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Biomedical subjects

L E Mount

Publications and source records attributed to L E Mount.

At least 19 recordsLinked to original sources
PubMed1978

The effects of plane of nutrition and environmental temperature on the energy metabolism of the growing pig. 1. Heat loss and critical temperature.

1. The heat losses and energy balances of thirty-eight individually housed pigs (initial body-weights 21--38 kg) were measured continuously for periods of 14 d when they were maintained at environmental temperatures of 10, 15, 20, 25 or 30 degrees. At each temperature four levels of feeding were given approximating to once, twice and three times the maintenance energy intake and the ad lib. level. The minimal maintenance energy requirement (M) was calculated to be 440 kJ metabolizable energy (ME)/kg0.75 per d at 25 degrees. 2. ME intake at the ad lib. level decreased from 1965 kJ/kg0.75 per d at 10 degrees to 1202 at 30 degrees. 3. Heat loss calculated from multiple regression analysis decreased to minimum levels between 20 and 25 degrees; 30 degrees was within the hyperthermic zone at each plane of nutrition. 4. The partition of heat loss into its sensible and evaporative components showed that evaporation increased from 25% at 10 degrees to 78% at 30 degrees. 5. Critical temperature was dependent upon food intake and decreased from 23.1 degrees at M to 20.7 degrees at 2M, 18.0 degrees at 3M and 16.7 degrees at 4M. 6. The extra food required to meet extra thermoregulatory heat production per 1 degrees below the effective critical temperature was 0.65 g/kg body-weight per d.

Animal Nutritional Physiological Phenomena↗
PubMed1975

The rate of heat loss during fasting in the growing pig.

1. The heat loss for individual growing pigs, whose initial body-weight was 25-40 kg, was measured continuously for periods of 14 or 21 d when they were maintained at an environmental temperature of either 20 or 30 degrees. For each temperature the feeding level before and after a period of fasting was held at either 39 or 45g/kg body-weight per d. Four pigs were given each treatment; food was withheld from three animals for a 4 d period in each experiment, and the fourth pig (control) was fed for the whole experimental period. 2. After the withdrawal of food, the heat loss decreased rapidly and minimum values were recorded during the third and fourth days of fasting. Fasting heat loss was higher at 20 degrees than at 30 degrees and was not significantly dependent on the preceeding level of feeding. The mean values obtained at 20 and 30 degrees were 457 and 380 KJ/kg 0.75 per d respectively. 3. The heat loss during the periods of feeding was significantly higher (P less than 0.05) at 30 degrees than at 20 degrees, and was also higher at the higher level of feeding. 4. The apparent efficiency of utilization of metabolizable energy for maintenance was calculated as 0.80. 5. It was concluded that the critical temperature for a fasting pig weighing 25-40 kg is approximately 25 degrees.

Animals↗
PubMed1971

Metabolic rate and thermal insulation in albino and hairless mice.

1. Rates of oxygen consumption of albino and hairless mice were measured in a metabolism chamber during periods of approximately 5 or 24 hr. Rectal temperature was measured before and after each period. The chamber temperatures used were 22, 30 and 32 degrees C for both albino and hairless, and in addition 34 and 36 degrees C for the hairless mice.2. The mean age and body weight of the albino mice were 102 days and 34.6 g; the corresponding values for the hairless mice were 87 days and 32.8 g.3. The mean minimum rates of oxygen consumption (ml./kg.min) were 31.0 for the albino and 38.8 for the hairless mouse; the corresponding estimated critical temperatures were in the ranges 30-32 degrees C for the albino mouse and 32-34 degrees C for the hairless mouse.4. The mean values for core-ambient thermal insulation ( degrees C.m(2).hr/kcal) were 0.418 and 0.328 for the albino mouse, and 0.275 and 0.221 for the hairless mouse, at 22 and 30 degrees C respectively in each case.

Animals↗
PubMed1970

The development of the metabolic response to thyroxine in the new-born pig.

1. Rectal temperature and the rate of oxygen consumption in the new-born pig were measured following the subcutaneous injection of L-thyroxine.2. Thyroxine stimulated oxygen consumption during the post-natal period; both immediate and latent increases were observed.3. The immediate effect occurred after thyroxine, 80 mug/kg, in suckled pigs aged 1-11 days; it was most marked at about 1-4 days of age with a peak increase (20%) in oxygen consumption and a rise in rectal temperature at about 4 hr following the injection.4. The peak increase (30%) in oxygen consumption associated with the latent effect of three successive daily injections of thyroxine, 300 mug/kg, occurred at 5-7 days of age, whether the pigs were first injected at 1 or at 4 days of age.5. It is concluded that there is a high sensitivity to thyroxine in the pig during the first week after birth, when the hormone is not bound to plasma proteins to the same degree as in the older animal.

Age Factors↗
PubMed1970

The relation between body size and maximum and minimum metabolic rates in the new-born pig.

1. Measurements of rates of oxygen consumption were made on a total of sixty-two Large White pigs aged between 1 hr and 6 days, with a range of body weight from 0.75 to 2.40 kg.2. The maximum rate was determined from the continuous estimation of oxygen consumption as the environmental temperature fell past the point at which the maximum occurred.3. The minimum rate was determined both as the environmental temperature rose through the zone of thermal neutrality, and from measurements at thermal neutrality.4. In animals aged 1-6 days the mean maximum rate was 49.0 ml. O(2)/kg.min, and the mean minimum was 15.3 ml. O(2)/kg.min. Both rates were proportional to body weight and not to surface area.5. Pigs less than 1 day old exhibited lower maximum and minimum rates than the older pigs.

Age Factors↗