The relationships of dairy ruminal odd- and branched- chain fatty acids to the duodenal bacterial nitrogen flow and volatile fatty acids

Abstract The objectives of the present research were to investigate the changes in duodenal bacterial nitrogen flow and volatile fatty acids (VFAs) with the different dietary ratios of forage and concentrate (F:C) and to determine the relationship of duodenal bacterial nitrogen flow and volatile fatty acids with ruminal odd- and branched-chain fatty acids (OBCFAs). The experimental design was a 3×3 Latin square. Three rumen- and duodenal-fistulated dry Holstein cows were fed three rations with different dietary ratios of forage and concentrate (F:C; 30:70, 50:50 and 70:30). The rumen and duodenal samples were collected every two hours over 3 consecutive days of each sampling period. The determined parameters included OBCFA profiles in the rumen, duodenal bacterial nitrogen flow, VFAs, ammonia nitrogen (NH3-N) content and pH. The results showed that ruminal OBCFA contents, duodenal bacterial nitrogen flow, VFAs, ammonia nitrogen (NH3-N) and pH were significantly influenced by the different dietary F:C ratios and sampling times (P