Effect of formaldehyde-treated barley or escape protein on the ruminal environment and digestion in steers

Abstract

Six Holstein steers fitted with ruminal and duodenal cannulae were fed three diets: formaldehyde-treated rolled barley (0.11% wt wt−1) with canola meal (FTB); untreated rolled barley supplemented with corn distillers' grain and fishmeal (EPB); and untreated rolled barley with canola meal (CON). Foam production from ruminal fluid did not differ among diets. Mean viscosity of ruminal fluid from steers fed FTB was lower (P < 0.02) than rumen fluid from steers fed CON. Ruminal fluid pH of steers fed FTB was lower 2 h after feeding than in steers fed the EPB or CON diets. FTB led to lower (P < 0.02) ruminal ammonia concentrations 1 and 2 h after feeding and lower (P < 0.1) plasma urea nitrogen concentrations 4 h after feeding compared to EPB or CON diets. FTB and EPB tended to lower the ruminal concentration of volatile fatty acids (VFA) associated with microbial amino acid metabolism. Intake, ruminal and postruminal digestion of DM, OM, starch and NDF were not influenced by diet. While EPB had no effect on total tract digestion, FTB increased (P < 0.1) total tract digestibility of starch and decreased (P < 0.1) the digestibility of NDF. EPB increased (P < 0.05) the supply of dietary protein and decreased the supply of microbial protein reaching the small intestine. FTB did not increase the amount of total nitrogen or starch reaching the small intestine of steers. Key words: Cattle, escape protein, starch, formaldehyde, barley