Submitted to: Journal of Agricultural and Food Chemistry
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 3/8/2012
Publication Date: 3/8/2012
Citation: Smith, D.J., Barri, A., Herges, G.R., Hahn, J., Yersin, A.G., Jourdan, A. 2012. In vitro dissolution and in vivo absorption of calcium [1-14C]butyrate in free or protected forms. Journal of Agricultural and Food Chemistry. 60:3151-3157.
Interpretive Summary: Efficient use of nutrients by livestock and humans is dependent upon a healthy gastrointestinal tract. In a similar manner, a healthy gastrointestinal tract allows food animals to better resist infection by harmful bacteria. A nutrient called butyrate (found in butter) has been proven to improve the health of gastrointestinal tissues of several species. Supplementation of butyrate into diets of animals would be beneficial for maintaining gastrointestinal health, but butyrate is so rapidly absorbed that it is not available to large portions of the intestine. This study was conducted to determine how rapidly butyrate, formulated into a slow-release product, is released and absorbed by broiler chicks. Chicks were chosen for their size, their ease of handling, and because broiler chicks could benefit from butyrate supplementation. Data clearly showed that the slow release formulation delayed butyrate absorption, but did not limit total butyrate absorption. The data suggest that encapsulated products could improve animal health.
Technical Abstract: Butyrate is a by-product of microbial carbohydrate fermentation that occurs primarily in the large intestine. When added to feed, butyrate quickly disappears in the upper digestive tract. Because butyrate is important for the epithelial cell development and for mucosal integrity, and for animal growth, an encapsulation technique has been developed which allows for the slow release of butyrate into the small and large intestines. The purpose of this study was to describe the in vitro release of calcium [1-14C]butyrate, formulated into a slow-release (protected) bead, into water and simulated intestinal fluids, and to compare the in vivo absorption and disposition of unprotected versus protected calcium [1-14C]butyrate in broiler chicks. Formulation of calcium [1-14C]butyrate into protected beads allowed release of 5.8 +/- 0.2 and 3.4 +/- 0.2% of the formulated radiocarbon into water and gastric fluid, respectively, after 2 h of incubation. Beads incubated in gastric fluid for 2 h and subsequently incubated in simulated intestinal fluid released at total of 17.4 +/- 0.8% of the formulated radioactivity. Release of respiratory [14C]CO2 after oral dosing of aqueous calcium [1-14C]butyrate in broiler chicks peaked at 15.2 +/- 5.2% per h 1.5 h after dosing; in contrast, maximal rates of release in chicks dosed with protected calcium [1-14C]butyrate occurred 4 h after dosing at 9.0 +/- 3.1% per h. The data suggested an improved efficacy of protected butyrate over non-protected butyrate. This study confirmed that encapsulation strategies designed to enhance delivery of ingredients to improve intestinal health are effective at prolonging intestinal exposure to butyrate. Encapsulation of such ingredients might benefit the food and feed industries.
■ INTRODUCTION
Efficient nutrient use of food animals is accomplished in many
ways, including maximizing nutrient digestibility and absorption.
Digestibility is optimized through efficient digestive
enzyme secretion, a balanced intestinal microbial population,
and maintenance of mucosal integrity throughout the length of
the gastrointestinal (GI) tract. Mucosal integrity is ensured by a
proper balance between mitotic rates of crypt stem cells and tip
villi apoptosis.1 For example, disproportionate rates of villi
proliferation are counteracted by an increase in apoptosis, and
vice versa, which results in a net gain of villi length.2,3 Butyrate,
a short-chain fatty acid (SCFA) produced by microbial
fermentation primarily in the large intestine, is an apoptosis
inhibitor of mucosal cells and could have direct effects on
mucosal cell proliferation.1,3 As a consequence, butyrate is
hypothesized to have marked effects on intestinal morphology
and function.1,4
Butyrate transport into mucosal epithelial cells is mediated by
a specific monocarboxylate transporter (MCT-I), which is
expressed in both the large and small intestinal tissues.3
However, because hindgut microbial fermentation is the major
source of butyrate, its production in, and availability to, the
small intestine is virtually nonexistent. The addition of butyrate
in feed may have a strong influence on the balance between
mucosal mitosis and apoptosis, and dietary butyrate is thought
to play an important role in small intestinal morphology and
efficiency.1,4 In addition, the bacteriostatic or bactericidal
mechanisms of organic acids in live animals have been
hypothesized to occur indirectly through the maintenance of
intestinal epithelial integrity.1,5 However, SCFA are very
quickly6 and quantitatively absorbed from sections of poultry
GI tracts cranial to Meckel’s diverticulum,7 which limits their
practical use as feed additives to maintain gastrointestinal tract
health.
Delivery of bioactive SCFAs in a form that will allow their
release along the length of the small and large intestines should
improve epithelial cell integrity and morphology of the whole
tissue. Although the efficacy of protected organic acids has been
demonstrated,1,8 data describing the release and disposition of
protected butyric acid in target organisms are not available.
Therefore, the objectives of this study were to (1) describe the
in vitro release of a labeled short-chain fatty acid, (calcium
[1-14C]butyrate) formulated into a protected bead (Micro-
PEARL), into water and simulated gastric and intestinal fluids
and (2) compare the in vivo absorption and disposition of
unprotected and protected calcium [1-14C]butyrate in broiler
chicks
■ RESULTS
In Vitro Dissolution Tests. Figure 1 (open circles) shows
the dissolution of protected calcium [1-14C]butyrate beads in
water at 37 °C during a 2 h incubation period. Data fit well to a
two-phase association curve (r2 = 0.9450) with rapid and slow
release half-lives estimated to be 3.5 and 36.7 min, respectively,
on the basis of a release plateau of 5.8 ± 0.3% of total
radioactivity within the beads. These release half-lives likely
represent dissolution of calcium butyrate from surface and
embedded compartments within the beads, respectively. Total
release of calcium [1-14C]butyrate at 0 min was significantly (P
< 0.001) less than the mean release of calcium [1-14C]butyrate
at 60 min; mean release at 60 min was also significantly (P <
0.001) less than at 120 min. However, the mean release of
calcium butyrate from the beads at 90 and 120 min did not
differ (P > 0.05).