The effect of fiber source in enteral products on fecal weight, mineral balance, and growth rate in rats.

The effect of two fiber systems in enteral formulas on fecal output, mineral balance, weight gain, and cecal short-chain fatty acid production was studied in rats. Enteral products tested had either no fiber; soy fiber (3.4 g of total dietary fiber/8 fluid oz); a fiber blend containing 75% oat fiber, 17.5% gum arabic, and 7.5% carboxymethylcellulose (3.4 g of total dietary fiber/8 fluid oz); or the same blend at 4 g of total dietary fiber/8 fluid oz. Food, feces, and urine were analyzed for nitrogen, calcium, magnesium, iron, and zinc. Cecal contents were analyzed for short-chain fatty acids. Weight gain, intake, food efficiency, and nitrogen balance were unaffected by fiber source. Fecal weight was increased by the fiber blend (p < .05). Calcium and magnesium balances were similar for all groups fed fiber-containing products but were lower for the fiber-free group (p < .05). Iron balance was significantly lower for rats fed the fiber blend at 4 g/8 fluid oz as compared with the other treatment groups (p < .05). Cecal acetate, propionate, and total short-chain fatty acid concentrations for rats fed the soy-fiber diet were significantly higher than for the other three diets (p < .05). Rats fed the fiber blend at the higher level had a significantly higher percentage of butyrate production than rats fed the other three diets (p < .05).(ABSTRACT TRUNCATED AT 250 WORDS)

Toxicity and tissue accumulation of copper in chicks fed casein and soy-based diets.

Experiments were conducted to study Cu toxicity in chicks fed casein or soy-containing diets containing graded levels of excess CuSO4.5H2O. Differences between diets in measures of Cu toxicity were pronounced. Addition of 800 mg of Cu/kg to a casein-dextrose semipurified diet decreased weight gains by 63%, but the same addition of Cu to a corn-soybean meal complex diet decreased gains by only 8%. At all levels of Cu supplementation (100, 200, 400 or 800 mg/kg), Cu deposition in the liver was increased markedly in chicks fed casein diets compared with those fed the complex diet. Substituting soy-protein concentrate for casein in the semipurified diet resulted in a marked decrease in Cu toxicity as measured by weight gain reductions and tissue accumulation of Cu.

Effect of soy products on methotrexate toxicity in rats.

Several experiments were conducted to determine the effect of various soy products on methotrexate (MTX) toxicity. Products tested included soybean meal, soybean concentrate, soybean isolate and soybean fiber, which were provided as replacements for casein or cornstarch in a semipurified diet. Soybean meal and soybean concentrate offered the greatest protection, completely alleviating MTX-induced anorexia and diarrhea when included as the sole protein source and fed 14 d prior to and 7 d following intraperitoneal MTX injection at 20 mg/kg body weight. Positive responses also were observed with soybean isolate and soybean fiber. Histological examination of the small intestine of MTX-injected animals revealed that soybean concentrate and soybean isolate prevented the necrosis observed in animals fed the casein-based semipurified diet. Methotrexate levels in plasma were similar for animals fed semipurified diets in which protein was supplied by casein, soybean concentrate or soybean isolate. Thus, altered plasma MTX levels did not explain the differences among protein sources in ameliorating MTX-induced anorexia and gut toxicity. White blood cell counts were depressed by MTX in animals fed all diets.

Effect of fiber, protein source and time of feeding on methotrexate toxicity in rats.

Several rat experiments were conducted to determine effects of fiber and alternate protein sources on methotrexate (MTX) toxicity associated with a casein-based semipurified diet. Additional experiments were conducted to determine the critical time of feeding in relation to toxicity development. Rats adapted to a casein-based semipurified diet developed severe anorexia and diarrhea on d 3 and 4 post-MTX dosing. Addition of amorphous cellulose to the semipurified casein-based diet slightly reduced toxicity symptoms. Additions of crystalline cellulose, hemicellulose and pectin did not lessen toxicity symptoms. Replacing casein with soybean concentrate totally alleviated the toxicity symptoms. Toxicity was lower when 25% of the protein normally supplied by casein was replaced with soybean concentrate, and no toxicity symptoms were present when 50% or more of the protein was provided by soybean concentrate. Replacing casein with whey isolate or hamburger had no effect on toxicity; replacing casein with egg albumen or corn gluten meal lessened toxicity symptoms but did not totally alleviate them. Feeding the casein-based diet only 1 d before and 1 d after MTX injection resulted in toxicity. However, feeding the same diet only after MTX injection did not cause toxicity. Results indicate that fiber sources have little effect on MTX toxicity, but replacing casein with soybean concentrate completely alleviates toxicity symptoms. Time of feeding affects subsequent development of toxicity.

Research note: bioavailability of copper in cupric oxide, cuprous oxide, and in a copper-lysine complex.

Young chicks were used in a 2-wk feeding study to evaluate Cu bioavailability (relative to CuSO4.5H2O used as a reference standard) in analytical grade CuO, Cu2O, and in a feed-grade Cu-lysine complex. A basal corn and soybean meal diet was formulated to contain 290 mg Cu/kg, and graded levels (0, 75, and 150 mg/kg) of supplemental Cu were added from each Cu source. Based upon accumulation of Cu in the liver, Cu2O and Cu-lysine furnished Cu as efficiently as CuSO4.5H2O, but CuO provided no bioavailable Cu to the chicks.

L-2-oxothiazolidine-4-carboxylate as a cysteine precursor: efficacy for growth and hepatic glutathione synthesis in chicks and rats.

Chick and rat experiments were conducted to determine the efficacy of L-2-oxothiazolidine-4-carboxylate (OTC) as a cysteine (Cys) precursor for growth and hepatic glutathione (GSH) biosynthesis. Isosulfurous graded increments of OTC and Cys were added to Cys-free purified amino acid diets that were adequate in methionine. Curvilinear responses to both Cys and OTC for chicks and rats were obtained. Hepatic GSH accumulated in chicks only at dietary Cys levels above 0.10%. In rats, hepatic GSH increased linearly as dietary Cys content increased from deficient to adequate and from adequate to excessive. Utilization of OTC by chicks was as efficacious as isosulfurous levels of Cys for growth and hepatic GSH biosynthesis. In rats, OTC was slightly inferior to Cys for growth and hepatic GSH biosynthesis. Exponential regression slope-ratio growth efficacy values for OTC were 78.5% for chicks and 70.2% for rats; multiple linear regression slope-ratio GSH biosynthesis efficacy values were 80.3% for chicks and 83.7% for rats. It is concluded that orally administered OTC is active as a Cys precursor.

Milk selenium of rural African women: influence of maternal nutrition, parity, and length of lactation.

The selenium content of milk samples from rural Gambian women (n = 55) was evaluated as a function of parity, stage of lactation, and maternal nutrition. Samples were collected during periods of relative food abundance (dry season) and food scarcity (rainy season). Milk selenium was lower (p less than 0.01) in the rainy than in the dry season (208 vs 256 nmol/L, respectively). Milk selenium was similar in samples from women in early (1-6 mo postpartum) and late (13-19 mo postpartum) lactation. During late lactation, parity, which ranged from 1 to 11, was negatively correlated with milk selenium regardless of plane of maternal nutrition (p less than 0.02). Measures of protein, glutathione peroxidase, and total peroxidase were not affected by stage of lactation or parity. Glutathione peroxidase activity accounted for 38% of the peroxidase activity in milk. Results show that although length of lactation alone had little impact, milk selenium secretion was influenced by both maternal nutritional adequacy and parity of rural Gambian women.

Influence of soybean meal and sorghum grain supplementation on intake, digesta kinetics, ruminal fermentation, site and extent of digestion and microbial protein synthesis in beef steers grazing blue grama rangeland.

Six beef steers (British x Brahman) cannulated at the rumen, duodenum and ileum (avg wt 334 kg) and three mature steers (British x British) cannulated at the esophagus were used in a replicated 3 x 3 latin square design and fed no supplement (C), .5 kg soybean meal (SBM) or .5 kg steam-flaked sorghum grain (SFS).head-1.d-1 (DM basis) while grazing blue grama rangeland. Periods of the latin square included a minimum of 14 d for adaptation and 11 d for esophageal masticate collection and digesta sampling. In September, October and November, respectively, forage collected by esophageally cannulated steers averaged 74.5, 88.8 and 71.0% grasses; 2.06, 1.53 and 1.77% N and 68.3, (P greater than .10) by treatment, but total N intake was greater (P less than .05) for SBM vs C and SFS treatments. No differences (P greater than .10) were detected among treatments in OM, NDF, ADF and N digestibilities in the rumen, small intestine or hindgut, but total tract OM digestibility was greater (P less than .10) for SBM and SFS than for C, and total tract N digestibility was greater (P less than .10) for SBM than for C or SFS. Duodenal ammonia N flow was greater (P less than .05) when SBM was fed that when SFS and C were fed, but microbial N and non-ammonia, non-microbial N flows and microbial efficiency were not altered by treatment. Likewise, ileal N flow was not affected (P greater than .10) by treatment. Particulate passage rate, gastrointestinal mean retention time, forage in vitro OM disappearance and in situ rate of forage NDF digestion also were not affected (P greater than .10) by treatments. Ruminal fluid volume was greater (P less than .05) for SFS vs SBM and C treatments, but no differences were noted in fluid dilution rate. Ruminal fluid ammonia concentration was greater (P less than .05) when SBM was fed than when SFS and C were fed (13.5, 9.9 and 8.7 mg/dl, respectively), whereas pH and total VFA concentrations were not different (P greater than .10). Proportion of acetate in ruminal fluid was less (P less than .10) for SBM and SFS than for C. Small amounts of supplemental SBM and SFS had little effect on forage intake, ruminal fermentation and site of digestion but both increased total tract OM digestion in steers grazing blue grama rangeland.

Steers grazing blue grama rangeland throughout the growing season. I. Dietary composition, intake, digesta kinetics and ruminal fermentation.

Four sampling periods on blue grama rangeland in northeastern New Mexico evaluated effects of advancing forage maturity and drought-induced dormancy on dietary nutrient and botanical composition, intake, digesta kinetics and ruminal fermentation in grazing beef steers. Six ruminally cannulated and three esophageally cannulated steers freely grazed a 12-ha pasture during the study. Sampling periods lasted 11 d and started June 2, during the early growing season (EGS); June 22, during early summer dormancy (ESD); July 21, during late summer dormancy (LSD); and August 25, 1985, during the late growing season (LGS). Forage availability was not limiting in any sampling period. Steers consumed a greater (P less than .05) percentage in forbs and lower percentage of grasses in EGS and ESD than in LSD and LGS. Dietary in vitro organic matter digestibility was lower (P less than .05) in ESD than in EGS, LSD and LGS. Dietary N content was higher (P less than .05) in EGs and LGS than in ESD and LSD. Neutral detergent fiber content was lower (P less than .05) in EGS than in other sampling periods, while dietary lignin contents were similar for all sampling periods. Voluntary organic matter intake was similar for all sampling periods; however, estimated gastrointestinal tract fill was greater (P less than .05) in ESD and LSD than in EGS and LGS. Particulate passage rate was slower (P less than .05) and total mean retention time longer (P less than .05) in LSD than in other sampling periods. Rate and lag time of neutral detergent fiber digestion were not different among sampling periods. Ruminal pH was greater (P less than .05) at 3 and 6 h after sunrise in ESD than in other sampling periods. Ruminal ammonia concentrations were lower (P less than .05) in ESD and LSD than in EGS and LGS at 3 and 6 h after sunrise. Total volatile fatty acid concentrations were lower (P less than .05) in ESD than in EGS and LSD at 3 h after sunrise and lower (P less than .10) than EGS and LGS at 9 h after sunrise. Molar proportions of acetate were greater (P less than .05) at 3 h after sunrise in ESD and LSD than in EGS and LGS. Changes in digesta kinetics and ruminal fermentation patterns observed in this study appeared to be related to both forage maturity and dietary botanical composition.

Steers grazing blue grama rangeland throughout the growing season. II. Site and extent of digestion and microbial protein synthesis.

Effects of advancing forage maturity and drought-induced summer dormancy on site and extent of digestion and microbial protein synthesis in beef steers grazing native blue grama rangeland were evaluated in four sampling periods. Five steers (avg initial wt 227 kg) fitted with ruminal, duodenal and ileal cannulae and three steers cannulated at the esophagus freely grazed a 12-ha study pasture. Sampling periods lasted 11 d and started June 2, which was during the early growing season (EGS); June 22, during early summer dormancy (ESD); July 21, during late summer dormancy (LSD); and August 25, 1985, during the late growing season (LGS). Dietary N content was lower (P less than .05) in ESD and LSD than in EGS and LGS. Neutral detergent fiber (NDF) content was lower (P less than .05) in EGS than in other sampling periods. Ruminal organic matter (OM) digestion was lower (P less than .05) in ESD than in EGS, probably because of increased dietary NDF and lower N content. Ruminal OM digestion was greater (P less than .05) in LSD and LGS than in ESD because of increased fiber digestion. Neutral detergent fiber and acid detergent fiber (ADF) digestion occurring in the rumen was greater (P less than .05) in LSD and LGS than in EGS and ESD. Organic matter digestion in the small intestine and OM, NDF and ADF digestion in the hindgut were similar for all sampling periods. Over 90% of the fiber digestion occurred ruminally.(ABSTRACT TRUNCATED AT 250 WORDS)

Utilization of the L- and DL-isomers of alpha-keto-beta-methylvaleric acid by rats and comparative efficacy of the keto analogs of branched-chain amino acids provided as ornithine, lysine and histidine salts.

Three experiments were conducted to quantitatively evaluate the growth-promoting capacity of alpha-keto analogs of the branched-chain amino acids (BCAA). Basal chemically defined diets were formulated to be singly deficient in the BCAA under study; analogs therefore were evaluated as sources of supplemental amino acid activity. Analogs of isoleucine tested included alpha-keto-beta-L-methylvalerate (L-KMV) as the Na salt (L-KMV-Na) and alpha-keto-beta-DL-methylvalerate (DL-KMV) as the Na (DL-KMV-Na), ornithine (DL-KMV-Orn) and lysine (DL-KMV-Lys) salts. Slope-ratio efficacy values were L-KMV-Na, 65%; DL-KMV-Na, 44%; DL-KMV-Orn, 41%; DL-KMV-Lys, 43%. Alloisoleucine accumulated in the plasma of rats fed all sources of KMV, but its concentration was three times greater when DL-KMV was fed than when L-KMV was fed. The analog of valine tested was alpha-ketoisovalerate as the ornithine (KIV-Orn) or lysine (KIV-Lys) salts. There was no significant difference in efficacy between salts (47 versus 44%, respectively). The analog of leucine, alpha-ketoisocaproate, was given as the ornithine (KIC-Orn), lysine (KIC-Lys) and histidine (KIC-His) salts with resulting efficacies of 50, 38 and 49%, respectively. Slope-ratio efficacies of KIC-Orn and KIC-His were statistically similar and efficacy of KIC-Lys was inferior to both KIC-Orn and KIC-His.

Potassium and lasalocid effects on performance and digestion in lambs.

Two trials were conducted to evaluate effects of dietary potassium (K) concentration and lasalocid (L) in lamb finishing diets. Treatments were arranged in a 2 X 2 factorial and consisted of a 65% concentrate diet with 1.1% K (C), .9% K + 21.3 mg L/kg (CL), 2.1% K (P) and 2.5% K + 20 mg L/kg (PL). In trial 1, 64 fine-wool lambs (initial wt 35.3 kg) were randomly assigned to the four treatments (two pens of four wethers and four ewes/treatment) for a 56-d feeding trial. Average daily gain was not affected by K, but was increased (P less than .10) by L (.23 vs .26 kg/d). Lasalocid tended (P less than .20) to improve feed:gain ratio (5.6 vs 6.3). A K X L interaction (P less than .06) was noted for feed intake, with values of 1.37, 1.45, 1.49 and 1.51 kg X head-1 X d-1 for the C, CL, P and PL groups, respectively. In trial 2, 16 wether lambs (four/treatment fed at 2% of body weight) were used in a site and extent of digestion and nitrogen (N) balance trial, using the same four diets as in trial 1. Site of digestion was estimated from abomasal samples taken at slaughter, with indigestible acid detergent fiber as a marker. Total tract organic matter digestibility was increased (P less than .05) with added K (80.1 vs 76.4%) and L (80 vs 76.4%). Ruminal starch digestibility was not affected by added K, but was decreased (P less than .10) by added L (71.8 vs 88.2%).(ABSTRACT TRUNCATED AT 250 WORDS)