Publications by authors named "Dagong Zhang"

10 Publications

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Interplay between grain digestion and fibre in relation to gastro-small-intestinal passage rate and feed intake in pigs.

Eur J Nutr 2021 May 5. Epub 2021 May 5.

Australian Research Council, Centre of Excellence in Plant Cell Walls, Centre for Nutrition and Food Sciences, Queensland Alliance for Agriculture and Food Innovation, The University of Queensland, St Lucia, Australia.

Purpose: The combined effects of grain digestibility and dietary fibre on digesta passage rate and satiety in humans are poorly understood. Satiety can be increased through gastric distention, reduced gastric emptying rate and when partially digested nutrients reach the terminal ileum to stimulate peptide release through the ileal/colonic brakes to slow the rate of digesta passage. This study determined the effects of grain digestibility and insoluble fibre on mean retention time (MRT) of digesta from mouth-to-ileum, feed intake (FI), starch digestion to the terminal ileum and faecal short chain fatty acids (SCFA) in a pig model.

Method: Twelve grain-based [milled sorghum (MS), steam-flaked-sorghum, milled wheat, and steam-flaked-wheat (SFW)] diets with different intrinsic rates of starch digestion, assessed by apparent amylase diffusion coefficient (ADC), and fibre from oat hulls (OH) at 0, 5 and 20% of the diet were fed to ileal-cannulated pigs.

Result: MRT was affected by grain-type/processing (P < 0.05) and fibre amount (P < 0.05). An approximate tenfold increase in ADC showed a limited decline in MRT (P = 0.18). OH at 20% increased MRT (P < 0.05) and reduced FI (P < 0.05). Ileal digestibility of starch increased and faecal SCFA concentration decreased with ADC; values for MS being lower (P < 0.001) and higher (P < 0.05), respectively, than for SFW.

Conclusions: Lower ileal digestibility of starch, higher faecal SCFA concentration and longer MRT of MS than SFW, suggest the ileal/colonic brakes may be operating. FI appeared to decrease with increasing MRT. MRT increased and intake decreased with grain-based foods/feeds that have low starch digestibility and substantial amounts of insoluble fibre.
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http://dx.doi.org/10.1007/s00394-021-02567-3DOI Listing
May 2021

Wheat bran and oat hulls have dose-dependent effects on ad-libitum feed intake in pigs related to digesta hydration and colonic fermentation.

Food Funct 2019 Dec;10(12):8298-8308

Australian Research Council, Centre of Excellence in Plant Cell Walls, Centre for Nutrition and Food Sciences, Queensland Alliance for Agriculture and Food Innovation, The University of Queensland, 4072, Australia.

Undigested nutrients and fermentable fibre in the distal ileum and colon stimulate intestinal brakes, which reduce gastric-emptying and digesta-passage-rate, and subsequently limit feed/food-intake. Fibre can also stimulate passage rate potentially increasing feed intake (FI). In order to experimentally determine the relationships between these two hypothesised actions of fibre, five levels of wheat-bran (WB) or oat-hulls (OH) were added to a highly digestible starch-based diet fed to pigs ad-libitum for three weeks. Average-daily-feed-intake (ADFI), faecal short-chain-fatty-acids (SCFA) and related parameters were determined at 7, 14 and 21d. A linear mixed model was fitted to FI and fermentation parameters. Overall, WB diets showed 8-11% lower ADFI (7-14d: p < 0.05; 7-21 & 0-21d: p = 0.053) than OH diets. WB diets produced over 20% more (21d: p < 0.01) SCFA than OH or Control diets. WB at 25% produced 22% more (7d: p < 0.05) SCFA than any other diet. Diets with WB at 25 and 35%, showed higher hydration capacity than any other diet (p < 0.001). OH at 10% had an unusually low FI and a markedly higher hydration capacity. With increasing levels of OH, intake of base diet was 7% more than control at 5% OH, but 8% less than control at 20% OH. With increasing WB content, intake of base diet decreased. From these results, we propose that three mechanisms control the effects of fibre on FI: initial increase in passage rate and feed intake at low concentrations of non-swelling fibres; a depression in FI from high fibre bulk; and reduced feed intake from stimulation of ileal and colonic brakes.
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http://dx.doi.org/10.1039/c8fo02496kDOI Listing
December 2019

Male grower pigs fed cereal soluble dietary fibres display biphasic glucose response and delayed glycaemic response after an oral glucose tolerance test.

PLoS One 2018 1;13(3):e0193137. Epub 2018 Mar 1.

Queensland Alliance for Agriculture and Food Innovation, Centre for Nutrition and Food Sciences, The University of Queensland, St Lucia Brisbane, Australia.

Acute and sustained soluble dietary fibre (SDF) consumption are both associated with improved glucose tolerance in humans and animal models (e.g. porcine). However, the effects on glucose tolerance in grower pigs, adapted to diets with a combination of SDF have not been studied previously. In this experiment, cereal SDF wheat arabinoxylan (AX) and oat β-glucan (BG) were fed individually and in combination to determine the effect on glucose tolerance in jugular vein catheterized grower pigs. Five groups of Large White male grower pigs were fed highly digestible diets containing either 10% AX, 10% BG, 5% AX with 5% BG, a model cereal whole wheat flour (WWF), or a control wheat starch diet (WS) with no SDF. Blood was collected via jugular vein catheters over 240 minutes following a feed challenge and an oral glucose tolerance test (OGTT) on two separate days. Postprandial blood samples were used to determine plasma glucose, insulin, non-esterified fatty acids (NEFA), glucose-dependent insulinotropic polypeptide (GIP), glucagon-like peptide-1 (GLP-1), peptide tyrosine tyrosine (PYY), ghrelin, glucagon and cortisol concentrations. No dietary effects on glycaemic response were observed following the feed challenge or the OGTT as determined by the area under the curve (AUC). A biphasic glucose and insulin response was detected for all pigs following the OGTT. The current study showed male grower pigs have tight glycaemic control and glucose tolerance regardless of diet. In addition, pigs fed the combined SDF had a reduced GIP response and delayed insulin peak following the feed challenge. Incretin (GLP-1 and GIP) secretion appeared asynchronous reflecting their different enteroendocrine cell locations and response to nutrient absorption.
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http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0193137PLOS
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5832219PMC
June 2018

Dietary pectin and mango pulp effects on small intestinal enzyme activity levels and macronutrient digestion in grower pigs.

Food Funct 2018 Feb;9(2):991-999

ARC Centre of Excellence in Plant Cell Walls, Queensland Alliance for Agriculture and Food Innovation, Centre for Nutrition and Food Sciences, The University of Queensland, St Lucia Brisbane, 4072, Australia.

The effects of refined pectin and mango pulp on macronutrient digestion and small intestinal enzyme activity were studied in grower pigs. Diets based on wheat starch with and without apple pectin or dried mango fruit pulp were fed to 30 grower pigs for 21 days. Pigs were euthanized two hours postprandially, and their gastrointestinal contents recovered. Starch and protein digestion as well as α-amylase activity were all increased in pigs fed pectin. In contrast, fat digestion, lipase and protease (trypsin) activities were all significantly reduced in these pigs. Pigs fed the mango fruit pulp diet had intermediate effects compared with pigs fed refined pectin and control diets. The data suggests that pectin has a significant effect on digestive enzyme activity and subsequent influence on macronutrient digestion. The fact that pectin caused either an increase (α-amylase) or decrease (lipase, protease) in enzyme activity in digesta, which either did (starch, lipid) or did not (protein) associate with residual nutrient differences illustrates the complexity of small intestinal responses to added fibre in diets.
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http://dx.doi.org/10.1039/c7fo00602kDOI Listing
February 2018

An updated method for the jugular catheterization of grower pigs for repeated blood sampling following an oral glucose tolerance test.

Lab Anim 2017 Aug 1;51(4):397-404. Epub 2016 Jan 1.

1 ARC Centre of Excellence in Plant Cell Walls, Queensland Alliance for Agriculture and Food Innovation, Centre for Nutrition and Food Sciences, University of Queensland, St Lucia, Brisbane, Australia.

Jugular catheterization is a common procedure used under experimental conditions. However, there is considerable variation in the reported techniques, particularly for grower pigs (>40 kg and <60 kg) when larger volumes of blood per sample (>10 mL) are required. This paper provides a complete methodology including the use of current equipment and anaesthetic regimen for grower pigs. This surgical jugular catheterization method was carried out in 30 large white grower pigs. Firstly, the pigs were habituated to human handling for at least two weeks prior to surgery. Animals were sedated and anesthetized. Following intubation, an incision was made in the jugular fossa, and the jugular vein was located. A catheter was then inserted and fixated. The wound was stapled and the catheter line secured to the back of the neck. The pigs recovered fully from the surgery and the catheters remained patent for the duration of the blood sampling period (min 72 h). Twenty millilitres of blood were collected every 15 min, taking approximately 2 min per pig. No haemolysis was detected in any samples. Jugular catheterization of pigs using this procedure proved successful both in terms of animal recovery and quality of samples. Catheters remained patent and pigs remained calm during sampling.
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http://dx.doi.org/10.1177/0023677216682772DOI Listing
August 2017

Randomised clinical trial on the effect of a single oral administration of l-tryptophan, at three dose rates, on reaction speed, plasma concentration and haemolysis in horses.

Vet J 2016 Jul 6;213:84-6. Epub 2016 May 6.

School of Earth, Environmental and Biological Sciences, Queensland University of Technology, Brisbane, QLD, 4001, Australia.

Tryptophan (TRP) is marketed as a calmative for horses despite reservations about its efficacy. The aim of this study was to measure the effect of oral TRP administration on the reaction speed of horses. Sixty mature horses were used in a two stage randomised, blind, cross-over study, receiving a placebo and an oral dose of TRP (30, 60 or 120 mg/kg body weight), before undergoing a reaction speed test. Blood samples were taken up to 96 h after TRP administration, to identify signs of acute haemolytic anaemia. Plasma TRP concentrations were increased (P <0.001) by the administration of TRP paste. However, TRP had no effect on the reaction speed of horses when startled. There was no evidence of alterations in clinical pathology parameters in 432 blood samples. While the safety of these doses of TRP can be confirmed, there was no evidence to suggest that a single dose of TRP is an effective calmative for horses.
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http://dx.doi.org/10.1016/j.tvjl.2016.05.003DOI Listing
July 2016

Soluble arabinoxylan enhances large intestinal microbial health biomarkers in pigs fed a red meat-containing diet.

Nutrition 2016 Apr 2;32(4):491-7. Epub 2015 Nov 2.

The University of Queensland, Australian Research Council Centre of Excellence in Plant Cell Walls, QAAFI Centre for Nutrition and Food Sciences, St. Lucia, Queensland, Australia.

Objectives: The aim of this study was to investigate how moderately increased dietary red meat combined with a soluble fiber (wheat arabinoxylan [AX]) alters the large intestinal microbiota in terms of fermentative end products and microbial community profiles in pigs.

Methods: Four groups of 10 pigs were fed Western-type diets containing two amounts of red meat, with or without a solubilized wheat AX-rich fraction for 4 wk. After euthanasia, fermentative end products (short-chain fatty acids, ammonia) of digesta from four sections of large intestine were measured. Di-amino-pimelic acid was a measure of total microbial biomass, and bacterial profiles were determined using a phylogenetic microarray. A factorial model determined effects of AX and meat content.

Results: Arabinoxylan was highly fermentable in the cecum, as indicated by increased concentrations of short-chain fatty acids (particularly propionate). Protein fermentation end products were decreased, as indicated by the reduced ammonia and branched-chain ratio although this effect was less prominent distally. Microbial profiles in the distal large intestine differed in the presence of AX (including promotion of Faecalibacterium prausnitzii), consistent with an increase in carbohydrate versus protein fermentation. Increased di-amino-pimelic acid (P < 0.0001) suggested increased microbial biomass for animals fed AX.

Conclusions: Solubilized wheat AX has the potential to counteract the effects of dietary red meat by reducing protein fermentation and its resultant toxic end products such as ammonia, as well as leading to a positive shift in fermentation end products and microbial profiles in the large intestine.
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http://dx.doi.org/10.1016/j.nut.2015.10.008DOI Listing
April 2016

Soluble arabinoxylan alters digesta flow and protein digestion of red meat-containing diets in pigs.

Nutrition 2015 Sep 7;31(9):1141-7. Epub 2015 Apr 7.

The University of Queensland, ARC CoE Plant Cell Walls, Centre for Nutrition and Food Sciences, St. Lucia, Queensland, Australia; The University of Queensland, School of Agriculture and Food Sciences, Gatton, Queensland, Australia.

Objectives: The aim of this study was to investigate how a moderate increase in dietary meat content combined (or not) with soluble fibre would influence protein digestion as well as digesta characteristics and flow.

Methods: Four groups of pigs were fed Western-style diets (high-protein/high-fat) containing two types of barbecued red meat, one with and one without a wheat arabinoxylan-rich fraction. After 4 wk, digesta samples were collected from small and large intestinal sites and analyzed for protein, amino acids, dry matter, and acid-insoluble ash. Tissue samples were also collected from each site.

Results: Arabinoxylan consumption led to somewhat lower apparent protein digestibility within the small and large intestines as well as shorter mean retention times. This suggests that the lowered protein digestibility is due, at least partly, to shorter access time to digestive proteases and absorptive surfaces. Additionally, digesta mass was higher in pigs fed arabinoxylan while dry matter (%) was lower, indicating an increased digesta water-holding capacity due to the presence of a soluble dietary fiber.

Conclusion: Data showed that solubilized wheat arabinoxylan provides potential health benefits through decreased protein digestibility, increased digesta mass, and reduced mean retention time, even for diets with a moderately higher protein content. These factors are associated with efficiency of digestion and satiety, both of which have implications for prevention of obesity and other health disorders.
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http://dx.doi.org/10.1016/j.nut.2015.03.006DOI Listing
September 2015

[Endoscopic pleomorphic adenoma of nasal septum resection assisted by low-temperature plasm radiofrequency: a case report].

Lin Chung Er Bi Yan Hou Tou Jing Wai Ke Za Zhi 2014 Nov;28(21):1713

We present an extremely rare case of pleomorphic adenoma of the nasal septum in a 24-year old woman who went to consultation because of right nasal neoplasm. The radiologic discoveries by computerized tomography showed a tumor in the right nasal septum. Incisional biopsy was done, with a histopathological report of pleomorphic adenoma. Later, nasal endoscopy was used to remove the neoplasm and histology revealed pleomorphic adenoma of the nasal septum.
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November 2014

An arabinoxylan-rich fraction from wheat enhances caecal fermentation and protects colonocyte DNA against diet-induced damage in pigs.

Br J Nutr 2012 May 24;107(9):1274-82. Epub 2011 Nov 24.

High Fibre Grains Cluster, CSIRO Food Futures National Research Flagship, Adelaide, SA 5000, Australia.

Population studies show that greater red and processed meat consumption increases colorectal cancer risk, whereas dietary fibre is protective. In rats, resistant starches (a dietary fibre component) oppose colonocyte DNA strand breaks induced by high red meat diets, consistent with epidemiological data. Protection appears to be through SCFA, particularly butyrate, produced by large bowel carbohydrate fermentation. Arabinoxylans are important wheat fibre components and stimulate large bowel carbohydrate SCFA production. The present study aimed to determine whether an arabinoxylan-rich fraction (AXRF) from wheat protected colonocytes from DNA damage and changed colonic microbial composition in pigs fed with a diet high (30 %) in cooked red meat for 4 weeks. AXRF was primarily fermented in the caecum, as indicated by higher tissue and digesta weights and higher caecal (but not colonic) acetate, propionate and total SCFA concentrations. Protein fermentation product concentrations (caecal p-cresol and mid- and distal colonic phenol) were lower in pigs fed with AXRF. Colonocyte DNA damage was lower in pigs fed with AXRF. The microbial profiles of mid-colonic mucosa and adjacent digesta showed that bacteria affiliating with Prevotella spp. and Clostridial cluster IV were more abundant in both the mucosa and digesta fractions of pigs fed with AXRF. These data suggest that, although AXRF was primarily fermented in the caecum, DNA damage was reduced in the large bowel, occurring in conjunction with lower phenol concentrations and altered microbial populations. Further studies to determine the relationships between these changes and the lowering of colonocyte DNA damage are warranted.
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http://dx.doi.org/10.1017/S0007114511004338DOI Listing
May 2012