Effect of butyrate sources in a high-concentrate diet on rumen structure and function in growing rams.

Dietary butyrate is considered to have mostly positive impacts on the ruminal epithelium. However, its supplementation in a high-concentrate diet may not be justified as excessive ruminal butyrate may negatively affect the rumen. Furthermore, butyrate impact on the rumen may depend on its source. Thirty-two Swiniarka growing rams (30.6 ± 2.5 kg; 11-14 months of age) were used to investigate the effect of a high-concentrate diet and sodium butyrate (SB) or tributyrin (TB) supplementation in a high-concentrate diet on the rumen structure and selected functions. The rams were allocated to four treatments and fed diets with: (1) low concentrate inclusion (22.5% of diet DM; L); (2) high concentrate inclusion (60% of diet DM; H); (3) H with SB (3.2% of diet DM; H+SB); and (4) H with TB (2.93% of diet DM; H+TB). The preplanned contrasts were used for treatment comparisons (L vs H treatments (H, H+SB, and H+TB), H vs H+SB, and H vs H+TB). The BW, BW gain and DM intake did not differ between treatments. In the atrium ruminis, epithelium thickness did not differ between the L and H treatments (P = 0.46), tended to be higher for H+SB than for H (P = 0.09) but did not differ between H+TB and H (P = 0.61). The expression of downregulated in adenoma was higher for L than for H treatments (P = 0.03) but was not affected by SB or TB supplementation (P ≥ 0.26). In the ventral rumen, the mucosa surface and epithelium thickness were lower for L than for H treatments (P < 0.01), were or tended to be higher for H+SB than for H (P ≤ 0.06) but did not differ between H+TB and H (P ≥ 0.26). The expression of monocarboxylate transporter 1 was lower for L than for H treatments (P = 0.02) but was not affected by SB or TB supplementation (P ≥ 0.28). The expression of putative anion transporter-1 and downregulated in adenoma did not differ between the L and H treatments (P ≥ 0.76); however, expression of the former tended to be higher and the latter tended to be lower for H+SB than for H (P ≤ 0.09), whereas no differences were observed between H+TB and H (P ≥ 0.14). In summary, SB supplementation, but not TB supplementation, in a high-concentrate diet stimulated ruminal epithelium growth and affected short-chain fatty acid transporters expression in the ruminal epithelium.

Effect of increased intake of concentrates and sodium butyrate supplementation on reticulorumen macroanatomy and reticulorumen fermentation in growing rams.

Increased ruminal butyrate production is considered to have mostly positive impacts on rumen macro- and microanatomy and its functions. However, excessive ruminal butyrate production may also affect the rumen negatively. Forty-two growing rams were allocated into six treatments and fed a diet with low (22.5% of diet DM; LOW) or high (60% of diet DM; HIGH) inclusion of concentrates in combination with no, low (1.6% of diet DM) or high (3.2% of diet DM) sodium butyrate (SB) supplementation to obtain low or high reticuloruminal (RR) pH with different concentrations of butyrate. Both absolute (L/day) and relative (% of BW) water intake increased linearly with increasing dose of SB (P ≤ 0.02). The RR fluid pH was lower for HIGH compared to LOW treatments (P < 0.01) but was not affected by SB supplementation (P = 0.35). Total short-chain fatty acid concentration, propionate and valerate concentrations in the RR fluid were higher for HIGH compared to LOW treatments (P ≤ 0.01), but were not affected by SB supplementation (P ≥ 0.22). Reticuloruminal butyrate was higher for HIGH compared to LOW treatments and increased linearly with increasing dose of SB (P < 0.01). High concentrate inclusion in the diet (P < 0.01) decreased and SB supplementation tended to (P = 0.10) decrease fibrolytic activity in the RR. Increasing doses of SB linearly decreased acetate, isovalerate and NH3-N concentrations in RR fluid, and RR digesta DM weight (g DM/kg BW; P ≤ 0.02). Relative RR and rumen tissue weights (g/kg BW) were higher for LOW compared to HIGH (P ≤ 0.03) treatments but were not affected by SB inclusion in the diet (P ≥ 0.35). Also, there was no impact of concentrates or SB inclusion in the diet on ruminal epithelium DM weight (mg/cm2), either in the ventral or dorsal sac of the rumen (P ≥ 0.14). Under conditions of the current study, SB supplementation in the diet decreased RR digesta DM concentration and weight, acetate, isovalerate and NH3-N concentration in the RR fluid, and tended to reduce fibrolytic activity in the RR. At least part of this response could be due to increased intake of water, and consequently passage of digesta from the RR to lower regions of the gastrointestinal tract.

Effect of increased intake of concentrates and sodium butyrate supplementation on ruminal epithelium structure and function in growing rams.

Increased ruminal butyrate production is considered to have a positive impact on rumen epithelium growth and function. However, excessive ruminal butyrate production may affect the rumen negatively, particularly when the rumen is already challenged with low pH. The aim of this study was to determine the effect of the inclusion of concentrates in the diet and sodium butyrate (SB) supplementation on ruminal epithelium growth and function in growing rams. Forty-two rams (27.8 ± 7.3 kg; 9-14 months of age) were allocated into six treatments and fed a diet with low (22.5% of diet DM; LOW) or high (60% of diet DM; HIGH) inclusion of concentrates in combination with no (SB0), 1.6% (SB1.6) or 3.2% (SB3.2) of diet DM inclusion of SB. There was no impact of the investigated factors on papilla dimensions and mucosa surface area, either in the atrium ruminis or ventral rumen (P ≥ 0.11). Stratum corneum thickness was higher for HIGH compared to LOW treatments (P ≤ 0.04), independently of the location in the rumen. In the atrium ruminis, the epithelium and living strata thickness quadratically increased due to SB supplementation for LOW treatments but quadratically decreased for HIGH treatments (concentrate inclusion × butyrate supplementation interaction; P ≤ 0.03); conversely, in the ventral sac of the rumen, a thicker epithelium was observed due to both increased concentrate inclusion in the diet and SB supplementation (P < 0.01) but living strata thickness was increased only by SB supplementation (linear effect; P < 0.01). The epithelium damage index in the ventral sac of the rumen was higher for LOW compared to HIGH treatments (P = 0.02). Increased inclusion of concentrates in the diet increased mRNA expression of monocarboxylate transporter 1 in both the epithelium of the atrium ruminis and ventral rumen, occludin in the epithelium of the atrium ruminis and downregulated in adenoma in the epithelium of the ventral rumen (P ≤ 0.02). Protein expression of claudin-4 in the epithelium of the ventral rumen was the highest for the HIGH/SB1.6 and HIGH/SB3.2 treatments (significant effect of interaction between main effects; P < 0.01). Under the conditions of the current study, increased intake of concentrates had mostly positive effects on ruminal epithelium in growing rams, and the same was observed for the effect of SB supplementation. However, the effect of SB supplementation was at least partially affected by the inclusion of concentrates in the diet.