Effect of different types of fibre supplemented with sunflower oil on ruminal fermentation and production of conjugated linoleic acids in vitro

Abstract

An in vitro study was conducted to determine the effect of different types of fibre supplemented with sunflower oil on ruminal fermentation and formation of conjugated linoleic acids (CLA) by mixed ruminal microorganisms. Cell wall components extracted from wheat straw (representing lignified fibre), soybean hulls (representing easily digestible fibre), and purified cellulose were used as substrates. Sunflower oil was supplemented at the same level for all three types of fibre. After 24 h of incubation, ruminal fermentation parameters (including 24 h gas production, pH value, concentration of ammonia nitrogen and volatile fatty acids) and the concentration of long chain fatty acids in the culture fluid were determined. Results showed that the type of fibre influenced ruminal fermentation traits and the biohydrogenation of unsaturated C18 fatty acids in vitro. Composition of LCFA and profile of CLA were altered by the fibre type. Compared to the digestible fibre and purified cellulose, lignified fibre significantly increased the production of cis-9, trans-11 CLA and total CLA (sum of cis-9, trans-11 CLA, trans-10, cis-12 CLA, trans-9, trans-11 CLA, and cis-9, cis-11 CLA) by ruminal microorganisms. It was concluded that ruminal fermentation and production of CLA can be affected by the type of dietary fibre.     

Digestive tract morphology and digestion in the wombats (Marsupialia: Vombatidae)

Summary Wombats consume grasses and sedges which are often highly fibrous. The morphology of the digestive tract and the sequence of digestion were studied in two species of wombats from contrasting habitats: Vombatus ursinus from mesic habitats and Lasiorhinus latifrons from xeric regions. Studies were performed on wild wombats consuming their natural winter diets, and on captive wombats fed a high-fibre pelleted straw diet. Vombatus had a shorter digestive tract (9.2 vs 12.5 times body length) of greater capacity (wet contents 17.9 vs 13.7% body weight) than Lasiorhinus. The most capacious region of the digestive tract was the proximal colon (62–79% of contents). The proportional length and surface area of the proximal colon were greater in Vombatus, but those of the distal colon were greater in Lasiorhinus. These digestive morphologies may reflect adaptations for greater capacity and longer retention of digesta in Vombatus, but greater absorption and lower faecal water loss in Lasiorhinus. Apparent digestion along the digestive tract was estimated by reference to lignin. The proximal colon was the principal site of fibre and dry matter digestion, whereas nitrogen was mainly digested in the small intestine. Depot fats in captive wombats were highly unsaturated and reflected those in the diet. Therefore, lipids, proteins and soluble carbohydrates in the plant cell contents were digested and absorbed in the stomach and small intestine. Conversely, dietary fibre was probably retained and digested by microbial fermentation along the proximal colon.Abbreviations ADF acid detergent fibre - DM dry matter - NDF neutral detergent fibre - SD standard deviation     

Digesta passage and functional anatomy of the digestive tract in the desert tortoise (Xerobates agassizii)

The herbivorous tortoise Xerobates agassizii contents with large fluctuations in the quality and abundance of desert pastures. Responses to grass (Schismus barbatus), herbage (Sphaeralcea ambigua) and pelleted diets were studied in captive animals. Digestive anatomy was investigated in wild tortoises. Cornified esophageal epithelia and numerous mucus glands along the digestive tract indicated a resistance to abrasive diets. Gastric contents were acidic whereas hindgut digesta were near neutral pH. The colon was the primary site of fermentation with short-chain fatty acids mainly comprised of acetate (69–84%), propionate (10–15%) and n-butyrate (1–12%). Fibre digestion was extensive and equivalent to 22–64% of digestible energy intakes. Large particles of grass (25 mm Crmordants) were excreted as a pulse but retained longer than either fluids (Co-EDTA) or fine particles (2 mm; Yb). Patterns of marker excretion suggested irregular mixing of only the fluid and fine particulate digesta in the stomach and the colon. Mean retention times of Crmordants were 14.2–14.8 days on the grass and highfibre pellets. Intakes of grass were low and accompanied by smaller estimates of digesta fill than for the high-fibre pellets. Digestive capacity was large and estimated at 11–21% of body mass on these diets. The capacious but simple digestive anatomy of the tortoise may provide the greatest flexibility in utilizing a variety of forages in its unreliable habitat.Abbreviations bm body mass - DM drymatter - EDTA ethylene-diamine tetra-acetic acid - MRT mean retention time - NDF neutral detergent fibre - SCFA short-chain fatty acid(s) - T _max time to maximum marker concentration     

Effect of different types of fibre supplemented with sunflower oil on ruminal fermentation and production of conjugated linoleic acids in vitro

An in vitro study was conducted to determine the effect of different types of fibre supplemented with sunflower oil on ruminal fermentation and formation of conjugated linoleic acids (CLA) by mixed ruminal microorganisms. Cell wall components extracted from wheat straw (representing lignified fibre), soybean hulls (representing easily digestible fibre), and purified cellulose were used as substrates. Sunflower oil was supplemented at the same level for all three types of fibre. After 24 h of incubation, ruminal fermentation parameters (including 24 h gas production, pH value, concentration of ammonia nitrogen and volatile fatty acids) and the concentration of long chain fatty acids in the culture fluid were determined. Results showed that the type of fibre influenced ruminal fermentation traits and the biohydrogenation of unsaturated C18 fatty acids in vitro. Composition of LCFA and profile of CLA were altered by the fibre type. Compared to the digestible fibre and purified cellulose, lignified fibre significantly increased the production of cis-9, trans-11 CLA and total CLA (sum of cis-9, trans-11 CLA, trans-10, cis-12 CLA, trans-9, trans-11 CLA, and cis-9, cis-11 CLA) by ruminal microorganisms. It was concluded that ruminal fermentation and production of CLA can be affected by the type of dietary fibre.     

Diet selection and digestion in Iguana iguana: the importance of age and nutrient requirements

Summary The green iguana, Iguana iguana, is herbivorous throughout life, and depends on a microbial fermentation system in the hindgut to degrade plant fiber. Because the metabolic rates of lizards are proportional to body mass raised to the 0.80 power, hatchling iguanas have 2X, and juveniles 1.4X, greater relative energy requirements (kJxg body mass^-1xday^-1) than full-grown adults. Growing animals also need a higher protein intake, for contruction of body tissues, than do mature animals. This study investigated how growing iguanas achieve a relatively greater nutrient intake than adults. Hatchling and juvenile iguanas do not have higher relative capacities of the digestive tract than mature iguanas, nor do they digest plant materials more effectively. Instead, growing iguanas select diets higher in digestible protein, and digest the same food 1.3X to 2X more rapidly, than adults. Young iguanas may accomplish their shorter food transit times by maintaining higher body temperatures.     

Effects of fibre-degrading enzymes in combination with different fibre sources on ileal and total tract nutrient digestibility and fermentation products in pigs

ABSTRACT

The study was conducted to determine effects of a complex of fibre-degrading enzymes (xylanase, cellulase and β-glucanase) on nutrient digestibility, fibre fermentation and concentrations of short chain fatty acids (SCFA) at different parts of digestive tract in pigs fed different fibre-rich ingredients. A total of 36 barrows fitted with T-cannulas in the distal ileum (initial body weight of 41.1 ± 2.7 kg) were randomly allotted to six dietary treatments with three different high-fibre diets including maize bran (MB), sugar beet pulp (SBP) and soybean hulls (SH) with or without supplementation of fibre-degrading enzymes. Enzyme supplementation improved (p < 0.05) apparent ileal digestibility (AID) of dietary gross energy (GE), crude protein, dry matter (DM), organic matter (OM), total dietary fibre (TDF), neutral detergent fibre (NDF) and apparent total tract digestibility (ATTD) of dietary GE, DM, OM, TDF, insoluble dietary fibre (IDF) when pigs were fed MB, SBP or SH diets. When compared to the SBP and SH diets, the AID of GE, DM, ash, OM and NDF in diet MB was higher (p < 0.05), but the hindgut disappearance and ATTD of nutrients, except for ether extract and crude ash, were lower (p < 0.05). Enzyme supplementation increased acetate and total SCFA concentrations in ileal digesta and faeces of pigs. In conclusion, enzyme addition improved IDF fermentation and SCFA concentration in the whole intestine of pigs, and there was a large variation of digestibility of fibre components among MB, SH and SBP owing to their different fibre composition. Therefore, fibre-degrading enzymes should be applied to fibrous diets to improve efficient production of swine, especially considering low fibre digestibility of fibre-rich ingredients.     

Digestion and metabolism of high-tanninEucalyptus foliage by the brushtail possum (Trichosurus vulpecula) (Marsupialia: Phalangeridae)

Summary The digestion and metabolism ofEucalyptus melliodora foliage was studied in captive brushtail possums (Trichosurus vulpecula). The foliage was low in nitrogen and silica but high in lignified fibre and phenolics compared with diets consumed by most other herbivores. The high lignin content was suggested as the main cause of the low digestibility ofE. melliodora cell walls (24%); microscopic observations of plant fragments in the caecum and faeces revealed few bacteria attached to lignified tissues. The conversion of digestible energy (0.34 MJ·kg^–0.75·d^–1) to metabolizable energy (0.26 MJ·kg^–0.75·d^–1) was low compared to most other herbivores, probably because of excretion of metabolites of leaf essential oils and phenolics in the urine. When the inhibitory effect of leaf tannins on fibre digestion was blocked by supplementing the animals with polyethylene glycol (PEG), intake of dry matter, metabolizable energy and digestible fibre increased. These effects were attributed to the reversal by PEG of tanninmicrobial enzyme complexes. It was concluded that the gut-filling effect of a bulk of indigestible fibre is a major reason why the brushtail possum does not feed exclusively onEucalyptus foliage in the wild.Abbreviations ADF acid-detergent fibre - AL acid-lignin - DE digestible energy - DM dry matter - ME metabolizable energy - NDF neutral-detergent fibre - PEG polyethylene glycol     

Effect of two levels of transgalactosylated oligosaccharide intake in rats associated with human faecal microflora on bacterial glycolytic activity, end-products of fermentation and bacterial steroid transformation

The effects of two levels of transgalactosylated oligosaccharide (TOS) intake on bacterial glycolytic activity, end products of fermentation and bacterial steroid transformation were studied in rats associated with a human faecal flora. Rats were fed a human-type diet containing 0, 5 or 10% TOS. Caecal pH decrease correlated with the amount of TOS in the diet. Intake of the TOS diet induced a decrease in blood cholesterol and a strong increase in β-galactosidase activity in the hindgut. TOS fermentation led to production of hydrogen and short chain fatty acids, whereas ammonia and branched-chain fatty acids were decreased. A diet containing 10% TOS increased caecal lactic acid concentrations and reduced β-glucuronidase activities and steroid transformation.     

In Vitro Study and Comparison of Caecal Methanogenesis and Fermentation Pattern in the Brown Hare (Lepus europaeus) and Domestic Rabbit (Oryctolagus cuniculus)

The brown hare and the domestic rabbit are mid-sized herbivorous mammals and hindgut fermenters, though their digestive physiologies differ in some traits. The objective of this study was to estimate and compare the caecal microbial activity in hares and rabbits via an analysis of the following end-products of in vitro caecal fermentation: methane, total gas production, short chain fatty acids and ammonia concentration. Hare caecal methanogenesis occurred at a much lower level (0.25 mmol/kg for samples incubated without substrate and 0.22 mmol/kg for samples incubated with substrate) than that of the rabbit (15.49 and 11.73 mmol/kg, respectively) (P<0.001). The impact of the substrate’s presence on caecal methanogenesis was not significant, though its presence increased the total gas production during fermentation (P<0.001). Hare caecal microflora produced a lower short chain fatty acids concentration than did rabbit microorganisms (P<0.05). In unincubated hare samples, the short chain fatty acids concentration was 28.4 mmol/kg, whereas in unincubated rabbit samples, the short chain fatty acids concentration was 51.8 mmol/kg. The caecal fermentation pattern of the hare was characterised by higher propionate and isobutyrate molar proportions compared with those observed in rabbit caecum (P<0.01). No significant changes in the ammonia concentration in either rabbit or hare caecum were found. The results obtained indicate some differences in the activity of the microbial populations colonising the hare and rabbit caecum, particularly in regards to methanogenic Archaea.     

Different fibrous ingredients and coarsely ground maize affect hindgut fermentation in the pig in vitro but not Salmonella Typhimurium survival

The fermentation kinetics of both fibre choice and maize particle size were studied in vitro from the ileal contents of cannulated pigs given five different experimental diets. Additionally, in vitro batch systems were used to study the quantitative effect of fibre choice and maize particle size on Salmonella Typhimurium growth. Freeze-dried ileal effluents obtained from five cannulated pigs given the five experimental diets in a latin square were used as incubation substrates. The experimental diets consisted of: (1) a standard maize-based diet (ST) where all the ingredients were milled to pass through a 2.5-ml screen, (2) the same diet with the maize ground using a 4.0-ml screen (CG), (3 and 4) two diets in which the maize was partially replaced by (3) sugar beet pulp (80 g/kg; BP) or (4) wheat bran (100 g/kg; WB), or (5) a combination of 80 g sugar beet pulp and 100 g wheat bran/kg (diet HF). Results showed that substrate from BP and HF generated more gas than substrate from ST (P<0.001). In addition, short chain fatty acids production during the entire incubation period was higher (P=0.001) for all the substrates compared to ST substrate (P<0.001) where lower acetate and higher propionate, valerate and branched-chain fatty acids molar ratios were measured. The molar ratio of acetate was highest and the branched-chain fatty acids was lowest for substrates from diets that included sugar beet pulp. The butyrate molar ratio was lower for all substrates compared to the ST diet except for the WB diet. After 12 h of incubation, HF substrate presented the lowest ammonia (91.7 mg/l vs. 125.3 mg/l, P=0.014) and the highest purine bases concentration (0.28 μmol/ml vs. 0.22 μmol/ml, P=0.009). None of the substrates showed any inhibitory effect on Salmonella growth when the batch systems were inoculated with S. Typhimurium. In summary, under the in vitro conditions used, the changes in hindgut fermentation promoted by the inclusion of different fibrous ingredients or by different maize particle size did not produce an inhibitory effect on the growth of S. Typhimurium.     

Effects of high‐ and low‐fiber diets on fecal fermentation and fecal microbial populations of captive chimpanzees

We examined fiber fermentation capacity of captive chimpanzee fecal microflora from animals (n=2) eating low‐fiber diets (LFDs; 14% neutral detergent fiber (NDF) and 5% of cellulose) and high‐fiber diets (HFDs; 26% NDF and 15% of cellulose), using barley grain, meadow hay, wheat straw, and amorphous cellulose as substrates for in vitro gas production of feces. We also examined the effects of LFD or HFD on populations of eubacteria and archaea in chimpanzee feces. Fecal inoculum fermentation from the LFD animals resulted in a higher in vitro dry matter digestibility (IVDMD) and gas production than from the HFD animals. However, there was an interaction between different inocula and substrates on IVDMD, gas and methane production, and hydrogen recovery (P<0.001). On the other hand, HFD inoculum increased the production of total short‐chain fatty acids (SCFAs), acetate, and propionate with all tested substrates. The effect of the interaction between the inoculum and substrate on total SCFAs was not observed. Changes in fermentation activities were associated with changes in bacterial populations. DGGE of bacterial DNA revealed shift in population of both archaeal and eubacterial communities. However, a much more complex eubacterial population structure represented by many bands was observed compared with the less variable archaeal population in both diets. Some archaeal bands were related to the uncultured archaea from gastrointestinal tracts of homeothermic animals. Genomic DNA in the dominant eubacterial band in the HFD inoculum was confirmed to be closely related to DNA from Eubacterium biforme. Interestingly, the predominant band in the LFD inoculum represented DNA of probably new or yet‐to‐be‐sequenced species belonging to mycoplasms. Collectively, our results indicated that fecal microbial populations of the captive chimpanzees are not capable of extensive fiber fermentation; however, there was a positive effect of fiber content on SCFA production. Am. J. Primatol. 71:548–557, 2009. © 2009 Wiley‐Liss, Inc.     

Functional metabolic capacity of pig colonocytes is differentially modulated by fermentable fibre and poorly digestible protein

The intestine is a highly metabolic organ that relies on energy production within the intestinal cells to sustain its functions. In the colon, intestinal cell metabolic function could be affected positively and negatively by microbiota-derived metabolites. Protein fermentation metabolites are known to negatively impact intestinal metabolic function, while fibre fermentation metabolites are generally thought beneficial. We aimed to investigate whether proteins of different digestibility in the absence and presence of fibres impact the energy metabolism of colonocytes, with potentially adverse health effects. We fed 32, 9-week-old boars one of four experimental diets for 14 days in a 2 × 2 factorial arrangement. Whey and collagen were added as a well and a poorly digestible protein source, respectively, and fibre was either included at 5% or 23%. We examined the effects of the diets on the flux of fermentation metabolites in colon digesta and assessed the impact of the diets on functional metabolic capacity of isolated colonocytes using the Seahorse XF analyzer. Feeding the poorly digestible protein source collagen indeed increased nitrogen flow into the colon by 135% compared to the well-digestible whey-protein source. Feeding high fermentable fibre increased colonic fluxes of both fibre-derived metabolites acetate, propionate, butyrate and caproate, but also increased flux of protein-derived metabolites ammonia, isobutyrate, isovalerate, valerate and isocaproate. To analyse the impact of the diets and the induced differential metabolic composition of the intestinal lumen on functional metabolic capacity of the intestine, we used extracellular flux analysis on freshly isolated pig colonocytes. Colonocytes isolated from high fermentable fibre-fed pigs in the whey-protein diet, but not in the collagen-protein diet, had a reduced mitochondrial capacity, as indicated by a 35% reduction of maximal respiration (interaction P < 0.05) and a 20% reduction of spare respiratory capacity (interaction P < 0.05). Colonocytes from high fermentable fibre-fed pigs had a 37% decreased glycolytic activity compared to the colonocytes isolated from the low fermentable fibre-fed pigs (P < 0.001). This indicated that different diets, and in particular different protein sources and fibre levels, differentially affect colonic epithelial cell metabolism in pigs. Especially, high fermentable fibre lowered both colonocyte mitochondrial and glycolytic metabolism, indicating that high-fibre intake in pigs could lower colonocyte energetic status. Because the metabolic capacity of colonocytes is tightly linked with their functionality, assessment of intestinal cell metabolic capacity may be a valuable tool for future research.     

Metabolic evidence of a 'rumen bypass' or a 'ruminal escape' of nutrients in roe deer (Capreolus capreolus)

As short chain fatty acids produced in the forestomach are insufficient to satisfy the energy requirements of the concentrate selecting roe deer (Capreolus capreolus), it is proposed that these animals may have other mechanisms to avoid energy losses due to microbial fermentation. Nutrients bypassing down the ventricular groove (rumen bypass) or ruminal escape of unfermented or partially fermented nutrients may be two alternatives. As metabolic evidence for incomplete fermentation in the forestomach we investigated: (1) the abundance of the sodium-dependent glucose co-transporter (SGLT1) in the duodenum; (2) enzyme activities of maltase, saccharase and alpha-amylase in duodenal and pancreatic tissue; and (3) the proportion of essential, polyunsaturated fatty acids in depot fat samples from ruminants of different feeding type and--for comparison--from animals with a simple stomach. The high abundance of SGLT1, high enzyme activity and the high proportion of polyunsaturated fatty acids in the concentrate selecting ruminants support the hypothesis of rumen bypass or ruminal escape of nutrients in roe deer and reflect differences in nutrient utilization by ruminants that belong to different feeding types.     

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)     

Nutrient digestibility and fecal characteristics are different among captive exotic felids fed a beef‐based raw diet

Nutrient digestibility has not been well characterized in exotic felids. The objective of this experiment was to evaluate differences in nutrient digestibility and fecal characteristics in five large exotic captive felid species, including bobcats, jaguars, cheetahs, Indochinese tigers, and Siberian tigers. All animals were individually housed and adapted to a beef‐based raw diet (Nebraska Brand^® Special Beef Feline, North Platte, NE) for 16 d. Total fecal collections were conducted from days 17 to 20. Fecal samples were weighed and scored on collection. Diet and fecal samples were evaluated for dry matter, organic matter, protein, fat, and energy to determine total tract digestibility. Fresh fecal samples were collected to determine fecal pH, ammonia, phenol, indole, short‐chain fatty acid, and branched‐chain fatty acid concentrations. Fecal scores were greater (P<0.01) in Indochinese tigers when compared with all other species, and cheetahs had greater (P<0.01) fecal scores than jaguars and bobcats. Fat digestibility was greater (P<0.01) in Siberian tigers, Indochinese tigers, and bobcats (96%) compared with cheetahs and jaguars (94%). Digestible energy was greater (P<0.05) in bobcats and Indochinese tigers at 93.5 and 92.9%, respectively, compared with cheetahs and jaguars, 91.6%. Fecal pH was greater (P<0.01) in bobcats compared with all other species evaluated. Indole concentrations were greater (P<0.05) in cheetahs and jaguars compared with bobcats and Indochinese tigers. Fecal ammonia concentrations were increased (P<0.05) in cheetahs compared with all other species. The beef‐based raw diet was highly digestible; however, differences in fat and digestible energy suggest that species should be considered when determining caloric needs of exotic felids. Zoo Biol 27:126–136, 2008. © 2008 Wiley‐Liss, Inc.     

Effect of crude protein concentration and sugar-beet pulp on nutrient digestibility, nitrogen excretion, intestinal fermentation and manure ammonia and odour emissions from finisher pigs

A 2 × 2 factorial experiment was conducted to investigate the interaction between high and low dietary crude protein (CP) (200 v. 150 g/kg) and sugar-beet pulp (SBP) (200 v. 0 g/kg) on nutrient digestibility, nitrogen (N) excretion, intestinal fermentation and manure ammonia and odour emissions from 24 boars (n = 6, 74.0 kg live weight). The diets were formulated to contain similar concentrations of digestible energy (13.6 MJ/kg) and lysine (10.0 g/kg). Pigs offered SBP-containing diets had a reduced (P < 0.05) digestibility of dry matter, ash, N, gross energy and an increased (P < 0.001) digestibility of neutral-detergent fibre compared with pigs offered diets containing no SBP. There was an interaction between CP and SBP on urinary N excretion and the urine : faeces N ratio. Pigs offered the 200 g/kg CP SBP-based diet had reduced urine : faeces N ratio (P < 0.05) and urinary N excretion (P < 0.05) compared with those offered the 200 g/kg CP diet without SBP. However, there was no effect of SBP in pigs offered 150 g/kg CP diets. Manure ammonia emissions were reduced by 33% from 0 to 240 h (P < 0.01); however, odour emissions were increased by 41% (P < 0.05) when pigs were offered SBP diets. Decreasing dietary CP to 150 g/kg reduced total N excretion (P < 0.001) and ammonia emissions from 0 to 240 h (P < 0.05). There was an interaction between dietary CP and SBP on branched-chain fatty acids (P < 0.001) in caecal digesta. Pigs offered the 200 g/kg CP SBP-containing diet reduced branched-chain fatty acids in the caecum compared with pigs offered the 200 g/kg CP diet containing no SBP. However, there was no effect of SBP in the 150 g/kg CP diet. In conclusion, pigs offered SBP-containing diets had a reduced manure ammonia emissions and increased odour emissions compared with diets containing no SBP. Pigs offered the 200 g/kg CP SBP-containing diet had a reduced urine : faeces N ratio and urinary N excretion compared with those offered the 200 g/kg CP diet containing no SBP.     

Harvesting, rumination, digestion, and passage of fruit and leaf diets by a small ruminant, the blue duiker

Because small ruminants (<15 kg) have a high ratio of metabolic rate to fermentation capacity, they are expected to select and require low-fiber, nutrient-dense concentrate diets. However, recent studies suggest that small ruminants may not be as limited in their digestive capacity as previously thought. In this study, we examined harvesting, rumination, digestion, and passage of three diets (domestic figs Ficus carica, fresh alfalfa Medicago sativa, and Pacific willow leaves Salix lasiandra) ranging from 10 to 50% neutral detergent fiber content (NDF) in captive blue duikers (Cephalophus monticola, 4 kg). Harvesting and rumination rates were obtained by observing and videotaping animals on each diet, and digestibility and intake were determined by conducting total collection digestion trials. We estimated mean retention time of liquid and particulate digesta by administering Co-EDTA and forages labelled with YbNO₃ in a pulse dose and monitoring fecal output over 4 days. Duikers harvested and ruminated the fig diet faster than the alfalfa and willow diets. Likewise, they achieved higher dry matter, energy, NDF, and protein digestibility when eating figs, yet achieved a higher daily digestible energy intake on the fresh willow and alfalfa than on the figs by eating proportionately more of these forages. Duikers maintained a positive nitrogen balance on all diets, including figs, which contained only 6.3% crude protein. Mean retention time of cell wall in the duikers’ digestive tract declined with increasing NDF and cellulose content of the diet. Digestibility coefficients and mean retention times of these small ruminants were virtually equivalent to those measured for ruminants two orders of magnitude larger, suggesting that they are well adapted for a mixed diet. Received: 10 August 1999 / Accepted: 16 November 1999     

The degree of dietary fatty acid unsaturation affects torpor patterns and lipid composition of a hibernator

Diets rich in unsaturated and polyunsaturated fatty acids have a positive effect on mammalian torpor, whereas diets rich in saturated fatty acids have a negative effect. To determine whether the number of double bonds in dietary fatty acids are responsible for these alterations in torpor patterns, we investigated the effect of adding to the normal diet 5% pure fatty acids of identical chain length (C18) but a different number of double bonds (0, 1, or 2) on the pattern of hibernation of the yellow-pine chipmunk, Eutamias amoenus. The response of torpor bouts to a lowering of air temperature and the mean duration of torpor bouts at an air temperature of 0.5°C (stearic acid C18:0, 4.5±0.8 days, oleic acid C18:1, 8.6±0.5 days; linoleic acid C18:2, 8.5±0.7 days) differed among animals that were maintained on the three experimental diets. The mean minimum body temperatures (C18:0, +2.3±0.3°C; C18:1, +0.3±0.2°C; C18:2,-0.2±0.2°C), which torpid individuals defended by an increase in metabolic rate, and the metabolic rate of torpid animals also differed among diet groups. Moreover, diet-induced differences were observed in the composition of total lipid fatty acids from depot fat and the phospholipid fatty acids of cardiac mitochondria. For depot fat 7 of 13 and for heart mitochondria 7 of 14 of the identified fatty acids differed significantly among the three diet groups. Significant differences among diet groups were also observed for the sum of saturated, unsaturated and polyunsaturated fatty acids. These diet-induced alterations of body fatty acids were correlated with some of the diet-induced differences in variables of torpor. The results suggest that the degree of unsaturation of dietary fatty acids influences the composition of tissues and membranes which in turn may influence torpor patterns and thus survival of hibernation.Abbreviations bm body mass - T _a air temperature - T _b body temperature - FA fatty acid - MR metabolic rate - MUFA monounsaturated fatty acids - PUFA polyunsaturated fatty acids - VO₂ rate of oxygen consumption - SFA saturated fatty acids - UFA unsaturated fatty acids - UI unsaturation index - SNK Student-Newman-Keuls test     

Effects of animal or plant protein diets on cecal fermentation in guinea pigs (Cavia porcellus), rats (Rattus norvegicus) and chicks (Gallus gallus domesticus)

Monogastric herbivores such as the guinea pig depend on energy supply from enteric fermentation as short-chain fatty acids (SCFA) corresponding to 30-40% of their maintenance energy requirements. They evolved specific digestive system to adapt their indigenous microflora to plant polysaccharides fermentation. No information has been available about the adaptability of microbial fermentation in hindgut of the monogastric herbivorous to an animal protein diet. We investigated if the guinea pig can fully retrieve energy of an animal protein diet by hindgut fermentation compared with a plant protein diet. For comparison, we also studied two omnivores. End products of in vitro cecal fermentation (SCFA, ammonia and gases) were measured to judge how well an animal protein diet could be fermented. The animal protein diet resulted in the less intensive fermentation with increased feed intake and volume of cecal contents than the plant protein diet only in guinea pigs. This may be due to a limited capacity of the hindgut microflora to adapt to the substrate rich in animal protein. We also found that chick cecal contents produced methane at higher emission rate than ruminants.     

单宁酸对布氏田鼠能量代谢的影响

为了解单宁酸对成年布氏田鼠(Lasiopodomys bandtii**)能量代谢和产热的影响,本文采用含0、3.3%和6.6%单宁酸浓度的食物饲喂布氏田鼠21 d,对其体重、基础代谢率、非颤抖性产热和能量收支等进行了测定。代谢率采用封闭式流体压力呼吸计测定;非颤抖性产热用皮下注射去甲肾上腺素诱导;能量摄人采用食物平衡法测定。结果发现:(1) 单宁酸食物对布氏田鼠的体重没有明显影响;(2)取食含6.6%单宁酸食物的动物的基础代谢率于第10 d高于对照组。20 d时,3组动物的基础代谢率没有显著差异;(3) 单宁酸食物对非颤抖性产热没有显著影响;(4) 食用含单宁酸食物的动物的摄人能和消化能于第10 d显著低于对照组,但第20 d时则差异不显著。这些结果表明:布氏田鼠的基础代谢率和能量摄入对单宁酸的反应具有时段性,短期内能量消耗增加,随着动物对食物的适应,生理功能恢复到正常水平。