit symptoms including reduced feed efficiency and milk production and decreased appetite. The objective of this study was to investigate the effects of different concentrations of AFB1 on rumen fermentation parameters by using the ANKOM gas production protocol. Rumen fluid was collected from a cannulated dry dairy cow, filtered with cheese-cloth and diluted (1:1) with a standard buffer. Triplicates of 75 mL flasks were fed 0,75g of feed (79% corn silage, 15% alfalfa and 6% concentrates) and inoculated with 0 (blank), 0,2, 0,5, 1 and 2 ppm of AFB1. Flasks were placed in a rotating incubation at 39°C for 96h and connected to ANKOM GP system. After 96h of incubation, the contents of each flask were centrifuged. Supernatants were analyzed for total VFA and AFB1 while precipitates were dried at 104°C for DM disappearance. The experimentation was repeated weekly 3 times and named wk1, 2 and 3. Statistical analysis was done by SPSS using a univariate model. Results showed no significant differences on GP max at 96h among AFB1 concentrations. Only wk 1 showed that higher AFB1 concentration (2 ppm) decreased significantly (P < 0,05) DM disappearance (- 8,2 pts) when compared to the blank. Total VFA contents (75,0 ± 1,6 mM) were not affected by AFB1. Wk 2 and 3 did not show any difference neither on DM disappearance nor on VFA (89,1 ± 1,6 mM; 110,2 ± 4,8 mM). It can be concluded that our in vitro model, GP did not reflect DM disappearance and it can be put forward that rumen fluid with low total VFA concentrations (≤ 75 mM) could be more sensible to AFB1 challenge.