Page 19 - New additives and ingredients in the formulation of aquafeeds

In terms of product development and manufacture Norel is one of top
worldwide producers of organic acid salts, being sodium butyrate our
primary focus. Our current R&D program concentrates on the investigation
of the individual effect of sodium butyrate as well as the synergetic effect
when combined with other NGPs on health and performance by elucidating
the different genomic and metabolic mechanisms involved.
Gustor Aqua Gustor Aqua contains sodium butyrate, which is the sodium salt form of
butyric acid. Butyric acid is naturally produced and present within the
intestine of both carnivorous and herbivorous fish (Holben et al., 2002,
Mountfort et al., 2002). As mentioned above, SCOA are commonly known
by their specific antimicrobial activity, however, other key benefits such as
trophic and immune properties have been attributed to sodium butyrate
(Gálfi and Bokori, 1990; Le Gall et al., 2009).
The magnitude of the antimicrobial effects of sodium butyrate is largely
dependent on two factors: concentration and gastrointestinal pH. The pKa
value of each SCOA represents the pH at which the acid is half dissociated,
thus determining the extent of dissociation/undissociation of the acid
(Figure 3). The undissociated state of SCOA is strongly lipophilic and
capable to diffuse across the membrane of gram negative bacteria (Gálfi
and Bokori, 1990). Once inside the bacterial cytoplasm, the more alkaline
pH causes dissociation of the acid resulting in two fatal incidents for the
bacteria; pH decline -and the consequent disruption of the metabolic
processes- and reduced energy availability due to the effort required to
transport the proton out of the bacteria (Dibner and Buttin, 2002). Table 6
shows the antimicrobial activity of butyric acid when compared to propionic
and valerianic acids. The subsequent reduction in the butyric acid intolerant
microorganisms contributes to a diminished risk of subclinical infections
and nutrient demand by the gut-associated immune system which leads
to enhanced health status and nutrient use. As reported by Page et al.
Figure 3.
Dissociation/undis-
sociated state of
butyric, formic and
lactic acids
Natural growth promoters in aquaculture practices 17