Dietary fibre has been proposed to decrease risk for colon cancer by altering the composition of intestinal microbes or their activity. In the present study, the changes in intestinal microbiota and its activity, and immunological characteristics, such as cyclo-oxygenase (COX)-2 gene expression in mucosa, in pigs fed with a high-energy-density diet, with and without supplementation of a soluble fibre (polydextrose; PDX) (30 g/d) were assessed in different intestinal compartments. PDX was gradually fermented throughout the intestine, and was still present in the distal colon. Irrespective of the diet throughout the intestine, of the four microbial groups determined by fluorescent in situ hybridisation, lactobacilli were found to be dominating, followed by clostridia and Bacteroides. Bifidobacteria represented a minority of the total intestinal microbiota. The numbers of bacteria increased approximately ten-fold from the distal small intestine to the distal colon. Concomitantly, also concentrations of SCFA and biogenic amines increased in the large intestine. In contrast, concentrations of luminal IgA decreased distally but the expression of mucosal COX-2 had a tendency to increase in the mucosa towards the distal colon. Addition of PDX to the diet significantly changed the fermentation endproducts, especially in the distal colon, whereas effects on bacterial composition were rather minor. There was a reduction in concentrations of SCFA and tryptamine, and an increase in concentrations of spermidine in the colon upon PDX supplementation. Furthermore, PDX tended to decrease the expression of mucosal COX-2, therefore possibly reducing the risk of developing colon cancer-promoting conditions in the distal intestine.

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Betaine and its precursor choline were compared in their efficiency in affecting the performance, carcass traits, and liver betaine concentration of growing-finishing pigs. Individually penned Finnish Landrace and Yorkshire pigs and their crosses (30 kg; no. = 70) were offered the basal diet with no added betaine or choline, or the basal diet supplemented with low to moderate doses (250, 500 or 1000 mg/kg) of betaine (Betafin® S1), or with a similar molar amount of choline (578, 1155 or 2310 mg/kg of choline chloride). The maize-soya-bean-meal basal diet was formulated to contain 12·3 MJ/kg digestible energy, 155 g/kg crude protein and 7·4, 4·4 and 4·3 g/kg digestible lysine, threonine and methionine + cystine, respectively. Oat hull meal (100 g/kg) was added to reduce the dietary energy concentration. The pigs were on a restricted feeding level, 1·5 to 3·0 kg food per day (proportionately 0·8 of ad libitum intake) for 75 days. Daily weight gain and food-to-gain ratio improved linearly (P < 0·01) with increasing dietary betaine. Carcass weight increased linearly (P < 0·01) but slaughter loss proportion, backfat and sidefat thicknesses and lean proportions in ham and carcass were unaffected by dietary betaine level. Liver betaine level increased linearly (by up to a proportion of 0·62 in comparison with the control) with dietary betaine addition (F < 0·05) and betaine tended to improve linearly the tensile strength of the proximal ileum (P = 0·07). The presence of choline had no effect on any of these parameters. These results indicate that low to moderate doses of dietary betaine improved the growth and the efficiency of food utilization of growing-finishing pigs. Pigs on betaine diets had heavier carcasses without a relative increase in carcass fat. Choline had no such effects in pigs offered the restricted amount of diet. Liver betaine concentration increased with level of betaine in the diet whereas the betaine precursor choline did not affect hepatic betaine.

In general, there is a lack of scientific documentation of nutritional value of marine by-products. The bone fraction from fish has been regarded as waste. Due to the high mineral content of fish bones, this material can be well suitable as a natural calcium source. In the present study, apparent calcium absorption of different fish bone sources was tested using growing pigs. The experimental diets consisted of boiled salmon frames, or salmon, saithe or cod bones treated with enzymes. Calcium carbonate (CaCO(3)) was used as control. The experimental diets were formulated to contain 0.7% total calcium of which the added calcium source to be tested contributed about 71% (study 1) and 86% (study 2). Except for the calcium and phosphorus sources, the animals received similar basal diets. Apparent calcium digestibility coefficient was calculated using yttrium as indicator (both studies) and was based on complete collection of faeces and urine (study 2). The experimental design was parallel and cross-over in study 1 and study 2, respectively. In study 1, piglets getting salmon bone treated with enzymes had significantly higher calcium absorption than piglets getting boiled fish bone or calcium carbonate. Therefore, in the second study only enzymatically treated fish bones were included. The higher calcium absorption from enzymatically treated salmon bone was also found in study 2, but this time not significant. Calcium from boiled salmon bones in study I, and from enzymatically treated saithe and cod bones in study II were absorbed as well as the calcium carbonate control. The results indicate that fish bones may be a useful and well absorbed calcium source. Due to the high mineral content of the bone fraction, salmon bones can be well suitable as a natural calcium and phosphorus source in, for example, food, feed or as supplement.

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