Interpretive Summary: Effect of ruminal acidosis and short-term low feed intake on indicators of gastrointestinal barrier function in Holstein steers.I
By: Surely Wallace
In a study published in the Journal of Animal Science in February 2018, researchers looked at the effects of low feed intake (LFI) and rumen acidosis (RA) on gastrointestinal tract (GIT) barrier of Holstein steers.
Nutritional challenges such as RA and LFI may have economic impacts on the meat industry by reducing productivity and health of steers. Barrier integrity of the GIT affects nutrient absorption and immune function, among other factors. The authors hypothesized that RA and LFI would both reduce GIT barrier function in Holstein steers.
The study took place in Saskatchewan, Canada. Holstein steers of similar age and weight were randomly assigned to control, RA, or LFI groups (n = 7 each). Normal ad lib feed consisted of (dry matter) 50% grass hay, 38% barley grain, 4% canola meal, with the remainder nutritional supplement. All animals were given normal feed followed by a 5-day study period. Normal feed was continued ad lib in the control group. In the LFI group, ad lib feed was reduced by approx. 25%. In the RA group, animals were given 2 days normal feed, 1 day LFI, and pelleted barely over-feeding on day 4 to induce RA. Steers were slaughtered on day 5. The GIT was analyzed ex vivo for permeability; digesta was analyzed for pH and short-chain fatty acid (SCFA) content.
Results indicated LFI steers weighed significantly less than controls (230 kg vs. 254 kg), with no difference between control and RA groups. In digesta, total reticulo-rumen SCFA concentration was greater in controls (~ 170 mM) than in the LFI and RA groups (< 100 mM). However, the authors note some SCFA ratios differed between treatment and controls. Rumen pH was decreased in the RA group and increased in the LFI group, compared to controls. In order to determine GIT permeability, mannitol/inulin flux rate, gene expression, and histological features of GIT were evaluated. The authors reported increased permeability of GIT in LFI (in proximal and distal colon) but not in RA groups; they attribute the latter to increased GIT barrier function gene expression. However, the authors also noted increased gene expression in the LFI group.
This small study suggests there may be complex interactions between gene expression and GIT barrier integrity in steers during LFI and RA nutritional challenges. The authors suggest that gut microbiome may additionally impact GIT barrier integrity, although they did not explore this specific area, so it is a question for future research. Overall, better understanding of the interaction between host, nutritional and potentially microbial factors is needed in order to find ways to prevent or treat negative impacts of LFI or RA in steers.
To view the full article, “Effect of ruminal acidosis and short-term low feed intake on indicators of gastrointestinal barrier function in Holstein steers,” visit the Journal of Animal Science.