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Cited by 15Effects of Environmental Stressors on LivestockThermoregulation and physiological responsesBuilding Energy and Comfort Optimization

A two-node mechanistic thermophysiological model for pigs reared in hot climates – Part 1: Physiological responses and model development

Huang, Tao, Rong, Li, Zhang, Guoqiang, Brandt, Pia, Bjerg, Bjarne, Pedersen, Poul, Granath, Simon W.Y.·2021·Biosystems Engineering
DOI 10.1016/j.biosystemseng.2021.08.024
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Abstract

Due to the climate change and the increasing heat production of modern pigs (e.g. larger size sows having a larger number of piglets nowadays), pigs are more frequently suffering heat stress. In order to prevent the occurrence of heat stress, there is a need to develop a model which can effectively and efficiently predict the effect of ambient thermal environments on pigs. This study developed a two-node mechanistic model to simulate processes of pig thermoregulation and heat release to an ambient hot environment based on biophysical laws. The two-node model consists of a passive system, which can simulate the heat transfer processes occurring in the body core and at the skin surface, and an active system, which controls the thermoregulatory system based on a positive deviation of core temperature from its reference value under thermal neutral conditions. Vasodilatation and panting in relation to the ambient environment were specifically investigated and mathematically described based on the experimental data from previously published studies. The functions to predict vasodilatation and panting provided a relatively more detailed modelling of the thermo-physiological processes of the pigs compared to the available mechanistic models. The proposed two-node model was expected to effectively predict the thermal status of pigs under various combinations of environmental conditions without further tuning.

AI snapshot

Written from the paper’s full text.

TL;DR

This paper develops a two-node mechanistic thermophysiological model for pigs in hot climates, combining a passive heat-transfer system with an active thermoregulatory system for vasodilatation, panting, and metabolic-rate change. It derives new sub-models for skin blood flow and pulmonary ventilation from published pig experiments, with validation deferred to Part 2.

Key findings

  • The model uses core and skin nodes and controls thermoregulation by the deviation of core temperature from its reference value; the active system includes pulmonary ventilation, vasodilatation, and change in metabolic rate.
  • For modern Danish sows, measured total heat production averaged 438.1 W, about 14% greater than the 385.6 W calculated by the CIGR equation; the model therefore increased that equation’s THP by 14%.
  • A 1 °C rise in rectal temperature increased skin blood flow by about 0.16 L min⁻¹ m⁻² for young pigs and 0.30 L min⁻¹ m⁻² for fattening pigs; pulmonary ventilation rose by 21.8, 24.7, and 36.4 L min⁻¹ m⁻² per 1 °C at RH 50%, 65%, and 80%, respectively, with a maximum set at 40 L min⁻¹ m⁻².
  • The conductive tissue heat transfer coefficient was estimated as about 15.2 W m⁻² °C⁻¹ for 61.7 kg pigs at 14 °C; the value near 11 W m⁻² °C⁻¹ from 6.26 kg pig data was considered an underestimation.

Methods

  • A two-node lumped model was built with core and skin segments: core assumed 97% and skin 3% of empty body mass, body specific heat capacity 4.0 kJ kg⁻¹ °C⁻¹, skin surface area estimated from body mass, and floor conduction neglected.
  • Active-system relationships were derived from published experiments: Stombaugh and Roller (1977) with a 6.26 kg restrained young pig, and Huynh (2005) with 61.7 kg growing pigs at RH 50%, 65%, and 80% and air temperatures from 16 °C to 32 °C; sow THP was estimated from CO₂ production in a Danish building with 900 sows averaging 287 kg at 20 ± 0.3 °C.
  • Dynamic simulations discretized the heat-balance differential equations explicitly and solved them iteratively; outputs were rectal and skin temperatures, with steady state obtained directly or by running until heat storage approached zero.

Limitations

  • The paper states that physiological responses were postulated from experimental data covering only a narrow body-mass range, no qualified data for larger pigs were found, and validity for other pig categories was assessed in Part 2.
  • The paper states that conductive heat flux to the floor was neglected, which could create uncertainty for cold-stress assessment, and that contact surface area in group-housed pigs was not considered, potentially overestimating skin heat release.
  • Evident from the text: Part 1 reports model development only, with validation and performance assessment deferred to Part 2; the paper also notes difficulty in acquiring inputs such as the convective heat transfer coefficient and mean radiant temperature.

Model-written summary. Check it against the paper before relying on it.

Integrity signals

Registry

Crossref · 10.1016/j.biosystemseng.2021.08.024

Cites

74 of 74 references verified0 citation errors · 0 not checkable

Statistics

Nothing to recompute.

Claims the paper makes

13 of 78 cited sources checked · 5 supported · 1 flagged · accuracy not yet measured

  • Premisecitation
    § 1. Introduction · p. 3

    Existing mechanistic models have not succeeded in explicitly interpreting panting and vasodilatation, which significantly influence the prediction ability of mechanistic models.

    “Based on the best knowledge of the authors, the existing mechanistic models (Bjerg, Pedersen, Morsing, & Zhang, 2017; Bruce & Clark, 1979; Fialho, Bucklin, Zazueta, & Myer, 2004; McArthur, 1987; Turnpenny, McArthur, Clark, & Wathes, 2000a; Turnpenny, Wathes, Clark, & McArthur, 2000b) have not succeeded in explicitly interpreting the two most essential interactions between the t”
    Quote in the paperSubstantial claim1 of 3 sources checked
    • cites Bjerg et al., 2017 source
    • cites Bruce & Clark, 1979 source
    • cites Fialho et al., 2004 source

      The paper explicitly represents both responses. In “Heat transfer across the skin” (page unavailable), it models vasodilatation through changes in the peripheral-tissue heat-transfer coefficient; in “Other modes of heat transfer” (page unavailable), it models increased breathing under heat stress and its contribution to heat loss. This contradicts the claim that this model did not explicitly interpret those responses. (LLM, conf=0.90)

      Checked by a reasoning model — may be wrong.

      Experimental — accuracy not yet measured
  • Interpretationcitation
    § 2.2. Metabolic rate · p. 5

    The observed 14% increment in THP was in line with values reported by Brown e Brandl et al. (2004; 2014).

    “This increment was in line with the values reported by Brown e Brandl et al. (2004; 2014).”
    Quote in the paperSubstantial claim1 of 2 sources checked
    • cites Brown e Brandl et al., 2004 source
    • cites Brown e Brandl et al., 2014

      Couldn’t be matched to a paper in Crossref, so it can’t be checked.

  • Premisecitation
    § 1. Introduction · p. 2

    Modern pigs have a total heat production (THP) 16%-20% higher than fatter counterparts from the previous generation.

    “Many studies (Brown e Brandl, Eigenberg, Nienaber, & Kachman, 2001; Brown e Brandl et al., 2014; Brown e Brandl, Nienaber, Xin, & Gates, 2004) reported that the total heat production (THP) of modern pigs was 16% e 20% higher than the THP of their fatter counterparts from the previous generation.”
    Quote in the paperSubstantial claim1 of 3 sources checked
    • cites Brown e Brandl et al., 2001 source
    • cites Brown e Brandl et al., 2014

      Couldn’t be matched to a paper in Crossref, so it can’t be checked.

    • cites Brown e Brandl et al., 2004 source

      The Conclusions report that heat production was 17.4% higher in pigs from 1988–2002 than in pigs from before 1988, but that figure applies under thermoneutral conditions. Across all experimental temperatures, the reported increase ranged from 12.4% to 35.3%, so the unqualified 16%–20% claim is too broad. The paper characterizes the older pigs as moderate-lean rather than explicitly calling them fatter counterparts. (LLM, conf=0.87)

      Experimental — accuracy not yet measured
  • Premisecitation
    § 2.3.1. Estimation of skin blood flow rate · p. 7

    The ideal temperature under thermal neutral conditions for 61.7 kg pigs was approximately 18 C.

    “According to Brown e Brandl et al. (2004), the ideal temperature (under the TN conditions) for 61.7 kg pigs was approximately 18 C.”
    Quote in the paperSubstantial claim1 of 1 sources checked
    • cites Brown e Brandl et al., 2004 source
  • Premisecitation
    § 2.4.1. Sensible heat release · p. 9

    The exact convective heat transfer coefficient strongly depends upon in-situ factors such as room air patterns, body sizes of pigs, and ventilation systems.

    “However, the exact convective coefficient strongly depends upon the in-situ factors such as room air patterns, body sizes of pigs, and ventilation systems (Huang et al., 2021).”
    Quote in the paperSubstantial claim1 of 1 sources checked
    • cites Huang et al., 2021 source
  • May combine two claims. 27
  • Classified as probably not a substantial claim. 14

  • May combine two claims.

    Premisecitation
    § 1. Introduction · p. 3

    Pulmonary ventilation rate has rarely been measured over a wide range of ambient temperatures and has normally been described by relatively simple relationships coupled with ambient environmental conditions in previous studies.

    “However, it has been rarely measured in the experiments over a wide range of ambient temperatures and has normally been described by relatively simple relationships coupled with the ambient environmental conditions in the previous studies (Huang et al., 2021).”
    Quote in the paperSubstantial claim1 of 1 sources checked
    • cites Huang et al., 2021 source

      Section 2.4.2 describes simple earlier treatments of panting: one model assumes constant respiratory heat loss across environmental conditions, while another uses a smooth function to estimate pulmonary ventilation rate from body temperature. The paper does not establish that ventilation was rarely measured across a wide range of ambient temperatures, and the cited ventilation-rate function is linked to body temperature rather than directly to ambient conditions. Page numbers are unavailable in our copy. (LLM, conf=0.84)

      Experimental — accuracy not yet measured

  • Probably not a substantial claim: may not pass S3 (load-bearing).

    Premisecitation
    § 1. Introduction · p. 2

    Heat stress reduces litter birth weight.

    “In addition, HS shortened the gestation period of sows and reduced litter birth weight (Lucy & Safranski, 2017).”
    Quote in the paperNot a substantial claim1 of 1 sources checked
    • cites Lucy & Safranski, 2017 source

      Section 3.4 reports that gestational heat stress shortened gestation by approximately 1.5 days and significantly reduced individual piglet birth weight. It does not report a reduction in total litter birth weight, which is distinct from the weight of each piglet. (LLM, conf=0.84)

      Experimental — accuracy not yet measured

  • Probably not a substantial claim: may not pass S3 (load-bearing).

    Premisecitation
    § 1. Introduction · p. 2

    Heat stress shortens the gestation period of sows.

    “In addition, HS shortened the gestation period of sows and reduced litter birth weight (Lucy & Safranski, 2017).”
    Quote in the paperNot a substantial claim1 of 1 sources checked
    • cites Lucy & Safranski, 2017 source

  • May combine two claims.

    Premisecitation
    § 1. Introduction · p. 3

    Rectal and skin temperatures have proven to be suitable indicators to represent pig thermal perceptions, level of heat stress, and health status.

    “The model outputs were rectal and skin temperatures since they have proven to be suitable indicators to represent the pig thermal perceptions, level of HS (Brown e Brandl et al., 2001, 2003; Sapkota, Herr, Johnson, & Lay, 2016; Seibert et al., 2018), and the health status of pigs (Soerensen & Pedersen, 2015).”
    Quote in the paperSubstantial claim1 of 3 sources checked
    • cites Brown e Brandl et al., 2001 source
    • cites Sapkota et al., 2016 source
    • cites Soerensen & Pedersen, 2015 source

      The citation to Soerensen and Pedersen is attached to the claim about pigs’ health status, not thermal perception or heat stress. The review treats rectal temperature as a measure of body temperature and discusses skin-temperature changes associated with fever and inflammation. But its Conclusions say further research is needed before infrared skin-temperature screening can be a reliable diagnostic tool, so describing both temperatures as proven indicators of health status overstates the source. (LLM, conf=0.88)

      Experimental — accuracy not yet measured

  • May combine two claims.

    Interpretationcitation
    § 2.4.2. Latent heat release · p. 9

    Pigs cannot release heat through sweat evaporation and only very limited water content can diffuse from the skin surface to the surrounding air.

    “They are therefore not able to release heat through sweat evaporation (Fox et al., 2014; Huynh et al., 2005) and only very limited water content can be diffused from the skin surface to the surrounding air.”
    Quote in the paperSubstantial claim1 of 2 sources checked
    • cites Fox et al., 2014 source
    • cites Huynh et al., 2005 source

      The available passages, including those labelled Abstract (no page given), contain bibliographic details rather than findings about heat loss. Searches for sweating, skin-water diffusion, and evaporative heat loss found no passage addressing the claim in our copy. (LLM, conf=0.72)

      Experimental — accuracy not yet measured

  • May combine two claims.

    Findingown data
    § 2.3.1. Estimation of skin blood flow rate · p. 7

    From experimental results, the upper critical temperature occurred at around 22 C, which was 4 C higher than the ideal temperature.

    “From the experimental results, the upper critical temperature occurred at around 22 C, which was 4 C higher than the ideal temperature.”
    Quote in the paperSubstantial claim

  • May combine two claims.

    Findingcitation
    § 2.3.1. Estimation of skin blood flow rate · p. 8

    The skin blood flow rate estimation from Huynh (2005) was consistent with previous estimates, showing a rising trend, except for RH of 80%, where skin blood flow stopped rising at 22 C.

    “It is consistent with the previous estimates with skin blood flow rate showing a rising trend, except for RH of 80%, where the skin blood flow stopped rising at 22 C.”
    Quote in the paperSubstantial claim0 of 1 sources checked
    • cites Huynh, 2005

      Couldn’t be matched to a paper in Crossref, so it can’t be checked.

  • May combine two claims.

    Findingown data
    § 2.3.1. Estimation of skin blood flow rate · p. 7

    The skin blood flow rate increased with the rise of ambient temperature and reached about 0.31 l min−1 m−2 at 37.5 C.

    “As shown in Fig. 5, the skin blood flow rate increased with the rise of the ambient temperature and reached about 0.31 l min 1 m 2 at 37.5 C.”
    Quote in the paperSubstantial claim

  • May combine two claims.

    Findingown data
    § 2.3.1. Estimation of skin blood flow rate · p. 7

    The internal heat transfer coefficient k with temperature below 30 C was nearly constant at around 11 W m−2 C−1 and started increasing with ambient temperature after 30 C.

    “It was observed that the internal heat transfer coefficient with temperature below 30 C was nearly constant at around 11 W m 2 C 1 and it started increasing with the ambient temperature after 30 C.”
    Quote in the paperSubstantial claim

  • May combine two claims.

    Findingcitation
    § 2.3.1. Estimation of skin blood flow rate · p. 6

    The metabolic heat production of the young pig in Stombaugh & Roller (1977) continuously decreased until ambient temperature reached 30 C, and the thermal neutral zone was achieved between 30 and 35 C.

    “As shown in Fig. 3 (a), the metabolic heat production of the young pig continuously decreased until the ambient temperature reached 30 C and the TN was then achieved between 30 and 35 C.”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites Stombaugh & Roller, 1977 source

  • May combine two claims.

    Findingown data
    § 2.3.1. Estimation of skin blood flow rate · p. 7

    No flat section occurred in the internal heat transfer coefficient curve for air temperatures ≤16 C, probably indicating that the lower critical temperature was ≤16 C.

    “No flat section occurred in the internal heat transfer coefficient curve for air temperatures 16 C, which probably indicates that the lower critical temperature was 16 C.”
    Quote in the paperSubstantial claim

  • May combine two claims.

    Findingown data
    § 2.3.1. Estimation of skin blood flow rate · p. 7

    The conductive heat transfer coefficient kt did not differ significantly among three levels of relative humidity and was around 15.2 W m−2 C−1 with an air temperature of 14 C.

    “As shown in Fig. 4 (b), the kt did not differ significantly among three levels of relative humidity and was around 15.2 W m 2 C 1 with an air temperature of 14 C.”
    Quote in the paperNot a substantial claim
    • The authors state this as an assumption: The lower critical temperature for 61.7 kg pigs is 4 C below the ideal temperature, i.e. at 14 C.

  • May combine two claims.

    Findingnone given
    § 2.3.1. Estimation of skin blood flow rate · p. 8

    The metabolic heat production decreased at higher ambient air temperatures and consequently led to lower heat transfer coefficient and skin blood flow rate.

    “Meanwhile, the metabolic heat production decreased at higher ambient air temperatures and consequently led to the lower heat transfer coefficient and skin blood flow rate.”
    Quote in the paperNot a substantial claim

  • Probably not a substantial claim: may not pass S3 (load-bearing). May combine two claims.

    Findingnone given
    § 2.3.1. Estimation of skin blood flow rate · p. 8

    The experimental data showed that the lowest skin temperature occurred at RH of 80%, resulting in the largest temperature difference between body core and skin surface.

    “The experimental data showed that the lowest skin temperature occurred at RH of 80%, resulting in the largest temperature difference between the body core and the skin surface.”
    Quote in the paperNot a substantial claim

  • May combine two claims.

    Findingcitation
    § 2.4.3. Estimation of pulmonary ventilation rate · p. 10

    Under thermoneutral conditions, pulmonary ventilation rate did not significantly differ with RH between 50% and 65%, while a relatively lower pulmonary ventilation rate was noticed at RH of 80%.

    “Under TN conditions, the pulmonary ventilation rate did not significantly differ with RH between 50% and 65%, while a relatively lower pulmonary ventilation rate was noticed at RH of 80%.”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites Huynh, (2005)

      Couldn’t be matched to a paper in Crossref, so it can’t be checked.

  • Classified as probably not a substantial claim.

    Findingcitation
    § 3.4. Change of the metabolic rate ð D \_ QM ; Wm 2 Þ · p. 13

    The relationship between the rise in rectal temperature and the rise in metabolic heat production (for 16 < Tair < 32) was plotted using data from Huynh (2005).

    “Therelationship between the rise in the rectal temperature and the rise in metabolic heat production (for 16 &lt; Tair &lt; 32 Þ wasplotted in Fig. 10 using data from Huynh, (2005).”
    Quote in the paperSubstantial claim0 of 1 sources checked
    • cites Huynh, (2005)

      Couldn’t be matched to a paper in Crossref, so it can’t be checked.

  • May combine two claims.

    Premisereasoning
    § 2.3.2. Estimation of conductive heat transfer coefficient of tissues · p. 8

    The conductive heat transfer coefficient of tissues varied with the structure and composition of tissues, or body mass.

    “The conductive heat transfer coefficient of tissues varied with the structure and composition of tissues, or straightforwardly, body mass.”
    Quote in the paperSubstantial claim

  • May combine two claims.

    Premisecitation
    § 2.1. Heat balance equations · p. 4

    Heat transfer via conduction between the pig and floor can be neglected because heat transfer via conduction is small due to a relatively small fraction of body surface area (10%-20%) in contact with the floor.

    “The heat transfer via conduction between the pig and floor was neglected as the heat transfer via conduction was small due to a relatively small fraction of body surface area (10% e 20%) in contact with the floor (Bruce &amp; Clark, 1979; Black et al., 1986).”
    Quote in the paperSubstantial claim0 of 2 sources checked
    • cites Bruce & Clark, 1979 source
    • cites Black et al., 1986

  • Classified as probably not a substantial claim.

    Premisecitation
    § 1. Introduction · p. 3

    The importance of skin blood flow in pig thermoregulation has been emphasised in a number of studies.

    “and its importance in pig thermoregulation has been emphasised in a number of studies (Mount, 1963; Ingram et al., 1972b; Stombaugh &amp; Roller, 1977; Black, Campbell, Williams, James, &amp; Davies, 1986; D ' Allaire et al., 1996; Quiniou &amp; Noblet, 1999; Herpin, Damon, &amp; Dividich, 2002).”
    Quote in the paperSubstantial claim0 of 3 sources checked
    • cites Mount, 1963 source
    • cites Ingram et al., 1972b

      Couldn’t be matched to a paper in Crossref, so it can’t be checked.

    • cites Stombaugh & Roller, 1977 source

  • Probably not a substantial claim: may not pass S4 (based).

    Premisenone given
    § 1. Introduction · p. 3

    Knowledge of the pulmonary ventilation rate is necessary to calculate heat release via respiration in mechanistic models.

    “Knowledge of the pulmonary ventilation rate is necessary to calculate the heat release via respiration in mechanistic models.”
    Quote in the paperNot a substantial claim

  • May combine two claims.

    Premisenone given
    § 1. Introduction · p. 3

    Existing mechanistic models for pigs have not exclusively considered the variation of skin blood flow rate under heat exposure nor heat transfer via the skin bloodstream.

    “Currently, neither the variation of the skin blood flow rate under heat exposure nor the heat transfer via the skin bloodstream has been exclusively considered in the existing mechanistic models for pigs.”
    Quote in the paperSubstantial claim

  • May combine two claims.

    Premisecitation
    § 2. Passive system · p. 4

    Temperature gradients between different tissue layers are relatively small during heat stress and skin temperature does not vary significantly at different body regions.

    “Secondly, the temperature gradients between different tissue layers were relatively small during HS and the skin temperature did not vary significantly at different body regions (Sapkota et al., 2016).”
    Quote in the paperSubstantial claim0 of 1 sources checked
    • cites Sapkota et al., 2016 source

  • Probably not a substantial claim: may not pass S3 (load-bearing).

    Premisecitation
    § 1. Introduction · p. 2

    Heat stress increases embryo mortality.

    “It also increased embryo mortality (Wildt, Riegle, &amp; Dukelow, 1975) and even influenced the performance of the offspring (Wegner, Lambertz, Das, Reiner, &amp; Gauly, 2016).”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites Wildt et al., 1975 source

  • May combine two claims.

    Premisecitation
    § 1. Introduction · p. 3

    During severe hyperthermia, the magnitude of skin blood flow is significantly large and the ability of heat transfer via convection of blood with postulated linear relationships might be wrongly estimated.

    “For example, Charkoudian (2003) reported that during severe hyperthermia, the magnitude of the skin blood was significantly large and the ability of heat transfer via heat convection of blood with the postulated linear relationships might be therefore wrongly estimated.”
    Quote in the paperSubstantial claim0 of 1 sources checked
    • cites Charkoudian, 2003 source

  • Probably not a substantial claim: may not pass S3 (load-bearing).

    Premisecitation
    § 1. Introduction · p. 2

    Heat stress influences the performance of the offspring.

    “It also increased embryo mortality (Wildt, Riegle, &amp; Dukelow, 1975) and even influenced the performance of the offspring (Wegner, Lambertz, Das, Reiner, &amp; Gauly, 2016).”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites Wegner et al., 2016 source

  • Probably not a substantial claim: may not pass S3 (load-bearing).

    Interpretationown data
    § 2.3.1. Estimation of skin blood flow rate · p. 8

    This blood flow rate is comparable to the average skin blood flow rate for an adult human (0.23 L min−1 m−2) with comparable body mass and similar ambient temperature level.

    “This is comparable to the average skin blood flow rate for an adult human (0.23 L min 1 m 2 ) with a comparable body mass and a similar ambient temperature level.”
    Quote in the paperNot a substantial claim

  • May combine two claims.

    Premisecitation
    § 2.3.2. Estimation of conductive heat transfer coefficient of tissues · p. 9

    The fattening pigs used by Huynh (2005) were group-housed and able to move freely.

    “In contrast, the fattening pigs used by Huynh, (2005) were grouphoused and able to move freely.”
    Quote in the paperSubstantial claim0 of 1 sources checked
    • cites Huynh, 2005

      Couldn’t be matched to a paper in Crossref, so it can’t be checked.

  • Probably not a substantial claim: may not pass S3 (load-bearing).

    Premisecitation
    § 2.3.2. Estimation of conductive heat transfer coefficient of tissues · p. 8

    Hovell et al. (1977) used 9 W m−2 C−1 as kt for a sow with body mass of 168 kg.

    “Hovell, MacPherson, Crofts, and Smart (1977) used 9 W m 2 C 1 as kt for a sow with body mass of 168 kg.”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites Hovell et al., 1977 source

  • May combine two claims.

    Interpretationreasoning
    § 2.3.2. Estimation of conductive heat transfer coefficient of tissues · p. 9

    The pigs in Huynh's experiment were more active, resulting in a higher level of THP.

    “Therefore, the pigs in Huynh ' s experiment (Huynh, (2005)) were more active, resulting in a higher level of THP.”
    Quote in the paperSubstantial claim0 of 1 sources checked
    • cites Huynh, 2005

      Couldn’t be matched to a paper in Crossref, so it can’t be checked.

  • May combine two claims.

    Premisereasoning
    § 2.3.2. Estimation of conductive heat transfer coefficient of tissues · p. 8

    The amount of subcutaneous fat increased with larger body mass, leading to a reduced conductive heat transfer coefficient of tissues.

    “The amount of subcutaneous fat increased with larger body mass, leading to a reduced conductive heat transfer coefficient of tissues.”
    Quote in the paperSubstantial claim

  • Classified as probably not a substantial claim.

    Premisecitation
    § 2.3.2. Estimation of conductive heat transfer coefficient of tissues · p. 8

    Bruce & Clark (1979) suggested the conductive heat transfer coefficient of tissues should be proportional to the 0.33rd power of body mass.

    “In addition, Bruce &amp; Clark, 1979 suggested the conductive heat transfer coefficient of tissues should be proportional to the 0.33rd power of the body mass.”
    Quote in the paperSubstantial claim0 of 1 sources checked
    • cites Bruce & Clark, 1979 source

  • May combine two claims.

    Premisereasoning
    § 2.4.3. Estimation of pulmonary ventilation rate · p. 9

    Brody (1945) modeled basal pulmonary ventilation rate under standard temperature and pressure conditions but it is hardly valid for pigs exposed to heat stress.

    “Brody (1945) modeled the basal pulmonary ventilation rate of animals under standard temperature and pressure conditions (0 C, 1 atm) but it is hardly valid for pigs exposed to HS.”
    Quote in the paperSubstantial claim0 of 1 sources checked
    • cites Brody (1945)

      Couldn’t be matched to a paper in Crossref, so it can’t be checked.

  • May combine two claims.

    Premisecitation
    § 2.4.2. Latent heat release · p. 9

    Skin diffusion also accounts for a fraction of latent heat loss in pigs, and skin diffusion heat loss is correlated with ambient climate conditions.

    “According to Morrison et al. (1967), skin diffusion ( Qdiff ; Wm 2 ) also shares a fraction of the latent heat loss. According to their results, skin diffusion heat loss is correlated with the ambient climate condition, as described in Eq. (24).”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites Morrison et al. (1967) source

  • Probably not a substantial claim: may not pass S3 (load-bearing).

    Interpretationreasoning
    § 3.3. Vasodilatation · p. 11

    Thinner pigs are expected to have a lower level of skin blood flow rate.

    “It was expected that thinner pigs would have a lower level of skin blood flow rate.”
    Quote in the paperNot a substantial claim

  • Classified as probably not a substantial claim. May combine two claims.

    Premisenone given
    § 2.3.2. Estimation of conductive heat transfer coefficient of tissues · p. 9

    The young pig used in Stombaugh's experiment was restrained during the experiments, meaning additional behavioural and postural defences were eliminated.

    “This might be because the young pig used in Stombaugh ' s experiment was restrained during the experiments, meaning that additional behavioural and postural defences were eliminated.”
    Quote in the paperSubstantial claim0 of 1 sources checked
    • cites Stombaugh & Roller, 1977 source

  • Probably not a substantial claim: may not pass S3 (load-bearing).

    Premisecitation
    § 2.3.2. Estimation of conductive heat transfer coefficient of tissues · p. 9

    This conflicted with the consensus that metabolic heat production rate reduces with body mass increasing.

    “This conflicted with the consensus that the metabolic heat production rate reduces with body mass increasing (Brown e Brandl et al., 2014; CIGR, 2002).”
    Quote in the paperNot a substantial claim0 of 2 sources checked
    • cites Brown e Brandl et al., 2014
    • cites CIGR, 2002

      Couldn’t be matched to a paper in Crossref, so it can’t be checked.

  • May combine two claims.

    Interpretationreasoning
    § 2.3.2. Estimation of conductive heat transfer coefficient of tissues · p. 9

    The measured data by Stombaugh and Roller (1977) reflected skin temperatures in the extremities and were lower than those in the central body.

    “The measured data by Stombaugh and Roller (1977) therefore reflected the skin temperatures in the extremities and were lower than those in the central body.”
    Quote in the paperSubstantial claim0 of 1 sources checked
    • cites Stombaugh & Roller, 1977 source

  • May combine two claims.

    Interpretationreasoning
    § 6. Conclusions · p. 14

    In general, the proposed model was computationally efficient and provided a better understanding of the thermo-physiological processes of the pigs compared to the available models.

    “In general, the proposed model was computationally efficient and provided a better understanding of the thermo-physiological processes of the pigs compared to the available models.”
    Quote in the paperSubstantial claim

  • May combine two claims.

    Study design and conductreasoning
    § 5. Advantages and limitations · p. 14

    The heat flux via conductivity was neglected in the proposed model, which could cause uncertainties if the model is used for cold stress assessment, although the influence on heat stress prediction may be small.

    “Secondly, the heat flux via conductivity in Eq. (1) was neglected in the proposed model. If this model was planned to be used in assessing the cold stress, uncertainties could occur although the influence on the prediction results could be small when it was applied to the evaluation of HS.”
    Quote in the paperNot a substantial claim
39 of 39

  • The authors state this as an assumption.

    The pig body can be represented as a lumped two-node system (core and skin) with no temperature distribution within different tissue layers and regions.

    “The pig body was assumed as a lumped system anddivided into two segments, as shown in Fig. 1.”

  • The authors state this as an assumption.

    For group-housed pigs in hot climates, the non-contact surface area is identical to the total skin surface area.

    “Therefore, the non-contact surface area was assumed to be identical to the total skin surface area in the proposed model.”

  • The authors state this as an assumption.

    The rising section of the internal heat transfer coefficient curve is induced by convection via skin blood flow, and skin blood flow effect on heat transfer from core to skin is insignificant below 30 C.

    “The rising section was assumed to be induced by convection via skin blood flow, while the skin blood flow became so low that its effect on the heat transfer from the core body to the skin surface was insignificant with the ambient temperature below 30 C.”

  • The authors state this as an assumption.

    The lower critical temperature for 61.7 kg pigs is 4 C below the ideal temperature, i.e. at 14 C.

    “In order to segregate a kt value, the lower critical temperature was assumed to be also 4 C below the ideal temperature, i.e. at 14 C.”

  • The authors state this as an assumption.

    Young pigs with less subcutaneous fat and smaller body mass have higher conductive heat transfer coefficients for tissues.

    “Young pigs with less subcutaneous fat and smaller body mass are assumed to have higher conductive heat transfer coefficients for tissues.”

  • The paper relies on this without support.

    Thermal sensation under heat exposure is less dependent upon uniformity of skin temperature but more on level of body core temperature.

    “In addition, it has been reported that the thermal sensation under heat exposure is less dependent upon the uniformity of the skin temperature but more on the level of body core temperature.”

  • The paper relies on this without support.

    The correlation between pulmonary ventilation rate and ambient temperature or skin/core temperature has not been reported in the literature.

    “To our knowledge, the correlation between the pulmonary ventilation rate and the ambient temperature or skin/core temperature has not been reported in the literature.”

  • The authors state this as an assumption.

    The basal pulmonary ventilation rate for RH less than 50% is identical to the value at RH of 50%.

    “Because the evaporation only becomes a major avenue of heat loss at high temperatures, the basal pulmonary ventilation rate for RH &lt; 50% was assumed to be identical to the value at RH of 50% in the proposed model.”

  • The authors state this as an assumption.

    The variation of skin blood flow rate follows a relationship similar to cardiac output being proportional to the 0.52nd power of body mass.

    “A similar relationship was assumed with regard to the variation of the skin blood flow rate.”

  • The authors state this as an assumption.

    The basal skin blood flow rate under thermoneutral conditions is zero.

    “where, Vblsk 0 represents the basal skin blood flow rate under TN. In the proposed model, it was assumed to be zero.”

  • The authors state this as an assumption.

    The increase of basal metabolic heat production follows Eq. (35) when a negative temperature signal occurs during iteration.

    “To avoid this issue, it was assumed that the increase of basal metabolic heat production also follows Eq. (35) when a negative temperature signal occurred during the iteration.”

  • The authors state this as an assumption.

    The decrease of skin surface area via interaction/contact of pigs housed in groups is not considered, which could overestimate heat release from the skin surface to the ambient.

    “Thirdly, the decrease of the skin surface area via the interaction/contact of pigs was not considered when the pigs were housed in groups. This assumption could somewhat overestimate the heat release from the skin surface to the ambient.”

  • The paper relies on this without support.

    Under thermoneutral conditions, metabolic heat production and rectal temperature do not vary significantly.

    “Under TN conditions, the metabolic heat production did not vary significantly, neither did the rectal temperature.”

  • The paper relies on this without support.

    Pigs reduce activity and feed intake to decrease metabolic heat production under heat stress.

    “As mentioned earlier, pigs reduced the level of activity and feed intake to decrease metabolic heat production suffering from HS.”

  • The paper relies on this without support.

    Panting and vasodilatation are two major avenues to release heat to the ambient.

    “In addition, panting and vasodilatation were two major avenues to release heat to the ambient.”

  • The paper relies on this without support.

    The condition of exhaled air depends on inhaled air: inhaled air temperature equals room air temperature, air is saturated in the windpipe and heated to core temperature, and exhaled air is partially cooled to an intermittent temperature between inhaled and core temperature.

    “The condition of the exhaled air depended upon the inhaled air to a certain degree. The inhaled air temperature equalled the room air temperature. As the air is inhaled, it is saturated in the windpipe and heated to the core temperature. When air is exhaled, it is partially cooled to an intermittent temperature between the inhaled air temperature and the core temperature.”
16 of 16

Claims other papers make about this one

Each is checked against this paper’s own text: does it say what the citing paper says it does?

Self-check

Percentages, sums and reported differences re-computed from the paper’s own numbers.

Each contradiction between two passages listed here was confirmed by an independent check.

  • The same heat response is described as both a decrease and an increase in metabolic rate

    Minor

    The paragraph says that, above the upper critical temperature, the rectal-temperature response decreases basal metabolic heat production. It then says that this effect causes a slight increment in metabolic rate.

1 of 1

Cites

Flagged first, then by citations

Research works printed but not linked: 3

  1. Bruce, 1977, Conductive heat loss from the recumbent animal, Farm Building R&D Studies, 8
  2. Loeffel, 1970, Growth in weight of selected organs tissues and systems in the pig historical research Bulletins of the Nebraska agricultural, Experiment Station, Vol. 73
  3. 2019, Ammoniak - og metanemission fra drægtighedsstalde (in Danish): SEGES svineproduktion, Den Rullende Afprøvning

Cited by

Sorted by citations

Related

Authors
Huang, T., Rong, L., Zhang, G., Brandt, P., Bjerg, B., Pedersen, P., & Granath, S. W. Y.
Affiliations
  • Aarhus University (DK)
  • University of Copenhagen (DK)
ORCID
Venue
Biosystems Engineering
Publisher
Elsevier BV
Published
2021-12
Volume
212
Pages
302-317
ISSN
1537-5110 (ISSN-L)
DOI
10.1016/j.biosystemseng.2021.08.024
OpenAlex
W3198228663
Semantic Scholar
7f5c69f6e3781b326b8d3ae81a5bc6b22ef4979d
Cited by
13
References
74
Citations by year
2026: 2 · 2025: 3 · 2024: 1 · 2023: 2 · 2022: 5
FWCI
1.34
Type
journal article
Language
en
Open access
closed
Licence
Locations
  • Biosystems Engineering (publishedVersion)
  • Research at the University of Copenhagen (University of Copenhagen) (publishedVersion)
Funders
Innovationsfonden (8055-00020B)
Topics
  • Life Sciences › Agricultural and Biological Sciences › Animal Science and Zoology › Effects of Environmental Stressors on Livestock
  • Health Sciences › Medicine › Physiology › Thermoregulation and physiological responses
  • Physical Sciences › Engineering › Building and Construction › Building Energy and Comfort Optimization
Keywords
heat stress, vasodilation, panting, core body temperature, skin heat transfer, thermoneutral zone, heat release

About these checks

Registry, retraction, Cites and statistics results are computed, not judged, with one exception: a printed reference that no index lists is read once by a model before it counts as a citation error. Claims are extracted by a model and kept only when their quote appears verbatim in the text; each cited source is then checked, with a model’s help, for whether it says what the claim relies on. Those verdicts can be wrong — read the claim’s quote and the cited source before relying on one.

Claims read by deepseek-v4.1-flash under definition version 3 (extract-v3) on 2026-10-11.

Classified by jev-1.13-20260917 (gold-guideline-v0.2) on 2026-10-11.

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