Tumorigenesis, metabolism, speciation, bioavailability, and tissue deposition of selenium in selenium-enriched ramps (Allium tricoccum).

Ramps (Allium tricoccum) were grown either in a mixture of vermiculite and peat moss or hydroponically with various concentrations of selenium as sodium selenate. The concentrations used were from 30 to 300 mg of selenium/kg of vermiculite-peat moss or from 10 to 120 mg/L in the hydroponic solutions. Levels as high as 784 mg of selenium/kg were obtained in the ramp bulbs when grown with high levels of selenium in the vermiculite-peat moss, and up to 600 mg of selenium/kg was obtained hydroponically. The predominant form of selenium in the ramp bulbs at all concentrations of selenium was Se-methylselenocysteine, with lower amounts of selenate, Se-cystathionine, and glutamyl-Se-methylselenocysteine. There was a approximately 43% reduction in chemically induced mammary tumors when rats were fed a diet with Se-enriched ramps. Dietary Se-enriched ramps for rats did not result in excessive tissue selenium accumulation or undesirable side effects. Bioavailability studies with rats indicated that selenium in ramps was 15-28% more available for regeneration of glutathione peroxidase activity than inorganic selenium as selenite. Therefore, Se-enriched ramps appear to have potential for the reduction of cancer in humans.

Biohydrogenation of unsaturated fatty acids in continuous culture fermenters during digestion of orchardgrass or red clover with three levels of ground corn supplementation.

Diet digestibility and outputs of biohydrogenation intermediates were assessed in a continuous culture of ruminal microorganisms. Orchardgrass or red clover harvested and frozen during spring or fall served as the primary substrates for fermentation. During 10-d incubations, fermenters were fed thawed forage (50 g of DM/d), forage (42 g/d) plus 8 g/d of corn, or forage (34 g/d) plus 16 g/d of corn. Effluents from the last 3 d of incubation were composited for analyses. Starch input increased from 5 to 27% of DM as corn input increased from 0 to 16 g/d. Corn input reduced (P < 0.01) pH, increased (P < 0.01) microbial DM yield, and increased (P = 0.01) digestibility of DM, NDF, CP, and nonstructural carbohydrates. Overall, apparent hydrogenation (percentage) of cis9-18:1, 18:2n-6, and 18:3n-3 was greater (P < 0.05) with orchardgrass than clover. Hydrogenation of cis9-18:1 and 18:2n-6 increased (P = 0.01), but hydrogenation of 18:3n-3 decreased (P = 0.01) linearly due to corn input, regardless of forage. As a result, output of trans11, cis15-18:2 also decreased (P = 0.01). Average output of cis9,trans11-18:2 was greater (P = 0.01) for clover (1.3 mg/d) compared with orchardgrass (0.6 mg/d), but corn input with either forage increased (P = 0.01) cis9,trans11-18:2 output by 205%. Output of trans11-18:1 was greater (P = 0.01) from orchardgrass compared with clover (174 vs. 90 mg/d), but corn increased (P = 0.01) trans11-18:1 output only from clover fermentations. Output of trans10-18:1 was greater (P = 0.01) in response to orchardgrass compared with clover (10 vs. 4 mg/d), but corn addition doubled the output regardless of forage type. Output of trans10,cis12-18:2, which did not differ due to forage type, increased (P = 0.01) twofold in response to corn. Cis9,cis11-18:2 was a primary conjugated isomer produced from forage fermentations, but its output decreased (P = 0.03) in response to corn input. When inputs of 18:2n-6 plus 18:3n-3 were less than 0.9% of total DM (clover), hydrogenation was low (87%). When 18:2n-6 plus 18:3n-3 inputs were from 1.2 to 1.5% of total DM (orchardgrass), hydrogenation averaged 96%. Despite greater hydrogenation, incremental additions of cis9-18:1 and 18:2n-6 from corn grain increased (P < 0.05) outputs of trans10-18:1, trans11-18:1, trans10,cis12-18:2, cis9,trans11-18:2, and trans,trans-18:2 in effluent. Results suggest that forage species alone or in combination with corn grain can alter hydrogenation and profiles of intermediates to varying degrees.

Update: dietary protein and microbial protein contribution.

Factors influencing microbial protein synthesis in the rumen have been reviewed several times in recent years. Original publications in the past 3 yr have reported microbial and feed protein nitrogen contribution postruminally when feeding a variety of dietary proteins. Ammonia is a satisfactory source of nitrogen for growth of the majority of rumen species, but substitution of intact protein for urea (source of ammonia) usually stimulates microbial protein production. Protein sources such as soybean meal appear to possess properties (perhaps rate of degradability) that optimize microbial growth in vivo. Protein sources more undegradable than soybean meal, when fed as the major nitrogen source, sometimes reduce microbial growth. However, nondegradable proteins may compensate for less microbial protein by supplying intact dietary protein postruminally, so the amino acids potentially available may be equal to or greater than those available when readily degradable protein is fed. Soybean meal may reduce microbial growth in diets containing grass silage at protein exceeding 16.8%. Various measurements of microbial and intact dietary protein postruminally show that the contribution of each can be manipulated. Accuracy of quantitative predictions of postruminal contribution depends on several factors that require more research.

Effect of sodium bicarbonate and disodium phosphate on animal performance, ruminal metabolism, digestion, and rate of passage in ruminating calves.

With a five-point radial response design, a control group, and several single factor points, effects of dietary sodium bicarbonate (0 to 4.5%) and disodium phosphate (0 to 2.0%) on calf growth, ruminal fermentation, ration digestibility, and rate of passage of liquid and particulate digesta were studied. Growth and intake data were collected age 7 to 14 wk. Rumen and blood were sampled three times. Digestion and rate of passage trials were during age 16 wk. Gains were not affected significantly but were maximized between 1 and 2% sodium bicarbonate and 0% disodium phosphate. Dry matter intake, feed efficiency, dry matter digestibility, volatile fatty acid ratio, ruminal pH, and buffering capacity were not altered by buffers. Ruminal osmolality and concentration of volatile fatty acids were increased by buffers. Digestibility of acid detergent fiber and neutral detergent fiber tended to be higher for rations containing buffers. Dilution rate of ruminal liquid increased by 40% with 2.0% sodium bicarbonate and .75% disodium phosphate, and ruminal volume was decreased. Passage rate of particulate digesta was increased by a similar amount.

Protein sources evaluated for ruminating Holstein calves.

Fifty calves were fed a basal diet of 11.6% crude protein or one of four diets (15.5% crude protein) containing added soybean meal, corn gluten meal, cottonseed meal, or fish meal. Diets were calculated 75% total digestible nutrients. Body weight gain increased an average of 17% with added protein. Fish meal and soybean meal generated highest rates of gain. Ruminal ammonia-nitrogen was higher for soybean meal and cottonseed meal than other diets, indicating greater rates of degradability. Molar proportions of rumen volatile fatty acids were not different among diets, but concentration was lower for fish meal. Serum urea nitrogen was lowest for the basal and fish meal diets. Microbial nitrogen in the abomasum was 33.6% of total nitrogen for corn gluten meal and 42.8% for soybean meal. Apparent dry matter and nitrogen digestibilities were greater for corn gluten meal and fish meal diets than for soybean meal or cottonseed meal diets. Rumen degradability of feedstuffs, as determined by dacron bag technique, ranged from 38.1% for corn gluten meal to 71.3% for soybean meal. Degradability of mixed diets reflected those of the protein supplement present in each diet except for diet containing cottonseed meal. Fish meal and soybean meal were better protein sources for growth of ruminating calves than were corn gluten meal or cottonseed meal.

Influence of ration form and nitrogen availability on ruminal fermentation patterns and plasma of growing bull calves.

Nine rations containing three forms (ground hay, .2 to 2 cm; chopped hay, 6 to 10 cm; or all concentrate) and three percents (30, 45, and 60%) of rumen degradable nitrogen were fed to 54 Holstein calves (3 X 3 factorial) between 8 and 20 wk of age. Rumen fluid samples were obtained at 8, 11, 14, 17, and 20 wk of age and plasma at 14 and 20 wk of age. Rumen fluid acetate concentration was greatest for ground hay and lowest for concentrate; propionate was greatest for concentrate and lowest for calves fed ground hay. Calves fed concentrate had highest valerate and total volatile fatty acid concentration, whereas lactate concentration and pH were least for concentrate. Ruminal ammonia nitrogen increased with increasing ruminally degradable protein feedstuffs in the ration. Plasma acetate was highest for chopped hay and lowest for concentrate, whereas calves fed concentrate and ground hay were comparable with higher propionate and glucose concentrations than calves fed chopped hay. Plasma urea nitrogen was highest for calves fed 60% ruminally degradable protein.

Postprandial blood glucose and insulin in cows fed high grain.

The effects of ration on postprandial serum glucose and insulin were detemined in 12 lactating Holstein cows. Six were fed a high grain ration of 15% hay and 85% concentrate (dry basis) and the other six a control ration of 55% corn silage, 10% hay and 35% concentrate. High grain feeding increased glucose and insulin at all hours postfeeding as compared to control cows. In the cows fed high grain, glucose increased from 63.3 to 72.2 mg/100 ml and insulin from 19.2 to 25.6 mu units/ml serum just before feeding to 3 h postfeeding. Values for 2, 3, and 4 h samples were greater than for other sampling time. Serum glucose was 55.5 mg/100 ml at 1 h in control cows which was above other sample. Serum insulin followed a pattern similar to glucose in controls but was not signigicantly different with time. The blood changes due to high grain feeding are probably related to low milk fat production.

Corn gluten meal or dried brewers grains as partial replacement for soybean meal in the diet of Holstein cows.

Holstein cows (n = 24, 9 primiparous) were assigned equally to diets based on corn silage and high moisture corn supplemented with soybean meal alone or with either corn gluten meal or dried brewers grains. In diets with two protein sources, the protein quantity from each source was similar. Dietary CP and ADF averaged 16.3 and 18.8%, and undegraded protein as a percentage of CP was 33.6, 41.1, and 41.8% for the respective diets. After parturition, cows were fed the soybean meal diet for a 3-wk covariant period, an experimental diet for 10 wk, the soybean meal diet for 3 wk, and the experimental diet for another 10 wk. Milk production by cows fed those diets averaged 30.9, 31.7, and 34.9 kg/d; protein averaged .90, .94, and 1.02 kg/d; and DMI averaged 16.8, 18.8, and 18.2 kg/d, respectively, for the two 10-wk periods. No dietary differences occurred for 3.5% FCM, estimated DM digestibility, BW, BW gain, or percentages of milk fat, protein, or SNF. Ruminal isobutyrate and isovalerate differed by diet; isovalerate was highest in the diet containing soybean meal plus corn gluten meal, probably because of the high Leu content of corn gluten meal. Ruminal NH3 N did not differ. The favorable production response by cows fed dried brewers grains can be explained by a more favorably balanced AA profile in the ruminally undegraded protein than in other diets.

Effect of orally administered duodenal fluid on serum proteins in neonatal calves.

This study was to determine if orally administered duodenal fluid, as a source of intestinal microorganisms, would influence absorption of gamma-globulin of colostrum in newborn calves. Duodenal fluid was obtained 2 h postfeeding from a cannulated milk-fed calf. Twenty-seven male and female Holstein calves obtained within 6 h of birth were assigned randomly to one of three treatments: 1) colostrum alone, 2) 200 ml duodenal fluid immediately followed by colostrum, and 3) 200 ml duodenal fluid followed 3 h later by colostrum. Pooled colostrum was fed at 10% of body weight in two daily feedings. Total protein, albumin, alpha-globulin, beta-globulin, and gamma-globulin of blood serum were determined prior to colostrum consumption, and again 24 and 48 h after administration of duodenal fluid. Total proteins, beta-globulin, and gamma-globulin of serum increased with age in all calves. Inocula interference with absorption was indicated by depressed values of serum in calves of treatment 3 as compared to treatment 1 calves for protein (5.28 to 6.28 g/dl), beta-globulin (.67 to .87 g/dl), and gamma-globulin (.76 to 1.33 g/dl). Protein was also lower in calves of treatment 3 (6.05 g/dl) compared to uninoculated calves (6.28 g/dl). Malabsorption of colostral proteins may be related to early establishment of large numbers of intestinal microorganisms in the newborn calf.

Dietary energy regulation during gestation on subsequent lactational response to soybean meal or dried brewers grains.

Forty-two Holstein cows were paired by body condition and mature equivalent milk production and fed either a high or low energy diet for the last 16 to 18 wk of lactation. Cows fed the high energy diet produced more milk (21.6 versus 17.6 kg/d), gained more body condition, and were heavier after calving (641 versus 591 kg) than cows fed the low energy diet. Beginning wk 3 postpartum, half the cows in each prepartum energy group were fed supplemental dried brewers grains or soybean meal. During wk 1 to 15 of lactation, cows from the high energy group produced more 3.5% fat-corrected milk (33.8 versus 31.3 kg/d), consumed less dry matter (23.2 versus 24.4 kg/d), and lost more body weight (-2.7 versus .9 kg/wk) compared with cows from the low energy group. Milk production, feed intake, and body weight change were not affected by protein source. The high amount of bound nitrogen in dried brewers grains resulting in decreased intestinal digestibility of escape protein may have been responsible for the lack of production response to this protein source.

Effects of dietary protein degradability and casein or amino acid infusions on production and plasma amino acids in dairy cows.

Responses to daily abomasal infusions of 400 g sodium caseinate, 400 g hydrolyzed casein, or 11.3 g L-methionine plus 30.1 g L-lysine were compared in eight Holstein cows fed diets with estimated ruminal protein degradabilities of 70 and 60.%. Basal diets contained corn silage and corn with either soybean meal or 66.7:33.3 soybean meal:corn gluten meal added. Infusion with Methionine plus lysine increased milk protein content when cows fed either diet but increased milk fat content and yield only when the soybean meal diet was fed. Sodium caseinate increased milk and milk protein production and decreased milk fat percentage. Concentration of total essential amino acids, branched chain amino acids, and urea cycle amino acids were increased by the infusion of both casein sources. Methionine-lysine infusion increased plasma lysine and taurine, a metabolite of methionine, suggesting that absorbed methionine was extensively metabolized. Results demonstrate an impact of both ruminal degradability of dietary protein and form of infused protein on amino acid nutrition of lactating daily cows.

Influence of ration physical form and nitrogen availability on ruminal morphology of growing bull calves.

Male Holstein calves were fed complete diets containing three physical forms (ground and chopped hay and all concentrate) and three rumen degradable protein percent. Calves were slaughtered at 20 wk of age. Weights of reticulorumen with and without contents wee recorded. Proportions of mucosa and muscle and gross morphology were determined on excised rumen wall. From nine additional calves rumen epithelial tissue was obtained for light microscopic examination of papillae to determined length, width, surface area, and morphological condition. Weights of reticulorumen with contents were heaviest for calves fed ground hay and tissue weights heaviest for calves fed concentrate. Ruminal content volume was greater for calves fed diets containing hay compared to all concentrate. Hay contents tended to be drier and less dense than concentrate contents. Ruminal epithelial lining was heavier in concentrate-fed and had more mucosa to muscle compared to rumen of calves fed ground or chopped hay. However, papillary length, number of papillae per field, and surface area/field was greater in calves fed hay. Morphological abnormalities of the rumen epithelium occurred more frequently in calves fed concentrate. Reticulorumen measures were unaffected by degradable protein percent. Absorptive capacity of calves fed all concentrate diets decreased compared to calves fed diets with 40% hay.

Transport of L-amino acids by brush border membrane vesicles from bovine small intestine.

Amino acid transport was studied using brush border membrane vesicles from bovine small intestine. Initial influxes of L-forms of alanine, lysine, methionine, phenylalanine, and proline were stimulated by the presence of a Na+ gradient (outside greater than inside). A relatively large proportion of total influx was by diffusion (e.g., as much as 50% of methionine and 62% of phenylalanine). Kinetic analyses indicated a single mediated transport system for alanine influx in the presence of Na+. This system had an apparent affinity for alanine of .67 mM with maximum flux of 129 pmol/mg protein/s. Mutual inhibition experiments indicated proline mediated transport is probably separate from the neutral amino acids. Alanine, methionine, and phenylalanine probably share common transport system(s), but in addition, methionine is also transported by a system(s) independent of alanine and phenylalanine. In general, methionine was a potent inhibitor of influx of other amino acids.

Isolation and characterization of brush border membrane vesicles from bovine small intestine.

Intestinal brush border membrane vesicles were prepared from 21-wk-old Holstein bulls. The method of preparation included magnesium precipitation, differential centrifugation and sucrose density gradient centrifugation. Purification of brush border membranes was indicated by sevenfold enrichment of alkaline phosphatase activity. Uptake of D-[U-14C]glucose was sodium-stimulated and exhibited characteristic "overshoot" phenomenon. Sodium-dependent and sodium-independent D-glucose uptake was into an osmotically active space. Phloridzin (100 mM) completely inhibited sodium-dependent, but did not affect sodium-independent transport. Sodium-dependent D-glucose transport was inhibited more by D-glucose than by D-galactose, which inhibited more than D-xylose did. The sodium-dependent D-glucose transport was not inhibited by D-fructose, D-ribose or D-arabinose. Sodium-independent D-glucose transport was unaffected by the sugars tested. Glucose transport in bovine intestinal brush border is similar to that in monogastric species and is composed of two pathways: a sodium-dependent inhibitable system and a diffusional system.

Response of lactating cows to pelleted and unpelleted soybean meal after partial protein depletion.

Twenty-four first-lactation cows, averaging 82 d postpartum, were protein depleted for 20 d by consuming a 9.4% crude protein diet. The cows were then assigned randomly and equally to a 2 X 3 factorial arrangement of dietary treatments in which either pelleted or unpelleted soybean meal containing 1% sodium bentonite was supplemented to corn or corn silage-based diets to yield 12.2, 15.4, or 18.1% crude protein, dry basis. Between 9 and 15 d of the depletion period, milk, milk protein production, and dry matter consumption decreased 20 to 25%. Blood hematocrit increased. On refeeding three amounts of protein, dry matter intake was greatest during week 4 of repletion. Milk production rapidly increased to a plateau averaging approximately 88% of preexperimental production with a somewhat greater response to the higher soybean rations. Neither intake, milk, milk protein production, plasma urea, serum albumin, or blood hematocrit provided any evidence that pelleted or unpelleted soybean meal differed nutritionally.

Supplementing pasture to lactating Holsteins fed a total mixed ration diet.

Beginning in September 1997, a 6-week study was conducted to compare performance and income-over-feed cost of lactating Holsteins cows fed either a total mixed ration diet (TMR) only, compared to TMR in the afternoon and pasture in the morning, or TMR in the morning and pasture in the afternoon. Fifty-four Holstein cows in midlactation, averaging 28.1 kg/d of milk, were used in the study. Cows were on pasture for 8 h/d after either the p.m. or the a.m. milking. Predominantly orchardgrass with lesser amounts of white clover and Kentucky bluegrass were grazed. Pasture was sampled once per week, and weekly composites were analyzed. Compressed sward height and herbage dry matter (DM) yield were estimated once per week. Milk yield was electronically recorded and was sampled biweekly. Body condition score and body weight (BW) was recorded at the beginning and end of the study. Income-over-feed cost was calculated for each treatment. Compressed sward height and DM yield averaged 12.7 cm and 1397 kg/ha, respectively. Pasture crude protein, neutral detergent fiber, and acid detergent fiber averaged 27.0, 55.7, and 26.9%, respectively, and net energy-lactation was 1.65 Mcal/kg of dry matter. Milk production was greater for cows on the TMR treatment (29.1 vs. 28.2 and 27.6). No significant difference occurred in percentage of milk fat (3.54, 3.42, and 3.46%), or protein (3.28, 3.20, and 3.22%) for the above respective treatments. The SNF content (8.77 vs. 8.67 and 8.63%) was higher in TMR cows. While BW change did not differ among treatments (23, 32, and 22 kg), body condition score change was greater in cows fed TMR only (0.14 vs. -0.06 and 0.01). As expected, TMR intake was greatest for cows fed TMR only and lowest for cows grazing after the p.m. milking (26.6 vs. 20.3 vs. 17.5 kg/d dry matter). Income-over-feed cost differed between treatments and was approximately 18.6 and 7.5% higher for cows grazing high quality pasture during the afternoon and the morning, respectively, compared with cows on the TMR treatment.