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Biomedical subjects

D S Kronfeld

Publications and source records attributed to D S Kronfeld.

At least 55 records · Page 3Linked to original sources
PubMed1994

Body condition of cats.

Explore the source record for details and available documents.

Animal Nutritional Physiological Phenomena↗
PubMed1994

Optimal nutrition for athletic performance, with emphasis on fat adaptation in dogs and horses.

Four mathematical approaches are proposed to determine optimal ranges of nutrients for specified purposes. For exercise, the diet must provide optimal mixtures of fuels, also optimal amounts of nutrients conducive to a sound structure, a desired power/weight ratio, a water-electrolyte system that resists dehydration and buffers hydrogen ions, a tolerance to the cumulative stress of repetitive competition and tractable attitude. The nutritional strategy of carbohydrate loading risks a variety of abnormalities in dogs and horses. An alternative strategy of fat adaptation (the combination of fat feeding and training) was found to improve aerobic performance in dogs and horses and to spare glycogen utilization and reduce lactate accumulation. Surprisingly, improved anaerobic performance has also been confirmed in fat-adapted horses that have been sprint trained. Fat adaptation increased the blood lactate responses to incremental tests and repeated sprints. Blood lactate accumulation during repeated sprints was affected synergistically by the combination of fat adaptation and sodium bicarbonate supplementation. Fat adaptation in horses appears to facilitate metabolic regulation to achieve power needs, with glycolysis decreasing during aerobic work but increasing during anaerobic work and with blood lactate changes following accordingly. Interactions between fat adaptation and dietary cation-anion balance need further investigation.

Adaptation, Physiological↗
PubMed1994

Dietary management of renal senescence and failure in dogs.

The need for dietary management of renal senescence and the beginning of chronic renal failure should be evaluated in all middle-aged dogs. One survey found that 35% were overweight and 10% underweight; another that 25% were mildly azotaemic, with 5% showing slight clinical signs of chronic renal failure. Dogs in prime condition or overweight are candidates for a diet low in energy (for example 3.0-3.3 kcal/g dry matter, DM), but thin dogs need a higher caloric density (such as 4.0-4.5 kcal/g DM). Healthy older dogs need higher dietary protein than the minimum for maintenance (about 20% on a metabolisable energy basis, ME) of young mature dogs. Thin older dogs showing signs of renal insufficiency may benefit from moderate protein and near-minimal phosphorus in the diet. In dogs with chronic renal failure, clinical, haematological and biochemical responses to the combination of low protein (13-16% ME) and low phosphorus (0.4% DM) were positive in one clinical trial but not in three others. Only beneficial responses, such as less proteinuria, less renal impairment and lower mortality, have been reported for diets containing low phosphorus and moderate protein (20-31% ME). Individual dietary goals for energy, protein and phosphorus should be chosen for each middle-aged or older dog; these goals may be met by a single product or mixtures of products.

Aging↗
PubMed1994

Effect of sample handling on measurement of plasma glucose and blood lactate concentrations in horses before and after exercise.

Collection of a satisfactory blood sample requires special procedures to prevent changes in glucose and lactate content after the sample has been obtained. Changes in measured plasma glucose and blood lactate concentrations attributable to anticoagulants and storage procedures, respectively, were examined in blood samples obtained from horses at rest and after exercise. To evaluate the effect of anticoagulants on measured plasma glucose concentration, blood was preserved with either sodium fluoride/potassium oxalate or lithium heparin. Measured plasma glucose concentration in blood obtained at rest and after exercise was 6 and 10% lower (P = 0.0038), respectively, when blood was preserved with fluoride/oxalate, compared with heparin. The erythrocyte volume in the blood sample was 15% smaller (P = 0.0001) in samples preserved with fluoride/oxalate, indicating a movement of water out of erythrocytes in the blood sample mixed with that anticoagulant. To evaluate the effect of storage procedure on measured blood lactate concentration, part of the blood sample was immediately deproteinized for blood lactate analysis, and the remaining blood was maintained for 30 and 60 minutes at either 0 or 22 C before deproteinization. When blood samples were maintained at 0 C prior to deproteinization, there was no difference in blood lactate concentration, regardless of the incubation time, compared with that in samples immediately deproteinized. Blood lactate concentration was greater (P < 0.01) in samples maintained at 22 C, compared with that in samples immediately deproteinized, and with that in equivalent samples maintained at 0 C.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1993

Kinetic analysis of D-xylose absorption after its intragastric administration to mares deprived of food.

Multicompartmental analysis was applied to study the kinetics of D-xylose distribution after its intragastric administration to healthy mares deprived of food for 12, 36, 72, and 96 hours. Disposition of D-xylose was described by a 5-compartment model. Maximal plasma D-xylose concentration was similar for 12 and 36 hours of food deprivation and was greater (P = 0.0001) than the values for 72 and 96 hours. Peak concentration of D-xylose appeared progressively later as food deprivation proceeded (P = 0.0001). Fractional rate of transfer (k1,6) was less after 96 hours of food deprivation, compared with 12 hours (P = 0.0001), and percentage of D-xylose absorbed was reduced (P = 0.0441) after food deprivation. Fractional rate of transfer (k6,5), representing gastric emptying, tended to progressively decrease with food deprivation. Results indicated that formal kinetic analysis can be applied to D-xylose absorption kinetics in horses. Reduction in the extent of D-xylose absorption after food deprivation may be partly caused by decreased rate of D-xylose absorption across the small intestinal mucosa, but other factors, such as gastric emptying and nonabsorptive losses, may also be involved.

Analysis of Variance↗
PubMed1993

Kinetic analysis of D-xylose distribution after intravenous administration to mares.

Multicompartmental analysis was applied to study the kinetics of D-xylose distribution after IV administration to healthy mares deprived of food for 12 and 96 hours. Urinary excretion of D-xylose was measured over a 15-hour period after administration. The plasma D-xylose concentrations in this study were in the range found after oral tolerance testing. The disposition of D-xylose was described by a two-compartment model with linear kinetic characteristics. Total volume of distribution decreased significantly (P < 0.025) from 0.270 L/kg of body weight after the 12-hour period of food deprivation to 0.235 L/kg after the 96-hour period. Fractional rate of transfer between the central and peripheral compartments did not change after 96 hours without food. Approximately a third of the D-xylose administered was recovered in the urine. Difference in urinary elimination between the 12- and 96-hour periods was not significant. Nonrenal elimination rate was determined to be twice the renal elimination rate. The results indicated that formal kinetic analysis can provide useful information about D-xylose distribution in horses. The decreased D-xylose space found after a 96-hour period of food deprivation would tend to increase the plasma D-xylose concentration, and this may help in the interpretation of the D-xylose absorption test applied to anorectic horses.

Animals↗
PubMed1992

Metabolic response of horses to a high soluble carbohydrate diet: effects of low-intensity submaximal exercise and sodium bicarbonate supplementation.

Four mares fed a low fiber, high soluble carbohydrate diet were used in a crossover design to evaluate the effects of dietary sodium bicarbonate (NaHCO3) supplementation during daily low-intensity submaximal working conditions. Mares were fed the diet at 1.7 times the maintenance energy requirement for mature horses at work. The horses tolerated the diet well and had no clinical abnormalities. Resting venous blood bicarbonate (HCO3), standard HCO3, and base excess (BE) concentrations significantly (P less than 0.05) increased with NaHCO3 supplementation, but no significant changes in resting venous blood pH or carbon dioxide tension (PCO2) were recorded. Venous blood HCO3, standard HCO3, BE, hemoglobin, and heart rate were significantly (P less than 0.05) increased and plasma lactate concentration was significantly (P less than 0.05) decreased in the control horses and in the horses given the NaHCO3 supplement during low-intensity submaximal exercise. There were no significant changes in venous blood pH, PCO2, or plasma protein concentration with exercise. Venous blood HCO3, standard HCO3, and BE concentrations were significantly (P less than 0.05) greater during submaximal exercise in horses given the NaHCO3 supplement. There were no significant differences in plasma lactate or total protein concentrations, blood pH, PCO2, or hemoglobin concentration between the 2 groups during exercise.

Acid-Base Equilibrium↗
PubMed1990

Clinical nutrition of sheep and goats.

Management systems and client goals are integral components of clinical nutrition and vary among and within sheep and goat producers. Evaluation includes client interview and history taking, record examination, forage analyses, animal examination, and occasionally blood or tissue assays. The types of nutritional disorders that are likely to be observed in sheep and goats vary according to the type of management and can be grouped according to feedlot, intensive production, farm flocks, dairy, and browse systems. Examples described include nutritional problems that may be overlooked (water deprivation), widespread (energy imbalance), currently difficult to prevent and treat (selenium deficiency), and reflective of soil-plant-animal complexities (copper-molybdenum balance).

Animal Nutritional Physiological Phenomena↗
PubMed1990

A conceptual approach to optimal nutrition of brood mares.

Cumulative nutritional demands on good brood mares are unrivalled among domestic livestock, but little attention has been given to the influence of nutrition on their reproductive performance and efficiency. We suggest that part of the decline in racing performance of progeny of mares over 10 years of age may be caused by suboptimal nutrition. This article contrasts the concepts of minimal and optimal nutrient requirements, revives Hammond's concept of nutrient partitioning to the conceptus and mammary gland, and discusses energy and nutrient requirements during gestation and lactation. Further consideration is given to the aged brood mare.

Animal Nutritional Physiological Phenomena↗
PubMed1990

Dietary aspects of developmental orthopedic disease in young horses.

The clinician may choose between two approaches to nutritional intervention. One is to evaluate the ration and make a painstaking effort to identify those specific factors operating in a particular case, then correct them. The second is to evaluate the ration, inspect for obvious aberrations, and, if finding none, proceed with no further delay to formulate an optimal diet, or a series, for the animals, and design a feeding program to suit farm management. Veterinarians should counsel clients on the possible or probable consequences of level of feeding on growth rate and clinical expression of DOD. In our view, retardation of growth rate by feeding poor quality hay is irresponsible. At present, we suggest that the new approach to retarded growth in weanlings and yearlings--a carefully formulated diet that specifically restricts starch and protein while supplying NRC minimum requirements of other essential nutrients--should be confined to selected individuals and be conducted under strict professional supervision.

Animal Nutritional Physiological Phenomena↗
PubMed1990

Responses of dairy cows in early lactation to bovine somatotropin and ruminally inert fat.

Bovine somatotropin (0 or 41.2 mg/d bST) and calcium salts of long-chain fatty acids (0 or .77 kg/d Ca-LCFA) were administered to 16 Holstein cows in early lactation. Cows remained on 0 or 41.2 mg/d bST for the entire 10 wk and received 0 or .77 kg/d Ca-LCFA in one of two 5-wk periods. Production data were recorded daily, milk fatty acids, and blood metabolites were determined once each period. Treatments did not affect feed intake. Fat-corrected milk (kg/d) and percentage of milk fat for cows receiving no supplementation, fatty acids alone, bST alone, and fatty acids and bST together were 33.8, 3.2; 33.5, 3.1; 37.4, 3.4; and 40.8, 3.5. Milk fatty acids below C16 were reduced with either bST or dietary fatty acids; C16 fatty acids were lower with bST but higher with dietary fatty acids; C18:0 fatty acids were reduced with dietary fatty acids; and C18:1 fatty acids were higher with either bST or dietary fatty acids. Blood acetoacetate concentrations were higher with both bST and dietary fatty acids, beta-hydroxybutyrate was not different, and FFA and insulin concentrations increased with bST. In this experiment, the energy supplied by Ca-LCFA acids enhanced the lactogenic effect of bST.

3-Hydroxybutyric Acid↗
PubMed1990

Effects of hard fats on in vitro and in vivo rumen fermentation, milk production and reproduction in dairy cows.

Adding 0, 5, 15, and 20% of substrate as prilled or unprilled fatty acids [palmitic (47 to 48%), stearic (36 to 37%), and oleic (14%) acids] to an in vitro rumen fermenter had no effect on total VFA production. Acetate:propionate ratio was reduced by fatty acid concentrations of 15 and 20% (prilled and unprilled). In a 4 x 4 Latin square, increasing dietary prilled fatty acids (0, 3, 6, or 9% of DM) decreased DM intake, increased percentage of milk fat, and had no effect on percentage of milk protein. Milk volume and FCM increased with 3% but decreased with 6 and 9% dietary fatty acids. Rumen fluid acetate:propionate decreased with increasing dietary fatty acids. Holstein cows in three herds in Pennsylvania and Friesian cows in an Israeli herd were assigned randomly to receive, from 0 to 110 to 150 d postcalving, diets containing 0 or 2% of DM prilled fat. In Israel, dietary fat increased milk yield, FCM, and fat percentage during the first 90 d postcalving. In Pennsylvania, prilled fat had variable effects on milk composition and little effect on milk yield and FCM. Conception rate was improved in cows consuming rations containing prilled fat: first service, 59.1 versus 42.6%; all services, 59.3 versus 40.7%. The inclusion of prilled fat at 2% of DM in dairy cattle rations had slight effects on rumen fermentation, variable effects on milk yield and composition, and beneficial effects on conception rate.

Animals↗