|Da Silva, G|
Submitted to: Beef Cattle Research in Texas
Publication Type: Experiment Station
Publication Acceptance Date: 11/12/2007
Publication Date: 8/1/2008
Citation: Da Silva, G.S., Aguiar, A.D., Neto, J.P., Chizzotti, M.L., Anderson, R.C., Tedeschi, L.O. 2008. Evaluating factors that impact the dynamics of in vitro fermentation using gas production technique. 1. Forage particle size. 2007 Beef Cattle Research in Texas. p. 89-91. Interpretive Summary: Cattle and sheep play an important role in animal agriculture because they can eat diets consisting largely of hard to digest feeds such as dried grass hay. They are able to eat and convert such low quality feeds to higher quality animal protein because they possess a compartmentalized stomach, the largest part called the rumen, that contains billions of bacteria that help them digest these feedstuffs. Research is needed, however, to find ways to increase the efficiency of digestion of these poor quality feeds so that farmers can optimize their animal production. We conducted several tests to see if we could improve a method that determines digestion efficiency by measuring the amount of gas produced as an end-product of the digestion of grass hay. Rumen bacteria from several different cows were incubated with a grass hay preparation to see if the bacteria in different cows affected this measurement technique. We found that the technique gave suitable results regardless of which cow the bacteria came from. We also compared two commonly used ways in which the hay is added to the measuring system, one by adding the hay directly to the incubation system and the other by first containing the hay in a small nylon bag and then adding that bag to the system. We found that digestion efficiency differed between the two different ways of adding the hay indicating that the system could be improved by standardizing the way in which the hay is added. This research will help scientists more accurately measure digestion efficiency which will ultimately help farmers and ranchers produce lower cost products for the American consumer. Additionally, because some of the end-products of digestion are thought to help inhibit the growth of undesirable bacteria such as Salmonella and E. coli O157:H7, which cause disease in humans who may eat contaminated meat, this research may help farmers and ranchers learn how to optimize digestion to produce a safer product.
Technical Abstract: The objectives of this study were to investigate the effects of rumen fluid donors (FD) (Trial 1) and different incubation methods (IM) (Trial 2) on the dynamics of in vitro fermentation. In trial 1, alfalfa hay (89.3% DM, 2 mm) was fermented using rumen fluid from 5 different cows. In Trial 2, alfalfa hay (1 mm) was allocated either inside 125-mL Wheaton bottles (FREE) or inside ANKOM F57 filter bags (BAG), which were placed inside 125-mL Wheaton bottles for subsequent fermentation. In each trial, 200 mg of forced-air dried sample was fermented for 48 h with continuous measurement of gas pressure using a computerized monitoring system. There was no FD effect on total gas production (a, ml; P = 0.25), lag time (c, h; P = 0.32), or fractional rate of degradation (b, %/h; P = 0.84), suggesting that possible differences in the rumen bacteria population of cows grazing mixed pasture may not affect in vitro fermentation dynamics. However, in the IM analysis, a (P = 0.003) and c (P = 0.026) estimates differed, suggesting fermentation inside a polyester/polyethylene-type bag may yield different fermentation kinetics.