Henry Jørgensen

The influence of dietary fibre and environmental temperature on the development of the gastrointestinal tract, digestibility, degree of fermentation in the hind-gut and energy metabolism in pigs.

The present study was undertaken to provide detailed information about the effect of dietary fibre (DF) level on the development of the digestive tract, on nutrient digestibility and on energy and protein metabolism of pigs housed in low (13 degrees) or high (23 degrees) thermal environments. Low- and high-fibre diets (59 v. 268 g DF/kg DM) were studied in three balance periods with fistulated pigs in the weight range 45-120 kg. Heat production was measured using open-circuit respiration chambers. Pea fibre and pectin were used to adjust the DF level in the high-fibre diet. Per kg empty body weight the stomach, caecum and colon and the length of colon were significantly greater in pigs consuming the high-fibre diet than in those on the low-fibre diet. Pigs kept at low temperature had significantly heavier caecums than those kept at the high temperature. Digestibilities of protein, DM and energy were lowest for the high-fibre diet. Only minor amounts of NSP and its constituent sugars were degraded anterior to the ileum, whereas in the hind-gut the fermentation of the total NSP fraction was high, being 0.77 for the high-fibre diet and 0.59 for the low-fibre diet. Feeding the high-fibre diet increased the flow of digesta through the terminal ileum 5-6-fold and an extra 460 g organic matter was fermented daily in the hind-gut compared with pigs fed on the low-fibre diet. The amount of retained energy as a proportion of metabolizable energy decreased in relation to the amount of energy fermented in the hind-gut. Based on the present data it was estimated that the relative value of energy derived from hind-gut fermentation was 0.73 in comparison with energy enzymically digested in the small intestine. There was negligible effect of the temperature--fibre interaction on energy metabolism. However, it could be calculated that the decrease in temperature from 23 degrees to 13 degrees was associated with an increase in heat production by 2.9 MJ/pig per d.

THE NET ENERGY VALUE OF DIETS FOR GROWTH IN PIGS IN RELATION TO THE FERMENTATIVE PROCESSES IN THE DIGESTIVE TRACT AND THE SITE OF ABSORPTION OF THE NUTRIENTS

Abstract The relationship between diet composition, site of absorption of energy yielding substances, and utilization of metabolizable energy in pigs was studied using six semi-synthetic diets. The diets were formulated to fulfil the requirements of the pigs for essential nutrients and to ensure a large range in the proportion of energy yielding substances which disappear from the caecum-colon. The amount of dietary energy absorbed from the small intestine and the caecum-colon, respectively, was determined on basis of 36 digestibility experiments with ileal cannulated female pigs weighing 50–90 kg. The proportion of digested energy disappearing in the caecum-colon increased from 18 to 33% as the content of potato starch plus organic cellulose in the diets increased from 2 to 32%. The digestibility of the nutrients and the utilization of metabolizable energy was studied in a balance/slaughter experiment including 36 pigs during the growth period from 20 to 90 kg. The pigs (3 litters of females and 3 litters of male castrates) were allotted to the six dietary treatments on a within litter basis taking into account the live weight of the pigs. The daily intake of the different diets was regulated in such a way that the daily gain in the different treatment groups was almost identical through the entire experimental period. Three digestibility and nitrogen balance experiments were performed with each pig. At approximately 90 kg live weight, the pigs were killed, dissected, ground, mixed and chemically analysed. The digestibility of gross energy and the efficiency of utilization of metabolizable energy decreased with increasing content of potato starch and organic cellulose in the diets. An increase in dietary content of crude fibre from organic cellulose by 1% depressed the digestibility of gross energy by 1.3% (1.1% units) and depressed the utilization of metabolizable energy by 0.9% (0.5% units). The efficiency of utilization of metabolizable energy decreased with decreasing energy concentration (ME/kg DM), which accounted for 91% of the variation in the net energy value. As energy concentration decreased, more of the dietary nutrients were transferred to caecum-colon, the formation of volatile fatty acids was increased and a larger part of digested energy disappeared in the caecum-colon. A 1% increase in the proportion of digested energy disappearing in the caecum-colon decreased the utilization of metabolizable energy by 0.8% (0.5% units). This indicates that energy concentration (ME/kg DM or ME/GE, % crude fibre, % crude fat) acts as an indicator of the amount of diet dry matter, site of absorption and chemical composition of the absorbed nutrients, which in turn depends on the chemical composition, technical treatment, volume, etc., of the feedstuffs used in the diets.

The digestive capacity of the caecum-colon and the value of the nitrogen absorbed from the hind gut for protein synthesis in pigs.

1. The aim of the investigation was to study the effects of lysine, methionine, crude protein, a complete balanced diet, maize starch and potato starch infused continuously into the caecum on the digestibility of the nutrients, urinary nitrogen excretion and N balance in the presence of a normal or a depressed (modified) microflora. 2. The effects of the the infused nutrients on digestibility differed when diets supplemented with antibiotics were compared with unsupplemented diets. 3. Infused lysine improved the digestibility of crude protein (0.004/g lysine), crude fibre (0.01/g lysine), gross energy (0.003/g lysine) and lysine (0.03/g lysine) when the diets were not supplemented with antibiotics. 4. Infused lysine, methionine and crude protein seemed to be of very little value for protein synthesis in the pigs, as the effects on N balance, although positive, were very small. 5. Despite the fact that a part of the infused lysine passed through the caecum-colon and into the faeces intact, the effect of N balance was negligible, indicating that the ability to absorb amino acids through the gut wall in the caecum-colon was very poor. 6. Crude protein, a complete balanced diet, maize starch and potato starch infused into the caecum were digested almost as well as if they had been given orally, thus demonstrating the large digestive capacity of the caecum-colon.

The influence of dietary fibre on body composition, visceral organ weight, digestibility and energy balance in rats housed in different thermal environments

The present study was undertaken to provide detailed information on the effect of dietary fibre (DF) level on body composition, visceral organ weight, nutrient digestibility and on energy and protein metabolism of rats housed in cold (16 degrees), warm (24 degrees) or hot (32 degrees) thermal environments. High- or low-fibre diets (257 v. 56 g DF/kg dry matter (DM)) were studied in a 6-week balance experiment (initial body weight about 100 g). Heat production was measured using open-air circuit respiration chambers. Pea fibre and pectin were used to adjust the DF level in the high-fibre diet. The ranking order of daily gain of rats kept in different environments was: 24 degrees > 16 degrees > 32 degrees, while the ranking order for carcass protein was: 16 degrees > 24 degrees > 32 degrees. Rats on the high-DF diet had a lower daily gain than those on the low DF diet, and more protein in DM of empty body weight (EBW) and less fat. The relative weights (g/kg EBW) of liver, heart and kidney decreased when increasing the environmental temperature. The relative weight of the heart was highest in rats on the high DF level, while liver and kidney weights were unaffected by DF. Per kg EBW, the stomach, small intestine, caecum and colon and the length of colon were significantly greater in rats consuming the high-fibre diet compared with those on the low-fibre diet. Rats kept at low temperature had a significantly heavier gastrointestinal (GI) tract than those kept at the highest temperature. Digestibility of protein, DM and energy was lowest for rats fed on the high-fibre diet. Heat production (HP) of fed rats as well as fasting HP decreased significantly as environmental temperature increased. HP as a proportion of metabolizable energy (ME) was significantly lower for rats at 24 degrees compared with the other environmental temperatures. The proportion of energy retained as protein was slightly higher in rats fed on the high-fibre than on the low-fibre diet. Based on the results of the present study the authors measured a net energy value of 5.4 kJ/g DF fermented; approximately 50% of the DF came from peas. Possible implications of the present findings are discussed.

Correlations of protein deposited in growing female pigs to ileal and faecal digestible crude protein and amino acids

Abstract The objective of the investigation was to study the value for protein synthesis of crude protein/amino acids disappearing in different intestinal segments by correlating deposited protein to the amounts disappearing in the small intestine, the caecum—colon and in the whole digestive tract, to learn whether practical diet formulation could be improved by replacing faecal digestible crude protein/amino acids with ileal digestible crude protein/amino acids. The study included 24 diets varying widely in chemical composition. The ileal and faecal digestibility of crude protein/amino acids was determined in five experiments per diet with growing cannulated female pigs and the protein deposition was determined in five N-balance experiments per diet with normal growing, uncannulated, bladdercatheterized female pigs under standardized conditions. The digestibility of crude protein/amino acids in the caecum—colon decreased with increasing levels of crude fibre and potato starch, whereas the digestibility of energy increased. Increasing dietary levels of crude protein increased the proportion of lysine and methionine disappearing in the caecum—colon. Ileal digestible crude protein/amino acids had considerably higher correlations to deposited protein than crude protein/amino acids disappearing in caecum—colon, and slightly higher correlations to deposited protein than crude protein/amino acids disappearing in the whole digestive tract.

The role of whole-wheat grain and wheat and rye ingredients on the digestion and fermentation processes in the gut--a model experiment with pigs.

The effect of wheat and rye breads made from white wheat flour with added refined fibre (WFL), whole-wheat grain, wheat aleurone flour (WAF) or rye aleurone flour (RAF) on digestion and fermentation processes in the gut was studied in a model experiment with pigs. The diets were similar in dietary fibre (DF) but differed in arabinoxylan (AX) content and composition. Twenty pigs were fed the breads three times daily (08.00, 13.00 and 18.00 hours) and the digesta collected through a T-cannula for two successive periods (breakfast: 8.00-13.00; lunch: 13.00-18.00 hours). Faeces were collected for 24 h and caecal and colonic contents at slaughter. The rigid nature of the aleurone cell walls encapsulated nutrients, which resulted in reduced (P < 0.01) digestibility of protein (WAF and RAF breads) and fat (RAF bread). For the RAF bread, the digestibility of starch was also lower (P < 0.001) than of the wheat-based diets primarily due to the higher intestinal viscosity. The DF composition had an impact on (P < 0.001) the site for fibre degradation in the large intestine. Thus, AX of the WAF bread, with the lowest degree of substitution, were fermented as much in the caecum as in the colon, whereas AX of the RAF bread, with an intermediary degree of substitution, were mainly fermented in the caecum. The WFL bread, rich in cellulose, was fermented more distally. Fermentation of experimental breads in the large intestine had no effect (P>0.05) on the production of metabolites, except for butyrate which was higher (P < 0.01) after the WAF bread consumption.

Digestion of carbohydrates and utilization of energy in sows fed diets with contrasting levels and physicochemical properties of dietary fiber.

Three experimental diets were used to investigate the digestion of carbohydrates and utilization of energy in sows fed diets with different levels and physicochemical properties of dietary fiber (DF). The low-fiber diet (LF; DF, 16%; soluble DF, 4.8%) was based on wheat and barley. The high-fiber 1 diet (HF1; DF, 41%; soluble DF, 11%) was based on wheat and barley supplemented with the coproducts: sugar beet pulp, potato pulp, and pectin residue, and the high-fiber 2 diet (HF2; DF, 44%; soluble DF, 7.3%) was based on wheat and barley supplemented with approximately 1/3 of the coproducts used in diet HF1 and 2/3 of brewers spent grain, seed residue, and pea hull (1:1:1, respectively). The diets were studied in 2 series of experiments. In Exp. 1, the digestibility and ileal and fecal flow of nutrients were studied in 6 ileal-cannulated sows placed in metabolic cages designed as a repeated 3 x 3 Latin square design. In Exp. 2, energy metabolism was measured in respiration chambers using 6 sows in a repeated 3 x 3 Latin square design. The DF level influenced the ileal flow of most nutrients, in particular carbohydrates, which increased from 190 g/d when feeding the LF diet to 538 to 539 g/d when feeding the HF diets; this was also reflected in the digestibility of OM and carbohydrates (P < 0.05). The ranking of total excretion of fecal materials was HF2 > > HF1 > LF, which also was reflected in the digestibility of OM, protein, and carbohydrates. Feeding HF diets resulted in greater CH(4) production, which was related to the amount of carbohydrates (r = 0.79) and OM (r = 0.72) fermented in the large intestine, but with no difference in heat production (12.2 to 13.1 MJ/kg of DM). Retained energy (MJ/kg of DM) was decreased when feeding HF1 compared with LF and negative when feeding HF2. Feeding sows HF1 reduced the activity of animals (5.1 h/24 h) compared with LF (6.1 h/24 h; P = 0.045).

Absorption of carbohydrate-derived nutrients in sows as influenced by types and contents of dietary fiber.

The current investigation was undertaken to study the absorption and plasma concentration of carbohydrate-derived nutrients [glucose, short-chain fatty acids (SCFA), and lactate] and the apparent insulin production in sows fed diets containing contrasting types and contents of dietary fiber. Six sows were fed 3 experimental diets, low fiber (LF; 177 g of dietary fiber and 44 g of soluble fiber/kg of DM), high soluble fiber (HF-S; 429 g of dietary fiber and 111 g of soluble fiber/kg of DM), and high insoluble fiber (HF-I; 455 g of dietary fiber and 74 g of soluble fiber/kg of DM), in a repeated crossover design. Variations in dietary concentration and solubility of dietary fiber were obtained by substituting starch-rich wheat and barley in the LF diet with dietary fiber-rich co-products (sugar beet pulp, potato pulp, pectin residue, brewers spent grain, pea hulls, and seed residue, which have distinct physicochemical properties). The main carbohydrate component of the LF diet was starch and nonstarch polysaccharides (cellulose and noncellulosic polysaccharides) for the 2 high dietary fiber diets. Consumption of the LF diet resulted in increased and rapid glucose absorption at 0 to 4 h postfeeding. With the HF-I diet, the glucose absorption pattern was similar but at a decreased rate, whereas it was decreased and delayed with the HF-S diet (diet, P < 0.001; time, P < 0.001). These differences were also reflected in the insulin response. The quantitative absorption of SCFA at 0 to 10 h postfeeding was greater when feeding the HF-S diet compared with the LF diet (P < 0.001) and intermediate when feeding the HF-I diet (P < 0.001). The study showed that feeding the high dietary fiber diets resulted in a increased and more uniform uptake of SCFA than when feeding the LF control. Moreover, the HF-S diet reduced diurnal variation in glucose and insulin concentrations.

The Influence of Different Protein, Fat and Mineral Levels on the Digestibility of Fat and Fatty Acids Measured at the Terminal Ileum and in Faeces of Growing Pigs

Abstract The influence of dietary protein, fat and mineral levels on crude fat and fatty acid digestibility was investigated in growing pigs. The experiment was a factorial design with two levels of protein (normal and high), two levels of dietary fat (3 and 15% of DM) and three levels of minerals (50, 100 and 150% of Danish Standard). Four litters, each of six female pigs, were used in the experiment. Increasing the dietary protein content resulted in a moderate but significant increase in the ileal digestibility of fatty acids. The increase was most pronounced for the saturated fatty acids. Addition of animal fat to the basal diet caused a substantial increase in ileal digestibility of all fatty acids except stearic acid (18:0). A variation in the dietary mineral content of ±50% of the Danish Standard had no significant influence on ileal digestibility of crude fat and fatty acids. Apparently, microbial hydrogenation occurred in the hind-gut, but the increase in stearic acid (18:0) excretion could not b...

Nutritional Regulation of Bile Acid Metabolism Is Associated with Improved Pathological Characteristics of the Metabolic Syndrome

Bile acids (BAs) are powerful regulators of metabolism, and mice treated orally with cholic acid are protected from diet-induced obesity, hepatic lipid accumulation, and increased plasma triacylglycerol (TAG) and glucose levels. Here, we show that plasma BA concentration in rats was elevated by exchanging the dietary protein source from casein to salmon protein hydrolysate (SPH). Importantly, the SPH-treated rats were resistant to diet-induced obesity. SPH-treated rats had reduced fed state plasma glucose and TAG levels and lower TAG in liver. The elevated plasma BA concentration was associated with induction of genes involved in energy metabolism and uncoupling, Dio2, Pgc-1α, and Ucp1, in interscapular brown adipose tissue. Interestingly, the same transcriptional pattern was found in white adipose tissue depots of both abdominal and subcutaneous origin. Accordingly, rats fed SPH-based diet exhibited increased whole body energy expenditure and heat dissipation. In skeletal muscle, expressions of the peroxisome proliferator-activated receptor β/δ target genes (Cpt-1b, Angptl4, Adrp, and Ucp3) were induced. Pharmacological removal of BAs by inclusion of 0.5 weight % cholestyramine to the high fat SPH diet attenuated the reduction in abdominal obesity, the reduction in liver TAG, and the decrease in nonfasted plasma TAG and glucose levels. Induction of Ucp3 gene expression in muscle by SPH treatment was completely abolished by cholestyramine inclusion. Taken together, our data provide evidence that bile acid metabolism can be modulated by diet and that such modulation may prevent/ameliorate the characteristic features of the metabolic syndrome.