Effects of cereal type and feed particle size on morphological characteristics, epithelial cell proliferation, and lectin binding patterns in the large intestine of pigs.

The present study was undertaken to investigate the effects of cereal type and feed particle size on the morphological characteristics and epithelial cell proliferation of the large intestinal tissue in pigs. Forty pigs, weighing approximately 30 kg, were fed diets containing either coarsely or finely milled barley or wheat for a period of 4 wk. Tissue samples were taken from the cecum and from the proximal, medial, and distal colon at slaughter. The pigs fed the coarse diets had significantly larger crypts, in terms of height as well as volume, than did pigs fed the fine diets. The cereal type had no effect on the mucosal architecture. The epithelial cell proliferation, in terms of counted native mitoses in the crypts, was significantly higher in pigs fed the coarse barley diet than in pigs fed the coarse wheat diet or the fine diets. The volume of the mucin granules in the crypts constituted from 32 to 52% of the crypt volume and was greatest in the pigs fed the coarse diets. This effect of feed particle size was observed for neutral as well as for acidic mucins and sulfomucins. Lectin binding patterns indicated that more of the terminal sugars on glycoconjugates of the apical membrane on the mucosal surface were the sialic acid alpha-2,3 neuraminic acid, but less were mannose in the pigs fed the coarse barley diet. Distinct regional differences were observed among the intestinal sites. These included a decline in the epithelial cell proliferation and an increase in the volume of mucin in the crypts along the intestinal tract. Furthermore, the sialic acid alpha-2,3 neuraminic acid was more abundant in the medial colon than in the cecum; the contrary was seen for mannose and galactose. This study shows that the feed particle size of barley and wheat diets, more than the cereal type itself, affects the mucosal architecture, epithelial cell proliferation, and production and composition of the mucins in the large intestine of pigs. The study suggests that pigs fed a coarse diet are better protected against intestinal infections than pigs fed a fine diet.

Intestinal degradation in pigs of rye dietary fibre with different structural characteristics.

In order to investigate the effects of dietary fibre (DF) characteristics on carbohydrate degradation and the metabolism in the large intestine, pigs were fed on four rye-bread diets (based on whole rye, pericarp/testa, aleurone or endosperm) with differences in characteristics and amount of DF. The degradability of DF in the large intestine varied greatly between diets. The pericarp/testa DF was hardly degraded in the large intestine, whereas endosperm DF was extensively and rapidly degraded in the caecum. Caecal degradation of aleurone DF was also limited, leaving more material to be degraded in the colon. The undegradable pericarp/testa DF was characterized by high contents of lignin, cellulose, ferulic acids and highly substituted arabinoxylans (the major DF component in rye). Ingestion of this diet resulted in increased faecal bulk and reduced transit time, but with low colonic pH and the lowest concentrations of shortchain fatty acids (SCFA). The aleurone diet, on the other hand, led to a fermentation pattern which may be considered more optimal, with lower colonic pH and higher concentrations of SCFA, in particular butyric acid. Despite the large differences in carbohydrate fermentation only minor significant effects on the presence of protein degradation products and on histological measurements (height and diameter of colonic crypts and thickness of the muscularis external) were observed.

Morphological characteristics, epithelial cell proliferation, and crypt fission in cecum and colon of growing pigs.

Morphological characteristics and cellular proliferation were investigated in the hindgut tissue of 25 pigs ranging from 5 to 261 days of age; the three youngest pigs were unweaned. Tissue samples were taken from the cecum and from the proximal, middle, and distal part of the colon. In the young pigs a high incidence of branched crypts was observed. During the first three to four months there was an increase in crypt height and proliferative activity, as determined by the mitotic count, as well as an increase in the mucin secretion, especially the sulfomucins. Distinct regional differences were observed between the four intestinal sites. In general, the crypts were deeper and more closely spaced and the turnover time was higher in the distal part of the colon as compared to the cecum and the proximal colon. Furthermore, a greater proportion of the mucins in the middle and distal part of the colon are acidic or sulfated as compared to the cecum, where the mucins are more of the neutral type. These regional and age-related differences in morphological characteristics of the hindgut in pigs may have significance for the etiology of intestinal infections.

The influence of the period of adaptation on the digestibility of diets containing different types of indigestible polysaccharides in rats.

In balanced experiments with rats the influence of the period of adaptation on nutrient digestibility in diets containing cellulose (CEL), guar gum (GG), pectin (PEC) or retrograded high amylose maize starch (RS) was studied. Inclusion level was 80 g/kg diet DM except for the retrograded high-amylose maize starch, where the level was 316 g/kg diet DM. A diet containing normal maize starch only acted as a control diet (FF). The apparent digestibilities of DM, NSP, starch and protein were determined after adaptation periods of 4 d and 2, 4, 6 and 8 weeks. The digestibility of nutrients was affected by diet (P < 0.001) as well as by the period of adaptation (P < 0.001). The digestibilities of DM, NSP and starch increased asymptotically during the course of the experiment. The asymptotic progress over time was most pronounced for the GG, PEC and RS diets. The estimated periods of adaptation required for stable DM digestibility were approximately 1 week for the GG, PEC and RS diets and < 4 d for the FF and CEL diets. The digestibility of NSP in the GG and PEC diets was also stable after approximately 1 week, while it was stable from < 4 d for the CEL diet. However, PEC increased the faecal content of uronic acids for at least 2 weeks. A stable starch digestibility required 1 month in the case of RS and 3-10 d for the other diets. The high faecal content of glucose for the RS diet decreased during all 8 weeks but was still high at the close of the experiment. The apparent protein digestibility changed over time in a parabolic rather than an asymptotic fashion. The GG, PEC and RS diets increased the amount of N excreted by the faecal route.

Protein quality and digestibility of new high-lysine barley varieties in growing rats.

Four new high-lysine barley mutants, the variety 'Lysimax', with the high-lysine gene lys3a and the mutants mother variety 'Sultan' were grown in a field trial in 1993 at Risø, Denmark. Mutants 609, 1242, 1385 and 1405 yielded in the range of 89 to 98 percent and cv 'Lysimax' yielded 102 percent of cv 'Sultan' (100 percent). One-thousand kernel weights for the mutants were in the range of 87 to 97 percent and cv 'Lysimax' 83 percent of cv 'Sultan' (100 percent). Protein contents of the mutants were slightly higher, in the range of 13.2 to 13.6 percent, than of cv 'Sultan' (13.1 percent) and 'Lysimax' which had a protein content of 12.6 percent. Fat content was higher in 'Lysimax' and in the mutants except for mutant 1385 than in cv 'Sultan' while dietary fibre contents of the barleys were similar. The levels of beta-glucans and starch were usually lower in 'Lysimax' and in the mutants. The highest lysine levels: 4.6, 4.0 and 3.7 g/16 g N occurred in cv 'Lysimax' and mutants 609 and 1405 compared to 3.3, 3.3 and 3.2 for cv 'Sultan' and mutants 1242 and 1385, respectively. Mutants 609 and 1405 and cv 'Lysimax' also had higher levels of threonine, histidine and valine. The increased lysine contents resulted in large, at most 20 percent, increases in biological value; 88.8, 81.7 and 78.3 percent for cv 'Lysimax' and mutants 609 and 1405 compared to 74.2 percent for cv 'Sultan'. True protein digestibilities and energy digestibilities were slightly lower in 'Lysimax' than in 'Sultan', 5.3 and 4.3 percentage units, respectively. It is concluded that the development of high-lysine barley varieties is very beneficial for meeting the requirements of indispensable amino acids for humans and monogastric animals. In addition, nitrogen excretion into the environment is drastically reduced due to the higher biological values of the mutants.

Gastrointestinal growth in rats as influenced by indigestible polysaccharides and adaptation period.

Hypertrophy of the small intestinal tissue evolved during the initial 9 days in rats fed pectin or guar gum. Hypertrophy of the caecal and colonic tissue continued beyond day 9. Caecal hypertrophy was observed in rats fed pectin, guar gum or resistant starch, while colonic hypertrophy was observed only in rats fed pectin or resistant starch. There is a time lag in the adaptive response of the caecum and colon as compared with the small intestine, at least for dietary polysaccharides. This time lag is suggested to be related to the time required for the microflora to adapt to the dietary PS.

Influence of growth conditions on the value of crisphead lettuce. 3. Protein quality and energy density as determined in balance experiments with rats.

Crisphead lettuce was cultivated under different growth conditions. Sixteen batches differed in time of planting (early and late), total nitrogen supply (200 kg N/ha, 150 kg N/ha, 100 kg N/ha, 50 kg N/ha) and time of harvest (early and late). Based on chemical analysis and balance studies on rats the nutritive value of each 16 batches was determined. The protein content increased progressively from 16.00 to 19.88% with fertilization level. This increase in protein caused a significant drop in essential amino acids (g/16 g N) demonstrating a lower biological value of this protein. Early planting or early harvest resulted in a higher protein content than in lettuce of late planting or late harvest. Total dietary fibre content was approximately 25% of DM-and this value was not much influenced by the different growth conditions. Soluble dietary fibre was approximately 20-25% of total dietary fibre. Due to the high fibre content, energy digestibility was relatively low. The contents of Cd and Pb were below what is considered as 'acceptable' levels.

Effect of dietary fiber (soy polysaccharide) on the severity, duration, and nutritional outcome of acute, watery diarrhea in children.

OBJECTIVE: To assess the effects of dietary fiber (soy polysaccharide) on the severity, duration, and nutritional outcome of acute, watery childhood diarrhea. METHODS: A total of 34 hospitalized Peruvian male infants between 2 and 24 months of age were randomly assigned to receive a soy-protein isolate, lactose-free formula with added soy polysaccharide (group SF, n = 19) or the same diet without added fiber (group S, n = 15). The consumption of formulas, stool amount and consistency, absorption of macronutrients, and change in anthropometric status were measured. RESULTS: Children in both groups were initially similar with regard to age, nutritional status, and prior duration and severity of diarrhea. Four patients in group SF (21%) and two in group S (13%) failed therapy because of recurrent dehydration or severe purging (P = .67). Formula intakes increased slightly during hospitalization (P = .03), but did not vary by dietary group (P = .73). Stool outputs declined significantly (P < .001) during hospitalization, but there were no significant differences by dietary group in either stool wet weight (P = .83) or dry weight (P = .87). Estimated median durations of liquid stool excretion after hospitalization were 43 hours in group SF and 163 hours in group S (P = .003). There were no significant differences in fractional or net absorption of macronutrients or change in anthropometric status by dietary group. CONCLUSIONS: Soy polysaccharide, while not affecting stool output, macronutrient absorption, or nutritional status during acute, watery childhood diarrhea, significantly and markedly reduced the duration of liquid stool excretion.