Influence of dry-rolled corn processing and distiller’s grain inclusion rate on ruminal pH, ammonia and volatile fatty acid concentration, in vitro methane production and enzyme activity

• Published in: Animal feed science and technology 2017-06, Vol.228, p.132-139
• Main Authors: Keomanivong, Faithe E., Ruch, Megan C., Liu, Jeng-Hung, Kirsch, James D., Bauer, Marc L., Dahlen, Carl R., Kapphahn, Marsha, Borhan, Md. S., Rahman, Shafiqur, Swanson, Kendall C.
• Format: Article
• Language: English
• Subjects: Bovine; Corn; Dried distiller’s grains with solubles; Enzyme; Fermentation
• ISSN: 0377-8401; 1873-2216
• DOI: 10.1016/j.anifeedsci.2017.04.016

•Corn particle size and DDGS inclusion did not influence rumen pH.•Rumen ammonia was greater in steers receiving 20% DDGS.•No differences in the acetate:propionate ratio were observed.•No differences in in vitro methane production were observed.•Rumen α-amylase increased with 20% DDGS and trypsin increased with 40% DDGS. The objective was to determine the effects of degree of dry-rolled corn processing and dried distiller’s grains with solubles (DDGS) inclusion rate on ruminal pH, NH3 and volatile fatty acid (VFA) concentration, total in vitro gas and methane production, and enzyme activity in cattle fed high-concentrate diets. Eight ruminally cannulated Holstein steers (526±3.6kg) were randomly assigned to four dietary treatments in a 2×2 factorial arrangement consisting of 1) 650g/kg coarse-rolled corn (2.5±0.008mm) with 200g/kg DDGS, 2) 450g/kg coarse-rolled corn with 400g/kg DDGS, 3) 650g/kg fine-rolled corn (1.7±0.002mm) with 200g/kg DDGS and 4) 450g/kg fine-rolled corn with 400g/kg DDGS. Diets met NRC recommendations and were offered for ad libitum intake. The experimental design was a 4×4 Latin square with 17-d periods allowing for 7 d of diet adaptation, 7 d of sample collection, and 3 d of rest in which all steers were offered an intermediate ration. There were no differences in ruminal pH among treatments. However, steers consuming 400g/kg DDGS tended (P=0.07) to have a pH less than 5.5 for a longer period of time (h/d) than those consuming 200g/kg DDGS. Ruminal NH3 was greater in steers receiving 200g/kg DDGS (P=0.02). Steers fed fine-rolled corn had greater (P=0.02) concentrations of butyric acid while those consuming coarse-rolled corn tended (P=0.06) to have greater concentrations of isovaleric acid. No difference in DM degradation rate was noted between treatments. In vitro methane concentration of the headspace was unaffected by treatment. Steers fed diets containing 200g/kg DDGS had greater (P