Influence of disodium malate on microbial growth and fermentation in rumen-simulation technique fermenters receiving medium- and high-concentrate diets

Abstract

Two incubation trials were carried out with the rumen-simulation technique (RUSITEC). In each trial, four vessels received a diet of grass hay and concentrate (600 and 400 g/kg DM, respectively; diet F), and the other four were fed a diet composed of concentrate and barley straw (900 and 100 g/kg DM, respectively; Diet C). Vessels were given 20 g of the corresponding diet daily, and half of them were supplemented with disodium malate to achieve a final concentration of 6·55 mM. There were no effects (P.0·05) of malate either on pH or on the daily production of NH 3 -N, but malate treatment increased (P,0·05) DM, neutral detergent and acid detergent fibre disappearance after 48 h incubation. The daily production of propionate and butyrate increased (P,0·001), and the ratio CH 4 :volatile fatty acids decreased (P,0·001) by supplementing both diets with malate. Whereas adding malate to the F diet produced an increase in acetate production (P¼ 0·011) and the growth of solid-associated micro-organisms (P¼ 0·037), no effects (P.0·05) were observed for diet C. For both diets, there were no differences (P.0·05) between treatments in the daily flow of liquid-associated micro-organisms measured using 15 N as a microbial marker. These results indicate that malate stimulated the in vitro fermentation of both diets by increasing the apparent disappearance of the diet and decreasing the ratio of CH 4 :volatile fatty acids, but a greater response was observed with diet F. If these results are confirmed in vivo, malate could be used as a feed additive for ruminants fed diets containing medium proportions of forage (i.e. dairy animals) and not only in animals fed high-concentrate diets, as has so far been proposed.

Nutritional strategies to control ruminal acidosis in feedlot cattle

“…The influence of malate supplementation on rumen fermentation seems to be dosedependent Carro and Ranilla, 2003), but is also affected by the type of diet and rumen microbial populations (Gómez et al, 2005;Tejido et al, 2005). The lack of effects of malate on rumen concentrations of NH 3 -N, lactate, and VFA observed in the current study is consistent with other studies in which beef cattle was fed high-grain diets and supplemented daily up to 134 g of malic acid or malate salts (Montaño et al, 1999;Carrasco et al, 2012;Vyas et al, 2015).…”

“…The lack of effect of MA and MAL in our study contrasts with previous in vitro studies in which malic acid or malate salts supplementation to different substrates (i.e., corn grain, barley grain, wheat grain, sorghum grain and different mixtures of forages and concentrates) consistently increased total VFA and propionate production in batch cultures (Carro and Ranilla, 2003;Newbold et al, 2005;Tejido et al, 2005) and Rusitec fermenters (Carro et al, 1999;Gómez et al, 2005). Although the magnitude of the effects of malic acid/malate on in vitro ruminal fermentation have been shown to be influenced by the incubated substrate (Carro and Ranilla, 2003;Newbold et al, 2005;Gómez et al, 2005;Tejido et al, 2005), there are other factors which could explain the lack of effects in our in vitro fermentation.…”

“…Although the magnitude of the effects of malic acid/malate on in vitro ruminal fermentation have been shown to be influenced by the incubated substrate (Carro and Ranilla, 2003;Newbold et al, 2005;Gómez et al, 2005;Tejido et al, 2005), there are other factors which could explain the lack of effects in our in vitro fermentation. For example, doses of malic acid/malate used in the previously cited in vitro studies ranged from 4 to 10 mM, and corresponded to levels from 37 to 92 g of malic acid/malate/kg of incubated substrate (DM basis).…”

“…1 and 2 is consistent with the absence of effects of the additives on concentrate intake and ruminal fermentation variables. Some authors (Gómez et al, 2005;Newbold et al, 2005;Tejido et al, 2005) suggested, based on in vitro results, that the effects of sodium malate may be more pronounced with diets containing a high proportion of forage (60-80%) than with high-concentrate diets such as those used in our studies. 1 CON = control; unsupplemented concentrate.…”

“…Although malic acid and malate salts have been repeatedly shown to have positive effects on in vitro ruminal fermentation by increasing ruminal pH and propionate production (Carro and Ranilla, 2003;Gómez et al, 2005;Newbold et al, 2005;Tejido et al, 2006), available information on effects of malate on in vivo ruminal fermentation and ruminant performance is limited and conflicting. Martin et al (1999) reported that supplementing DL-malate at rates of 3.7 and 7.1 g/kg DM to feedlot steers fed a corn based diet improved ADG and F:G, and Flores et al (2003) found that supplementing malate salts at 1.1 g/kg diet DM improved growth and digestibility of intensively fattened lambs.…”