Main content area

Effect of the addition of malate on in vitro rumen fermentation of cereal grains

Carro, M.D., Ranilla, M.J.
British journal of nutrition 2003 v.89 no.2 pp. 181-188
Merino, absorbance, acetates, alfalfa hay, barley, bottling, butyrates, corn, feed additives, fermentation, malates, methane, methane production, microorganisms, mixed culture, pH, propionic acid, rumen, rumen fermentation, sheep, volatile fatty acids, wheat, Spain
Batch cultures of mixed rumen micro-organisms were used to study the effects of different concentrations of malate (Rumalato; Norel & Nature S.A., Barcelona, Spain; composed of disodium malate–calcium malate (0·16:0·84, w/w)) on the fermentation of four cereal grains (maize, barley, wheat and sorghum). Rumen contents were collected from four Merino sheep fed lucerne hay ad libitum and supplemented with 300 g concentrate/d. Rumalato was added to the incubation bottles to achieve final concentrations of 0, 4, 7 and 10 mm-malate. Gas production was measured at regular intervals up to 120 h. Malate increased (P<0·01) the average fermentation rate of all substrates, and the lag time decreased (P<0·05) linearly with increasing concentrations of malate for all substrates, with the exception of sorghum. In 17 h incubations, the final pH and total volatile fatty acid production increased (P<0·001) linearly for all substrates as malate concentration increased from 0 to 10 mm. Propionate and butyrate production increased (P<0·05), while the value of the acetate : propionate ratio and l-lactate concentrations decreased (P<0·05) linearly with increasing doses of malate. Malate treatment increased (P<0·05) the CO2 production and decreased the production of CH4, although this effect was not significant (P>0·05) for maize. Malate at 4 and 7 mm increased (P<0·05) optical density of the cultures measured at 600 nm for maize, with no differences for the other substrates. The results indicate that malate may be used as a feed additive for ruminant animals fed high proportions of cereal grains, because it increased pH and propionate production and decreased CH4 production and l-lactate concentrations; however, in general, no beneficial effects of 10 compared with 7 mm-malate were observed.