Effect of ruminal acidosis and short-term low feed intake on indicators of gastrointestinal barrier function in Holstein steers

Abstract

The objective of this study was to determine effect of ruminal acidosis (RA) and low feed intake [LFI] on the regional barrier function of the gastrointestinal tract. Twenty-one Holstein steers were fed for ad libitum intake for 5 d (control [CON]), fed at 25% of ad libitum intake for 5 d (LFI), or provided 2 d of ad libitum intake followed by 1-d of feed restriction (25% of ad libitum intake), 1 d where 30% of ad libitum dry matter intake (DMI) was provided as pelleted barley followed by the full allocation (RA) and fed for ad libitum intake the following day. Tissues and digesta from the rumen, omasum, duodenum, jejunum, ileum, cecum, proximal, and distal colon were collected. Permeability was assessed using the mucosal-to-serosal flux of inulin (JMS-inulin) and mannitol (JMS-mannitol). Digesta pH was 0.81, 0.63, and 0.42 pH units less for RA than CON in the rumen, cecum, and proximal colon; while, LFI had pH that was 0.47 and 0.36 pH units greater in the rumen and proximal colon compared to CON. Total ruminal short-chain fatty acid (SCFA) concentration were less for LFI (92 mM; P = 0.010) and RA (87 mM; P = 0.007) than CON (172 mM) steers. In the proximal colon, the proportion of butyrate (P = 0.025 and P = 0.022) and isobutyrate (P = 0.019 and P = 0.019) were greater, and acetate (P = 0.028 and P = 0.028) was less for LFI and RA, respectively, when compared to CON steers. Ruminal papillae length, width, perimeter, and surface area were 1.21 mm, 0.78 mm, 3.84 mm, and 11.15 mm2 less for LFI than CON; while, RA decreased papillae width by 0.52 mm relative to CON. The JMS-mannitol was less for LFI steers than CON in the proximal colon (P = 0.041) and in the distal colon (P = 0.015). Increased gene expression for claudin 1, occludin, tight-cell junction protein 1 and 2, and toll-like receptor 4 were detected for LFI relative to CON in the rumen, jejunum, and proximal colon. For RA steers, expression of toll-like receptor 4 in the rumen, and occludin and tight-cell junction protein 1 were greater in the jejunum than CON. An acute RA challenge decreased pH in the rumen and large intestine but did not increase tissue permeability due to increases in the expression of genes related to barrier function within 1 d of the challenge. Steers exposed to LFI for 5 d had reduced ruminal SCFA concentrations, smaller ruminal papillae dimensions, and increased tissue permeability in the proximal and distal colon despite increases for genes related to barrier function and immune function.

Effects of subacute ruminal acidosis on colon epithelial morphological structure, permeability and expression of key tight junction proteins in a dairy goat model

“…In the present study, the increase of Occludin in colonic epithelium was basically consistent with the results of studies by Pederozoli et al [63] and Tao et al [41]. Reasons for the difference may be related to severity of SARA challenge, experimental animals, different dietary structures and the degree of damage to the intestinal epithelium.…”

Potential for a localized immune response by the ruminal epithelium in nonpregnant heifers following a short-term subacute ruminal acidosis challenge

“…As such, we speculate that ruminal biopsies collected closer in time to the grain overload might have revealed a proinflammatory response associated with the initial stages of inflammation, and this speculation is supported by the model in Aschenbach et al (2019). Indeed, recent work from our laboratory (Pederzolli et al, 2018) reported an upregulation in TLR4 and TLR2 in rumen papillae of steers and lambs 24 h following an acidosis challenge, indicating a proinflammatory response. Future work incorporating earlier time points is needed to further investigate the effects observed in the present study.…”

Interactions Between Rumen Microbes, VFAs, and Host Genes Regulate Nutrient Absorption and Epithelial Barrier Function During Cold Season Nutritional Stress in Tibetan Sheep

“…Expression levels of rumen epithelial barrier genes Claudin-4 and ZO-1 are significantly lower in the cold season than in the warm season ( P < 0.05). Some studies have shown that when the feed intake of ruminants decreases, permeability of the gastrointestinal tract barrier increases ( Zhang et al, 2013a , b ; Pederzolli et al, 2018 ). Claudin-4 and ZO-1 , as the main components of the rumen epithelial barrier, control the permeability of this barrier, thereby regulating the absorption of nutrients and preventing entry of harmful substances ( Zhang et al, 2018 ; Aschenbach et al, 2019 ).…”