Submitted to: Journal of Animal Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 8/17/2014
Publication Date: 11/10/2014
Citation: Orr, A.N., Soder, K.J., Brito, A., Rubano, M.D., Dell, C.J. 2014. Effect of sprouted barley grain supplementation of an herbage-based or haylage-based diet on ruminal fermentation and methane output in continuous culture. Journal of Animal Science. 97:7856-7869.
Interpretive Summary: Feeding sprouted grains is an old technology gaining renewed interest with dairy farmers looking for a reliable source of high quality feed. No information is available regarding the feeding value of sprouted barley with high quality forages such as the conserved forages and pastures found on grazing dairy farms. The purpose of this study was use continuous culture fermentation to assess the effect of supplementing sprouted barley or barley grain with an herbage- or haylage-based diet on nutrient digestibility, volatile fatty acid production, bacterial protein synthesis, and methane output.
Technical Abstract: A 4-unit dual-flow continuous culture fermentor system was used to assess the effect of supplementing 7-d sprouted barley (SB) or barley grain (BG) with an herbage-based or haylage-based diet on nutrient digestibility, volatile fatty acid (VFA) profiles, bacterial protein synthesis, and methane output. Treatments were randomly assigned to fermentors in a 4 × 4 Latin square design with a 2 × 2 factorial arrangement using 7 days for diet adaptation and 3 days for sample collection. Experimental diets were: 1) 55.5 g dry matter (DM) herbage + 4.5 g DM SB; 2) 56.0 g DM herbage + 4.0 g DM BG; 3) 55.5 g DM haylage + 4.5 g DM SB; and 4) 56.0 g DM haylage + 4.0 g DM BG. Forages were fed at 0730, 1030, 1400, and 1900 hours while SB and BG were fed at 0730 and 1400 hours. Gas samples for methane analysis were collected at 0725, 0900, 1000, 1355, 1530, and 1630 hours on days 8, 9 and 10. Fluid samples for were taken once daily on days 8, 9, and 10 for pH measurements and for ammonia-N and VFA analysis and analyzed for DM, organic matter, crude protein, neutral detergent fiber, and acid detergent fiber for determination of nutrient digestibilities and estimation of bacterial protein synthesis. Orthogonal contrasts were used to compare effect of forage source (haylage vs. herbage), supplement (BG vs. SB), and the forage × supplement interaction. Apparent and true DM and organic matter digestibilities, as well as apparent crude protein digestibility were not affected by forage source. However, true DM digestibility was greatest for diets supplemented with SB. Apparent neutral and acid detergent fiber digestibilities of herbage-based diets were higher than haylage-based diets but fiber digestibility was not affected by supplement. Diets supplemented with SB had higher mean and minimum pH than BG; however, maximum pH was not affected by diet. Supplementation with BG produced a greater concentration of total VFA compared to diets supplemented with SB. Haylage-based diets produced greater methane output compared with herbage-based diets but supplementation did not affect methane output. Efficiency of bacterial protein synthesis was greater for herbage-based diets compared with haylage-based diets with no effect of supplementation. Overall, supplementation with SB marginally increased true DM digestibility of herbage- and haylage-based diets but did not impact fiber and crude protein digestibilities, methane output, and bacterial efficiency, compared to BG.