The effect of simulated altitude on the heat increment of feed in sheep

1. Sheep given constant feed were exposed to environments in which the oxygen concentration in air was either 200 or 150 ml/l. There were no differences in daily heat production, methane production, urinary energy or faecal energy losses measured over periods of 4 d.2. When the sheep were fasted there were no differences in heat production to be ascribed to the O2 concentration in air. The thermic response to feed was unaffected by the O2 concentration in the air.

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On the calculation of heat production from open-circuit calorimetric measurements

British Journal Of Nutrition ◽

10.1079/bjn19720130 ◽

1972 ◽

Vol 27 (3) ◽

pp. 597-600 ◽

Cited By ~ 89

Author(s):

J. A. McLean

Keyword(s):

Oxygen Concentration ◽

Heat Production ◽

Methane Production ◽

Respiratory Quotient ◽

Ventilation Rate ◽

Open Circuit ◽

Calorimetric Measurements ◽

Ruminant Animals ◽

New Form

1. The equation used for calculating heat production of ruminant animals is expressed in a new form, convenient for application to open-circuit calorimetry.2. It is shown that in open-circuit calorimetry the possible error involved in making the assumption that respiratory quotient is equal to unity is small compared with the possible error involved in neglecting methane production.3. In open-circuit calorimetry heat production can be predicted with accuracy to within ± 2% solely from the measurement of oxygen concentration and ventilation rate.

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PO-191 The effect of hypoxic training at different simulated altitude on the antioxidant activity mediated by Nrf2 in mice skeletal muscle

Exercise Biochemistry Review ◽

10.14428/ebr.v1i4.12843 ◽

2018 ◽

Vol 1 (4) ◽

Author(s):

Weixiu Ji ◽

Ying Zhang

Keyword(s):

Skeletal Muscle ◽

Antioxidant Activity ◽

Oxygen Concentration ◽

Training Group ◽

Control Group ◽

Simulated Altitude ◽

Wild Type ◽

High Quality ◽

Hypoxic Training ◽

Nrf2 Protein

Objective It is generally believed that the long-term hypoxic training could impact oxidation resistance. Nrf2-Keapl signaling pathway is a key pathway of cell oxidative stress reaction. This research attempts to investigate the role and mechanism of Nrf2 in oxidation resistance to hypoxic training of different oxygen concentration. Methods Part one, 8-week-old Nrf2 knockout mice and wild type mice were divided into normoxic control group (NC), simulated altitude of 3500m hypoxic training group (3500HT) and simulated altitude of 5000m hypoxic training group (5000HT) randomly and respectively. The mice run on treadmill in speed of 12 m/min, 1h/day, 6day/week, for 4 weeks. Oxygen concentration in hypoxia was 13.3% and 10%. Mice were treated for 4 weeks, 8h/day. 48 h after the last training, the mice were sacrificed and skeletal muscles of legs were collected. Western Blot tested Nrf2 and antioxidant enzyme protein. Antioxidant enzymes mRNA were tested by RT-PCR. High quality fluorescence measurement was used to test ROS levels in skeletal muscle. Part two, The 30 C57BL/6J mice were divided into three groups: control group (WC), hypoxia group (WH), hypoxic training group (WHT). The hypoxic training arrangement was same as before. After both the interventions, the mice were sacrificed and collected skeletal muscle of legs. The expression of Nrf2, Keap1 and p-Nrf2 were analyzed by western blot. High quality fluorescence assay was done to detect ROS level in skeletal muscle of mice. Results (1) Compared with the same type mice NC group, Nrf2 protein, the mRNA and protein of CAT, GPX-1, GCLm, the mRNA of SOD1, SOD2, HO-1 were increased in wild type mice 3500HT group. And the Nrf2 protein, the mRNA and protein of SOD1, SOD2, the mRNA of CAT, NQO-1, GCLc, GCLm mRNA, the protein of HO-1 were decreased, and the ROS levels was higher in wile type mice 5000HT group. The mRNA of CAT, HO-1 in Nrf2-KO mice 3500HT group were increased, the mRNA and protein of SOD1, the mRNA of SOD2, the protein of GCLc were decreased, but the GCLc mRNA was increased in Nrf2-KO mice 5000HT group. When compared with the same intervention wild type mice, the mRNA and protein of SOD1, GPX-1, SOD2, HO-1, the mRNA of CAT, NQO-1, GCLc, GCLm were decreased in Nrf2-KO mice 3500HT group. The mRNA of GCLm, NQO-1, the protein of GCLc, HO-1 were decreased, but the GCLc mRNA was increased. (2) Nrf2/Keap1 complex contents in mice skeletal muscle of WH and WHT groups were significantly increased compared with WC group respectively. The free Nrf2 in mice skeletal muscle of WH、WHT groups were significantly reduced compared with WC group respectively. After both types of intervention, free Keap1 had no change nearly in skeletal muscle of mice. Compared with WC group, p-Nrf2 in mice skeletal muscle of WH and WHT groups were significantly reduced. The ROS level in mice skeletal muscle of WHT group significantly increased compared with WC group mice. Conclusions: Hypoxia and hypoxia training three interventions could increase Nrf2/Keap1 combination in skeletal muscle of mice, reduce the volume of free Nrf2; Phosphorylation of Nrf2 in skeletal muscle of mice in hypoxia training group was significantly lower, which may be result in marked increase in ROS level. Conclusions (1) Hypoxic training could affect antioxidant activity via Nrf2 in mice skeletal muscle, which is connected with the oxygen concentration. (2) Moderate hypoxia training (at the altitude of 3500m) can promote the antioxidant activity via Nrf2. However, extremely hypoxic training (at the altitude of 5000m) can restrain the antioxidant activity via Nrf2 through the inhibition of Nrf2/Keap1 dissociation.

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Hormonal factors in reduced postprandial heat production of exercise-trained subjects

Journal of Applied Physiology ◽

10.1152/jappl.1984.56.3.772 ◽

1984 ◽

Vol 56 (3) ◽

pp. 772-776 ◽

Cited By ~ 34

Author(s):

J. LeBlanc ◽

P. Diamond ◽

J. Cote ◽

A. Labrie

Keyword(s):

Exercise Training ◽

Heat Production ◽

Human Subjects ◽

Resting Metabolic Rate ◽

Glucose Disposal ◽

Plasma Norepinephrine ◽

Trained Subjects ◽

Enhanced Sensitivity ◽

Heat Increment Of Feeding ◽

Heat Increment

The influence of exercise training on postprandial heat production was investigated in human subjects. Whereas resting metabolic rate was comparable for trained and nontrained subjects, the heat increment of feeding (HIF) after subjects consumed a meal containing 755 kcal was approximately 50% smaller in the trained subjects. Measurements of respiratory quotient also indicated a reduction of about 50% in glucose oxidation associated with exercise training. The levels of plasma norepinephrine increased significantly (P less than 0.01) from 200 to 300 pg/ml in the sedentary subjects, but the changes observed in trained subjects were not significant. During the early phase of the meal, plasma levels of insulin were increased, even before nutrients appeared in the blood. Throughout the study the enhanced sensitivity to insulin of the trained subjects was confirmed. the postprandial heat production was diminished in exercise-trained subjects, and it is suggested that this could be related to a reduced activity of the sympathetic nervous system. Another possibility is that this reduction in HIF is related to a facilitation of glucose disposal in the form of glycogen rather than in the form of lipids.

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Compensatory effect of the heat increment of feeding on thermoregulation costs of white-tailed deer fawns in winter

Canadian Journal of Zoology ◽

10.1139/z99-111 ◽

1999 ◽

Vol 77 (9) ◽

pp. 1474-1485 ◽

Cited By ~ 23

Author(s):

Paul G Jensen ◽

Peter J Pekins ◽

James B Holter

Keyword(s):

Metabolic Rate ◽

Heat Production ◽

Resting Metabolic Rate ◽

Energetic Cost ◽

Critical Temperatures ◽

Metabolic Chamber ◽

Heat Increment Of Feeding ◽

Heat Increment ◽

Minor Portion ◽

A Minor

For northern white-tailed deer (Odocoileus virginianus) fawns, the energetic cost of thermoregulation (HcE) during severe winters can result in substantial catabolism of body-tissue reserves. The heat increment of feeding (HiE) has the potential to offset thermoregulatory energy expenditure that would otherwise require the catabolism of these reserves. During winters 1996 and 1997, we conducted 18 fasting and 18 on-feed heat-production trials using indirect respiration calorimetry in a metabolic chamber. Nonlinear regression analysis was used to estimate the lower critical temperatures (Tlc) and determine the fasting metabolic rate (FMR) and resting metabolic rate (RMR). Resulting models were used to calculate HiE, HcE, and percent substitution of HiE for HcE. For fawns fed a natural browse diet, estimated FMR and RMR were 352 and 490 kJ·kg body mass (BM)-0.75·d-1, respectively; this 40% increase in thermoneutral heat production reduced Tlc from -0.8 to -11.2°C between the fasted and fed states, respectively, and reduced HcE by 59% for fed fawns. For fawns fed a concentrate diet, estimated FMR and RMR were 377 and 573 kJ·kg BM-0.75·d-1, respectively. Level of browse intake had a significant effect on RMR andTlc. RMR was 12% higher for fawns on a high versus a low level of intake, and estimated Tlc was -15.6 and -5.8°C, respectively. Our data indicate that the energetic cost of thermoregulation is probably a minor portion of the energy budget of a healthy fawn consuming natural forage.

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Energy exchanges of pregnant and lactating ewes

Australian Journal of Agricultural Research ◽

10.1071/ar9640127 ◽

1964 ◽

Vol 15 (1) ◽

pp. 127 ◽

Cited By ~ 46

Author(s):

N McCGraham

Keyword(s):

Heat Production ◽

Nitrogen Loss ◽

Metabolizable Energy ◽

Energy Utilization ◽

Carbon And Nitrogen ◽

Direct Measurements ◽

Heat Increment ◽

Energy Retention ◽

Energy Exchanges ◽

Pregnant Ewe

At intervals throughout gestation, the energy, carbon, and nitrogen exchanges of four Merino ewes were determined with the aid of closed-circuit indirect calorimetry. Six similar but non-pregnant animals were studied at the same time. The food consisted of equal parts of lucerne and wheaten hay; half the sheep in each group were given a constant 600 g/day and half 900 g/day, and the non-pregnant ewes were fasted on one occasion. Free fatty acids, glucose, and ketones in the blood were also determined during the final stages of pregnancy. Balance measurements were continued during lactation, the ewes being given 1200 g food/day for the first month and 900 g for the second. The digestibility of the food was not affected by pregnancy or lactation, but urinary nitrogen loss decreased as pregnancy advanced and was least during lactation. Although a constant amount of food was eaten, the heat production of each pregnant animal increased throughout gestation. The heat increment of pregnancy at term was 90 kca1/24 hr/kg foetal tissue. The most direct measurements of oxygen uptake by the foetus in utero indicate much lower levels of heat production per kilogram of tissue; it is concluded that these are underestimates. The metabolic rate was unusually high immediately before parturition, and in two cases decreased to near non-pregnant levels 24 hr after lambing. The total energy retention of the ewes became smaller as pregnancy advanced, and in two cases was negative at term. Metabolizable energy was used for reproduction with a gross efficiency of 15–22% and a net efficiency of 13%. The metabolizable energy used per kilogram of foetus was approximately 10% of the maintenance requirement of the ewe herself. Daily energy utilization by the conceptus at term probably accounted for 70% of the glucogenic substances available from the food. There was no evidence of increased gluconeogenesis from protein by the pregnant ewe. The nutrition of the ewe during gestation affected lactation mainly in the first week or two. The data indicate that nitrogen intake rather than energy intake limited milk production. Irrespective of the amount of energy in the milk, the heat increment due to feeding was 20% smaller for lactating than for dry fatteningewes. It is suggested that efficient use of acetate by the mammary gland permits more efficient lipogenesis by other tissues.

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Calorimetric studies on the effect of dietary energy source and environmental temperature on the metabolic efficiency of energy utilization by mature Light Sussex cockerels

The Journal of Agricultural Science ◽

10.1017/s0021859600024928 ◽

1969 ◽

Vol 72 (3) ◽

pp. 479-489 ◽

Cited By ~ 33

Author(s):

D. W. F. Shannon ◽

W. O. Brown

Keyword(s):

Heat Production ◽

Environmental Temperature ◽

Metabolizable Energy ◽

Energy Utilization ◽

Metabolic Efficiency ◽

Heat Increment ◽

Energy Retention ◽

Calorimetric Studies ◽

The Relationship ◽

Maize Oil

SUMMARYExperiments to determine the net availabilities of the metabolizable energy (NAME) of a cereal-based diet and a maize-oil diet for maintenance and lipogenesis and the effect of environmental temperature on the NAME of the cereal-based diet are described. Four 1- to 2-year-old Light Sussex cockerels were used.The relationship between ME intake and energy retention was linear for each diet. The NAME'S of the cereal-based diet given at 22° and 28 °C (70.6 ± 1.83 % and 73.6 ± 3.54%, respectively) were significantly (P < 0.05) lower than the NAME of the maize-oil diet (84.1 ± 1.85%). It is concluded that the beneficial effect of maize oil on the efficiency of energy utilization is due to a reduced heat increment rather than a reduction in the basal component of the heat production. The higher efficiency from the maize-oil diet led to an increase in the energy retained as fat.The mean fasting heat production at 28 °C was 15 % lower than at 22 °C (43.2 ± 1.45 and 51.2 ± 1.09 kcal/kg/day, respectively). The NAME of the cereal-based diet was not significantly different when the birds were kept at 22° or 28 °C. The lower metabolic rate at 28 °C was reflected in a lower maintenance requirement and in an increase in the deposition of body fat.

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Further studies on the energy and protein metabolism of pigs growing at a high ambient temperature, including measurements with fasting pigs

Animal Science ◽

10.1017/s0003356100022777 ◽

1974 ◽

Vol 19 (2) ◽

pp. 211-220 ◽

Cited By ~ 20

Author(s):

C. W. Holmes

Keyword(s):

High Temperature ◽

Heat Production ◽

Protein Metabolism ◽

Live Weight ◽

High Ambient Temperature ◽

Metabolizable Energy ◽

Energy Losses ◽

Apparent Digestibility ◽

Energy Retention ◽

Urinary Nitrogen

SUMMARY1. The experiment was designed to compare the protein and energy metabolism of pigs growing at 25°c or 34°C. The pigs were given two levels of feeding while growing between 25 and 75 kg live weight.2. The high temperature was associated with increases in rectal temperature of 1·2 to 20°C. Both pigs on the higher level of feeding at 34°C became lame in their hind legs.3. The high temperature was also associated with increases in heat production and in urinary nitrogen and energy losses for pigs fed at the higher level of feeding only; however fasting heat production was not affected significantly by temperature. The high temperature had no effect on the apparent digestibility of the diet.4. It was calculated from data for pigs at both levels of feeding kept at 25°C, that efficiency of utilization of metabolizable energy (ME) above maintenance was 71%, and the maintenance requirement for ME was 100 kcal/kg0·75 day. Energy retention was reduced at 34°C in pigs fed on the higher level of feeding.

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Intake, digestibility, methane and heat production in bison, wapiti and white-tailed deer

Canadian Journal of Animal Science ◽

10.4141/a97-089 ◽

1998 ◽

Vol 78 (4) ◽

pp. 681-691 ◽

Cited By ~ 22

Author(s):

J. K. Galbraith ◽

G. W. Mathison ◽

R.J. Hudson ◽

T. A. McAllister ◽

K.-J. Cheng

Keyword(s):

Key Words ◽

Heat Production ◽

Methane Production ◽

Dry Matter ◽

Methane Emissions ◽

Factorial Experiment ◽

Dry Matter Intake ◽

Energy Requirements

A 3 × 2 factorial experiment was conducted in which the digestibility of alfalfa pellets and methane and heat productions were measured in bison, wapiti and white-tailed deer in February/March 1995 and in April/May 1995. Voluntary dry matter intake (DMI) while animals were individually fed averaged 70, 87 and 68 g kg−0.75 d−1, respectively (P = 0.05), and was generally higher in April/May than in February/March. Corresponding organic digestibilities were 52.9, 54.1 and 49.1% (P = 0.10). There was also a trend (P < 0.1) for fiber digestibilities to be lowest for deer. Methane production (L kg−1 DMI), was 30.1, 23.5, and 15.0 L kg−1 for bison, wapiti and deer, respectively (P = 0.01), with more (P < 0.01) methane being produced in February/March than in April/May (28 vs. 18 L kg−1 DMI). No differences in heat production (kJ kg−0.75) or estimated energy requirements for maintenance could be detected between species, although animals numerically produced 40% more heat (881 vs. 632 kJ kg−0.75, P = 0.13) in April/May when feed intakes were higher than in February/March. It was concluded that DMI of native ungulates is higher in spring than winter and that methane emissions per unit feed consumed were the highest with bison and the least with white-tailed deer. Key words: Bison, deer, wapiti, digestibility, methane, calorimetry

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The effect of environmental temperature on the energy metabolism of cattle

The Journal of Agricultural Science ◽

10.1017/s0021859600023236 ◽

1960 ◽

Vol 55 (3) ◽

pp. 359-364 ◽

Cited By ~ 16

Author(s):

A. Rogerson

Keyword(s):

Food Intake ◽

Heat Production ◽

Environmental Temperature ◽

Energy Losses ◽

Net Energy ◽

Retention Data ◽

Respiration Chamber ◽

Energy Retention ◽

Environmental Temperatures ◽

Different Levels

1. A relatively inexpensive closed-circuit respiration chamber for cattle is described.2. Experiments with two steers are reported in which heat production and energy retention data were measured at different levels of food intake and at different environmental temperatures.3. The energy lost in faeces increased with improving plane of nutrition but was not significantly affected by the environmental temperature. Urine energy losses fell with increasing environmental temperature at low planes of nutrition. Methane losses increased with improving nutritional plane but were reduced by high environmental temperatures at high levels of food intake.4. The heat production of fasting animals, or animals on low planes of nutrition was not influenced by the environmental temperature in the range 20–40° C. On higher planes of nutrition an increasing environmental temperature increased the animals' heat production.5. The major factor determining energy retention in different environments is the heat production of the animal. Net energy values consequently vary with temperature.

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