Digesta flow.

López, Secundino

doi:10.1079/9780851998145.0049

Cited by 28 publications

(26 citation statements)

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“…First, the greater food intakes of the free‐living koalas mentioned above and second, limitations of the particle‐associated marker Ru‐P used by Cork & Warner (1983). Adsorption of Ru‐P to the surface of particles is not irreversible, and thus the marker is in equilibrium with available binding sites in the digesta particle pool; this favours net movement of Ru‐P from larger to smaller particles because of their relatively larger surface areas (Faichney & Griffiths 1978; Faichney 2005). Cork & Warner (1983) reported that, in vitro , within 3 h of preparing large particles marked with Ru‐P, the Ru‐P was largely associated with particles that passed through a 109 µm mesh screen, and almost exclusively so after 24 h. Thus although their estimate of particle MRT may be based on some large particles cleared rapidly from the gut it is likely to be based predominantly on small particles selectively retained in the hindgut (Cork & Warner 1983).…”

Section: Discussionmentioning

confidence: 99%

“…Thus, the influence of the gastric component is likely to be insignificant relative to the hindgut, and the first‐order kinetic model should provide realistic estimates of whole‐tract MRT. Faichney (2005) provides an alternative, non‐compartmental model for calculation of MRT from marker concentrations without complete collection of faeces. That model requires that all sampling periods be represented and collection be extended until levels reach background.…”

Section: Discussionmentioning

confidence: 99%

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A flexible digestive strategy accommodates the nutritional demands of reproduction in a free‐living folivore, the Koala (Phascolarctos cinereus)

Krockenberger

Hume

2007

Functional Ecology

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Summary1. Small mammalian folivores, such as the koala, are considered to be energetically limited by their relatively small gut capacity compared with metabolic requirements and the gut-filling effect of their poorly digestible leaf diet. However, during peak lactation, female koalas increase their food intake (35%) to meet the nutritional demands of reproduction. 2. This study examines mechanisms by which reproductive female koalas overcome limitations to food intake. 3. Digesta retention in the gastrointestinal tract was measured in free-living koalas using inert solute (cobalt (Co) complexed with EDTA) and particle markers (chromium (Cr)-mordanted to cell wall constituents' 600-1180 µ m in diameter). 4. The whole gut rate of passage of both markers was 2-3 times faster than in captive koalas, probably because of 35%-69% greater food intakes in the wild. As in captive koalas, the solute marker was retained longer than the particle marker in free-living animals, indicating selective retention of fluid, solutes and small particles (including bacteria) in the hindgut caecum and proximal colon.The digesta retention of both markers were unaffected by the 35% increase in food intake associated with reproduction, largely due to a 42% increase in the solute marker pool size in lactating animals. The pool size of large particles in the digesta was unchanged. 5. Thus, female koalas meet the nutritional demands of reproduction at least partly by an increased solute digesta pool size, minimizing the detrimental effects of increased food intake on digestion of solutes and small particles, and on faecal loss of microbial protein. There was some indication that they also increase the passage rate of large particles or increase the efficiency of separation of large and small particles to reduce the gut-filling effects of large, poorly digestible particles. 6. Clearly the digestive strategy of the koala is more flexible, and limitations to food intake less stringent, than previously thought. Female koalas accommodate the increased food intake required to meet the demands of free-living and reproduction without compromising nutrient extraction from their eucalypt leaf diet. We suggest that similar flexibility in digestive strategy is likely to play an important role in the way that most small mammalian herbivores, especially arboreal folivores, meet the nutritional demands of reproduction.

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Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

A flexible digestive strategy accommodates the nutritional demands of reproduction in a free‐living folivore, the Koala (Phascolarctos cinereus)

Krockenberger

Hume

2007

Functional Ecology

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“…The survival times for DNA in silage and maize grain in the rumen are summarised in Table 1. Neither maize grain nor silage was detected in faecal material and DNA prepared from faeces did not contain amplifiable plant DNA target sequences. Rate of passage of digesta is slow in ruminants, but the last sample of faeces was collected 72 h after initial feeding of the test material and, with a daily intake of about 1000 g DM/d it is clear that plenty of opportunity was given for test food to have passed completely through the digestive tract (Faichney, 1993). Considering that only the smaller transgene sequence was detected in rumen samples collected after 24 h, the possibility of biologically significant DNA sequences in material passing through the sheep intestine, however, seems extremely low.…”

Section: Resultsmentioning

confidence: 99%

Fate of genetically modified maize DNA in the oral cavity and rumen of sheep

2003

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The polymerase chain reaction (PCR) technique was used to investigate the fate of a transgene in the rumen of sheep fed silage and maize grains from an insect-resistant maize line. A 1914-bp DNA fragment containing the entire coding region of the synthetic cryIA(b ) gene was still amplifiable from rumen fluid sampled 5 h after feeding maize grains. The same target sequence, however, could not be amplified from rumen fluid sampled from sheep fed silage prepared from the genetically modified maize line. PCR amplification of a shorter (211-bp), yet still highly specific, target sequence was possible with rumen fluid sampled up to 3 and 24 h after feeding silage and maize grains, respectively. These findings indicate that intact transgenes from silage are unlikely to survive significantly in the rumen since a DNA sequence 211-bp long is very unlikely to transmit genetic information. By contrast, DNA in maize grains persists for a significant time and may, therefore, provide a source of transforming DNA in the rumen. In addition, we have examined the biological activity of plasmid DNA that had previously been exposed to the ovine oral cavity. Plasmid extracted from saliva sampled after incubation for 8 min was still capable of transforming competent Escherichia coli to kanamycin resistance, implying that DNA released from the diet within the mouth may retain sufficient biological activity for the transformation of competent oral bacteria.

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“…The mean retention time (MRT) of digesta in the terminal ileum and in the whole digestive tract was calculated from the concentration of solute (Co) and particle markers (Yb) in the digesta and faeces according to Faichney (1993) as follows:…”

Section: Calculations and Statistical Methodsmentioning

confidence: 99%

Effects of a dietary organic acid mixture and of dietary fibre levels on ileal and faecal nutrient apparent digestibility, bacterial nitrogen flow, microbial metabolite concentrations and rate of passage in the digestive tract of pigs

Partanen

Jalava

Valaja

2007

Animal

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Six 34-kg barrows were fitted with a post-valve T-caecum cannula and assigned to six dietary treatments according to a 6 £ 5 change-over design to study how a mixture of formic acid, sorbate, and benzoate (0 or 8.4 g/kg feed) influences apparent ileal and faecal digestibility coefficients, bacterial nitrogen (N) flow, microbial metabolite concentrations, and passage rate in pigs fed isoenergetic diets with medium, high, or very high fibre content (neutral-detergent fibre (NDF): 199, 224, and 248 g/kg dry matter, respectively). These barley and soya-bean meal based diets contained 0, 75, and 150 g/kg barley fibre (NDF: 577 g/kg) and 0, 8, and 16 g/kg rapeseed oil, respectively. The dietary organic acid mixture improved the apparent ileal digestibility of 14 of the 17 amino acids analysed (P , 0.05). Increasing levels of dietary fibre linearly decreased the apparent ileal digestibility of six of the 17 amino acids analysed (P , 0.05). Ileal flows of bacterial N and amino acids as assessed on the basis of purine flow were decreased by the dietary organic acid mixture (P , 0.05) but were not affected by dietary fibre level (P . 0.05). As assessed on the basis of diaminopimelic acid flow, bacterial N flow was increased by both the dietary organic acid mixture and increased dietary fibre levels (P , 0.05). The dietary organic acid mixture reduced the concentration of lactic acid and increased that of acetic acid in ileal digesta (P , 0.05), while dietary fibre levels had a quadratic effect on concentrations of acetic, propionic, and butyric acid (P , 0.05). The mean retention time of Co (solute marker) and Yb (particle marker) in the large intestine decreased in a linear manner by increasing dietary fibre levels (P , 0.05) but was not affected by the dietary organic acid mixture (P . 0.05). The results show that a dietary organic acid mixture has a positive effect on the apparent ileal digestibility of most amino acids irrespective of dietary fibre levels. This could be at least partly related to changes in bacterial N flow in the ileum. However, different bacterial markers showed opposite effects on bacterial N flow, which makes it questionable to use a constant bacterial marker / bacterial N ratio to estimate bacterial N flow. Increasing levels of dietary fibre had negative effects on the apparent ileal amino acid digestibilities and shortened the mean retention time of digesta in the large intestine.

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Digesta flow.

Cited by 28 publications

References 0 publications

A flexible digestive strategy accommodates the nutritional demands of reproduction in a free‐living folivore, the Koala (Phascolarctos cinereus)

A flexible digestive strategy accommodates the nutritional demands of reproduction in a free‐living folivore, the Koala (Phascolarctos cinereus)

Fate of genetically modified maize DNA in the oral cavity and rumen of sheep

Effects of a dietary organic acid mixture and of dietary fibre levels on ileal and faecal nutrient apparent digestibility, bacterial nitrogen flow, microbial metabolite concentrations and rate of passage in the digestive tract of pigs

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