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Biomedical subjects

I H Burger

Publications and source records attributed to I H Burger.

15 recordsLinked to original sources
PubMed2000

Maintenance energy requirements and the effect of diet on performance of racing Greyhounds.

OBJECTIVES: To determine maintenance energy requirements and effect of diet on performance of racing Greyhounds. ANIMALS: 7 adult racing Greyhounds. PROCEDURE: Dogs were fed a higher fat and protein (HFP) or a lower fat and protein (LFP) diet for 8 weeks in a crossover design. Dogs were exercised for 15 minutes twice daily in a paddock and raced 500 m twice weekly. Blood gas, hematologic, and serum biochemical analyses were performed before and after racing, and race times were compared at the end of each diet period. RESULTS: Mean race time was significantly shorter (32.81+/-0.65 seconds vs. 33.05+/-0.71 seconds), and mean racing speed over 500 m was significantly faster (15.25+/-0.30 vs. 15.13+/-0.30 m x s(-1)) when dogs were fed the HFP diet than when they were fed the LFP diet. Diet had little or no effect on results of blood gas, hematologic, and serum biochemical analyses, except that Hct was 4% greater before and after racing when the HFP diet was fed than when the LFP diet was fed. Mean SD metabolizable energy intake from weeks 1 through 16 was 155+/-9 kcal x kg(-0.75) x d(-1). CONCLUSIONS AND CLINICAL RELEVANCE: Racing Greyhounds ran faster when fed a diet containing higher fat and protein and lower carbohydrate contents. Their maintenance metabolizable energy requirement was slightly higher than that of moderately active dogs.

Animal Feed↗
PubMed1994

Energy needs of companion animals: matching food intakes to requirements throughout the life cycle.

An animal's primary demand from its diet is for energy. Unlike an individual nutrient, there is no range of acceptable intakes, but rather a specific energy requirement for a given set of conditions. Accurate assessments of both food energy density and the energy needs of the animal are implicit in providing reliable feeding recommendations. The metabolizable energy content of a food is best measured using in vivo testing in the target species. However, the demands of biological testing mean that a set of factors is desirable to provide reasonable estimates. Assessment of energy requirement in dogs is confounded by their wide range of body weights. It should be expressed on an allometric basis, but the precise value for the exponent is still a matter of some debate. For cats recent studies suggest there may be an allometric relationship over a weight range of 2.5-6.5 kg. Energy requirement is dependent on a number of other factors, in particular, activity, environmental temperature and life stage. Demand increases most in lactation (four times) and growth (up to three times). Old animals show a decline in energy requirement, but this may reflect principally a decrease in activity, rather than any underlying change in metabolism.

Animals↗
PubMed1991

Dogs large and small: the allometry of energy requirements within a single species.

Dogs are unique among mammals in having a 100-fold range in body weight for nonobese adults. This variation makes the calculation of the power function for metabolic body size and hence the allometry of energy requirements a particularly challenging subject. Several functions have been proposed from W0.68 to W0.88 (W = body weight in kg). In the present study we measured the heat output of 22 dogs representing seven breeds, aged 1-10 y with W from 5.8 to 48.8 kg, using a whole-body calorimeter specifically designed for this purpose. Regression of log energy output against log W gave the equation 678 W0.64 (r = 0.96; P less than 0.001), which is considered to represent resting energy expenditure (REE) as kJ/d. If estimates of the energy cost of activity are added to REE, new equations of 655 W0.69 (low activity) and 643 W0.73 (higher activity) are obtained, depending on the amount of activity included in the calculation. From these results we suggest that the allometry of energy requirements of adult dogs is a function of different exponents for REE and the energy cost of activity. It does not appear to exceed W0.75 and may be nearer to W0.67.

Animal Feed↗
PubMed1986

[Nutritional aspects in relation to the feline urological syndrome (FUS)].

The 'ideal' diet for minimising FUS risk may not involve a single food but would aim, by various measures, to achieve the conditions listed below: Low urine pH. This may entail the use of urinary acidifiers which must be consumed with or in the food. Some researchers say that the alkaline tide effect must be abolished for the treatment to be completely effective. Low magnesium intake. One figure quoted is a magnesium concentration of 20 mg per 100 kcal DE (about 0.08% dry matter) or less. Nevertheless is appears that FUS risk is appreciably increased only when magnesium concentration reaches about 0.25% dry matter. High urine volume. This entails an adequate water intake with the amount of faecal water maintained as low as possible. This in turn means highly digestible, 'low bulk' foods. Having said this, these aspects are probably important only for the susceptible cats in the population and if all the conditions are achieved the type of diet fed is unlikely to be a crucial factor.

Animal Feed↗
PubMed1982

Sulfur-containing amino acid requirements of growing dogs.

Three experiments were undertaken to establish the total sulfur-containing amino acid requirement of growing dogs. In experiment 1, six Labradors failed to grow normally when fed a soy isolate diet of 0.28% methionine with 0.18% cystine but grow well when the food was supplemented to either 0.57% or 0.74% methionine. In the next experiment, 12 Labradors and 21 beagles were fed the soy isolate diet containing either 0.39%, 0.57% or 0.74% methionine in the presence of 0.15% cystine for 12 weeks. Dogs fed 0.39% methionine had significantly lower body weights, nitrogen retentions, food intakes and feed efficiencies than their littermates fed the two higher levels. This diet provided 468 kcal metabolizable energy (ME) per 100 g, therefore a level of 116 mg total sulfur-containing amino acids (TSAA)/100 kcal ME was not adequate for growth. The lowest level found to be adequate was 0.57% methionine, or 154 mg TSAA/100 kcal ME, which is similar to the requirement of other young omnivores. A final experiment with a free amino acid diet indicated that a level of 117 mg TSAA/100 kcal ME while inadequate for Labradors, may be sufficient for some beagles, highlighting differences between intact protein and free amino acid diets and suggesting possible breed differences.

Amino Acids, Sulfur↗
PubMed1975

Mitochondrial enzyme pathways and their possible role during curing.

The velocity of oxidation of exogenous ferrocytochrome c by nitrite under anaerobic conditions in the presence of skeletal muscle mitochondria is dependent upon pH over at least the range 5.6-6.7, increasing markedly as the pH is lowered. A product of the reaction is the complex formed between nitric oxide and ferricytochrome c. At levels up to 20 mM, nitrite inhibits aerobic cytochrome oxidase action; at higher concentrations, however, a partial resuscitation of the oxidation of ferrocytochrome c occurs, the enhancement of reaction velocity being considerably greater at pH 6.0 than at 6.5. Mitochondrial respiration is also inhibited by nitrite but no similar resurgence was, however, observed and thus the oxidation of ferrocytochrome c by high levels of nitrite is considered to be a direct non-enzymic action. Under anaerobic conditions, the rate of increase of the velocity constant of the oxidation of ferrocytochrome c with nitrite concentration in the presence of muscle mitochondria similarly decreased with rise of pH over the same range. The permeability of the muscle mitochondrion to nitrire has been demonstrated by swelling studies and by the rapid conversion of endogenous ferrocytochrome a3 into its nitrosyl-derivative. Over longer periods of anaerobic incubations of mitochondria with nitrite, oxidation of endogenous cytochromes occurs with the formation of nitrosylferricytochrome c. Above a nitrite concentration of 0.3 mM, the mitochondrial enzyme system probably involved is increasingly inhibited but by a concentration of 30 mM a direct non-enzymic oxidation has intervened. Commercial vacuum packed bacons were examined by electron microscopy. Mitochondria were clearly recognisable although they contained fewer cristae than those observed in fresh meat.

Electron Transport Complex IV↗