Bjørn O. Eggum

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.

Blood urea measurement as a technique for assessing protein quality.

1. Three factors were investigated which influence blood urea content, namely the protein content in the diet, the time after feeding and the protein quality of the diet. 2. To investigate the relationship between the protein content in the diet and the blood urea content, seventeen experiments with rats given increasing amounts of protein in the diet were carried out. The experimental results show that there is a positive correlation (r = 0.95) between the protein content in the diet and the blood urea content. 3. For investigation of the influence of time after feeding on the urea content in the blood, a pig was used having a catheter in the portal vein for blood sampling at intervals. The results from this experiment showed that the blood urea content increases for the first 3–4 h after feeding and thereafter reaches a plateau. 4. To use blood urea measurement as a technique for assessing protein quality it is necessary to work under standardized conditions, especially in regard to the two factors just discussed. 5. Forty-two feeding-stuffs of widely differing quality were used in nitrogen balance trials with rats. The results showed that there is an inverse relation between the blood urea content and the biological value of the diet which is sufficiently accurate (coefficient of variation = 53%) to provide ausefulmethod for the predictionof protein quality from measurement of urea levels.

The influence of dietary fibre source and level on the development of the gastrointestinal tract, digestibility and energy metabolism in broiler chickens

The present study was undertaken to provide detailed information about the effect of fibre source (pea fibre, wheat bran or oat bran) at inclusion levels of 0, 187 and 375 g/kg diet on the development of the digestive tract, nutrient digestibility and energy and protein metabolism in broiler chickens. Heat production was measured using open-air-circuit respiration chambers. Diets with increasing levels of pea fibre decreased the DM in droppings and increased excreta output (2.5-fold) relative to DM intake. Adaptation to increased dietary fibre levels included increases in the size of the digestive system, with pea fibre exerting a stronger impact than wheat bran or oat bran. The length of the intestine, and particularly the length and weight of the caecum, increased with the fibre level. The digestibility of all nutrients also decreased with increasing fibre level. The decrease in the digestibility in relation to NSP for the three fibre sources was bigger for oat bran (0.0020 per g dietary NSP) than for pea fibre and wheat bran (0.0014 and 0.0016 per g dietary NSP) indicating that the cell walls in oat bran (aleurone and subaleurone) had a significant negative effect on the digestibility of cellular nutrients, i.e. protein and fat. The degradation of the NSP constituents was far lower in chickens than found in other animal species such as pigs and rats, thus supporting the view that chickens do not ferment fibre polymers to a great extent. Excretion of organic acids (mainly lactic acid and acetic acid) accounted for up to 2% of metabolizable energy (ME) intake with the highest excretion for the high-fibre diets. H2 excretion was related to the amount of NSP degraded and indicated higher microbial fermentation with increasing fibre levels. The chickens feed intake responded to a great extent to dietary ME concentration but expressed in terms of metabolic body size (W0.75) ME intake was depressed at the high fibre levels. Dietary NSP was able to explain between 86% (oat bran) and 96% (pea fibre) of the variation in ME concentration. The amount of energy available from fermentation of NSP appears to reach a maximum of 42 kJ/d independent of fibre source and level. Expressed in relation to ME intake the NSP fermentation contributed 3-4%. With increasing fibre intake the partitioning of retained energy between body protein and body fat changed in favour of protein.

Gene for Improved Nutritional Value in Barley Seed Protein

Genetically dependent 20 to 30 percent increase in lysine per 16 grams of nitrogen results in improved nutritional values in feeding trials with mice and rats. The recessive gene was selected from the World Barley Collection. Other amino acids are also influenced by the gene. Protein content segregates independently of the changed amino acid pattern. The gene putatively influences the matrix proteins, which characteristically adhere to the starch grains in meal preparations. The morphological character permits rapid microscopic screening of single seeds without affecting viability. Low yield is considerably improved by crossing and selection.

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.

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...

The Influence of Rapeseed Oil on Digestibility, Energy Metabolism and Tissue Fatty Acid Composition in Pigs

Abstract The influence of rapeseed oil on digestibility, energy metabolism and tissue composition in growing pigs was determined. Rapeseed oil (0, 4, 8 and 16%) was added to a soyabean meal and barley basal diet. Essential amino acids relative to net energy (NE) were kept constant by adjusting with crystalline amino acids. Rapeseed oil has a high content of the unsaturated fatty acids 18:1n-9, 18:2n-6 and 18:3n-3, and is rich in natural tocopherols, which act as antioxidants. The apparent protein digestibility was enhanced with increasing levels of rapeseed oil. Improving the ratio of essential to non-essential amino acids decreased nitrogen execretion in faeces and urine by 21% and 26%, respectively. The amount of digestible fat increased from 29 to 218 g day−1 from the control diet to the diet with 16% rapeseed oil, resulting in a fat retention of 195 to 213 g day−1. This demonstrates the ability of pig for de novo synthesis of fatty acids. The digestibility of the rapeseed oil was high (92.7), and the ...

The energy value of short-chain fatty acids infused into the caecum of pigs

The present work was undertaken to study the energy value of a mixture of acetic, propionic and butyric acids (0.682:0.226:0.092) infused intracaecally in growing pigs. A basal diet low in fibre (42 g NSP/kg DM) was given at below the requirement for maximum weight gain. In six 2-week periods, N and energy balance measurements in eight growing pigs were carried out with and without infusion of short-chain fatty acids (SCFA). Heat production was measured using open-circuit chambers and the concentration of SCFA in faeces was determined. Less than 1% of the infused SCFA was excreted in faeces illustrating the capacity of the hind-gut to absorb and metabolize SCFA. Infusion of SCFA did not affect the digestibility of nutrients and energy. However, N retention increased demonstrating that SCFA are an energy source for protein gain when pigs are fed at below the requirement of energy. Increased CH4 production together with an increased excretion of branched-chain fatty acids in faeces suggested that there was a higher microbial activity in the hind-gut during infusion. The partial utilization of the infused energy in SCFA was 0.821. A small proportion of the infused energy in SCFA was retained in protein (0.099) and a considerable amount was retained as fat (0.722).

Dehulled protein-rich rapeseed meal as a protein source for early weaned piglets

Abstract Dehulled protein-rich rapeseed meal (DPR-meal) was produced by aqueous enzymatic extraction. Based on chemical analyses and balance experiments with piglets, the nutritive value was determined. The dry matter of the DPR-meal contained 56% crude protein, 27% HCl-fat, 12% carbohydrates, 5% ash and 1 μmol g −1 glucosinolates. Four diets containing 0, 6, 12 and 18% DPR-meal were manufactured and tested in a balance trial as well as in two production trials with 4-week-old weaned piglets. In the balance trial, 16 pigs were reared in single cages and fed semi ad libitum. Each production trial was performed with 80 pigs, reared in pairs and fed ad libitum. The period of treatment lasted 4 weeks. Substitution of the highly digestible protein sources skim milk powder and fish meal with DPR-meal caused decreased digestibility of protein and energy with increasing dietary levels of DPR-meal. Deposited N and deposited N as a percentage of digested N were equal for the four diets. In addition, no negative effects on protein utilisation from the glucosinolates were observed. The decrease in digestibility of energy ( r 2 = 0.91) and protein ( r 2 = 0.90) correlated well with the insoluble dietary fibre (IDF) content. In the first production trial a significant decrease in voluntary feed intake and reduced growth rate ( P ⩽ 0.001) of the pigs with increasing levels of DPR-meal was observed. In the second production trial, in which flavouring (Flavodan SW-783) was added to the DPR-meal, the decrease in voluntary feed intake was almost halved and the growth rate was not significantly affected ( P ⩾ 0.05). In both production trials the feed to gain ratio was unaffected by the level of DPR-meal in the diets.

Protein digestibility of a feed mixture in a relation to the protein digestibility of the individual protein components

1. Protein digestibility of two proteins was measured when these proteins were given together and separately to rats. 2. The influence of carbohydrates on protein utilization (true protein digestibility, biological value and net protein utilization) was also studied. Autoclaved potato starch was replaced by increasing amounts of glucose, sucrose, fructose and lactose respectively. Glucose, fructose and sucrose appeared to have no specific influence on protein utilization when given in increasing amounts and when compared with autoclaved potato starch. Higher concentrations of lactose, however, caused diarrhoea. 3. The true digestibility of the protein components in a mixture was directly related to the true digestibility of each protein component, including proteins of low digestibility.