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Biomedical subjects

R A Erdman

Publications and source records attributed to R A Erdman.

At least 55 records · Page 3Linked to original sources

Factors affecting body tissue mobilization in early lactation dairy cows. 2. Effect of dietary fat on mobilization of body fat and protein.

Twenty-two multiparous Holstein cows were fed either a control diet or a control diet plus 3% added fat (dry matter basis) to determine the effect of added dietary fat on body tissue mobilization and milk production. Body composition measurements were taken using the D2O dilution technique at -2, 5, and 12 wk postpartum. Cows fed added fat produced 2.7 kg/d more milk than did those fed the control diet alone, but milk production, milk composition, and dry matter intake were not affected by diet. The maximum amount of body tissue loss occurred between -2 and 5 wk postpartum when cows fed both diets mobilized 46 kg of body fat and 12 kg of body protein. Between 5 and 12 wk postpartum, only small changes in both body protein and body fat were observed. Even though cows fed added fat showed a tendency toward reduced body fat mobilization (66 kg for cows fed the control diet vs. 37 kg for cows fed the control diet plus added fat) and increased body protein mobilization (4.8 kg for cows fed the control diet vs. 19.5 kg for cows fed the control diet plus added fat), the differences were not significant. Apparent differences in fat mobilization between diets might have been due to initial body fat stores (159 kg for cows fed the control diet vs. 126 kg for cows fed the control diet plus added fat). Across diets, one unit of change in body condition score corresponded to about 55 kg of empty body fat. Supplemental dietary fat did not reduce body tissue mobilization in early lactation.

Adipose Tissue↗

Milk choline secretion as an indirect indicator of postruminal choline supply.

The objectives of this study were to evaluate milk choline as an indicator of choline absorption and to use milk choline to evaluate the efficacy of a rumen-protected choline supplement. In a preliminary 4-wk experiment, two Holstein cows in early lactation were abomasally infused with either 0 or 60 g/d of choline chloride in 2 L of water, which was used as a carrier. Choline infusion increased milk choline secretion from 1.95 to 3.95 g/d during the 2-wk choline infusion period. In Experiment 2, four Holstein cows in early lactation were abomasally infused with 0, 25, 50, and 75 g/d of choline chloride in 2 L of water using a 4 x 4 Latin square design with 1-wk experimental periods. Milk choline secretion was 2.56, 3.62, 3.72, and 3.82 g/d for the respective choline treatments. In Experiment 3, 10 Holstein cows in midlactation were fed either 0 or 50 g/d of choline using an experimental rumen-protected choline supplement during a 2-wk experiment. Milk choline secretion was increased from 2.12 to 2.99 g/d with the supplemental choline. Results of these experiments demonstrated that milk choline is responsive to postruminal choline supply and can be used as a qualitative indicator of choline absorption.

Abomasum↗

Performance, ruminal fermentation, and site of starch digestion in early lactation cows fed corn grain harvested and processed differently.

Two experiments were conducted to assess the effects of corn grain processing on performance, ruminal fermentation, and starch digestion in early lactation dairy cows. Diets were based on wilted alfalfa silage and high moisture or dry corn grain that was either ground or rolled. Thirty-four cows (17 multi-parous) were used to measure effects on intake and lactational performance in a free-stall environment during wk 2 to 15 postpartum. Grinding increased dry matter intake, particularly for cows fed diets containing dry corn, and tended to increase yields of milk, protein lactose, and SNF. Cow performance was not affected by the moisture content of the corn grain. In the digestion experiment, six cows (43 d of lactation) with ruminal, duodenal, and ileal cannulas were used to measure ruminal and intestinal digestion. Search digestion in the rumen and small intestine was greater for high moisture corn, but disappearance of starch in the large intestine was greater for dry corn. Both the grinding process and the high moisture content of the corn increased starch digestibility in the total tract. Flow of microbial N in the duodenum was not affected by treatment. High moisture corn increased starch digestion in the rumen and total tract and enhanced ruminal fermentation as indicated by increased volatile fatty acids and decreased NH3 concentrations in the rumen. In the production experiment, however, only grinding improved the value of corn; ensiling at high moisture content had little effect.

Animals↗

Using milk urea nitrogen to predict nitrogen excretion and utilization efficiency in lactating dairy cows.

Because animal agriculture has been identified as a major source of nonpoint N pollution, ways to reduce the excretion of N by production animals must be examined. The objective of this research was to develop and evaluate a mathematical model that integrates milk urea N to predict excretion, intake, and utilization efficiency of N in lactating dairy cows. Three separate digestibility and N balance studies (10 diets, 40 cows, and 70 observations) were used to develop the model, and 19 independent studies (93 diets) were used for evaluation. The driving variables for the model were milk urea N (milligrams per deciliter), milk production (kilograms per day), milk protein (percentage), and dietary crude protein (percentage). For the developmental data set, the model accurately predicted N excretion and efficiency with no significant mean or linear bias for most predictions. Residual analysis revealed that a majority of the unexplained model error was associated with variation among cows. For the independent data set, model prediction error was approximately 15% of mean predictions. A mean of at least 10 cows was determined to be appropriate for model predictions. Target milk urea N concentrations were determined from expected urinary N excretion for cows that were fed according to National Research Council recommendations. Target values calculated in this manner were 10 to 16 mg/dl, depending on milk production. Milk urea N is a simple and noninvasive measurement that can be used to monitor N excretion from lactating dairy cows.

Animals↗

Glucose metabolism and milk yield of cows infused abomasally or ruminally with starch.

The effect of ruminal or abomasal starch infusion on milk yield and glucose metabolism of early lactation cows was measured. Four cows were continuously infused in the rumen or abomasum with partially hydrolyzed starch (1500 g/d) or were not infused (control) for three 14-d periods during wk 4 to 12 postpartum. Milk yield averaged over 40 kg/d throughout the experiment. Milk and milk lactose yields tended to increase when starch was infused and DMI was decreased, regardless of the site of infusion. Starch infusion increased mean insulin concentration and tended to decrease the concentration of serum nonesterified fatty acids. Ruminal starch infusion did not affect glucose irreversible loss rate but tended to increase glucagon concentration and decrease glucose oxidation. The increased milk yield that occurred when starch was infused ruminally relative to the milk yield of control cows could be a result of increased microbial protein supply or increased energy availability. Compared with ruminal starch infusion, abomasal starch infusion tended to increase the irreversible loss rate of glucose and to increase glucose oxidation. Abomasal infusion tended to increase plasma insulin concentration and to decrease the nonesterified fatty acid concentration relative to ruminal infusion. Infusion of starch abomasally resulted in increases of most uses of glucose, including milk lactose production, glucose oxidation, and the possible storage of glucose as body fat, which indicates that the early lactation dairy cow has a greater capacity for glucose metabolism than is provided by voluntary feed intake of average diets, but that not all available glucose is partitioned to the mammary gland. These data should be useful in testing current concepts and equations in nutritional and metabolic models of dairy cattle.

Abomasum↗

Dietary fatty acids modulate hormone responses in lactating cows: mechanistic role for 5'-deiodinase activity in tissue.

Supplemental dietary fat provides excess fatty acids (FA), which can alter circulating concentrations of several hormones. To test the effects of fatty acid isomer type and possible sites of regulation, we abomasally infused fat mixtures high in cis-C18:1 FA (iCIS), high in trans-C18:1 FA (iTRS) or no infusion (NI) and performed intravenous arginine (ARG) and intramuscular thyrotropin-releasing hormone (TRH) challenges. The experimental design was a replicated 3 x 3 Latin square. Challenges were conducted on Days 10 (ARG) and 12 (TRH) after initiation of fat infusion on each of three 4-wk experimental periods. Plasma concentrations of IGF-I were lower (P < 0.01) when cows received iCIS or iTRS compared with NI. Plasma insulin concentrations increased with ARG but responses were not affected by FA. Plasma growth hormone (GH) was unchanged after ARG. Peak plasma GH and thyroid-stimulating hormone (TSH) responses to TRH were blunted (P < 0.05 and P < 0.1, respectively), whereas thyroxine (T4) and triiodothyronine (T3) responses were augmented post-TRH (P < 0.01) when cows received either FA isomer. Prolactin responses to TRH were not different between infusion treatments, although basal plasma concentrations before TRH were higher in cows infused with iTRS (P < 0.05). To focus on fat regulation of the thyroid axis, we tested directly in vitro the ability of fatty acids dissolved with sodium taurocholate to affect Type-I 5'-deiodinase (5'D) activity in bovine liver homogenates. Homogenate 5'D was not affected by C2:0-C10:0 fatty acids, but decreased linearly (P < 0.01) with increasing concentrations of C12:0-C16:0 and C18:1 isomers. Cis C18:1 decreased 5'D more than the trans-isomer (P < 0.01), but the difference was only apparent at concentrations greater than 0.25 mM. The data suggest that various aspects of pituitary hormone regulation are differentially affected by FA composition. Fatty acid infusion may accentuate end organ responses in the thyroid axis and decrease IGF-I in the somatotropic axis. The data also suggest that FA isomer may alter patterns of extrathyroidal generation of thyroid hormones via direct influences on 5'D.

Animals↗

Modification of physical activity 5 months after myocardial infarction: relevance of biographic and personality characteristics.

The relation between modification of physical activity, a risk factor for coronary heart disease, and personality characteristics was assessed in 166 survivors of a first myocardial infarction (MI). Physical activity was assessed before MI in retrospect and again 5 months after MI. Patients were divided into 3 categories according to their current daily-life physical activities: less active than before MI (n=24), equally active as before MI (n=82), or more active than before MI (n=60). A significant differentiation was found between patients who became less physically active than before MI and the other 2 categories. This less active category was characterized by feelings of disability, a low level of vigor, and feelings of anxiety. In addition, this patient group was on average older and more often female. The results were adjusted for participation in a cardiac rehabilitation program. Finally, the discussion recommends involving psychological intervention in the exercise program for the less active category of patients to diminish feelings of anxiety and disability and to improve vigor.

Journal Article↗

The effect of abomasal infusion of casein and recombinant somatotropin hormone injection on nitrogen balance and amino acid fluxes in portal-drained viscera and net hepatic and total splanchnic blood in Holstein steers.

Six Holstein steers, 6 mo of age, with a BW range of 180 to 200 kg were used to determine effects of abomasal casein infusion and recombinant bovine somatotropin on amino acid absorption and metabolism in the gut and liver. Catheters were positioned in the hepatic vein, the hepatic portal vein, two mesenteric veins, and a mesenteric artery. Using the same basal diet, treatments consisted of 1) basal diet only (Control), 2) abomasal casein infusion of 300 g/d (Casein), and 3) abomasal casein infusion plus daily injection of 20 mg of bovine somatotropin (ST). All steers were fed the basal diet at a rate of 24 g/kg of BW on a DM basis, in 12 equal meals at 2-h intervals. Initially, Casein and ST treatments were in a balanced cross-over design, and then all steers received the Control treatment. Casein infusion tended to increase BW gain but did not affect BW gain per unit of N intake. The ST treatment increased weight gain (P < .01) and efficiency of dietary DM (P < .01) and N (P < .01) utilization by more than 40% and increased the percentage of absorbed N retained. Nonessential, essential, and total amino acid fluxes in portal-drained viscera (PDV) and their net removal by the liver were not affected by casein infusion. However, ST tended to reduce PDV flux of essential, nonessential, and total amino acids by approximately 30%, and their removal by the liver (P < .08). As a result, ST increased, compared with casein, release of essential (P < .06) and total (P < .10) amino acids from the total splanchnic pool (TSP) into peripheral blood. The ST treatment increased the availability of absorbed amino acids to peripheral tissues, but it did not affect the amino acid profile delivered from splanchnic tissues, especially that of essential amino acids.

Abomasum↗

Factors affecting body tissue mobilization in early lactation dairy cows. 1. Effect of dietary protein on mobilization of body fat and protein.

Twenty Holstein cows were fed diets that were formulated with 16 or 19% crude protein (CP) that contained, respectively, 6 and 9% ruminally undegradable protein (RUP) (dry matter basis) to study the effect of increased RUP on tissue mobilization and production parameters. Cows were enrolled in the study from -14 to 114 d postpartum. Body composition measurements using the D2O dilution technique were made at -2, 5, and 12 wk postpartum. Maximum loss of body tissue occurred between wk 2 prepartum and wk 5 postpartum during which time cows fed both treatments mobilized a mean of 54 kg of body fat and 21 kg of body protein. Cows continued to mobilize 18 kg of body fat through wk 12 postpartum, but the amount of body protein was unchanged. One unit of change in body condition score corresponded to about 40 kg of empty body fat. Partitioning of empty body energy between empty body fat and protein indicated that, for each unit of change in body energy, 93% was lost or gained as body fat, and body protein accounted for only 7%. Increasing RUP in the diet had no effect on the postpartum amounts of empty body protein, empty body fat, or empty body energy. Milk production was 39.8 kg for cows fed the 16% CP diet and 42.4 kg for cows fed the 19% CP diet. There was an interaction of treatment by week postpartum. Both dry matter intake and milk production were lower during the first 6 wk postpartum but were greater thereafter for cows fed the 19% CP diet than for cows fed the 16% CP diet. Milk CP percentage was higher (3.08% vs. 2.89%), and milk CP yield tended to be greater (1.29 vs. 1.15 kg/d), for cows fed the 19% CP diet.

Adipose Tissue↗

Effect of dietary forage concentration and buffer addition on duodenal flow of trans-C18:1 fatty acids and milk fat production in dairy cows.

Milk fat depression in cows fed high grain diets has been shown to be related to increased trans-C18:1 fatty acids in milk. Trans-C18:1 fatty acids are produced as a result of incomplete biohydrogenation of dietary polyunsaturated fatty acids in the rumen. The objective of this study was to determine the effects of varying amounts of dietary concentrate and buffer addition on duodenal flow, apparent absorption, and incorporation of trans-C18:1 fatty acids into milk fat. Four ruminally and duodenally cannulated multiparous Holstein cows in midlactation were fed diets consisting of 60% (high) or 25% (low) forage with or without buffer (1.5% NaHCO3 and 0.5% MgO). Treatments were arranged in a 2 x 2 factorial within a 4 x 4 Latin square design. The diet containing low forage and no buffer increased the flow of trans-C18:1 fatty acids to the duodenum compared with the effects of other diets (120 vs. 57 to 66 g/d). Ruminal pH was lower for cows fed the low forage diets. The addition of buffer increased ruminal pH by 0.19 and 0.02 units for cows fed the low forage and high forage diets, respectively. Cows fed the diet containing low forage and no buffer produced milk with a lower fat percentage. The addition of buffer to the low forage diet partially corrected milk fat depression. Milk trans-C18:1 fatty acids were higher for cows fed the low forage diet without buffer than for cows fed the other diets (5.8% vs. 3.0%). Altered ruminal function resulting from low ruminal pH for cows fed the low forage diet and no buffer may play a role in the increased production of trans-C18:1 fatty acids in the rumen.

Animal Feed↗

Effect of fat source on duodenal flow of trans-C18:1 fatty acids and milk fat production in dairy cows.

The objective of the study was to determine the effects of dietary fat source on duodenal flow, apparent absorption, and milk fat incorporation of trans-C18:1 fatty acids. Four ruminally and duodenally cannulated multiparous Holsteins cows in mid to late lactation were fed a basal diet containing 36% corn silage, 24% alfalfa haylage, and 40% concentrate (dry matter basis). Diets contained 0% supplemental fat (control diet), 3.7% high oleic sunflower oil, 3.7% high linoleic sunflower oil, or 3.7% partially hydrogenated vegetable shortening; treatments were administered in a 4 x 4 Latin square design with 3-wk experimental periods. The flow of trans-C18:1 to the duodenum was higher for cows fed diets supplemented with fat than for cows fed the control diet (283 vs. 64 g/d). Incomplete biohydrogenation accounted for the increased flow of trans-C18:1 to the duodenum in cows fed diets containing high oleic and high linoleic sunflower oil. Increased flow of trans-C18:1 in cows fed the diet containing partially hydrogenated vegetable shortening most likely originated from the trans-C18:1 in the diet. Milk fat percentages were 3.48, 3.07, 3.18, and 3.38% for cows fed the control diet and diets containing high oleic sunflower oil, high linoleic sunflower oil, and vegetable shortening, respectively. Milk trans-C18:1 increased from 2.9 to 11.2% of the total fatty acids for cows fed the control diet and the diets supplemented with fat, respectively. Milk trans-C18:1 were equal across all diets supplemented with fat. Ruminal and total tract digestion of organic matter, neutral detergent fiber, and N did not change with fat supplementation. Results showed that trans-C18:1 is increased in the milk of cows with reduced milk fat; however, excessive amounts of trans-C18:1 in milk do not necessarily correspond directly to milk fat depression.

Animal Nutritional Physiological Phenomena↗

Effects of a long daily photoperiod on milk yield and circulating concentrations of insulin-like growth factor-1.

Relative to a short daily (24-h) photoperiod, exposure to a long daily photoperiod increases the milk yield of dairy cows. However, the endocrine basis for this phenomenon is unknown. The present study was designed to test the hypothesis that a long daily photoperiod is associated with increased circulating insulin-like growth factor (IGF)-I, a hormone that is galactopoietic in ruminants. Forty lactating cows were exposed to either a natural photoperiod (< or = 13 h of light/d) or to a long daily photoperiod (18 h of light and 6 h of darkness) between January and April 1995. Cows were fed for ad libitum intake a total mixed diet formulated to meet the nutritional demands of lactation. Milk yield and dry matter intake were quantitated each day, and blood samples were collected by coccygeal venipuncture every 14 d. Plasma was harvested and assayed for IGF-I. The long photoperiod increased milk yield relative to the natural photoperiod (36.1 +/ 0.6 vs. 33.9 +/ 0.6 kg/d); the increase became significant after 28 d of treatment and was maintained for the duration of the study. In addition, cows exposed to a long photoperiod had greater circulating concentrations of IGF-I than did cows exposed to the ambient natural photoperiod (60.1 +/ 2.0 vs. 52.6 +/ 2.0 ng/ml). Concentrations of IGF binding protein -2 and -3 in plasma did not differ between treatments. These results support the hypothesis that a long daily photoperiod increases circulating concentrations of IGF-I in lactating cows and reveal a possible endocrine mechanism for the galactopoietic response to a long daily photoperiod.

Animal Nutritional Physiological Phenomena↗

Prenylation of a Rab1B mutant with altered GTPase activity is impaired in cell-free systems but not in intact mammalian cells.

Previous studies have reached differing conclusions as to whether or not guanine-nucleotide-dependent conformational changes affect the ability of Rab proteins to undergo post-translational modification by Rab:geranylgeranyltransferase (Rab-GGTase). We now show that the ability of a Rab1B mutant [Q67L (Gln-67-->Leu)] with reduced intrinsic GTPase activity to undergo geranylgeranylation in cell-free assays depends on the guanine nucleotide composition of the system. When GTP is the predominant nucleotide in the assay, Rab1BQ67L is a poor substrate. However, when GDP is present and GTP is omitted, prenylation of the Q67L mutant is comparable with that of the wild-type (WT) protein. These studies, coupled with the poor prenylation of Rab1BWT in the presence of the non-hydrolysable GTP analogue guanosine 5'-[gamma-thio]triphosphate, support the notion that Rab-GGTase prefers substrates in the GDP conformation. When the abilities of Rab1BQ67L and Rab1BWT to undergo prenylation were compared by metabolic labelling of transiently expressed proteins in cultured human 293 cells, we did not observe a decline in prenylation of the mutant protein as predicted on the basis of the cell-free assays. Moreover, the Q67L mutant was comparable with the wild-type Rab1B in its ability to associate with co-expressed Rab GDP dissociation inhibitors in 293 cells. These findings raise the possibility that unidentified proteins present in intact cells may compensate for the reduced intrinsic GTPase activity of the Q67L mutant, allowing a significant proportion of the nascent Rab1BQ67L to assume a GDP conformation. The differential prenylation of Rab1BQ67L in cell-free systems versus intact cells underscores the importance of evaluating the post-translational modification of specific Rab mutants in vivo, where poorly characterized regulatory proteins may have a significant effect on GTPase activity or nucleotide exchange rates.

Amino Acid Sequence↗

Association of Rab1B with GDP-dissociation inhibitor (GDI) is required for recycling but not initial membrane targeting of the Rab protein.

We have identified the Rab1B effector-domain mutant (D44N) that, when geranylgeranylated by Rab:geranylgeranyltransferase (GGTase II) in cell-free systems or intact cells, fails to form detectable complexes with GDP-dissociation inhibitors (GDIs). GDI-Rab complexes were collected on anti-FLAG affinity beads after incubating recombinant geranylgeranylated Rab1B with FLAG epitope-tagged GDI in vitro, or transiently coexpressing Myc-tagged Rab1B with FLAG-GDI-alpha or FLAG-GDI-2 in human embryonal kidney 293 cells. [3H]Mevalonate labeling and immunoprecipitation studies confirmed that the inability of Myc-Rab1BD44N to associate with GDI in vivo was not due to failure of the mutant to undergo geranylgeranylation. Immunofluorescence localization and immunoblot analysis of subcellular fractions indicated that expressed Myc-Rab1BD44N was efficiently delivered to intracellular membranes in 293 cells. This was confirmed when the fate of the prenylated pool of Rab1BD44N in 293 cells was traced by labeling the geranylgeranyl groups attached to the nascent protein with [3H]meval onate. However, in contrast to the prenylated Rab1BWT, which was distributed in both the membrane and soluble fractions, the prenylated Rab1BD44N was completely absent from the cytosol. Overexpression of Myc-Rab1BD44N did not impair ER --> Golgi glycoprotein trafficking in 293 cells, which was assessed by monitoring the Golgi-dependent processing of coexpressed beta-amyloid precursor protein. The current findings suggest that nascent prenylated Rab1B can be delivered to intracellular membranes in intact cells without forming a stable complex with GDI, but that recycling of prenylated Rab1B to the cytosolic compartment is absolutely dependent on GDI interaction.

Amino Acid Sequence↗

Modification of smoking habits five months after myocardial infarction: relationship with personality characteristics.

The relationship between personality characteristics and spontaneous modification of smoking habits was assessed in 164 patients after their first myocardial infarction (MI). Smoking habits before the MI were investigated in retrospect and 5 months later. Smoking appeared to have decreased significantly. Persistent smokers could be differentiated from nonsmokers and exsmokers by a significantly high level of state-anxiety and depression. Young persistent smokers had a high level of depression; elderly persistent smokers were highly anxious and had a low level of somatization. The relationship between smoking behaviour modification and personality characteristics is discussed in association with intervention programmes.

Adult↗

Empirical psychological modeling of chest pain: a comparative study.

In this study the psychological profiles of 67 patients with noncardiac chest pain (NCA) and 47 patients with coronary artery disease (CAD) were analyzed to construct an empirical-psychological model that would be able to discriminate these two groups. All patients were suffering from chest pain at the time of referral by their general practitioner. The noncardiac patients were significantly younger, more often female, single, and nonsmokers. The two groups differed significantly on anxiety, somatization, obsessive compulsive behavior, psychoneuroticism, and hyperventilation. Logistic regression analysis on the variables jointly, showed that age, gender, anxiety, and hyperventilation contributed significantly to the model for discriminating between the two groups. Crossvalidation showed that the constructed model was stable.

Adult↗

Glucose and norepinephrine challenges during abomasal infusion of cis or trans octadecenoates in Holstein cows.

This experiment determined the effects of infusion of mixtures of fat containing predominantly cis-C18:1 or trans-C18:1 fatty acids into the abomasum on responses of cows to glucose and norepinephrine challenges administered i.v. Six lactating Holstein cows, each with a rumen cannula, were arranged in two Latin squares with 21-d periods. The common basal diet contained 40% forage and 60% concentrate. Treatments were the uninfused control, 750 g/d of a cis fat mixture (65% high oleic sunflower oil and 35% cocoa butter), and 750 g/d of a trans fat mixture (93% shortening and 7% corn oil) infused into the abomasum via a tube that passed through the rumen cannula. Glucose challenges (0.4 mg/kg of BW, administered i.v.) were conducted on d 18, and norepinephrine challenges (0.7 microgram/kg of BW, administered i.v.) were conducted on d 19 of each experimental period. Despite a lower percentage of fat in milk for trans than for cis treatment, disappearance rates of glucose, secretion of insulin after glucose challenge, and appearance rates of NEFA and triglycerides after norepinephrine challenge were similar between treatments. Thus, these data support the hypothesis that trans-C18:1 fatty acids affect the synthesis of milk fat in the mammary gland of lactating cows.

Abomasum↗