Author
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Mertens, David |
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Submitted to: Journal of Dairy Science
Publication Type: Abstract Only Publication Acceptance Date: 6/20/1999 Publication Date: N/A Citation: N/A Interpretive Summary: Technical Abstract: Gas production during fermentation may be used to estimate digestion kinetics of feeds, but source and method of preparing inoculum may impact results. The objective was to determine if blending ruminal solids and centrifuging inocula would affect early gas production. About .11 gm of 24 substrates was fermented with 8 ml of buffered media in sealed bottles with hhead spaces of about 48 ml. Bottles with sample and media were warmed to 39C, purged with CO2 and reduced before inoculation. Ruminal contents were collected in the AM and PM on 3 days from two cows for each trial. In trial 1, 50 gm of strained solids and 100 ml of strained fluid from each cow were combined and blended for 45 sec. The ruminal fluid or blended material were strained through four layers of cheesecloth to obtain SRF or BRF, and both were centrifuged at 500g for 5 min to produce CSRF and CBRF. In trial 2, 50 ml of strained solids from each cow were combined with 220 ml of warmed, reduced in vitro media and blended for 45 sec. Blended material and 200 ml of strained fluid were strained through four layers of cheesecloth to obtain blended ruminal media (BRM). In trial 1, SRF obtained more gas production from samples than BRF. Centrifuging reduced gas production by blanks after 3 h for both CSRF and CBRF (2.38 vs 6.08 and 3.68 vs 5.82 ml), but also resulted in lower gas production by samples (5.30 vs 7.46 and 5.02 vs 6.29 ml). Reduced activity of CSRF and CBRF may be due to lower temperatures at inoculation when centrifuged (33C) or blended (<37C). In trial 2, BRM resulted in slightly higher blank gas production than SRF (5.52 vs 4.60 ml) but increased gas production of samples (8.27 vs 6.53 ml). To maximize early fermentation strained fluid should be combined with warm, reduced media that has been blended with ruminal solids. |
