influence of processing of barley grain on characteristics of digestion, ruminal fermentation and digestible energy of diet inlactating cows

a digestion trial using cannulated lactating cows was conducted to evaluate the influence of barley grain processing on characteristics of ruminal fermentation and the site and extent of digestion. the experiment consisted in 4 periods and lasted 84 days. the total mixed rations contained 39.86% of grains and 42.90% of alfalfa hay and the rest of ration was composed mainly by cane molasses, fat, fishmeal and minerals. the barley grains were processed by dry-rolled and steam-flaking with two densities of flake (0.39 and 0.26 kg/l). dry rolled corn was used as reference to determine energy value of barley grain. compared to dry rolled barley, steam-flaked barley increased ruminal digestion of organic matter(om) and starch, and energy of diet, but decreased dry matter intake. decreasing steam-flaked density of barley from 0.30 to 0.26 kg/l increased ruminal digestion of starch and ruminal propionate and decreased dry matter intake and ruminal nitrogen digestion. compared to corn, cows fed barley diets shown a greater dietary energy as result of greater total tract om digestion, greater microbial protein efficiency and lower ruminal acetate and methane production. however, barley treatments had a lower ruminal ph and this was exacerbated as flake density decreased. the energy value of barley was improved (p