Effect of concentrate feeding sequence on equine hindgut fermentation parameters

Feeding a diet with a small amount of hay and a high proportion of concentrate given in large meals entails a risk of colic to horses as this can impact the hindgut microbial ecosystem. To counteract this potential negative effect, one feeding strategy is to modify the distribution sequence of concentrate and hay. The purpose of the present study was to assess the impact of feeding the concentrate meal before or with the hay meal on fermentative parameters postprandial variations in caecum and right ventral colon contents and faeces. We focused on the comparison of pH value and volatile fatty acid (VFA) concentrations between the three compartments. Four horses fitted with two cannulas in the caecum and right ventral colon were fed a 100% hay diet (H) for a 3-week period, and then a 40% concentrate–60% hay diet for two consecutive periods of 3 weeks each. Concentrate and hay were offered simultaneously in two equal meals at 0800 and 1700 h (HC1) during one period, or separately in two equal meals at 0800 and 1600 h for the concentrate and at 1000 and 1730 h for hay (HC2) during the second one. During the 2^nd week of each diet period (H, HC1, HC2), caecal, right ventral colonic and faecal samples were collected before (0) and at 2, 4, 6 and 8 h after the morning meal. pH values and VFA concentrations were measured. Adding concentrate to the hay was associated with a decrease of pH value in the caecum, right ventral colon and faeces and an increase of faecal VFA concentrations (P<0.01). An impact of the concentrate feeding sequence was observed on caecal pH and faecal propionate concentration (P<0.001) but none on the other parameters investigated. In the caecum and right ventral colon, pH values decreased and VFA concentrations increased within the range of 4 to 8 h after the morning meal. Our data suggested that the variation of faecal pH could be an indicator of those of the caecal and right ventral colonic pH with a delay of 2 h. The present study showed that hay and commercial pelleted could be safely distributed simultaneously, thus making easier every day horse feeding.     

Comparison of the bacterial community structure within the equine hindgut and faeces using Automated Ribosomal Intergenic Spacer Analysis (ARISA)

The horse’s hindgut bacterial ecosystem has often been studied using faecal samples. However few studies compared both bacterial ecosystems and the validity of using faecal samples may be questionable. Hence, the present study aimed to compare the structure of the equine bacterial community in the hindgut (caecum, right ventral colon) and faeces using a fingerprint technique known as Automated Ribosomal Intergenic Spacer Analysis (ARISA). Two DNA extraction methods were also assessed. Intestinal contents and faeces were sampled 3 h after the morning meal on four adult fistulated horses fed meadow hay and pelleted concentrate. Irrespective of the intestinal segment, Principal Component Analysis of ARISA profiles showed a strong individual effect (P<0.0001). However, across the study, faecal bacterial community structure significantly (P<0.001) differed from those of the caecum and colon, while there was no difference between the two hindgut communities. The use of a QIAamp® DNA Stool Mini kit increased the quality of DNA extracted irrespective of sample type. The differences observed between faecal and hindgut bacterial communities challenge the use of faeces as a representative for hindgut activity. Further investigations are necessary to compare bacterial activity between the hindgut and faeces in order to understand the validity of using faecal samples.     

Comparative fibre-degrading capacity in foals at immediate and late post-weaning periods

Total tract apparent digestibility of dietary fibrous components and parameters of the faecal digestive ecosystem were compared at immediate and late post-weaning periods using five foals. The foals were abruptly weaned (day 0) from their mares at 6 months of age. Immediately (day 0 to day 14) and later (day 131 to day 194) after weaning, foals received the same basal diet consisting of hay and pellets. Pellets were fed at 0.36% BW. Hay was offered ad libitum and corresponded to 120% of the average voluntary hay intake measured individually during the immediate (days 1 to 4) and late (days 180 to 183) post-weaning periods. Total feed intake was measured during the two post-weaning periods (from days 7 to 10 and from days 187 to 190). Total tract apparent digestibility of DM, organic matter (OM), NDF and ADF was assessed using a 4-day partial collection of faeces (from days 8 to 11 and from days 188 to 191). Major bacterial groups in faeces, Fibrobacter succinogenes, DM, pH and volatile fatty acids were quantified at days −1, 1, 3, 7, 14 and 180. During the post-weaning period, minor changes were observed in the composition and activity of the faecal microbiota. The amylolytic count in faeces decreased immediately after weaning (between days 1 and 7) (P<0.05). Later (from days 14 to 180), the molar proportion of propionate decreased (P=0.03). The limited alteration seen in the hindgut ecosystem was probably due to the fact that the foals had undergone a gradual dietary transition from milk to solid feed before weaning. Such conclusions have also been reported in other animal species. Between the immediate and late post-weaning periods, the average daily feed intake and the digestibility coefficients of DM, OM, NDF and ADF increased (P<0.05). These results could suggest an increase in the fibre-degrading capacity of foals after weaning.     

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

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.     

Digestive physiology of wild capybara

The capybara (Hydrochaeris hydrochaeris) is a hindgut fermenter whose digestive efficiency is comparable to that of ruminants on similar diets. It is an interesting case for study because it is the largest caecum fermenter and uses coprophagy as part of its digestive strategy. It practices coprophagy in the early morning and forages and defaecates in the evening. Its anatomy is well known but the limited information available about its digestive physiology has been obtained from captive animals. In this work we studied the capybara's digestive physiology, using microbial and chemical information from samples taken from wild capybaras in the early wet season in the morning (0600–0700 hours), noon (1200–1300 hours) and evening (1800–1900 hours), key points in the digestive cycle. Bacteria (cellulolytic and non-cellulolytic) and protozoa were present in high concentrations in the caecum and colon. There were no significant differences in nitrogen concentrations between digestive tract compartments in the coprophagy period (0600 hours), but in the other two periods nitrogen concentrations were significantly higher in the caecum than in the stomach and colon. This is suggestive of selective retention of microbial cells with fluid digesta in the caecum and of cecotrophy (the production of two distinctly different kinds of faeces — one kind called cecotrophes formed from caecal contents and ingested). The capybara hindgut (caecum and colon) with its content, was heavier during the dry season (period of poor diet quality) than in the wet season, but there were no significant seasonal differences between the stomach or small intestine and their contents. This suggests changes in the capacity of the hindgut, the site of microbial fermentation, related to seasonal variation in resource quality.Abbreviations NDF neutral-detergent fibre - SCFA Short-chain fatty acid(s)     

Influence of condensed tannins from Brazilian semi-arid legumes on ruminal degradability,microbial colonization and ruminal enzymatic activity in Saanen goats

The present study aimed at determining the influence of condensed tannins present in the Brazilian legume species Mimosa hostilis, Mimosa caesalpinifolia and Bauhinia cheilantha on ruminal degradability, microbial colonization and enzymatic activity. Polyethylene glycol (PEG) was used to reduce the astringency and concentration of soluble condensed tannins. Four ruminally-cannulated Saanen goats (60 ± 8 kg BW) were fed, in two experimental periods, with a hay diet based on the studied legumes treated or non-treated with PEG. Voluntary intake, microbial colonization, DM, CP, NDF, and ruminal degradability of PEG treated and non-treated forage leaves, as well as pH, ammonia and 1,4 β-endoglucanase activity of the rumen content were evaluated. Astringency and soluble tannin concentration of the studied legumes were reduced by approximately 70% and 50%, respectively, with PEG treatment. Average DM intake was higher for the treated diet (16.76 g DM/kg BW/day against 13.06 g DM/kg BW/day). Percentile values for degradation parameters and for potential and effective degradabilities of DM, CP and NDF were also affected by the tannins, but at different intensities. Electron microscopic observations of ruminally-incubated legume leaves showed a more effective microbial colonization of PEG-treated leaves for all legume species. A decrease in pH and an increase in ammonia concentration and in endoglucanase activity in the ruminal content was also observed for PEG-treated diets at all sampling periods. Condensed tannins of the studied legume species have influenced the adhesion conditions, colonization and enzymatic activity of the microbial ecosystem, and consequently the ruminal degradation of the different dietary fractions. For this reason, the reduction in condensed tannin would be of great importance to improve the nutrition of ruminant feeding of these species.     

The effect of dietary carbohydrate composition on apparent total tract digestibility,feed mean retention time,nitrogen and water balance in horses

A total of four diets with different carbohydrate composition were investigated in a 4×4 Latin square design experiment with four Norwegian Coldblooded trotter horses. The objective of the present study was to increase the fermentable fibre content and reduce the starch intake of the total ration obtained by partly substituting mature hay and barley with sugar beet pulp (SBP), a soluble fibre source. The diets investigated were hay only (HAY), hay (85% of dry matter intake (DMI)) and molassed SBP (15% of DMI) (SBP), hay (68% of DMI) and barley (32% of DMI) (BAR), and hay (68% of DMI), barley (26% of DMI) and SBP (6% of DMI) (BAR+SBP). The feeding level was 18.5, 17.3, 15.7 and 15.7 g DM/kg BW per day for the HAY, SBP, BAR and BAR+SBP diets, respectively. Each diet was fed for 18 days followed by 10 days of data collection, where apparent total tract digestibility (ATTD), total mean retention time (TMRT) of ytterbium-labelled hay, water balance, digestible energy (DE) intake and nitrogen balance were measured. An enzymatic chemical dietary fibre (DF) method was used to get detailed information on the composition and ATTD of the fibre fraction. Inclusion of SBP in the diet increased the ATTD of the constituent sugars galactose and arabinose (P<0.01). Feeding the HAY and SBP diets resulted in a lower TMRT owing to a higher DF intake than the BAR and BAR+SBP diets (P<0.01). There was no difference in water intake between HAY and SBP, but faecal dry matter was lower for HAY than the other diets (P=0.017), indicating that water was more tightly bound to fibre in the HAY diet. The diets were iso-energetic and provided enough DE and protein for light to moderate exercise for a 550 kg horse. In conclusion, this study showed that the DF intake had a larger effect on TMRT than partly substituting hay or barley with SBP, and that highly fermentable pectin-rich soluble DF from SBP maintains high nutrient utilization in horses.     

Does adding water to a dry starter diet improve calf performance during winter?

Very recently, we added water to a dry texturized starter diet and found substantial improvements in calf performance during summer, leading to the hypothesis that the wet starter diet would also benefit calf performance during winter. Forty-five 3-day-old male Holstein calves (BW 43.4±3.4 kg) were blocked by initial BW and distributed randomly to one of three starter diets (1 calf per pen; 15 pens per treatment) that differed only in moisture content as 90%, 75% and 50% dry matter (DM; DM90, DM75 and DM50, respectively). The starter diet comprised 55.1% ground ingredients (soybean meal, barley and corn gluten meal), 21.9% whole corn, 10% rolled barley and 10% chopped alfalfa hay. The mean ambient temperature averaged 2.1±0.9°C during the 70-day experiment. Calves were weaned at day 50 of the study. Although starter feed intake remained unaffected by treatment, the calves receiving DM75 and DM50 consumed more starter feed (DM basis) than those receiving DM90 diet during the first 20 days of the experiment. Body weight at weaning exhibited a quadratic response with the heaviest weaning weight (76.8 kg) occurring when calves consumed DM75 diet. Adding water to the dry starter diet tended to linearly increase final BW. Average daily gain during the pre- (0.67 kg/day) and post-weaning (1.22 kg/day) periods was the greatest for calves receiving DM75 and DM50, respectively. Although feed efficiency during the pre-weaning and overall periods did not differ across the treatments, a quadratic effect was detected in the post-weaning feed efficiency, with the lowest value being observed with DM75 diet. No difference was noted on skeletal growth parameters measured on days 50 and 70. Adding water to the dry starter diet linearly increased total volatile fatty acids concentration in the rumen. No difference among treatments existed in calf behavior recorded on days 35 and 70. As moisture content of the starter diet increased, the extent of sorting for long particles (>2 mm) and against fine particles (<0.125 mm) decreased. During the 70-day winter trial, adding water to the dry texturized starter diet with 10% chopped alfalfa hay resulted in a higher feed intake during the first weeks of life, a quadratic tendency toward improved growth rate during the pre-weaning period, and possibly a more functional rumen fermentation. A wet starter diet with 75% DM in the physical form offered in this study can be recommended to improve calf performance during winter.     

Variation in faecal digestibility values related to feed efficiency traits of grower-finisher pigs

Providing pigs a diet that matches their nutrient requirements involves optimizing the diet based on the nutrient digestibility values of the considered feed ingredients. Feeding the same quantity of a diet to pigs with similar BW but with different requirements, however, can result in a different average daily gain (ADG) and backfat thickness (BF) between pigs. Digestibility may contribute to this variation in efficiency. We investigated variation in feed efficiency traits in grower-finisher pigs associated with variation in faecal digestibility values, independent of feed intake at the time of measuring faecal digestibility. Considered traits were ADG, average daily feed intake (ADFI), feed conversion ratio (FCR), BF and residual feed intake (RFI). Feed intake, BW, and BF data of one hundred and sixty three-way crossbreed grower-finisher pigs (eighty female and eighty male) were collected during two phases, from day 0 of the experiment (mean BW 23 kg) till day 56 (mean BW 70 kg) and from day 56 to slaughter (mean BW 121 kg). Pigs were either fed a diet based on corn/soybean meal or a more fibrous diet based on wheat/barley/by-products, with titanium dioxide as indigestible marker. Faecal samples of one hundred and five pigs were collected on the day before slaughter and used to determine apparent faecal digestibility of DM, ash, organic matter (OM), CP, crude fat (CFat), crude fibre (CF), and to calculate the digestibility of nonstarch polysaccharides (NSPs) and energy (E). The effects of diet, sex and covariate feed intake at sampling (FIs) on faecal digestibility values were estimated and were significant for all except for CFat. Faecal digestibility values of each individual pig determined at the day before slaughter, corrected for diet, sex and FIs, were used to estimate their association with ADG, ADFI, FCR, BF, and RFI. In the first phase, a one percent unit increase in faecal digestibility of DM, ash, OM, E, CP, CFat, CF, NSP, and Ash individually was related to 0.01–0.03 unit reduction in FCR and 6–23 g/day reduction in RFI. A unit increase in CP digestibility was related to 0.1 mm increase in BF and 10 g/day increase in ADG. In the second phase, a one percent unit increase in faecal digestibility of DM, CP and Ash was related to a decrease of 16–20 g/day in RFI. In conclusion, the relationship between variation in feed efficiency traits and faecal digestibility values is different across the developmental stages of a pig.     

Feeding grape seed extract to horses: effects on health, intake and digestion

A feeding trial involving four Thoroughbred race horses was undertaken to establish whether inclusion of grape seed extract (GSE) in the diet of horses undergoing mild exercise had any effects on their general health, intake and digestion. Supplementation with GSE had no effect on either feed or water intake of the horses and the supplement was readily palatable to the horses at all levels of inclusion. Feeding GSE caused no adverse effects in terms of animal health (temperature, pulse and respirations rates), and there were some positive effects related to a presumed alteration in fermentation in the hindgut. Feeding GSE increased faecal pH, changing from acid faeces (pH 6.6) when no GSE was fed to neutral faeces (pH 7.0) when 150 mg GSE/kg body weight (BW) was fed. In addition, blood glucose concentrations were significantly (P < 0.05) decreased when GSE was fed at 100 and 150 mg/kg BW (5.50 ± 0.26 and 5.32 ± 0.72 mmol/l, respectively) compared with the control diet (5.77 ± 0.31 mmol/l). The actual mechanisms causing these alterations are yet to be elucidated, but could have important implications for the prevention of acidosis.     

Effects of extrusion of corn on growth performance, nutrient digestibility and short-chain fatty acid profiles in the hindgut of weaned piglets

The experiment was conducted to investigate the effects of different inclusion levels of extruded corn on growth performance, nutrient digestibility and short-chain fatty acids profiles in the hindgut of weaned piglets. Ninety weaning piglets (28 d of age; 8.21 +/- 0.69 kg BW) were allotted to one of five dietary treatments only substituted for unprocessed corn at varying levels (0, 1/4, 2/4, 3/4, 4/4) with extruded corn in a 28-d experiment. On day 28, 30 piglets were killed to measure concentrations and molar ratios of short-chain fatty acids in the hindgut. From day 0-14, digestibility of DM, N and GE was increased linearly and diarrhea frequency was decreased due to the increasing inclusion levels of extruded corn. From day 14-28, digestibility of GE and N was enhanced linearly due to the increasing proportion of extruded corn. On day 28, as proportion of extruded corn increased, the level of butyrate in the caecum and colon was increased linearly and the relative proportion of propionate was reduced. Results indicated that increasing proportions of extruded corn had no effect on growth performance, but significantly improved digestibility of N and energy at day 10 of trial and may be advantageous to the intestinal health of piglets.     

Feeding Jerusalem artichoke reduced skatole level and changed intestinal microbiota in the gut of entire male pigs

Different levels of dried Jerusalem artichoke were fed to entire male pigs 1 week before slaughter. The objective was to investigate the effect on skatole level in the hindgut and in adipose tissue, as well as the effect on microflora and short-chain fatty acids (SCFA) in the hindgut. Five experimental groups (n = 11) were given different dietary treatments 7 days before slaughtering: negative control (basal diet), positive control (basal diet + 9% chicory-inulin), basal diet + 4.1% Jerusalem artichoke, basal diet + 8.1% Jerusalem artichoke and basal diet + 12.2% Jerusalem artichoke. Samples from colon, rectum, faeces and adipose tissue were collected. Effect of dietary treatment on skatole, indole and androstenone levels in adipose tissue and on skatole, indole, pH, dry matter (DM), microbiota and SCFA in the hindgut was evaluated. Feeding increasing levels of Jerusalem artichoke to entire male pigs reduced skatole in digesta from colon and in faeces (linear, P < 0.01). There was also a tendency towards a decreased level of skatole in adipose tissue (linear, P = 0.06). Feeding Jerusalem artichoke decreased DM content in colon and faeces and pH in colon (linear, P < 0.01). Increasing levels of Jerusalem artichoke resulted in a reduced level of Clostridium perfringens in both colon and rectum (linear, P < 0.05) and a tendency towards decreased levels of enterobacteria in colon (linear, P = 0.05). Further, there was an increase in total amount of SCFA (linear, P < 0.05), acetic acid (linear, P < 0.05) and valerianic acid (linear, P < 0.01) in faeces. In conclusion, adding dried Jerusalem artichoke to diets for entire male pigs 1 week before slaughter resulted in a dose-dependent decrease in skatole levels in the hindgut and adipose tissue. The reduced skatole levels might be related to the decrease in C. perfringens and the increase in SCFA with subsequent reduction in pH.     

Evaluation of titanium dioxide and chromic oxide as digestibility markers in ponies fed alfalfa hay in relation to marker dosing frequency

In equines, Cr₂O₃ is widely accepted as an indigestible marker, but there are health concerns regarding the carcinogenic properties of Cr₂O₃. Recently, TiO₂ has been suggested to be an alternative digestibility marker in equines. However, a comparison between Cr₂O₃ and TiO₂ has not been made in equines. Six Welsh pony geldings (initial BW: 254±3 kg; 7 years of age) fed chopped alfalfa hay were used to evaluate the use of TiO₂ (Ti) and Cr₂O₃ (Cr) as markers for calculating apparent digestibility and to investigate the effect of frequency of marker administration on the measurement of digestibility values. Diets contained 4.65 kg dry matter (DM) chopped alfalfa hay supplemented with minerals, vitamins, TiO₂ (3.3 g Ti/day) and Cr₂O₃ (3.2 g Cr/day). Ponies were dosed with either 3.3 g Ti and 3.2 g Cr once daily (DF1) or with 1.65 g Ti and 1.60 g Cr twice daily (DF2). After adaptation to the diets and procedures for 14 days, voluntary voided faeces were collected quantitatively over 7 days and analysed for moisture, ash, Ti and Cr. Apparent total tract DM digestibility (DMD) and organic matter digestibility (OMD) were calculated using the total faecal collection (TFC) and marker method (Ti and Cr). The overall mean cumulative faecal recovery of Cr and Ti (as % of intake) were 102.0% and 96.6%, respectively. Mean daily faecal recoveries of Cr as well as of Ti were not different (P=0.323; P=0.808, respectively) between treatments. Overall daily faecal recovery of Cr differed (P=0.019) from 100% when the marker was dosed once daily, whereas overall daily faecal recovery was similar to 100% for both administration frequencies when Ti was used as a marker. For both markers, the coefficient of variation of the mean faecal marker recovery between horses was lower when the markers were administrated twice per day. Across treatments, cumulative DMD and OMD estimated with Ti were similar (P=0.345; P=0.418, respectively) compared with those values determined by TFC method. When Cr was used, the calculated cumulative DMD tended (P=0.097) to be greater compared with those estimated with TFC, and cumulative OMD values were overestimated (P=0.013). Orally supplemented Ti recovery in the faeces of ponies fed chopped alfalfa hay with Ti administered once or twice daily was close to 100%, making it the preferred marker for digestibility trials in equines.     

Effects of extrusion of corn on growth performance,nutrient digestibility and short-chain fatty acid profiles in the hindgut of weaned piglets

Abstract

The experiment was conducted to investigate the effects of different inclusion levels of extruded corn on growth performance, nutrient digestibility and short-chain fatty acids profiles in the hindgut of weaned piglets. Ninety weaning piglets (28 d of age; 8.21 ± 0.69 kg BW) were allotted to one of five dietary treatments only substituted for unprocessed corn at varying levels (0, 1/4, 2/4, 3/4, 4/4) with extruded corn in a 28-d experiment. On day 28, 30 piglets were killed to measure concentrations and molar ratios of short-chain fatty acids in the hindgut. From day 0 – 14, digestibility of DM, N and GE was increased linearly and diarrhea frequency was decreased due to the increasing inclusion levels of extruded corn. From day 14 – 28, digestibility of GE and N was enhanced linearly due to the increasing proportion of extruded corn. On day 28, as proportion of extruded corn increased, the level of butyrate in the caecum and colon was increased linearly and the relative proportion of propionate was reduced. Results indicated that increasing proportions of extruded corn had no effect on growth performance, but significantly improved digestibility of N and energy at day 10 of trial and may be advantageous to the intestinal health of piglets.     

Application of long-chain alcohols as faecal markers to estimate diet composition of horses and cattle fed with herbaceous and woody species

Utilization of long-chain alcohols (LCOH) as diet composition markers in horses and cattle was assessed in a study conducted with 12 mature crossbreed mares (385±47 kg BW) and six adult non-lactating cows (499±36 kg BW) of Asturiana de los Valles breed. The LCOH data were combined with alkane and long-chain fatty acid (LCFA) data to test the applicability of combining these markers to estimate diet composition. Animals were randomly divided into groups of three animals and received a daily total amount of 1.0 kg dry matter/100 kg BW of diets composed of different proportions of ryegrass (Lolium perenne) and woody species (Ulex gallii and heather). Diet composition was estimated from even-chain LCOH (C₂₀-OH to C₃₀-OH) combined or not with alkane (C₂₅-C₃₁ and C₃₃) and/or LCFA (C₂₂-FA to C₂₈-FA, C₃₀-FA, C₃₂-FA and C₃₄-FA) concentrations in diet components and faeces by least-squares procedures, using marker faecal concentrations uncorrected for incomplete faecal recovery (FR0) or corrected using mean recoveries across diets within animal species (FR1). Results showed large differences between plant species in their LCOH profiles, and that these markers offered additional discriminatory information to that provided by alkanes and LCFA. The LCOH markers were incompletely recovered in the faeces of both animal species. In cattle, LCOH FR tended to increase with carbon-chain length in a linear manner in both diets (P<0.001), whereas in horses overall data showed a curvilinear relationship between these variables. Combination of LCOH, LCFA and alkanes resulted in more accurate diet estimates. Correction of faecal LCOH concentrations to incomplete FR led to more accurate diet composition estimates in both animal species. Results obtained in this study suggest the usefulness of LCOH markers combined with alkanes and LCFA to estimate diet composition of horses and cattle grazing mixed grassy–woody plant communities.     

Influence of barley grain particle size and treatment with citric acid on digestibility,ruminal fermentation and microbial protein synthesis in Holstein calves

Chemical and physical treatments of barley grain increase ruminally resistant starch and can improve the rumen fermentation pattern. The objective of the present study was to evaluate the effects of chemical (addition of citric acid, CA) and physical (grinding to two different particle sizes, PS) treatment of barley grain on performance, rumen fermentation, microbial protein yield in the rumen and selected blood metabolites in growing calves. In all, 28 male Holstein calves (172±5.1 kg initial BW) were used in a complete randomised design with a factorial arrangement of 2 barley grain particle sizes×2 levels of citric acid. The diets were as follows: (i) small PS (average 1200 µm) barley grain soaked in water (no CA addition); (ii) small PS barley grain soaked in a CA solution (adding 20 g CA/kg barley); (iii) large PS (average 2400 µm) barley grain soaked in water (no citric acid addition) and (iv) large PS barley grain soaked in a citric acid solution (adding 20 g CA/kg barley). Barley grain was then incorporated at 35% in a total mixed ration and fed to the calves for 11 weeks. Feeding small PS barley decreased feed intake (P=0.02) and average daily weight gain (P=0.01). The addition of CA to barley grain did not affect intake but increased weight gain (P<0.01) and improved feed to gain ratio (P=0.03). Digestibility of organic matter and NDF tended (P<0.10) to increase, whereas faecal scoring was improved (P=0.03) and the presence of undigested grain particles in faeces was reduced (P<0.01) with CA-treated barley grain. Glucose and urea concentrations were increased (P<0.01) in the blood of calves fed the CA-treated barley grain. Ruminal pH tended (P=0.08) to be decreased with more finely ground barley and was increased when barley grain was treated with CA. Total volatile fatty acid concentrations in the rumen did not differ among treatments (P>0.05). However, the molar proportion of propionate was increased (P=0.03) when barley was more finely ground, and that of acetate was increased (P=0.04) when CA was added to barley grain. The ruminal concentration of ammonia nitrogen was increased (P<0.01) and microbial nitrogen synthesis in the rumen tended to decrease by adding CA to barley. Treating barley grain with citric acid increased fibre digestibility of total mixed rations, attenuated the decrease in ruminal pH, and improved weight gain and feed efficiency in male Holstein growing calves fed a high-cereal diet (550 g cereal grain/kg diet).     

Diet choice by goats as effect of milk production level during late lactation

The diet self-regulation ability of goats during late lactation has been studied with regard to their production level. Two groups of seven Girgentana goats producing 1100 ± 157 g/day (H group) and 613 ± 138 g/day (L group) were housed in individual pens and were given alfalfa pelleted hay (1.5 kg), whole grains of maize (0.5 kg), barley (0.5 kg), faba bean (0.5 kg) and pelleted sunflower cake (0.5 kg) on a daily basis. During a 7-day pre-experimental period, goats received a mixed ration based on the same feeds used during the experimental period (1.5 kg of hay and 0.4 kg of each concentrate). Individual choice of feeds was continuously recorded for 7 days using a 24-h IR video surveillance system equipped with four video cameras. The nutrient intake in both groups was much higher than needed. Goats in the H group ate more (2016.3 v. 1744.3 g dry matter (DM)/day) and selected less hay (26.9% v. 34.6% DM), more high-protein feeds (faba bean and sunflower cake: 14.0% and 15.9% v. 8.8% and 7.9% DM, respectively) and less maize (21.5% v. 25.0% DM), reaching a higher CP concentration in the diet (17.3% v. 15.0% DM) compared with the goats in the L group. During the 24-h trial period, hay was more constantly selected (on average never reaching <20% of the total hourly basis feeding time, apart from the first hour after feed administration) compared with concentrate feeds. This feeding behaviour has probably exercised a ‘curative’ effect that enabled the goats to continue to take in very high levels of starch and protein, without manifesting any symptom of metabolic disease. Shifting goats from the pre-experimental diet, based on a mixture of the same feeds used during the experimental period, to the free-choice feeding caused more than 20% increase in milk production in both groups. From the results of the intake, we are unable to conclude that the goats can select their diet to meet their requirements, as goats consumed much more than needed. However, when free to choose their diet, the animals improved milk performance, despite the late-lactation stage.     

Prawn Shell Chitosan Has Anti-Obesogenic Properties,Influencing Both Nutrient Digestibility and Microbial Populations in a Pig Model

The potential of natural products to prevent obesity have been investigated, with evidence to suggest that chitosan has anti-obesity effects. The current experiment investigated the anti-obesity potential of prawn shell derived chitosan on a range of variables relevant to obesity in a pig model. The two dietary treatment groups included in this 63 day study were: T1) basal diet and T2) basal diet plus 1000 ppm chitosan (n = 20 gilts per group (70 ± 0.90 kg). The parameter categories which were assessed included: performance, nutrient digestibility, serum leptin concentrations, nutrient transporter and digestive enzyme gene expression and gut microbial populations. Pigs offered chitosan had reduced feed intake and final body weight (P< 0.001), lower ileal digestibility of dry matter (DM), gross energy (GE) (P< 0.05) and reduced coefficient of apparent total tract digestibility (CATTD) of gross energy and nitrogen (P<0.05) when compared to the basal group. Fatty acid binding protein 2 (FABP2) gene expression was down-regulated in pigs offered chitosan (P = 0.05) relative to the basal diet. Serum leptin concentrations increased (P< 0.05) in animals offered the chitosan diet compared to pigs offered the basal diet. Fatness traits, back-fat depth (mm), fat content (kg), were significantly reduced while lean meat (%) was increased (P<0.05) in chitosan supplemented pigs. Pigs offered chitosan had decreased numbers of Firmicutes in the colon (P <0.05), and Lactobacillus spp. in both the caecum (P <0.05) and colon (P <0.001). Bifidobacteria populations were increased in the caecum of animals offered the chitosan diet (P <0.05). In conclusion, these findings suggest that prawn shell chitosan has potent anti-obesity/body weight control effects which are mediated through multiple biological systems in vivo.     

Factors affecting degradation of barley straw in sacco and microbial activity in the rumen of cows fed fibre-rich diets: III. The amount of supplemental energy

A basic diet composed of 76.2% untreated barley straw +23.8% grass hay was given to three non-lactating cows at 90% of ad libitum intake; the diet was supplemented with fishmeal to make the ration up to 12% protein on dry matter basis, a mineral–vitamin mixture and either 1.5 kg; 3.0 kg or 4.5 kg of rolled barley/cow×day in a Latin Square design. The inclusion of rolled barley affected the degradability of DM, OM and individual components of the cell wall of barley straw incubated in nylon bags for up to 72 h. The higher the energy level of supplementation, the lower the digestion of the cell wall components. The amount of starch influenced rumen pH, ammonia and VFAs concentrations, ATP and protozoal numbers, but no treatment effect could be detected upon the outflow rate of liquid or particulate phases. The ATP and DNA concentrations found inside the nylon bags suggest the presence of an inactive or less active population towards the substrate after 24 h of incubation.     

Measuring the gut microbiome in birds: Comparison of faecal and cloacal sampling

The gut microbiomes of birds and other animals are increasingly being studied in ecological and evolutionary contexts. Numerous studies on birds and reptiles have made inferences about gut microbiota using cloacal sampling; however, it is not known whether the bacterial community of the cloaca provides an accurate representation of the gut microbiome. We examined the accuracy with which cloacal swabs and faecal samples measure the microbiota in three different parts of the gastrointestinal tract (ileum, caecum, and colon) using a case study on juvenile ostriches, Struthio camelus, and high‐throughput 16S rRNA sequencing. We found that faeces were significantly better than cloacal swabs in representing the bacterial community of the colon. Cloacal samples had a higher abundance of Gammaproteobacteria and fewer Clostridia relative to the gut and faecal samples. However, both faecal and cloacal samples were poor representatives of the microbial communities in the caecum and ileum. Furthermore, the accuracy of each sampling method in measuring the abundance of different bacterial taxa was highly variable: Bacteroidetes was the most highly correlated phylum between all three gut sections and both methods, whereas Actinobacteria, for example, was only strongly correlated between faecal and colon samples. Based on our results, we recommend sampling faeces, whenever possible, as this sample type provides the most accurate assessment of the colon microbiome. The fact that neither sampling technique accurately portrayed the bacterial community of the ileum nor the caecum illustrates the difficulty in noninvasively monitoring gut bacteria located further up in the gastrointestinal tract. These results have important implications for the interpretation of avian gut microbiome studies.