Impact of barley form on equine total tract fibre digestibility and colonic microbiota

Abstract

This study aimed at assessing the impact of four barley forms on total tract apparent digestibility of dietary fibre in horses fed a large amount of starch in the morning meal (0.27% BW). Processed barley forms had a greater pre-caecal starch digestibility than the whole form. Based on this result, we hypothesised that using barley-processing methods would limit the potential dumping of undegraded starch in the hindgut of horses and, consequently, the potential negative effect on fibre degradation in the hindgut. In a 4 × 4 latin square design, four mature geldings fitted with a right ventral colon-fistula were fed a meadow hay : concentrate (62 : 38; dry matter (DM) basis) diet at 1.7% BW. The concentrate was made of 80% barley distributed either as whole grain or as processed forms: 2.5 mm ground, pelleted or steam-flaked. For each period, total tract apparent digestibilities of DM, NDF and ADF were determined over 3 consecutive days by total faecal collection, whereas pH, volatile fatty acids (VFA) concentrations and cultural functional bacteria counts (total anaerobic, cellulolytic bacteria, lactic acid producers, amylolytic bacteria and lactic acid utilisers) in colonic content were evaluated on 1 day 4 h after the morning meal. Total tract apparent digestibility of DM and dietary fibre was influenced ( P < 0.05) by barley form. Diets including thermo-mechanically treated barley forms led to a higher ( P < 0.05) total tract apparent digestibility of NDF than those constituted of ground barley and also led to a greater ( P < 0.05) total tract apparent digestibility of ADF than those made of whole or ground barley forms. However, no significant difference was observed in colonic pH, VFA concentrations and cultural bacteria concentrations. Owing to a high starch supply in the morning meal, the concentration of the functional bacteria in the colonic content averaged 7.8 log CFU/ml, 5.9 NPM/ml, 6.9 and 7.3 CFU/ml for total anaerobic, cellulolytic, amylolytic and lactic acid-utilising bacteria, respectively. Consequently, providing horses with pelleted or steam-flaked instead of ground barley forms may limit the negative impact of starch on fibre digestibility in horses fed a high level of starch in the morning meal (0.27% BW). Moreover, the fibre-to-starch ratio fed in this experiment did not cause any digestive upset.

Effect of age and the individual on the gastrointestinal bacteriome of ponies fed a high-starch diet

“…Furthermore, both the botanical source and feed processing of starch have been shown to impact upon starch digestion [12,13]. Feeding thermo-mechanical forms of barley as opposed to whole grain or mechanically-treated forms of barley has been shown to result in greater ADF (acid detergent fibre) digestibility, and suggests that feeding thermomechanical forms of barley may limit the amount of undigested starch reaching the hindgut [14,15].…”

Interaction between the sequence of feeding of hay and concentrate, and boiling of barley on feed intake, the activity of hydrolytic enzymes and fermentation in the hindgut of Arabian mares

“…Concentrate feeding was therefore reported to cause changes in the hindgut microbial ecosystem in horses (Grimm, Philippeau, & Julliand, ; Julliand, De Fombelle, Drogoul, & Jacotot, ; Moore & Dehority, ). In particular, the cellulolytic bacteria (Julliand et al., ) and the total population of functional bacteria in the colonic contents of horses (Philippeau, Sadet‐Bourgeteau, Varloud, & Julliand, ) are compromised by concentrates like barley. In the literature, it has been shown that feeding concentrate after or along with the forage portion of the diet could, to some extent, help maintaining an appropriate hindgut physiochemical environment (Jensen, Austbø, & Tauson, ; Sadet‐Bourgeteau et al., ; Zeyner, Geiβler, & Dittrich, ).…”

“…Philippeau et al. () demonstrated that using thermo‐mechanically treated cereals limits the potential negative impact of starch on fibrolytic activity in horses. To our knowledge, the combination of a strategic feeding sequence (FS) and a hydrothermal processing of cereals with the purpose of improving hindgut fermentation in concentrate‐fed horses has not yet been tested.…”

“…Julliand, De Fombelle, and Varloud (2006) reported that hydrothermally processed and thus gelatinized starch of cereal grains through steam cracking of the membranes of the starch granules makes the starch well available to small intestinal digestion. Philippeau et al (2015) demonstrated that using thermomechanically treated cereals limits the potential negative impact of starch on fibrolytic activity in horses. To our knowledge, the combination of a strategic feeding sequence (FS) and a hydrothermal processing of cereals with the purpose of improving hindgut fermentation in concentrate-fed horses has not yet been tested.…”

Detecção e enumeração de <i>Streptococcus</i> spp. e <i>Lactobacillus</i> spp. nas fezes de equinos recebendo dietas contendo níveis crescentes de Farelo de Glúten de Milho 21

“…Em animais de produção, alterações na composição da dieta podem levar a mudanças significativas na ecologia microbiana gastrointestinal, concorrendo para a queda de produtividade destes animais (CALLAWAY et al, 2010). Dentre os animais, podemos destacar os equinos, os quais são alvos de pesquisas sobre a microbiota intestinal (MUHONEN et al, 2009;SHEPHERD et al, 2012;COSTA et al, 2015b;PHILIPPEAU et al, 2015;COVERDALE, 2016). Existe uma abundância de microrganismos que colonizam todo o TGI dos equinos como fungos, bactérias, protozoários e arqueas (CUMMINGS e MACFARLANE, 1997;FRAPE, 2008); com isso, pesquisas têm sido realizadas para fornecer informações sobre populações alvo específicas (DE-FOMBELLE et al, 2003;AL JASSIM et al, 2005;HARLOW et al, 2015 (MOREAU et al, 2014;AL JASSIM et al, 2005;DE-FOMBELLE et al, 2003).…”