Effect of the addition of malate on in vitro rumen fermentation of cereal grains.
Batch cultures of mixed rumen micro-organisms were used to study the effects of different concentrations of malate (Rumalato(R); 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(R) 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.
Carro
M D
MD
Departamento Producción Animal I. Campus de Vegazana, Universidad de León, 24071 León, Spain. DP1MCT@UNILEON.ES
Ranilla
M J
MJ
D000821:Animal Feed; D000818:Animals; D019587:Dietary Supplements; D002523:Edible Grain; D005232:Fatty Acids, Volatile / Q000378:metabolism; D005285:Fermentation; D001467:Hordeum; D006863:Hydrogen-Ion Concentration; D019344:Lactic Acid / Q000378:metabolism; D008293:Malates / Q000008:administration & dosage*; D008697:Methane / Q000378:metabolism; D012417:Rumen / Q000378:metabolism*; D012434:Secale; D012756:Sheep / Q000378:metabolism*; D014908:Triticum; D003313:Zea mays
D005232:Fatty Acids, Volatile; D008293:Malates; D019344:Lactic Acid; C030298:malic acid; D008697:Methane