Cholate and deoxycholate counteract the calcium-induced lowering of fat digestion in rats

The objective of the present experiment was to investigate whether deoxycholate and cholate would differ in their effectiveness of counteracting the inhibitory effect of calcium on fat digestibility in rats. Rats were fed one of four experimental diets, a diet low in calcium, high in calcium or high in calcium with either 0.5% sodium cholate or 0.5% sodium deoxycholate. Both deoxycholate and cholate supplementation of the high-calcium diet reduced feed intake and body-weight gain. Low-calcium intake increased fat digestibility. Supplemental bile acids partially counteracted the calcium-induced inhibition of fat digestion, cholate being more effective than deoxycholate. The outcome is explained by the suggestion that cholate is bound to the calcium phosphate sediment in the small intestinal lumen with less affinity than deoxycholate. As a result, more cholate than deoxycholate would be available to support the process of fat digestion. Rats fed cholate had higher liver and serum cholesterol concentrations than did the rats fed deoxycholate.     

Faecal bacterial profile,nitrogen excretion and mineral absorption in healthy dogs fed supplemental oligofructose

In a cross-over trial, five healthy dogs were fed a dry food without or with 1% (w/w) oligofructose to assess any oligofructose-induced effects on the faecal bacterial profile, nitrogen excretion and mineral absorption. The diets were given for a period of 3 weeks. Oligofructose feeding significantly raised the number of Bifidobacteria, Streptococci and Clostridia in faeces. The numbers of faecal anaerobic and aerobic bacteria were raised after ingestion of oligofructose. The faecal pH was unchanged. There was no effect of oligofructose feeding on the route of nitrogen excretion which was associated with a lack of effect on faecal ammonium and urinary urea excretion. It is suggested that the absence or presence of an effect of oligofructose on urinary and faecal nitrogen excretion depends on the background composition of the diet, in particular the content of non-digestible, fermentable carbohydrates. In the diets used, the content of non-digestible, fermentable carbohydrates was not measured. Both apparent magnesium and calcium absorption were significantly raised by oligofructose feeding, but phosphorus absorption was unaffected. The data presented may contribute to the qualification of the use of oligofructose in dog foods.     

The influence of dietary linoleic and alpha-linolenic acid on body composition and the activities of key enzymes of hepatic lipogenesis and fatty acid oxidation in mice

We have recently suggested that feeding the C18 polyunsaturated fatty acid, alpha-linolenic acid (ALA), instead of linoleic acid (LA) reduced body fat in mice. However, the difference in body fat did not reach statistical significance, which prompted us to carry out this study using more animals and diets with higher contents of ALA and LA so that the contrast would be greater. The diets contained either 12% (w/w) LA and 3% ALA or 12% ALA and 4% LA. A low-fat diet was used as control. The diets were fed for 35 days. The proportion of body fat was not influenced by the type of dietary fatty acid. Plasma total cholesterol and phospholipids were significantly lower in ALA-fed mice than in mice fed LA. Activities of enzymes in the fatty acid oxidation pathway were significantly raised by these two diets when compared with the control diet. alpha-Linolenic acid vs. LA did not affect fatty acid oxidation enzymes. In mice fed the diet with LA activities of enzymes of de novo fatty acid synthesis were significantly decreased when compared with mice fed the control diet. alpha-Linolenic acid vs. LA feeding did not influence lipogenic enzymes. It is concluded that feeding mice for 35 days with diets either rich in LA or ALA did not significantly influence body composition.     

Clinicopathology of gout in growing layers induced by high calcium and high protein diets

1. An experiment was conducted to test the independent and combined effects of high dietary calcium and protein concentrations on the induction of visceral gout in growing birds of a layer strain. 2. One hundred and sixty healthy birds were randomly divided into 4 groups at 35 d of age. The different groups were given 4 diets containing normal or high concentrations of dietary calcium or crude protein in a 2 x 2 factorial experiment for 30 d. The diets contained normal calcium (Ca) and crude protein (CP) (NCNP, 8.5 g Ca/kg and 175g CP/kg), high calcium and normal protein (HC, 36.3 g Ca/kg and 175 g CP/kg), normal calcium and high protein (HP, 8.8 g Ca/kg and 245 g CP/kg) or high calcium and high protein (HCHP, 36.8 g Ca/kg and 242 g CP/kg), respectively. 3. Typical visceral gout was induced by the HCHP diet. The HCHP and HC diet caused severe kidney damage. The HP diet did not cause kidney damage, but significantly increased plasma uric acid and inorganic phosphorus concentrations. 4. The HC diet significantly increased plasma uric acid, calcium and sodium, but significantly decreased plasma inorganic phosphorus, potassium and magnesium concentrations. The HCHP diet significantly increased plasma uric acid, calcium and sodium. 5. Urine volumes were significantly higher on the HCHP and HC diets than on the control. The growers raised on HC and HCHP diets had significantly higher total quantity of 24 h urinary excretion of uric acid, calcium, magnesium, inorganic phosphorus and potassium and a significantly lower 24 h urinary excretion of sodium. The growers fed on the HP diet had a higher 24 h urinary excretion of uric acid and inorganic phosphorus than the control. 6. It is concluded that growing layer birds should not be fed on layer rations.     

Xylanase and beta-glucanase supplementation improve conjugated bile acid fraction in intestinal contents and increase villus size of small intestine wall in broiler chickens fed a rye-based diet

This study was performed with growing chickens (4 to 22 d of age) to evaluate the effects of feeding a rye-based diet supplemented with commercial enzyme preparation containing xylanase and beta-glucanase (Quatrazyme HP, Nutri-Tomen, France) on small intestine wall morphology, bile acid composition, nutrient digestibility, and bird performance compared with unsupplemented rye- or corn-based diets. The rye-based diet decreased (P < or = 0.05) weight gain, feed intake, and feed efficiency and increased water intake compared with the corn-based diet. Moreover, rye consumption reduced crude fat and protein digestibility as well as apparent metabolizable energy (P < or = 0.05). The small intestine wall showed that villus length, width, and surface were decreased in broiler chickens fed the rye-based diet compared with those fed the corn-based diet. However, crypt morphometry parameters were not affected by diet type. The concentration of conjugated bile acids in the small intestine contents of broiler chickens fed the rye-based diet was decreased (P < or = 0.05) compared with those fed the corn-based diet. These findings suggest that feeding a rye-based diet reduces villus capacity for nutrient absorption and bile acid capacity for fat solubilization and emulsification, resulting in decreased bird performance. The addition of xylanase and beta-glucanase to the rye-based diet improved (P < or = 0.05) weight gain, feed intake, and feed efficiency, and decreased water intake. The digestibility of nutrients and apparent metabolizable energy were also increased (P < or = 0.05). Addition of xylanase and beta-glucanase increased (P < or = 0.05) villus size and the villus height-to-crypt depth ratio, as well as the concentration of conjugated bile acids (P < or = 0.05) in the small intestine contents. Exogenous enzymes improved nutrient digestibility and broiler chicken performance, probably by improving the absorption capacity ofthe small intestine through increased villus surface and intestinal concentration of conjugated bile acids.     

Dietary lactulose decreases apparent nitrogen absorption and increases apparent calcium and magnesium absorption in healthy dogs

To study the effect of lactulose on the route of nitrogen excretion, we fed six healthy, adult dogs on diets containing either 0, 1 or 3 g lactulose/MJ metabolizable energy according to a 3 × 3 Latin square design. The results were analysed to identify statistically significant linear trend effects of lactulose. Faecal pH was significantly lowered by lactulose. Faecal ammonium and nitrogen excretion tended to be raised by lactulose feeding whereas urinary urea excretion was significantly reduced. Lactulose feeding significantly lowered apparent nitrogen digestibility. It is concluded that lactulose feeding shifts nitrogen excretion from urine to faeces in dogs which may be beneficial for liver patients. The data are in line with the concept that lactulose stimulates bacterial growth in the colon which in turn enhances faecal nitrogen excretion and lowers the entry of colonic ammonia into the bloodstream, leading to a lesser workload for the liver and less urinary nitrogen excretion. Lactulose consumption was also found to produce a dose-dependent increase in the apparent absorption of calcium and magnesium, but not phosphorus.     

水貂不同赖氨酸、蛋氨酸水平颗粒饲料对营养物质消化代谢的影响

为确定水貂适宜氨基酸组成、降低饲料成本,试验选取成年健康公母水貂各60只,随机分成6组,采用2×3因子试验设计,即赖氨酸2个水平,分别为1.85%和1.7%,蛋氨酸3个水平分别为0.81%、0.99%和1.24%,对采食正常试验组水貂进行了消化代谢试验。结果表明:①日粮赖氨酸水平的变化对公母貂干物质摄入、排出及消化率影响不显著(P>0.05);蛋氨酸水平的变化对母貂干物质摄入、排出及消化率影响不显著(P>0.05),公貂粪干物质排出量蛋氨酸水平为0.99%组显著低于蛋氨酸水平为1.24%组(P<0.05),公貂干物质消化率蛋氨酸水平为0.99%组极显著地高于蛋氨酸水平为0.81%组和1.24%组(P<0.01)。②日粮赖氨酸水平的变化对公母貂有机物摄入、排出及消化率影响不显著(P>0.05);蛋氨酸水平的变化对公母貂有机物摄入、排出及母貂消化率影响不显著(P>0.05),公貂蛋氨酸水平为0.99%组有机物消化率显著高于蛋氨酸水平为0.81%组(P<0.05),与蛋氨酸水平为1.24%组差异不显著(P>0.05)。③公母貂蛋白质消化代谢受赖氨酸水平变化的影响不显著(P>0.05);公母貂蛋白质摄入及粪蛋白的排出受蛋氨酸水平变化影响不显著(P>0.05),蛋氨酸为1.24%时公貂尿蛋白排出显著高于0.99%水平组(P<0.05),与0.81%水平组尿蛋白排出差异不显著(P>0.05);公貂蛋白存留0.99%水平组极显著高于1.24%水平组(P<0.01);公貂蛋白质消化率0.99%水平组显著高于1.24%水平组(P<0.05),与0.81%水平组差异不显著(P>0.05);母貂蛋氨酸水平变化对各消化代谢率指标影响不显著(P>0.05)。④1.85%赖氨酸水平组公貂赖氨酸摄入、尿排出及消化代谢率均显著高于1.7%赖氨酸水平组(P<0.05),母貂间差异不显著(P>0.05),赖氨酸水平对公母貂蛋氨酸摄入、粪尿排出及消化代谢率无显著影响(P>0.05);蛋氨酸水平对公母貂赖氨酸摄入、粪尿排出无显著影响(P>0.05),蛋氨酸0.99%水平公貂赖氨酸消化代谢率均极显著高于蛋氨酸1.24%水平和0.81%水平公貂(P<0.01),蛋氨酸水平对母貂间赖氨酸消化代谢率无显著影响(P>0.05);蛋氨酸水平对公母貂蛋氨酸摄入、粪尿排出及消化代谢率均有显著影响(P<0.05),随着蛋氨酸水平的降低,蛋氨酸的摄入逐渐降低,而尿排出蛋氨酸1.24%组显著高于0.99%和0.81%水平组(P<0.05);蛋氨酸0.99%和1.24%水平组公母貂蛋氨酸的消化代谢率均极显著高于0.81%水平组(P<0.01),蛋氨酸0.99%和1.24%水平组公母貂蛋氨酸的消化代谢率无显著差异(P>0.05)。     

High calcium intake lowers apparent digestibility of energy in veal calves.

Veal calves aged 8 weeks were fed iso-energetic amounts of milk replacers with either a low (7.1 g of calcium/kg of air-dry diet) or a high concentration of calcium (11.6 g of calcium/kg of air-dry diet) for a period of 10 weeks. The extra calcium was added in the form of calcium formiate. Final body weight of the two dietary groups was similar. Faeces were collected during the final week of the trial. The high calcium diet raised faecal dry matter output by 87% and faecal energy by 70%. The extra output of faecal dry matter was composed of 36% and 37% of crude fat and ash, respectively. The extra faecal energy output was for 75% in the form of crude fat. The high versus low calcium intake not only depressed apparent digestibility of total lipids but also that of crude protein, carbohydrates and ash. It is concluded that a high calcium intake by veal calves reduced energy availability without affecting body weight gain.     

High intake of calcium formiate depresses macronutrient digestibility in veal calves fed milk replacers containing either dairy proteins or whey protein plus soya protein concentrate

A study to determine whether calcium intake and the type of dietary protein would show an interaction with regard to macronutrient digestibility in veal calves was carried out. Eighty four male calves, about 8 weeks of age, were fed four experimental milk replacers in a 2  2 factorial design. The diets contained either dairy protein as a sole source of protein or whey protein (76% of total protein) plus soya protein concentrate (24% of total protein) and either a low or high concentration of calcium. Calcium was added to the high-calcium diets in the form of calcium formiate. The concentration of calcium was on average 0.64% of air-dry matter in the low-calcium rations and 1.25% in the calcium-rich rations. After the experimental diets had been fed for 10 weeks, body-weight gain was significantly lower (on average 5.5 kg) in the calves that had been fed on the diets containing soya protein concentrate and whey protein. Calcium intake did not significantly influence weight gain. In the calves that were fed soya proteins, digestibility of protein and carbohydrates was significantly lower than in those fed dairy protein only, but fat digestion was unaffected. High calcium intake significantly reduced the digestibility of protein, fat and carbohydrates. With regard to carbohydrate digestibility there was an interaction between the amount of calcium and type of protein in the diet such that the effect of calcium was greater when the diet contained 24% of protein in the form of soya protein instead of dairy protein only.     

Effect of partial replacement of oats with sugar beet pulp and maize oil on nutrient utilisation in horses.

The objective of the present work was to assess the influence of partial replacement of oats with dried unmolassed sugar beet pulp (SBP) and/or maize oil on nutrient utilisation in horses fed a traditional hay and concentrate diet. The total tract digestibility of nutrients, urinary excretion and plasma parameters were studied in a 4 x 4 Latin-square design experiment with purebred Arabian geldings. Horses fed the SBP diets responded with a reduced (P<0.05) apparent digestibility of crude protein and feeding of maize oil resulted in an increased (P<0.05) apparent digestibility of crude fat. The apparent energy digestibility was unaffected by the replacement of oats with SBP, but increased (P<0.05) when maize oil replaced part of the oats. The urinary excretion of nitrogen increased (P<0.05) when maize oil replaced oats and the excretion of energy was higher (P<0.05) on the diets where oats were replaced by maize oil and SBP. There was a significant (P<0.05) effect across treatments of postprandial blood sampling time on plasma glucose and insulin concentrations. Also, plasma concentrations of glucose and insulin tended to be higher on the oats than on the SBP diets. In conclusion, the limited effects on the digestibility of nutrients and energy suggest that it should be possible to partially replace oats with maize oil and/or SBP in diets for horses without any impairing effects on the overall nutrient utilisation. However, the dietary-induced changes in the urinary excretion of energy and on plasma glucose and insulin levels, indicate a possible influence of dietary carbohydrate composition on nutrient utilisation at the organ level, which requires further study.     

The effects of phytase and phytic acid on the loss of endogenous amino acids and minerals from broiler chickens

1. The effects of myo-inositol hexaphosphate (IP6) and phytase (EC 3.1.3.26) on the excretion of endogenous compounds were investigated using growing broiler chickens. 2. A total of 32 female Ross broilers were used in a precision feeding assay involving a 2 x 2 factorial arrangement of treatments. The materials administered were glucose, glucose + 1000 units of phytase activity (FTU), glucose + 1 g of IP6 and glucose + 1 g of IP6 + 1000 FTU. Excreta were collected quantitatively over a 48-h period following intubation of the test materials. The excretion of nitrogen, amino acids, minerals, sialic acid and phytate phosphorus was determined. 3. The ingestion of 1 g of IP6 by broilers increased the excretion of endogenous nitrogen, amino acids, iron, sodium, sulphur and sialic acid compared with birds fed on glucose. Supplementation of IP6 with exogenous phytase reduced the excretion of endogenous amino acids, calcium, sodium, phytate phosphorus and sialic acid compared with birds fed IP6. 4. It can be concluded that IP6 increases the excretion of endogenous minerals and amino acids in broiler chickens. Part of the beneficial effects of the addition of exogenous phytases to the diets of poultry appears to be mediated through a reduction in endogenous losses of these nutrients.     

Macronutrient digestibility, nitrogen balance, plasma indicators of protein metabolism and mineral absorption in horses fed a ration rich in sugar beet pulp

In a cross-over study with six mature horses, the effect of iso-energetic replacement of dietary glucose by beet pulp on macronutrient digestibility, nitrogen metabolism and mineral absorption was studied. The test ration contained 25% beet pulp in the total dietary dry matter. Beet pulp feeding significantly lowered crude fat and non-structural carbohydrate digestibility, but had no significant effect on digestibility of other macronutrients, faecal and urinary nitrogen excretion and the faecal to urinary nitrogen excretion quotient. However, on the beet pulp diet, plasma ammonia and creatinin concentrations were significantly lower than on the glucose diet. No diet effect on magnesium absorption was observed. It is suggested that dietary beet pulp stimulates the conversion of ammonia into urea.     

Effects of Dietary Zinc and Calcium on Select Immune Functions of Channel Catfish

Abstract

The effects of dietary zinc and calcium on immunocompetence of channel catfish Ictalurus punctatus (mean initial weight = 3.1 g/fish) were determined after a 10-week feeding trial. Fish were fed daily amounts equal to 3% of their body weight of one of six purified diets that were deficient in zinc (2 mg/kg of diet), calcium (0.02% of diet), or both; replete with zinc (20 mg/kg of diet) and calcium (0.5% of diet); or excessive in zinc (200 mg/kg of diet) or calcium (2.5% of diet). Immunocompetence of immunized and nonimmunized fish fed the various diets was assessed by measuring serum immunoglobulin M levels and mortality after an intraperitoneal injection of live Aeromonas hydrophila. Channel catfish fed diets deficient in zinc, calcium, or both had significantly (P ≤ 0.05) less weight gain and survival as compared with those fed diets replete with or excessive in zinc or calcium. Tissue mineral concentrations of fish indicated that various levels of zinc and calcium nutriture existed when immune functions were tested. Diet affected mortality of only nonimmunized fish in the bacterial-challenge test; zinc deficiency and calcium excess decreased mortality. Whereas growth and survival of fish were reduced by dietary zinc or calcium deficiency, the measured immunological characteristics were not equally impaired by these mineral deficiencies.     

Prediction of nutrient digestibility in grower-finisher pigs based on faecal microbiota composition

Microbiota play an important role in total tract nutrient digestion, especially when fibrous diets are fed to pigs. This study aimed to use metagenomics to predict faecal nutrient digestibility in grower-finisher pigs. The study design consisted of 160 three-way crossbreed grower-finisher pigs (80 female and 80 male) which were either fed a diet based on corn/soybean meal or a more fibrous diet based on wheat/barley/by-products. On the day before slaughter, faecal samples were collected and used to determine faecal digestibility of dry matter, ash, organic matter, crude protein, crude fat, crude fibre and non-starch polysaccharides. The faecal samples were also sequenced for the 16S hypervariable region of bacteria (V3/V4) to profile the faecal microbiome. With these data, we calculated the between-animal variation in faecal nutrient digestibility associated with variation in the faecal microbiome, that is the “microbiability”. The microbiability values were significantly greater than zero for dry matter, organic matter, crude protein, crude fibre and non-starch polysaccharides, ranging from 0.58 to 0.93, as well as for crude fat with a value of 0.37, but not significantly different from zero for ash. Using leave-one-out cross-validation, we estimated the accuracy of predicting digestibility values of individual pigs based on their faecal microbiota composition. The accuracies of prediction for crude fat and ash digestibility were virtually 0, and for the other nutrients, the accuracies ranged from 0.42 to 0.63. In conclusion, the faecal microbiota composition gave high microbiability values for faecal digestibility of dry matter, organic matter, crude protein, crude fibre and non-starch polysaccharides. The accuracies of prediction are relatively low if the interest is in precisely predicting faecal nutrient digestibility of individual pigs, but are promising from the perspective of ranking animals in a genetic selection context.     

The apparent digestibility of fibre in trotters when dietary soybean oil is substituted for an iso-energetic amount of glucose.

An attempt was made to quantify the effect of extra fat intake on fibre utilization in horses. In a 4 x 4 cross-over trial with feeding periods of 24 days each, eight mature trotting horses (age 4 to 12 years, 407 to 531 kg BW) were given four diets. The concentrates were formulated to contain either soybean oil or an iso-energetic amount of glucose or combinations of the two ingredients. The concentrates were fed in combination with the same amount of hay so that the whole diets contained 30, 50, 77 or 108 g EE/kg DM. Apart from the amounts of fat and glucose the four diets were identical. With an increase of 10 g/kg DM of soybean oil the apparent total tract digestibility of crude fibre was reduced with 0.9 percentage units. Extra fat intake also reduced apparent protein and NFE digestibility, but raised apparent fat digestibility. Although the present results may hold specifically for the conditions of this study, it is suggested that the observed interaction between fat content of the diet and macronutrient utilization might have consequences for practical horse feeding in that calculating the energy content of high-fat diets on the basis of feedstuff tables will lead to over- or underestimating the amount of energy provided by the various ingredients of the diets.     

Effects of lecithin and corn oil on site of digestion, ruminal fermentation and microbial protein synthesis in sheep

Six Hampshire wethers with ruminal and duodenal cannulas were fed three diets in a replicated 3 X 3 latin square to compare phospholipids with triglycerides for their effects on ruminal digestion. The diets (56% concentrate, 44% bermuda-grass hay, air-dried basis) contained either no added fat (control), 5.2% soybean lecithin or 2.4% corn oil on a DM basis. All diets were isonitrogenous and both fat-supplemented diets had similar fatty acid and energy contents. Fat added to the diet, regardless of source, reduced digestibilities of DM, energy, ADF and fatty acids in the rumen but had no effect on total tract digestibility coefficients. Lecithin slightly increased (P = .06) fatty acid digestion in the hindgut compared to corn oil (91.0 and 87.0%, respectively). Both fat sources decreased (P less than .01) ruminal ammonia concentration and increased (P less than .10) N flow to the duodenum. Added fat also reduced ruminal (P less than .01) and total tract (P less than .05) N digestibilities. Microbial N flow to the hindgut was not affected by diet, but adding fat increased (P less than .06) true efficiency of microbial protein synthesis. Overall, phospholipids from soybean lecithin inhibited ruminal fermentation similarly to triglycerides from corn oil. Despite ruminal degradation of lecithin by microbial phospholipases as shown in other studies, feeding lecithin tended to increase fatty acid digestion in the hindgut.     

Influence of cellulose fibre length on faecal quality,mineral excretion and nutrient digestibility in cat

In dogs, faeces quality and nutrients digestibility were affected by different types of cellulose ( Wichert et al., 2002 ). In this study, it was investigated whether there are comparable effects of cellulose type in cats. Seven adult, healthy cats were fed a moist commercial complete cat food with three different cellulose type added at a level of 4% for a 1 week period. Faeces quality was between 1 and 3 on the scale used from 1 to 5. The addition of long fibre cellulose resulted in significantly firmer faeces. Addition of cellulose decreased the digestibility of dry matter and energy, whereas the impact on protein and fat digestibility was not significant. The type of cellulose affected faecal bulk and faecal water excretion. Faecal excretion of sodium and potassium was exponentially correlated to faecal water, faecal bulk and to a lesser extent to faecal dry matter excretion. Faecal calcium, magnesium and phosphorus excretion showed an exponential correlation to faecal dry matter excretion. A weaker correlation existed in all three elements to faecal bulk, whereas the effect of faecal water excretion was small. Results suggest a remarkable likeness between cats and dogs with regard to the digestive physiology of major minerals.     

鸡盲肠对饲料磷的消化作用

本文采用去盲肠和有盲肠公鸡的对比试验方法研究了盲肠对饲料磷的消化作用。结果表明：（１）去盲肠鸡内源磷排泄量为４９ｍｇ／日．只,有盲肠鸡的内源磷排泄量为４２ｍｇ／日．只,两者差异极显著（Ｐ〈０．０１）,可见,盲肠能够消化吸收内源磷;（２）当公鸡采食含豆粕、棉仁粕、菜籽粕、花生粕或胡麻粕的半纯合日粮时,植酸磷采食量较高,有盲肠鸡磷的排泄量显著低于去盲肠鸡,真消化率显著高于去盲肠鸡（Ｐ〈０．０５）,表明     

Transiency of the different cholesterolaemic responses to dietary cellulose and psyllium in pigs and two strains of hamsters

The time course of the cholesterolaemic effects of dietary cellulose and psyllium was studied in two strains of hamsters and in pigs. In the first experiment, the ShHan:AURA strain from Harlan was used. Hamsters were first fed a cholesterol‐enriched (0.1%, w/w) semipurified diet containing 3% cellulose for a period of 2 weeks. Then, one group (n = 14) continued on the cellulose diet and another group (n = 14) was transferred to the psyllium diet. After 1.5 weeks on the diets, the psyllium‐fed hamsters showed a steep decrease in plasma cholesterol levels whereas the cellulose group maintained high cholesterol levels. Then, however, the cellulose‐fed hamsters showed a gradual decrease in plasma cholesterol levels and after 9.5 weeks on the diets, they had plasma cholesterol levels comparable to the hamsters fed psyllium. In the second study, the Lake View strain from Charles River was used. Two groups of hamsters (n = 14 per group) were fed a cholesterol‐enriched (0.1%, w/w) semipurified diet containing either 3% cellulose or 3% psyllium. The psyllium‐fed group had significantly lower plasma cholesterol concentrations than the cellulose group after 2, 4, and 6 weeks on the diets. After 8 weeks on the diets, however, the cholesterol levels in the cellulose group had decreased to levels similar to those in the psyllium group. In the third experiment, pigs were fed a cholesterol‐enriched (0.5%, w/w) semipurified diet containing either 5% cellulose or psyllium. After 1 and 2 weeks on the diets, the cellulose‐fed pigs had elevated plasma cholesterol concentrations, whereas the psyllium‐fed pigs maintained low cholesterol levels. After 3 weeks on the diets, the cholesterol concentrations in the cellulose‐fed pigs had decreased to the same level as in the psyllium‐fed pigs. There was no significant effect of cellulose and psyllium on liver cholesterol in the three studies, but psyllium tended to increase the faecal excretion of bile acids. Thus, the present studies showed a cholesterol lowering effect of dietary psyllium compared with cellulose in hamsters and pigs, but this effect was transient.     

Effects of supplemental fat source on nutrient digestion and ruminal fermentation in steers

Five Holstein steers (235 kg of BW) fitted with ruminal, duodenal, and ileal cannulas were used in a 5 x 5 Latin square design experiment to determine the effects of supplemental fat source on site and extent of nutrient digestion and ruminal fermentation. Treatments were diets based on steam-flaked corn containing no supplemental fat (control) or 4% (DM basis) supplemental fat as tallow, dried full-fat corn germ (corn germ), corn oil, or flax oil. Fat supplementation decreased (P < 0.08) ruminal starch digestion but increased (P < 0.03) small intestinal starch digestion as a percentage of intake. Feeding corn germ decreased (P < 0.09) ruminal starch digestion and increased (P < 0.03) large intestinal starch digestion compared with steers fed corn oil. Large intestinal starch digestion was less (P < 0.04), and ruminal NDF digestion was greater (P < 0.09) for steers fed tallow compared with steers fed other fat sources. Small intestinal (P < 0.08) and total tract NDF digestibilities were greater (P < 0.02) for steers fed corn germ than for those fed corn oil. Feeding tallow increased total ruminal VFA (P < 0.03) and NH(3) (P < 0.07) concentrations compared with steers fed the other fat sources. Feeding corn germ led to a greater (P < 0.02) rate of ruminal liquid outflow compared with corn oil. A diet x hour interaction (P < 0.04) occurred for ruminal pH, with steers fed corn oil having the greatest ruminal pH 18 h after feeding, without differences at other time points. Fat supplementation increased (P < 0.09) ruminal concentrations of Fusobacterium necrophorum. Duodenal flow of C18:3n-3 was greater (P < 0.01) for steers fed flax oil compared with those fed corn oil. Feeding corn germ led to less (P < 0.01) ruminal biohydrogenation of fatty acids compared with corn oil. Steers fed tallow had greater small intestinal digestibility of C14:0 (P < 0.02) and C16:1 (P < 0.04) than steers fed the other fat sources. Fat supplementation decreased (P < 0.06) small intestinal digestibility of C18:0. Feeding corn germ decreased (P < 0.10) small intestinal digestibility of C18:1 compared with corn oil. It appears that source of supplemental fat can affect the site and extent of fatty acid and nutrient digestion in steers fed diets based on steam-flaked corn.