Tannic acid and oxidized tannic acid on the functional state of rat intestinal epithelium

Diets containing tannic acid at the level of 3% of dry matter were fed to rats in order to ascertain the origin of fecal nitrogen and the effect of tannic acid on the intestinal mucosa. At the same time in order to explain the effect of oxidation of tannins, we administered diets containing oxidized tannic acid or tannic acid associated with an antioxidizer (sodium sulfite) at the level of 1% of dry matter. The increased excretion of sialic acid and glucosamine during ingestion of tannic acid indicated that the excess of fecal nitrogen mainly corresponds to the mucus hypersecretion observed by histology. Fecal analysis revealed perturbations in movements of water and ions. The study of the metabolic activity of isolated enterocytes and the activity of some enzymes in a homogenate of these cells showed an inhibition of oxygen consumption and succinic dehydrogenase activity. Addition of reducing agent (sodium sulfite) to the diet had little effect on the action of tannic acid; but previous oxidation of the tannin reduced the effects observed, particularly in the case of fecal nitrogen loss.     

Cigarette smoking as a determinant of high-grade carotid artery stenosis in Hispanic, black, and white patients with stroke or transient ischemic attack

The effect of chitin, poly-beta-(1 --> 4)-N-acetyl-glucosamine, and chitosan, a polymer of glucosamine obtained by the deacetylation of chitin, on growth and nutrient digestibility was studied in grass shrimp, Penaeus monodon. Shrimp were fed for 8 wk diets containing no supplement (control) or 2, 5 or 10 g/100 g chitin or chitosan. Each diet was fed to triplicate groups of shrimp with a mean initial body weight of 0.45 +/- 0.05 g. Significantly higher body weight gains were observed in shrimp fed the 5% chitin diet than in those fed the 10% chitin or the control diet. The weight gain of shrimp decreased as dietary chitosan supplementation level increased (r = 0. 87, P < 0.05). Feed efficiencies (FE) and protein efficiency ratios (PER) followed the same pattern. Lower protein and lipid digestibilities and lower body protein and lipid contents were observed in shrimp fed all chitosan-containing diets than in controls (P < 0.05). Carbohydrate digestibility was lower in shrimp fed the 10% chitosan diet than in those fed the control diet. Lower protein and lipid digestibilities, body lipid content and blood cholesterol concentration were observed in shrimp fed the 10% chitin diet compared with controls (P < 0.05). Higher weight gains, body lipid contents and blood cholesterol concentrations were observed in shrimp fed the 2 and 5% chitin diets than in those fed the chitosan diets. Shrimp fed the 5% chitin diet had higher protein and lipid digestibilities and higher body protein content than those fed the 5% chitosan diet (P < 0.05). These data suggest that dietary chitin, supplemented at 5%, enhances P. monodon growth, whereas chitosan depresses shrimp growth, regardless of the supplementation level.     

Tannins and human health: a review

Tannins (commonly referred to as tannic acid) are water-soluble polyphenols that are present in many plant foods. They have been reported to be responsible for decreases in feed intake, growth rate, feed efficiency, net metabolizable energy, and protein digestibility in experimental animals. Therefore, foods rich in tannins are considered to be of low nutritional value. However, recent findings indicate that the major effect of tannins was not due to their inhibition on food consumption or digestion but rather the decreased efficiency in converting the absorbed nutrients to new body substances. Incidences of certain cancers, such as esophageal cancer, have been reported to be related to consumption of tannins-rich foods such as betel nuts and herbal teas, suggesting that tannins might be carcinogenic. However, other reports indicated that the carcinogenic activity of tannins might be related to components associated with tannins rather than tannins themselves. Interestingly, many reports indicated negative association between tea consumption and incidences of cancers. Tea polyphenols and many tannin components were suggested to be anticarcinogenic. Many tannin molecules have also been shown to reduce the mutagenic activity of a number of mutagens. Many carcinogens and/or mutagens produce oxygen-free radicals for interaction with cellular macromolecules. The anticarcinogenic and antimutagenic potentials of tannins may be related to their antioxidative property, which is important in protecting cellular oxidative damage, including lipid peroxidation. The generation of superoxide radicals was reported to be inhibited by tannins and related compounds. The antimicrobial activities of tannins are well documented. The growth of many fungi, yeasts, bacteria, and viruses was inhibited by tannins. We have also found that tannic acid and propyl gallate, but not gallic acid, were inhibitory to foodborne bacteria, aquatic bacteria, and off-flavor-producing microorganisms. Their antimicrobial properties seemed to be associated with the hydrolysis of ester linkage between gallic acid and polyols hydrolyzed after ripening of many edible fruits. Tannins in these fruits thus serve as a natural defense mechanism against microbial infections. The antimicrobial property of tannic acid can also be used in food processing to increase the shelf-life of certain foods, such as catfish fillets. Tannins have also been reported to exert other physiological effects, such as to accelerate blood clotting, reduce blood pressure, decrease the serum lipid level, produce liver necrosis, and modulate immunoresponses. The dosage and kind of tannins are critical to these effects. The aim of this review is to summarize and analyze the vast and sometimes conflicting literature on tannins and to provide as accurately as possible the needed information for assessment of the overall effects of tannins on human health.     

Site of digestion and milk production by cows fed fats differing in saturation, esterification, and chain length

Four cannulated cows in a 4 x 4 Latin square design were used to study the effects of supplemental dietary fatty acids from roasted soybeans combined with tallow or partially hydrogenated fats, varying in esterification and fatty acid chain length, on nutrient digestion and lactation performance. Diets were formulated to contain (DM basis) 48% forage in addition to 1.5% fatty acids from roasted soybeans and 2.5% fatty acids from tallow, partially hydrogenated tallow triglycerides, partially hydrogenated tallow fatty acids, or a blend of 30% tallow and 70% hydrogenated fatty acids that were rich in palmitic acid. Apparent total tract digestibilities of OM, N, and NDF were similar among diets. Supplemental fat as fatty acids, compared with triglycerides, increased digestibilities of total fatty acids and C18:1 in the small intestine, perhaps indicating that lipolysis was rate-limiting. Fatty acids also increased milk fat percentage and efficiency of 4% FCM production. Although intake of C16 fatty acids was higher for cows fed the fat rich in palmitic acid than for those fed the tallow fatty acids, total duodenal flows of C16 fatty acids were similar, and digestibility in the small intestine was unaffected. Dry matter intake, 4% FCM production, and milk protein percentage were similar among treatments.     

Resistant proteins alter cecal short-chain fatty acid profiles in rats fed high amylose cornstarch

The objective of this study was to examine the physiologic importance of undigested protein on cecal fermentation in rats fed a low (LAS) and high (HAS) amylose cornstarch. In Experiment 1, rats were fed diets containing LAS (655 g/kg diet) with one of four protein sources: casein, rice (RP), potato (PP) or soybean protein (SP) at 250 g/kg diet for 15 d. Apparent digestibilities of casein, RP, SP and PP were 96, 94, 93 and 92%, respectively. In rats fed the LAS diet with casein, acetate, propionate and succinate were the major cecal organic acids. The succinate pools in rats fed RP or SP were significantly lower than in those fed casein, whereas butyrate did not differ. Butyrate was significantly higher in rats fed PP, but succinate was the same as in rats fed casein. In Experiment 2, rats were fed diets containing HAS (200 g/kg diet) with one of the four protein sources at 250 g/kg diet for 10 d. HAS was substituted for the same amount of LAS. In rats fed the HAS diet, succinate was the major acid in rats fed casein; in rats fed RP or PP, however, the pools of this acid were significantly lower than in those fed casein, whereas butyrate was significantly higher in rats fed RP or PP. Fecal starch excretion was significantly lower in rats fed RP or PP than in those fed casein. In Experiment 3, rats were fed the casein-HAS diet with graded levels of PP (0, 10, 30, 50, 100 and 250 g/kg diet) for 14 d. The PP was substituted for the same amount of casein. Cecal butyrate was low in rats fed up to 100 g of PP/kg diet and then rose with 250 g of PP/kg diet. In Experiment 4, ileorectostomized rats were used and fed the same diets described in Experiment 3 for 9 d. The ileal starch/nitrogen ratio declined with increasing dietary PP, due solely to greater nitrogen excretion, whereas starch excretion was unaffected. In Experiment 5, rats were fed the casein-HAS diet with or without 60 g of artificial resistant protein/kg diet for 10 d. The resistant protein (apparent digestibility, 63%) was substituted for the same amount of casein. Rats fed the casein-HAS diet with resistant protein had significantly greater cecal butyrate and lower succinate than those fed the casein-HAS diet. These data show that large bowel fermentation of starch is altered by dietary protein. They support the hypothesis that nondigested protein, namely, resistant protein, may control fermentation efficiency as well as the fermentation profile of HAS, possibly as a result of a change in microflora through the change in the ratio of starch to nitrogen in the cecum.     

Substitution of neutral detergent fiber from forage with neutral detergent fiber from by-products in the diets of lactating cows

Four lactating dairy cows that were ruminally and duodenally cannulated were used in an experiment with a 4 x 4 Latin square design to determine the effects of the substitution of neutral detergent fiber (NDF) from forage with NDF from wheat middlings, corn gluten feed, or a blend of distillers dried grains and hominy. Dietary crude protein and NDF averaged 18 and 31%, respectively, for the diet with 71.2% of the NDF from forage (control diet) and for diets with 55% of the NDF from forage (by-product diets). The substitution of NDF from these by-products for forage NDF did not affect dry matter intake (20.1 kg/d) or digestibility of organic matter. Total tract digestibility of acid detergent fiber was lower for cows fed the diet containing a blend of distillers dried grains and hominy than for cows fed the diet containing corn gluten feed. Microbial crude protein synthesis, milk production (23.9 kg/d), and milk fat percentage were similar for all cows, regardless of diet. Cows fed the diets containing wheat middlings or a blend of distillers dried grains and hominy had reduced ruminal pH compared with that of cows fed the diet containing corn gluten feed or the control diet. Diets containing 55% of total NDF from forage with 31% of total NDF from corn gluten feed, wheat middlings, or a blend of distillers dried grains and hominy can supply sufficient effective fiber to maintain normal ruminal function.     

Energy metabolism and protein balance in growing rats housed in 18 degree C or 28 degree C environments and fed different levels of dietary protein

A study was performed to investigate the effect of environmental temperature and increasing levels of protein in the diet on visceral organ size, digestibility, protein balance and energy metabolism in rats. Thirty-six male Wistar rats, initial body weight 77-80 g, were used in a factorial design consisting of three levels of dietary protein and two environmental temperatures of either 18 or 28 degrees C. Three fish meal-based diets were prepared to contain 91, 171 and 262 g protein (N X 6.25/kg diet). Gas-exchange measurements were made and urine and feces were quantitatively collected. The weights of the visceral organs from rats housed at 18 degrees C were greater (P < 0.05) than those of rats housed at 28 degrees C. The digestibilities of dry matter and protein were not affected by environmental temperature, whereas fat and energy digestibilities were higher (P < 0.05) at 18 degrees C than at 28 degrees C. As the level of protein was increased, the digestibilities of protein, energy and fat increased (P < 0.05). Protein intake and protein retention were higher at 18 degrees C (P < 0.05) than at 28 degrees C and increased (P < 0.05) as dietary protein concentration increased. Apparent biological value was lower (P < 0.05) at 18 degrees C than at 28 degrees C and decreased (P < 0.05) as dietary protein level increased. Heat production as a percentage of metabolizable energy was higher (P < 0.05) for the low protein diet than for the medium and high protein diets. The efficiency of energy utilization was depressed (P < 0.05) for the high protein diet when rats were kept at 28 degrees C. The results suggest that thermogenesis was induced when low protein was fed. The increase in thermogenesis may have been important in regulating energy balance and maintaining a constant body temperature in a cold environment.     

Female pelvic floor: endovaginal MR imaging of normal anatomy

Five types of processed corn were compared to determine the effects of processing on lactational performance and nutrient digestibilities in dairy cows. Forty lactating Holstein cows averaging 160 +/- 60 d in milk were randomly divided into five groups on the basis of pretreatment milk yields and were fed diets containing 40% corn grain for 56 d. Treatments were 1) finely ground corn, 2) coarsely ground corn, 3) steam-flaked corn at a low density, 4) steam-flaked corn at a medium density, and 5) steam-rolled corn. Cows fed the diet containing steam-flaked corn at a medium density had a higher milk yield (37.1 kg/d) than did cows fed the diets containing coarsely ground corn, steam-flaked corn at a low density, or steam-rolled corn; cows fed the diet containing finely ground corn had an intermediate milk yield (35.5 kg/d). Efficiency of feed utilization was greater, and dry matter intake was lower, for cows fed the diet containing finely ground corn than for cows fed the other diets. The fat content of milk was higher for cows fed the diets containing coarsely ground corn and steam-rolled corn than for cows fed the diet containing steam-flaked corn at a medium density. Milk protein and SNF contents and yields of protein, lactose, and SNF did not differ among diets. Apparent starch digestibilities in the total digestive tract were lower for diets containing coarsely ground corn (87.4%) and steam-rolled corn (91.3%) than for the other diets (X = 96.3%). Milk yield was highest for cows fed the diet containing steam-flaked corn with a medium density. Fine grinding resulted in the greatest efficiency of feed utilization.     

Interaction of tannin with human salivary proline-rich proteins

Tannins are polyphenolic compounds, widely distributed in plant-based foods, which have harmful effects on animals including humans. Salivary proline-rich proteins (PRPs) may act as a defence against tannins by forming complexes with them and thereby preventing their interaction with other biological compounds and absorption from the intestinal canal. The aim here was to compare the ability of members of the family of human PRPs to form insoluble complexes with tannin and to assess the stability of such complexes under conditions similar to those in the alimentary tract. Basic PRPs (BPRPs), which have no other known biological functions, were very effective in forming insoluble complexes with both condensed tannin and tannic acid. Practically no tannin bound to acidic PRPs (APRPs) and glycosylated PRPs (GPRPs), suggesting that tannin in the diet would not affect their biological activities. There were only small differences in the tannin-precipitating ability of various BPRPs of different sizes or sequences, indicating that, although there is considerable phenotypic variation of PRPs, it is not likely to cause marked individual variation in tannin-binding ability. Tryptic digestion of an APRP led to a marked increase in tannin binding to the resulting proline-rich peptides, supporting observations in other studies that there may be an interaction between the proline-poor N-terminal and the proline-rich C-terminal regions in native APRPs, which inhibits the biological activities of the proteins. Deglycosylation of a GPRP also led to a dramatic increase in tannin-binding ability, showing that the carbohydrate side-chains prevent binding of tannin. Most of the condensed tannin-PRP complexes remained insoluble under conditions similar to those in the stomach and small intestine, supporting the proposal that PRPs act as a defence against tannin.     

Nutritional utilization by rats of chickpea (Cicer arietinum) meal and its isolated globulin proteins is poorer than that of defatted soybean or lactalbumin

The effects on performance, digestibility, N utilization and plasma amino acid concentrations of dietary chickpea (Cicer arietinum, var. Kabuli) seed meal, globulin proteins or buffer-insoluble residue [starch + non-starch polysaccharides (NSP) + lignin] were studied in growing rats. Chickpea meal, defatted soybean meal, chickpea globulins and lactalbumin were each incorporated into diets as the sole source of dietary protein (100 g/kg). In addition, chickpea insoluble residue was included in a control diet in the same proportion found in the chickpea meal. Rats were killed while under halothane anesthesia after 10 d of consuming the diets, and ileal contents were washed out and freeze-dried for digestibility measurements. Weight gains and gain:feed ratios of rats fed chickpea diets for 10 d did not differ from those of rats fed defatted soybean but were significantly lower than those of rats given the control (lactalbumin) diet. However, ileal and fecal N digestibilities and N retention by rats fed the chickpea diet were significantly lower than those obtained with the lactalbumin or soybean diet. The inclusion of both chickpea meal or its globulin proteins in the diet significantly increased the amount of N excreted, primarily as urea, through the urine. However, although ileal N digestibility values for chickpea meal were significantly lower, those for its constituent globulins did not differ from control values. Urea levels in plasma in rats fed diets containing chickpea meal, globulins or soybean meal were significantly higher than in those fed lactalbumin. Furthermore, the concentrations of glycine, phenylalanine, histidine, arginine and ornithine in the plasma of rats fed chickpea meal, its globulins or defatted soybean were significantly higher, whereas those of threonine, leucine, lysine and tryptophan were significantly lower than lactalbumin-fed controls. The chickpea insoluble residue had no adverse effects on performance or N utilization by rats. We conclude that the low nutritional value of chickpea meal is likely to be due mainly to adverse effects of its globulin proteins on growth and N metabolism rather than to the action of any known antinutritional factor present in the diet.     

Influence of sorghum grain processing on performance and nutrient digestibilities in dairy cows fed varying concentrations of fat

Forty Holstein cows averaging 85 +/- 50 d in milk were assigned to five dietary treatments for 56 d to determine the effects of ruminal starch degradability and supplemental fat on milk yield and composition and nutrient digestibilities. Treatments were 1) dry-rolled sorghum, no added fat; 2) dry-rolled sorghum plus 2.5% prilled fatty acids; 3) steam-flaked sorghum, no added fat; 4) steam-flaked sorghum plus 2.5% prilled fatty acids; and 5) steam-flaked sorghum plus 5% prilled fatty acids. Fat supplementation at 2.5 and 5% increased the content of fatty acids in diets from 3.0 to 5.4 and 7.7%, respectively. Milk yield was increased 2.0 kg/d when steam-flaked sorghum plus 0 or 2.5% added fat was fed and was 2.4 kg/d higher when prilled fatty acids were fed at 2.5 versus 0%. Cows fed supplemental fat at 5% did not increase milk yield over that of cows fed no added fat. For cows fed 2.5% fat, steam-flaking decreased dry matter intake 12% and increased efficiency of conversion of feed to milk 11%. Milk composition was unaffected by treatments, except that lactose was depressed by fat supplementation. Milk protein yield and efficiency of conversion of dietary protein to milk protein were increased when steam-flaked sorghum was fed. Starch digestibilities were increased from 92.6 to 98.2% when sorghum was steam-flaked compared with dry-rolled and fat supplementation tended to decrease digestibility of neutral detergent fiber. Steam-flaking tended to improve, and the addition of 2.5% fat did improve, the lactational performances of the cows. These effects appeared additive, but 5% fat appeared to be excessive.     

Digestion and energy balance in lactating dairy cows fed varying ratios of alfalfa silage and grain

Forty-four multiparous and 43 primiparous Holstein cows were used to study the effect of dietary alfalfa silage: grain ratio on digestion, passage of digesta, and energy balance in a complete lactation experiment. Cows were placed on one of five treatments with forage contents from 38.2 to 98.2% (DM basis) during the first 12 wk of lactation. Forage content was increased during wk 13 to 26 of lactation to give diets containing 48.2 to 98.2% forage and again during wk 27 to 44 to give diets containing 68.2 to 98.2% forage. Both DMI and DM digestibilities decreased as proportion of dietary forage increased. The DM digestibilities for multiparous and primiparous cows ranged between 69.3 and 57.3% during early lactation and 64.9 and 55.5% during late lactation. Increased percentage of forage in the diet decreased and then increased (quadratic relationship) the ruminal retention time of La, a marker applied to the alfalfa silage in early and late lactation. Time cows spent eating and ruminating per kilogram of DMI increased as proportion of forage in the diet increased. Cows fed diets with a high proportion of alfalfa silage remained in negative energy balance longer than cows fed high grain diets. Intake of NEL (calculated by either of two methods) minus NEL output (milk, maintenance, and BW change) resulted in net balances of NEL after 36 wk of lactation within 5% of NEL intake and indicated that estimates of the NEL value of feedstuffs used in this experiment were reasonably accurate.     

Dose- and time-dependent effects of ethanol on functional and structural aspects of the liver sinusoid in the mouse

Two experiments were conducted to investigate the factors responsible for the adverse effects of guanidinated proteins on feed intake in chickens. In Experiment 1, male broiler chicks were fed one of five purified diets containing casein or guanidinated casein (G-casein) as the sole source of protein (230 g crude protein/kg diet) from d 6 to 13 post-hatching. A casein-based diet containing 17.2 g lysine/kg, served as the control. In the experimental diets, casein was substituted by G-casein and lysine was added at 0, 5.6, 11.4 and 17.0 g/kg diet, respectively. Feed intake and weight gains of chicks fed the G-casein diet without added lysine were markedly depressed (P < 0.05), but this depression was largely overcome by additional lysine. The intake and gains of chicks fed the G-casein diet plus 17.0 g lysine/kg were lower (P < 0.05) than those fed the G-casein diet plus 11.4 g lysine/kg and this was associated with a higher plasma lysine:arginine ratio. Tissue analysis showed that homoarginine is distributed throughout body tissues following absorption. Brain lysine concentrations were lower (P < 0.05) in chicks fed diets containing G-casein without added lysine, but increased (P < 0.05) with supplemental lysine. In Experiment 2, the effect of homoarginine per se on feed intake was investigated in two short-term intake studies using 5-wk-old broiler chickens. Significant (P < 0.05) depressions in feed intake were observed within the first hour after oral administration of 400 mg homoarginine-HCl. The results suggest that both lysine deficiency and homoarginine per se were responsible for the adverse effects of guanidinated proteins on feed intake in chickens.     

Gender affects rats' central nervous system histaminergic responses to dietary manipulation

The histaminergic system (histamine and its H1-receptor) of the central nervous system has been implicated in control of food intake. The reported studies were designed to examine the effects of food restriction and very low (1%) protein diets on central nervous system H1-receptors in male and female rats. In a series of experiments, groups of rats were freely fed a 25% protein diet, a 1% protein diet, or fed the 25% protein diet at 4 g/100 g body weight for 14-20 d. When freely fed 25% protein diets, females had higher whole-brain H1-receptor binding than males on d 1 (female 122.36 +/- 4.53 and male 65.78 +/- 3.82 pmol/g protein; P < 0.001). Changing diets affected central H1-receptor binding in both males and females (P < 0.003). When rats were fed both restricted levels of food and 1% protein diets, the receptor binding of males increased by d 5 whereas that of females decreased by d 5 (P < 0.001). When fed 1% protein diets, females had decreased H1-receptor binding (98.4 +/- 2.38 pmol/g protein) and that in males increased to 119.81 +/- 5.09 pmol/g protein. After 15 d, females had eaten significantly more food than males: females 166 +/- 4.9 g, males 124 +/- 1.9 g (P< 0.0007). Males had a significantly greater weight loss than females: males -28.8 +/- 2.6 g, females -17.08 +/- 0.97 g (P < 0.0007). When fed restricted diets, females had decreased H1-receptor binding (93.81 +/- 5.58 pmol/g) whereas binding in males increased to 111.27 +/- 8.55 pmol/g. Preliminary saturation binding studies indicated that restricted food intake lowered receptor density (females consuming 25% protein: 715 +/- 30 pmol/g protein; female restricted: 467 +/- 28 pmol/g protein, P < 0.05), while 1% protein increased receptor sensitivity, i.e., lowered KD (males consuming 25% protein: 15.3 +/- 1.8 nmol; males fed low protein: 2.8 +/- 0.27 nmol). This study suggests that dietary manipulation affects central H1-receptor binding in a gender-specific manner, thereby modulating central histaminergic activity during food or protein deficit.     

Effects of dietary carbohydrate, fat and protein on growth, body composition and blood metabolite levels in the dog

Six semipurified canned diets ranging in composition from 0 to 62% of energy from carbohydrate and from 20% to 48% of energy from protein were fed to female beagle dogs for 8 months. Additionally, three commercial-type diets were also fed. The effects of these diets on growth, body composition and selected blood metabolite levels in the dogs were studied. The dogs readily consumed each of the nine diets fed. The level of carbohydrate, fat or protein in the diet did not influence body weight gain during the first 16 weeks nor was nitrogen balance affected by the diets. At the end of the 32-week study, dogs fed the high-carbohydrate (62% of energy) diet contained less body fat but an equal-free mass, than did dogs fed lower-carbohydrate (20--42% of energy) diets with a similar quantity of protein. Consumption of carbohydrate-free diets did not influence postprandial levels of circulating glucose or insulin in the dogs. Plasma cholesterol levels were elevated in dogs consuming in the diets high in fat but plasma triglyceride levels were not influenced by the diets fed. Consumption of high-protein (46--48% of energy) diets elevated plasma urea nitrogen levels but had minimal influence on plasma amino acid levels. The general response of these young dogs was not markedly influenced by consumption of diets ranging from carbohydrate-free to high-carbohydrate and from adequate-protein to high-protein.     

Fatty acid composition of milk from Holstein cows fed oleamide or canola oil

Based on previous in vitro results that showed reduced biohydrogenation of oleamide by ruminal microbes, this study was conducted to determine whether the addition of oleamide to the diets of dairy cows would enhance the C18:1 concentration in milk. Nine first lactation Holstein cows were fed three diets in a 3 x 3 Latin square replicated three times. Each period lasted 3 wk. The total mixed diets consisted of 42% corn silage and 58% concentrate (dry matter basis) with either no added fat (control), 3.5% high oleic canola oil, or 3.5% oleamide. Dry matter intake was reduced when oleamide was added to the diet but not when canola oil was added. Milk yields were the same for cows fed all three diets. Canola oil reduced fat-corrected milk yield and milk fat concentration, but these were not affected by oleamide. Milk protein concentration was lower for cows fed oleamide than for cows fed canola oil. Milk C18:1 averaged 23.16% of total fatty acids for cows fed the control diet and increased to 35.13% when canola oil was fed. Oleamide further increased C18:1 to 48.16% of total fatty acids in milk. All fatty acids with > or = 16 carbon chain length were reduced by oleamide. Oleamide was more effective than was canola oil in this study at increasing the oleic acid content of bovine milk. Oleamide reduced dietary intake when added at 3.5% of the dietary dry matter but still had no effect on milk yield or milk composition.     

Mechanism of inhibition of tannic acid and related compounds on the growth of intestinal bacteria

Tannic acid, propyl gallate and methyl gallate, but not gallic acid, were found to be inhibitory to the growth of intestinal bacteria Bacteroides fragilis ATCC 25285, Clostridium clostridiiforme ATCC 25537, C. perfringens ATCC 13124, C. paraputrificum ATCC 25780, Escherichia coli ATCC 25922, Enterobacter cloacae ATCC 13047, Salmonella typhimurium TA98 and S. typhimurium YG1041 at 100-1000 microg/ml in culture broth. Neither Bifidobacterium infantis ATCC 15697 nor Lactobacillus acidophilus ATCC 4356 was inhibited by any of the above compounds up to 500 microg/ml. Tannic acid has a much greater relative binding efficiency to iron than propyl gallate, methyl gallate or gallic acid. The inhibitory effect of tannic acid to the growth of intestinal bacteria may be due to the strong iron binding capacity of tannic acid; whereas the effect of propyl gallate and methyl gallate probably occurs by a different mechanism. The growth of E. coli was restored by the addition of iron to the medium after the precipitate caused by tannic acid was removed. Neither B. infantis nor L. acidophilus require iron for growth. This probably contributes to their resistance to tannic acid. Because tannins are abundant in the human diet, tannins may affect the growth of some intestinal bacteria and thus may have an impact on human health.     

Dietary linoleic acid increases and palmitic acid decreases hepatic LDL receptor protein and mRNA abundance in young pigs

The present study was conducted to determine the effects of dietary fatty acids on hepatic LDL receptor (LDLr) protein abundance and mRNA levels. Sixty pigs were randomized into 10 groups and fed corn-soybean meal diets containing three cholesterol levels (0.25%, 0.5%, and 1.0%, w/w) with no added fat, or fats rich (30% of calories) in palmitic acid or linoleic acid. A control group was fed the base diet with no added fat. After 30 days, plasma LDL-cholesterol (LDL-C) levels increased as the dietary cholesterol increased (P < 0.05); however, there was no significant effect of either fatty acid. Dietary fatty acids, however, had distinctly different effects on hepatic LDLr protein (analyzed by ELISA) and mRNA (analyzed by Northern blot) abundance. When pigs consumed diets containing 0.25% cholesterol, linoleic acid increased hepatic LDLr protein 40% whereas palmitic acid reduced it 40% (P < 0.05). These changes in LDLr protein abundance were accompanied by parallel changes in hepatic LDLr mRNA; linoleic acid increased LDLr mRNA 2-fold (P < 0.01), whereas palmitic acid decreased it 60% (P < 0.01). The differential effects of fatty acids on LDLr expression were only observed at 0.25% cholesterol, suggesting that higher intakes of cholesterol have a dominant and repressive effect on regulation of LDLr expression. Cholesterol intake increased hepatic total cholesterol levels (P < 0.01) while dietary fatty acids had no effect on hepatic sterols. In summary, our results indicate that dietary linoleic acid and palmitic acid have markedly different effects on hepatic LDLr protein abundance that are mediated by differential effects on LDLr mRNA and protein levels. Further studies are needed to fully elucidate the molecular mechanisms by which fatty acids regulate LDLr mRNA and protein levels.     

Effect of ammonia via prepyriform cortex on regulation of food intake in the rat

Studies were made on whether ammonia, which is an obligatory intermediate of amino acid metabolism, depresses the food intake of rats fed a low-casein (basal) diet containing imbalanced amino acid mixtures (imbalanced diets). Bilateral lesions in the prepyriform cortex caused normalization of food intake of rats fed amino acid-imbalanced diets, confirming the work of Leung and Rogers (Am. J. Physiol. 221:929-935, 1971). Unlike normal rats, animals with prepyriform cortical lesions consumed as much of a diet containing 3% NH4Cl as they did of the basal diet. However, like normal rats, they rejected a diet containing a mixture of keto acids. Unilateral injection of NH4Cl into prepyriform cortical areas reduced the food intake to a greater extent than injection of NaCl into these areas or injection of NH4Cl into other parts of the brain. These results suggest that ammonium ions influence the appetite through their effect on prepyriform cortical areas.     

Effects of fish meal in beef cattle diets on growth performance, carcass characteristics, and fatty acid composition of longissimus muscle

We investigated the effects of fish meal (FM) in beef cattle diets on growth performance, carcass characteristics, and fatty acid (FA) composition of longissimus muscle in 63 yearling steers (335 +/- 23 kg). High-moisture corn and alfalfa silage diets were supplemented with either a corn gluten/blood meal mixture or FM at 10% of the diet. Fish meal contained (as-is basis) 5.87 g/kg eicosapentaenoic acid (EPA) and 9.84 g/kg docosahexaenoic acid (DHA). Seven strategies were developed to feed either a control diet (no FM) or diets containing 5 or 10% FM with FM fed for either 56, 112, or 168 d before slaughter. Average daily gain and feed efficiency were not affected (P > .10) by FM feeding but DMI decreased. Within FM diets, cattle fed 5% FM consumed more (P < .01) DM and gained more (P < .02) than cattle fed 10% FM. Carcass traits were not affected (P > .05) by feeding strategy except for fatter (P < .05) and lower (P < .06) yielding carcasses in cattle fed 5 vs 10% FM diets. Fish meal feeding increased (P < .01) concentrations of (n-3) FA, including EPA and DHA, and decreased (P < .05) concentrations of arachidonic acid. Increasing the amount of dietary FM further increased (P < .01) concentrations of EPA and DHA and decreased (P < .05) concentrations of (n-6) FA. We estimate that a 114-g steak from cattle fed 10% FM would supply 35 to 90% of the current average daily intake of EPA and DHA in North America. The results indicate that FM may have a role in niche marketing of beef provided that eating quality is not compromised.