Starch digestion in horses: The impact of feed processing

The aim of this study was to assess the apparent digestibility of broken rice using total collection of feces and the pepsin-cellulase in vitro technique to provide updated and more accurate digestion coefficients for this by-product when fed to horses. The in vivo digestibility trial was consecutively performed, using five adult geldings, weighing 555.6 kg on average. First, hay was given as the only feedstuff, while second, the experimental diet consisted of the same hay plus broken rice at a forage-to-concentrate ratio of 70/30 (on dry matter (DM) basis). Feces were collected over 6 days preceded by a 14-day adaptation period. The digestibility trial was carried out to determine the digestion coefficients for DM, organic matter (OM), CP and gross energy in both diets, while apparent digestion coefficients for the same parameters were calculated for broken rice alone, using the difference between the two sets of results. At the same time, an in vitro trial was carried out using pepsin-cellulase technique on the samples of hay and broken rice tested during the in vivo trial. As expected, supplementation with broken rice increased digestibility according to all the parameters used. The high OM digestion coefficients of broken rice were confirmed both by the calculated in vivo method and by the predicted results of pepsin-cellulase technique (92.6% and 87.1%, respectively), underlining the high digestibility of this by-product when fed to horses.Keywords: horse, broken rice, apparent digestibility, pepsin-cellulase technique ImplicationsMixed feed incorporating broken rice is used for horses but estimates of its nutritive value are based on determinations using rice by-products in pig, ruminant and poultry feeds. The importance and the novelty of this experiment is that similar studies carried out on horses in Europe are not available in the scientific literature, but only dated works performed in Australia with different rice cultivars on different livestock species. The present study updates the chemical composition and digestion coefficients of Italian broken rice for horses. Our results should enable companies to produce well-rationed mixed feeds for horses. IntroductionRice (Oryza sativa) is the seed of an annual plant belonging to the Gramineae family, one of the most widespread grain crops in the world. Indeed, in 2010, rice was the grain with the second-highest worldwide production, behind maize. Italy produces large amounts of rice, especially in the North. Consequently, many by-products of the rice cleaning process are available for livestock use. Among these, broken rice separated out after the polishing stage has the same chemical composition as polished rice; even though the quantities available are not very high, this by-product is a palatable, energy-rich and easily utilized feed. Another characteristic of this by-product is that it has a low-protein content but of high quality: its protein is richer in lysine than that of other major cereals.In literature, studies on broken rice digestibility in h...

Section: Resultsmentioning

confidence: 99%

Apparent digestibility of broken rice in horses using in vivo and in vitro methods

Marco

Peiretti

Miraglia

et al. 2014

“…Equine hindgut microbiota and faecal biomarkers This study examined two very different diets: high-fibre hay and high-starch hay/barley mix. The hay/barley (B) diet was formulated to provide more than the maximum recommendation of 200 g/100 kg BW of starch in the morning meal (Julliand et al, 2006) and less than the minimal recommendation of 1 kg DM/100 kg BW of hay per day (NRC, 2007). As expected the data showed modifications in the hindgut ecosystem in agreement with those observed by other studies testing concentrate diets (Julliand et al, 2001, Medina et al, 2002de Fombelle et al, 2003) whereby caecal and RV colonic functional bacteria group concentrations (cellulolytics, lactate utilizers) varied, and caecal and colonic microbial activity moved towards an amylolytic activity profile (increase in propionate proportions, valerate and D/L-lactate concentrations and decrease in acetate proportion and VFA ratio [(C2 + C4)/C3]).…”

Section: Discussionmentioning

confidence: 99%

“…High-starch diets have been reported to be an important risk factor for negatively altering the microbiota (Julliand et al, 2006). When more than 200 g DM of starch/meal per 100 kg BW is fed, it is not entirely degraded in the small intestine by the digestive enzymes, and residual starch enters the hindgut where it can cause acidosis due to the increased population of the bacteria which produce acid as a by-product of starch fermentation (Julliand et al, 2006). Two studies were published which were specifically designed to measure the impact of a high-starch diet versus a fibre-rich feed on the bacterial profiles of the hindgut and the faeces (de Fombelle et al, 2003;Julliand and Goachet, 2005).…”

mentioning

confidence: 99%

Faecal parameters as biomarkers of the equine hindgut microbial ecosystem under dietary change

Grimm

Philippeau

Julliand

2017

Self Cite

Faeces could be used for evaluating the balance of the equine hindgut microbial ecosystem, which would offer a practical method for assessing gut health and how this relates to disease. However, previous studies concluded that faeces microbial ecosystem was not representative of the proximal hindgut (caecum and ventral colon). This study aimed to evaluate if variations of the faecal microbial ecosystem were similar to those observed in the proximal hindgut. Six horses, fistulated in the caecum and right ventral (RV) colon, were subjected to a gradual change of diet, from a 100% hay (high fibre) diet (2.2 DM kg/day per 100 kg BW) to a 57% hay + 43% barley (high starch) diet (0.8 DM kg/day per 100 kg BW hay and 0.6 DM kg/day per 100 kg BW barley). The two diets were iso-energetic and fed over a 3-week trial period. Samples of digesta from the caecum, RV colon and faeces were collected two times on the 10th and 20th day of the trial, for each diet to assess the microbial ecosystem parameters by both classical culture technics and biochemical methods. The variations observed in the caecal and colonic bacterial composition (increase in total anaerobic, amylolytic and lactate-utilizing and decrease in cellulolytic bacteria concentrations) and microbial activity (changes in volatile fatty acids concentrations and increase in lactate concentrations) demonstrated that the hay + barley diet caused changes in the hindgut microbial ecosystem. Similar variations were observed in the faecal microbial ecosystem. Feeding the hay + barley diet resulted in higher concentrations of faecal lipopolysaccharides. The functional bacterial group concentrations (cellulolytics, amylolytics and lactate utilizers) were significantly correlated between caecum and faeces and between colon and faeces. From analyses of the metabolites produced from microbial activity, only valerate concentration in the caecum and the proportion of propionate were significantly correlated with the same parameters in the faeces. Results of the principal component analysis performed between all the caecal/faecal and colonic/faecal parameters revealed that the total anaerobic and cellulolytic bacteria concentrations, as well as valerate, L-lactate and lipopolysaccharide concentrations were strongly correlated with several microbial parameters in the caecum ( P < 0.027; r > |0.45|) and in the colon ( P < 0.013; r > |0.50|). This demonstrated that faecal samples and their bacterial analyses could be used to represent caecum and RV colon hindgut microbial ecosystem in terms of variations during a change from a high-fibre to a high-starch diet, and thus could be markers of particular interest to diagnostic proximal hindgut microbial disturbances.

“…However, the enzymatic capacity of the small intestine to hydrolyse starch is limited in horses because of low amylase secretion in comparison with other animal species (Alexander and Hickson, 1970;Kienzle, 1994). In this respect, feeding at least 0.35% (Potter et al, 1992), 0.3% (Zeyner, 2008) or even 0.2% (Julliand et al, 2006) BW per meal may lead to a dumping of undigested starch in the hindgut. In this digestive segment, the rapid microbial fermentation of starch produces organic acids, which can lead to a decrease in pH and depress the proportion of cellulolytic bacteria and the cellulolytic activity .…”

Section: Introductionmentioning

confidence: 99%

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

Philippeau

Sadet-Bourgeteau

Varloud³

et al. 2015

Self Cite

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.