Effect of natural betaine and ractopamine HCl on whole-body and carcass growth in pigs housed under high ambient temperatures

2017 ◽  
Vol 95 (7) ◽  
pp. 3047
Author(s):  
S. M. Mendoza ◽  
R. D. Boyd ◽  
C. E. Zier-Rush ◽  
P. R. Ferket ◽  
K. D. Haydon ◽  
...  
Keyword(s):  
Whole Body ◽  
Ambient Temperatures

Effects of hypoxia and ambient temperature on gaseous metabolism of newborn rats

1992 ◽  
Vol 263 (2) ◽  
pp. R267-R272 ◽  
Author(s):  
J. P. Mortola ◽  
A. Dotta
Keyword(s):  
Heat Dissipation ◽  
Metabolic Response ◽  
Whole Body ◽  
Newborn Rats ◽  
Open Flow ◽  
Ambient Temperatures ◽  
Limited Effectiveness ◽  
Old Rats ◽  
Per Se ◽  
Maintain Body Temperature

Whole body metabolic rate was measured by open-flow respirometry in 2-day-old rats at ambient temperatures (Ta) between 40 and 15 degrees C, changed at a rate of 0.5 degrees C/min, during normoxia or hypoxia (10% inspired O2). In normoxia, the thermoneutral range was found to be very narrow, at around 33 degrees C, suggesting a limited effectiveness in the mechanisms controlling heat dissipation. At lower or higher Ta, metabolism was at first increased; this increase could be maintained for at least 30 min at 30 and 35 degrees C, i.e., slightly below or above thermoneutrality, but it was not maintained at lower Ta. The metabolic response to Ta was not sufficient to maintain body temperature (Tb). In hypoxia, at all Ta, oxygen consumption (VO2) was consistently less than in normoxia and was linearly related to Ta (Q10 approximately 1.4). The rat's specific heat was 4 J.g-1.degrees C-1, and the time constant of passive heat exchange was 2.2 +/- 0.5 min; from these values it was calculated that the normoxic VO2 of the 2-day-old rat could be per se sufficient to maintain Tb of 35-36 degrees C at Ta of 33 degrees C, while at lower Ta the metabolic response could not be adequate to maintain Tb. In hypoxia, Tb was directly dependent on Ta.(ABSTRACT TRUNCATED AT 250 WORDS)

The respiratory responses of the fowl to hot climates

1982 ◽  
Vol 97 (1) ◽  
pp. 301-309
Author(s):  
H. Kassim ◽  
A. H. Sykes
Keyword(s):  
Heat Stress ◽  
Tidal Volume ◽  
Respiratory Rate ◽  
Linear Relation ◽  
Domestic Fowl ◽  
Whole Body ◽  
Second Phase ◽  
Direct Relation ◽  
Ambient Temperatures ◽  
Respiratory Responses

Respiratory rate (f) and tidal volume (VT) have been measured at normal and at warm ambient temperatures (Ta) in adult domestic fowl by means of a whole body plethysmograph. Resting values of f = 23 +/− 9 min-1 and of VT = 25.6 +/− 0.9 ml min-1 were found. At Ta 30, 35 or 40 degrees C f increased in direct relation to the severity of the heat stress reaching a maximum values of 273 +/− 12 min-1; VT fell uniformly in all three climates to a minimum of 9.0 +/− 0.5 ml. Total ventilation (V) showed a linear relation with f during first-phase panting. Second-phase panting occurred only at Ta 40 degrees C; V increased at first but subsequently fell as the decline in f became more pronounced.

Endogenous thermoregulatory rhythms of squirrel monkeys in thermoneutrality and cold

1999 ◽  
Vol 276 (5) ◽  
pp. R1397-R1407 ◽  
Author(s):  
Edward L. Robinson ◽  
Charles A. Fuller
Keyword(s):  
Whole Body ◽  
Similar Time ◽  
Direct Calorimetry ◽  
Ambient Temperatures ◽  
Timing System ◽  
Circadian Timing System ◽  
Tightly Coupled ◽  
Free Running ◽  
Time Courses ◽  
Body Heat

Whole body heat production (HP) and heat loss (HL) were examined to determine if the free-running circadian rhythm in body temperature (Tb) results from coordinated changes in HP and HL rhythms in thermoneutrality (27°C) as well as mild cold (17°C). Squirrel monkey metabolism ( n = 6) was monitored by both indirect and direct calorimetry, with telemetered measurement of Tb and activity. Feeding was also measured. Rhythms of HP, HL, and conductance were tightly coupled with the circadian Tb rhythm at both ambient temperatures (TA). At 17°C, increased HP compensated for higher HL at all phases of the Tb rhythm, resulting in only minor changes to Tb. Parallel compensatory changes of HP and HL were seen at all rhythm phases at both TA. Similar time courses of Tb, HP, and HL in their respective rhythms and the relative stability of Tb during both active and rest periods suggest action of the circadian timing system on Tb set point.

The effect of low ambient temperatures on the energy metabolism of sows

1974 ◽  
Vol 19 (1) ◽  
pp. 1-12 ◽  
Author(s):  
C. W. Holmes ◽  
N. R. McLean
Keyword(s):  
Heat Production ◽  
Low Temperatures ◽  
Live Weight ◽  
Relative Effect ◽  
Metabolizable Energy ◽  
Whole Body ◽  
Energy Requirements ◽  
Ambient Temperatures ◽  
Lower Critical Temperature ◽  
Different Levels

SUMMARY1. The heat production of four sows, approximately 17 months old at the start of the experiment, was measured at five ambient temperatures from 23° to 6°C. Food intake was controlled at different levels for different sows; one sow conceived during the experiment.2. Heat production increased consistently as temperature decreased from 23° to 6°C; the relative effect on heat production of exposure to low temperatures was greater the lower the level of feeding.3. Estimated values for whole body conductance decreased as ambient temperature decreased to minimum values of 73 to 77 kcal/m2. day. °C for three sows and 87 kcal/m2. day.°C for the fourth sow, which had a considerably thinner backfat than the others.4. Estimated values for lower critical temperature varied from 10° to 20°C, with the lower values associated generally with the higher levels of feeding; nevertheless heat production was consistently lower at 23°C than at 18°C.5. Differences in level of feeding were generally associated with differences in live weight, and it was difficult to obtain reliable estimates of metabolizable energy requirements for maintenance and of net efficiency of utilization of metabolizable energy above maintenance; however analysis on the basis of live weight0·75 produced values of 92 kcal/kg0·75 per day at 23°C and 106 kcal/kg0·75 per day at 18°C for maintenance and between 67 and 75% for the efficiency of utilization above maintenance.

Open-loop gain of evaporative heat loss during radiant heat exposure in the mouse

1982 ◽  
Vol 242 (3) ◽  
pp. R275-R279
Author(s):  
C. J. Gordon
Keyword(s):  
Ambient Temperature ◽  
Heat Exposure ◽  
Radiant Heat ◽  
Open Loop ◽  
Whole Body ◽  
Evaporative Heat Loss ◽  
Loop Gain ◽  
Evaporative Water ◽  
Future Studies ◽  
Ambient Temperatures

Whole-body evaporative water loss of the mouse during radiant heating was determined at ambient temperatures of 20-35 degrees C. The ratio of evaporated to absorbed heat per gram body weight, which is equal to open-loop gain (OLGEHL), increased over sixfold with each 1 degrees C increase in ambient temperature. At 35 degrees C, OLGEHL was equal to 0.8, which implies that the mouse evaporates 80% of the absorbed radiant heat. At 20 degrees C, less than 1% of the absorbed heat is evaporated and the remainder of the heat load is dissipated passively. A previous estimate of OLG for the mouse is similar to the data from this study at an ambient temperature of 35 degrees C. Determining OLG with natural ambient stimulation may make future studies in thermoregulation comparable.

Thermal, Metabolic, and Cardiovascular Responses to Various Degrees of Cold Stress

1975 ◽  
Vol 53 (2) ◽  
pp. 293-298 ◽  
Author(s):  
Peter B. Raven ◽  
James E. Wilkerson ◽  
Steven M. Horvath ◽  
Nils W. Bolduan
Keyword(s):  
Cardiac Output ◽  
Steady State ◽  
Ambient Temperature ◽  
Heat Production ◽  
Thermal Gradient ◽  
Cardiovascular Responses ◽  
Whole Body ◽  
Third Order ◽  
Ambient Temperatures ◽  
Body Heat

The metabolic, thermal, and cardiovascular responses of two male Caucasians to a 2 h exposure to ambient temperatures ranging between 28 °C and 5 °C were studied and related to the respective ambient temperatures. The metabolic heat production increased linearly with decreasing ambient temperature, where heat production (kcal∙m−2∙h−1) = −2.79 Ta °C + 103.4, r = −0.97, P < 0.001. During all exposures below 28 °C, the rate of decrease in mean skin temperature [Formula: see text] was found to be an exponential function dependent upon the ambient temperature (Ta) and the time of exposure. Reestablishment of [Formula: see text] steady state occurred at 90–120 min of exposure, and the time needed to attain steady state was linearly related to decreasing Ta. The net result was that a constant ratio of 1.5 of the external thermal gradient to the internal thermal gradient was obtained, and at all experimental temperatures, the whole body heat transfer coefficient remained constant. Cardiac output was inversely related to decreasing Ta, where cardiac output [Formula: see text], r = −0.92, P < 0.01. However, the primary reason for the increased [Formula: see text], the stroke output, was also described as a third-order polynomial, although the increasing stroke volume throughout the Ta range (28–5 °C) was linearly related to decreasing ambients. The nonlinear response of this parameter which occurred at 20 °C ≥ Ta ≥ 10 °C suggested that the organism's cardiac output response was an integration of the depressed heart rate response and the increasing stroke output at these temperatures.

Body composition and skin temperature variation

1990 ◽  
Vol 68 (2) ◽  
pp. 540-543 ◽  
Author(s):  
J. Frim ◽  
S. D. Livingstone ◽  
L. D. Reed ◽  
R. W. Nolan ◽  
R. E. Limmer
Keyword(s):  
Skin Temperature ◽  
Temperature Variation ◽  
Subcutaneous Fat ◽  
Fat Distribution ◽  
Skinfold Thickness ◽  
Whole Body ◽  
Ambient Temperatures ◽  
Body Fat Content ◽  
The Mean ◽  
A Site

Temperature variations near four common torso skin temperature sites were measured on 17 lightly clad subjects exposed to ambient temperatures of 28, 23, and 18 degrees C. Although variations in skin temperature exceeding 7 degrees C over a distance of 5 cm were observed on individuals, the mean magnitude of these variations was 2-3 degrees C under the coolest condition and less at the warmer temperatures. There was no correlation between the temperature variation and skinfold thickness at a site or with estimations of whole body fat content. These findings imply that errors in mean skin temperature measurement could arise from probe mislocation and/or subcutaneous fat distribution and that the problem becomes more acute with increasing cold stress. However, the magnitudes of these errors cannot be easily predicted from common anthropometric measurements.

Effects of temperature on ventilatory response to hypercapnia in newborn mice heterozygous for transcription factor Phox2b

2007 ◽  
Vol 293 (5) ◽  
pp. R2027-R2035 ◽  
Author(s):  
N. Ramanantsoa ◽  
V. Vaubourg ◽  
B. Matrot ◽  
G. Vardon ◽  
S. Dauger ◽  
...  
Keyword(s):  
Heart Rate ◽  
Transcription Factor ◽  
Temperature Regulation ◽  
Ventilatory Response ◽  
Whole Body ◽  
Wild Type ◽  
Newborn Mice ◽  
Phox2b Gene ◽  
Ambient Temperatures ◽  
Hypercapnic Ventilatory Response

Congenital central hypoventilation syndrome (CCHS) is a rare disease with variable severity, generally present from birth and chiefly characterized by impaired chemosensitivity to hypercapnia. The main cause of CCHS is a mutation in the PHOX2B gene, which encodes a transcription factor involved in the development of autonomic medullary reflex pathways. Temperature regulation is abnormal in many patients with CCHS. Here, we examined whether ambient temperature influenced CO2 sensitivity in a mouse model of CCHS. A weak response to CO2 at thermoneutrality (32°C) was noted previously in 2-day-old mice with an invalidated Phox2b allele ( Phox2b+/−), compared with wild-type littermates. We exposed Phox2b+/− pups to 8% CO2 at three ambient temperatures (TAs): 29°C, 32°C, and 35°C. We measured breathing variables and heart rate (HR) noninvasively using a novel whole body flow plethysmograph equipped with contact electrodes. Body temperature and baseline breathing increased similarly with TA in mutant and wild-type pups. The hypercapnic ventilatory response increased linearly with TA in both groups, while remaining smaller in mutant than in wild-type pups at all TAs. The differences between the absolute increases in ventilation in mutant and wild-type pups become more pronounced as temperature increased above 29°C. The ventilatory abnormalities in mutant pups were not associated with significant impairments of heart rate control. In both mutant and wild-type pups, baseline HR increased with TA. In conclusion, TA strongly influenced the hypercapnic ventilatory response in Phox2b+/− mutant mice. These findings suggest that abnormal temperature regulation may contribute to the severity of respiratory impairments in CCHS patients.

Do metabolism and contour plumage insulation vary in response to seasonal energy bottlenecks in superb fairy-wrens?

2006 ◽  
Vol 54 (1) ◽  
pp. 23 ◽  
Author(s):  
Alan Lill ◽  
Jeffrey Box ◽  
John Baldwin
Keyword(s):  
Critical Temperature ◽  
Metabolic Rate ◽  
Thermal Conductance ◽  
Whole Body ◽  
Ambient Temperatures ◽  
The North ◽  
General Metabolism ◽  
Lower Critical Temperature ◽  
Heat Conservation ◽  
Low Altitude

Many small birds living at mid-to-high latitudes in the North Temperate Zone display seasonal increases in general metabolism and plumage insulation. We examined whether superb fairy-wrens at low altitude in temperate Australia, where winter is milder and the winter–spring transition less pronounced, exhibited similar adjustments. Their oxygen-consumption rate at ambient temperatures in and below their thermoneutral range was measured overnight in winter, spring and summer. Contour plumage mass was also compared in individuals caught in all seasons of the year. Resting-phase metabolic rate in the thermoneutral zone did not vary seasonally. The relationship between ambient temperature and whole-body metabolic rate below lower critical temperature differed in summer and winter, but the regression for spring did not differ from those for summer or winter. Plumage mass was greater (4.04% v. 2.64% of body mass) and calculated whole-bird wet thermal conductance lower (1.55 v. 2.24 mL O2 bird–1 h–1 °C–1) in winter than in summer. Enhanced plumage insulation could have improved heat conservation in autumn and winter. No increase in standard metabolism occurred in winter, perhaps because this season is relatively mild at low altitude in temperate Australia. However, superb fairy-wrens at 37°S operated below their predicted lower critical temperature for most of winter and the early breeding season, so they have presumably evolved as yet unidentified mechanisms for coping with the energy bottlenecks encountered then.

scholarly journals Seasonal and Diurnal Variation in Metabolism and Ventilation in House Sparrows

The Condor ◽  
2005 ◽  
Vol 107 (2) ◽  
pp. 433-444
Author(s):  
Jeremy R. Arens ◽  
Sheldon J. Cooper
Keyword(s):  
Thermal Conductance ◽  
Passer Domesticus ◽  
Active Phase ◽  
Time Of Day ◽  
Minute Volume ◽  
Open Circuit ◽  
Respiratory Frequency ◽  
Whole Body ◽  
House Sparrows ◽  
Ambient Temperatures

Abstract Passerines that are year-round residents in temperate climates undergo seasonal acclimatization that facilitates maintenance of thermoregulatory homeostasis. These changes in thermoregulatory metabolism must be supported by equivalent changes in oxygen transport. We measured the effects of ambient temperature and time of day on metabolism and ventilation in House Sparrows (Passer domesticus) in summer and winter. House Sparrows were exposed to ambient temperatures (Ta) ranging from −12°C to 15.5°C in summer and 17.5°C in winter. Open-circuit respirometry was used to measure oxygen consumption (V̇O2) and ventilation was recorded using whole-body plethysmography. In both summer and winter, V̇O2 increased with decreasing Ta. V̇O2 was significantly higher during the active phase compared to the resting phase of the daily cycle in both summer and winter. Thermal conductance was significantly lower in nighttime birds compared to daytime birds. With increased oxygen demands, minute volume (V̇I) increased in both summer and winter. In summer, only respiratory frequency (f) was significantly affected by time of day. In winter, active-phase birds had significantly higher respiratory frequency and minute volume (V̇I) than rest-phase birds. Winter birds in their rest phase had significantly higher oxygen extraction efficiency (EO2) than active-phase birds. Winter birds at rest phase also had significantly higher EO2 than summer birds. Variación Estacional y Diaria en el Metabolismo y la Ventilación en Passer domesticus Resumen. Las aves paserinas que residen a lo largo del año en climas de la zona templada pasan por un proceso de aclimatación estacional que facilita el mantenimiento de su homeostasis termorregulatoria. Estos cambios en el metabolismo termorregulatorio deben estar apoyados por cambios equivalentes en el transporte de oxígeno. En este estudio medimos los efectos de la temperatura del ambiente y la hora del día sobre el metabolismo y la ventilación en Passer domesticus en verano e invierno. Las aves fueron expuestas a temperaturas ambiente (Ta) en un rango de −12°C a 15.5°C en el verano, llegando a 17.5°C en el invierno. Empleamos respirometría de circuito abierto para medir el consumo de oxígeno (V̇O2) y registramos la ventilación usando pletismografía de cuerpo entero. Tanto en el verano como en el invierno, V̇O2 aumentó con disminuciones en Ta. V̇O2 fue significativamente mayor durante la fase activa en comparación con la fase de descanso del ciclo diario, tanto en verano como en invierno. La conductancia térmica fue significativamente menor en aves estudiadas en la noche que en aves estudiadas durante el día. Con incrementos en la demanda de oxígeno, el volumen minuto (V̇I) aumentó en verano y en invierno. En verano, sólo la frecuencia respiratoria (f) fue afectada por la hora del día. En invierno, la frecuencia respiratoria y el volumen minuto (V̇I) fueron significativamente mayores en las aves en fase activa que en las aves en fase de descanso. Las aves de invierno en su fase de descanso presentaron una eficiencia de extracción de oxígeno (EO2) siginificativamente mayor que la de las aves en fase activa. La EO2 de las aves de invierno en fase de descanso también fue significativamente mayor que la de las aves de verano.

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