Effects of dairy cow diets supplied with flaxseed oil and propolis extract, with or without vitamin E, on the ruminal microbiota, biohydrogenation, and digestion

The effects of supplying diets with flaxseed oil and a propolis-based product, with or without vitamin E, on dry matter intake, ruminal and total digestibility, ruminal parameters, biohydrogenation, and bacterial and protozoal populations in dairy cows were evaluated. Four Holstein cows, with a mean weight of 584 ± 52 kg and 90 ± 39 days in milk, were randomly assigned to a 4 × 4 Latin square. Diets were composed of 600 g/kg of dry matter (DM) as roughage and 400 g/kg of concentrate for the following diets: control diet; diet with 25 g flaxseed oil/kg DM (FO); diet with flaxseed oil, 1.2 g propolis-based product/kg DM (PBP); diet with flaxseed oil, PBP, and 375 IU vitamin E/kg DM. The flaxseed oil diet tended to reduce populations of Entodinium and total protozoa (P = 0.09) and significantly increased Butyrivibrio fibrisolvens (P = 0.008) count. However, Anaerovibrio lipolytica (P < 0.001) and Methanobrevibacter ruminantium counts (P = 0.013) were significantly reduced with the flaxseed oil diet. The PBP diet, with or without vitamin E, tended to enhance Butyrivibrio fibrisolvens (P = 0.09) count. The flaxseed oil diet tended to decrease the intake of organic matter (P = 0.09) and total carbohydrates (P = 0.05). Ruminal and total digestibility of crude protein and ether extract were higher with flaxseed oil. The PBP did not influence omasal nutrient flow, digestibility, short-chain fatty acid concentrations, pH, and ammonia in the rumen. Flaxseed oil addition in diets significantly increased (P < 0.05) the production of fatty acid (FA) cis3-18:3 and CLA cis9,trans11-18:2 in milk, and tended (P < 0.10) to increase FA 18:0 and cis9-18:1. PBP in diet significantly increased (P < 0.05) the production of CLA cis9,trans11-18:2 in milk. Among the ingredients added to the diets, flaxseed oil had the greatest effect on the parameters evaluated, and both PBP and PBP-E diets did not interfere with flaxseed oil activity in the rumen.