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DELIVERY OF BUTYRATE PRECURSORS IN THE GASTROINTESTINAL TRACT OF RUMINANTS AS A STRATEGY TO SUPPORT GASTROINTESTINAL FUNCTION AND DEVELOPMENT

Date

2023-09-28

Journal Title

Journal ISSN

Volume Title

Publisher

ORCID

0009-0001-2166-6149

Type

Thesis

Degree Level

Doctoral

Abstract

The general hypothesis for the four experiments reported in this thesis was that increasing the intestinal supply of butyrate will stimulate gastrointestinal tract development and functionality, leading to greater growth rates and feed efficiency in ruminants. The first study evaluated the dose response of hydrogenated fat-embedded calcium gluconate (HFCG), a butyrate precursor. Growing lambs were assigned to dietary treatments containing HFCG: 0.0% (CON), 0.075% (LOW), 0.3% (MED), or 0.6% (HIGH) of the diet (DM basis). Increasing dose of HFCG linearly decreased dry matter intake (DMI), average daily gain (ADG), and final body weight (BW). In the cecum, increased dose of HFCG linearly increased the molar proportion of acetate and linearly decreased the molar proportion of propionate, while the total short-chain fatty acid (SCFA) concentration was cubically affected, where LOW had the greatest concentration. Increased butyrate molar proportion was not observed in any of the of the intestinal regions analyzed. The second study aimed to compare the post-ruminal provision of calcium gluconate (CaG) and calcium butyrate (CaB) to explore the mode of action of CaG relative to butyrate. Four treatments were used, aiming to provide the same amount of butyrate post-ruminally (excluding CON) for beef heifers: 1) negative control (CON; ruminal infusion of double-distilled water); 2) abomasal infusion of CaB (AB; 0.029% of BW); 3) abomasal infusion of CaG (AG; 0.0077% of BW); and 4) ruminal infusion of HFCG (RG; 0.0192% of BW). Relative to CON, both AB and CaG treatments (AG + RG) reduced the molar proportion of acetate and increased the molar proportion of propionate in the colon. The ruminal disappearance of total SCFA, acetate, propionate, and butyrate were increased for AB but not for CaG, relative to CON. Barrier function was not affected by treatments when measured in vivo using urinary excretion of Cr-EDTA; however, when measured using ex vivo conditions, AB tended to decrease mannitol flux across ruminal tissue relative to CON. Neither AB nor CaG increased the intestinal molar proportion of butyrate. In the third experiment, HFCG was fed to finishing heifers at 0.0% (CON), 0.09% (CG09), or 0.18% (CG18) of the diet (DM basis). Increasing the dose of HFCG did not affect feed intake or growth; however, feed efficiency and ruminal stratum corneum thickness tended to be quadratically affected by HFCG dose. Quadratic effects were observed for jejunal pH, molar proportion of acetate, valerate, and isovalerate in the colon, and meat cook loss; however, changes in the molar proportion of butyrate were not observed in the intestinal regions analyzed. Treatments did not affect carcass characteristics and descriptive sensory analysis of the meat. Finally, in the fourth experiments, tributyrin (TB) was used as a butyrate source and was provided in two forms: unprotected (UTB) and rumen protected (RTB). Eighty-four lambs were divided in two groups that were fed with different diets containing moderate (MF) or low forage (LF) inclusion, and within each group lambs were assigned to 1 of 6 treatments including a negative control (CON; no dietary inclusion of TB), dietary inclusion of RTB at 0.1% (RTB1), 0.2% (RTB2), and 0.3% (RTB3), or dietary inclusion of UTB at 0.1% (UTB1) and 0.3% (UTB3). Relative to RTB3, lambs fed UTB3 tended to finish heavier and tended to have an overall higher ADG when fed the MF diet. When lambs were fed the LF diet, RTB tended to increase DMI, and decrease feed efficiency and blood BHBA concentration relative to dietary inclusion of UTB. The use of CaG as a butyrate precursor did not increase the butyrate concentration in the intestine. When compared to the abomasal supply of CaB, post-ruminal supply of CaG did not yield the same results on ruminal SCFA disappearance, leading to the speculation that the site of exposure of butyrate in the gastrointestinal tract could yield different outcomes. The first three studies indicate that post-ruminal supply of CaG when provided at different doses, in differing diets, and ruminant species did not yield positive responses in growth and feed efficiency as the literature reports on the butyrate supply. As well, TB delivery both ruminally and post-ruminally did not increase carcass characteristics in lambs fed either with a MF or a LF diet.

Description

Keywords

Butyrate, Gastrointestinal tract

Citation

Degree

Doctor of Philosophy (Ph.D.)

Department

Animal and Poultry Science

Program

Animal Science

Part Of

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DOI

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