Modelling the effect of heat stress on food intake, heat production and growth in pigs

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

Heat balance models predict the effect of the thermal environment on variables such as body temperature.

“Heat balance models, such as the one described by Fialho et al. (2004) and Turnpenny et al. (2000a and b), predict the effect of the thermal environment on some variables, like body temperature.”

• cites Fialho et al. (2004) sourceSupported
• cites Turnpenny et al. (2000a and b)Not matched

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

May combine two claims.

Changes in Tcb affect heat loss under cold stress, while Thb affects the animal's response in the heat.

“The effect of changes in Tcb is evident under cold stress, while Thb changes the animal's response in the heat.”

May combine two claims.

At lower temperatures, observed heat production increased, while simulated values stayed approximately constant.

“At lower temperatures, observed heat production increased, while simulated values stayed approximately constant.”

May combine two claims.

Changing the hot value of rwp and rvr had no influence on heat loss in the cold environment, but changing their cold value affected the response in the hot environment.

“Changing their 'hot' value had no influence on heat loss in the cold environment, but changing their 'cold' value affected the response in the hot environment.”

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

Teb slightly affects heat loss in hot environments.

“The evaporative critical body temperature ( Teb ) affects heat loss in hot environments slightly.”

May combine two claims.

Under default conditions, predicted heat loss was 16,521 kJ/day in the cold environment and 9,314 kJ/day in the hot environment.

“Under the default conditions, heat loss was 16 521 and 9 314 kJ/ day, for the cold and hot conditions, respectively.”

May combine two claims.

In the cold environment, air temperature was important, but humidity had a very small effect on heat loss, due to decreased importance of evaporative losses.

“In the cold environment, air temperature was also important, but humidity had a very small effect, due to the decreased importance of evaporative losses.”

May combine two claims.

Changing the cold value of rww, ka and ct had no influence on heat loss in the hot environment, but changing their hot value had a small effect in the cold environment.

“Changing the 'cold' value of these parameters had no influence on heat loss in the hot environment, but changing their 'hot' value had a small effect in the cold environment.”

May combine two claims.

ka has an equally important effect on heat loss as kA but in the opposite direction.

“Similarly, k a (the fraction of the animal's skin in contact with itself or with other animals) has an equally important effect but in the opposite direction.”

May combine two claims.

The mean square prediction errors were 0.0164 for daily food intake and 8.65 for body weight, corresponding to deviations of 0.128 kg/day and 2.94 kg, respectively.

“The mean square prediction errors (MSPE) were 0·0164 and 8·65 for daily food intake and body weight, respectively, which correspond to a deviation of 0·128 kg/day and 2·94 kg, respectively.”

May combine two claims.

Although predicted food intake behaved similarly to observed, the observed decrease in food intake at higher temperature was much more severe than predicted.

“Although the predicted food intake behaved in a manner similar to the observed, the observed decrease in food intake at higher temperature was much more severe than was predicted.”

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

The single measurement with air temperature lower than thermoneutral (19.6oC) was also lower than the corresponding thermoneutral value.

“Curiously, the single measurement with air temperature lower than thermoneutral (19·6ºC) was also lower than the corresponding thermoneutral value.”

May combine two claims.

Both food intake and heat production increased in colder temperatures after the thermal conductance change, similar to experimental observations.

“Both food intake and heat production increased in colder temperatures, in a manner similar to changes in the experimental observations.”

May combine two claims.

Both food intake and body weight were underestimated by the model at higher temperatures in the Collin et al. (2001) simulation.

“Although the behaviour of simulated data was compatible with the observations, both food intake and body weight were underestimated by the model at higher temperatures.”

• cites Collin et al. (2001) sourceNot checked — no full text of the source

May combine two claims.

The general shape of the food intake and heat production curves seems to be correct, with an approximately constant value around the thermoneutral zone and increased and decreased values below and above it, respectively.

“Most important, the general shape of the food intake and heat production curves seems to be correct, with an approximately constant value around the thermoneutral zone and increased and decreased values below and above it, respectively.”

May combine two claims.

The decomposition of MSPE showed proportions due to bias, regression error and disturbances of 0.371, 0.343 and 0.286 for daily food intake and 0.515, 0.376 and 0.109 for body weight.

“These were, respectively, 0·371, 0·343 and 0·286 for daily food intake and 0·515, 0·376 and 0·109 for body weight.”

May combine two claims.

Higher critical body temperatures cause the animal to respond faster to cold stress and slower to heat stress, reducing heat loss in both cases.

“Higher critical body temperatures mean that the animal will respond faster to cold stress and slower to heat stress, and in both cases heat loss is reduced.”

Classified as probably not a substantial claim.

Food intake varied with body weight according to the function described before (NRC, 1998).

“Food intake varied with body weight according to the function described before (NRC, 1998).”

• cites NRC, 1998Not matched

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

May combine two claims.

Using a larger value for cpb artificially increases the heat buffering capacity of the animal, allowing a stable solution with a larger time step.

“When a larger value for c pb is used, the heat buffering capacity of the animal is artificially increased, and a stable (non-chaotic) solution may be reached with a larger time step.”

May combine two claims.

rvr and kx may have significantly different values, which would substantially affect heat loss.

“They may, therefore, have significantly different values, which would result in a substantial effect on heat loss.”

May combine two claims.

Metabolizable energy intake may be calculated using relationships described by Noblet (1996), who considered energy loss as methane to be 0.004 of digestible energy and energy loss in urine as 3 kJ/g of catabolized protein.

“Metabolizable energy intake may be calculated using the relationships described by Noblet (1996), who considered energy loss as methane to be 0·004 of digestible energy, and energy loss in the urine as 3 kJ/g of catabolized protein.”

• cites Noblet (1996)Not matched

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

May combine two claims.

A larger value of ka reduces the area of skin available for heat exchange and therefore reduces heat loss.

“A larger value of k a effectively reduces the area of skin available for heat exchange, and therefore reduces heat loss.”

May combine two claims.

Body temperature was used to represent the combined effect of all environmental factors because it is directly affected by the thermal balance.

“Body temperature (estimated by the heat balance model) was used to represent the combined effect of all environmental factors (temperature, humidity, air speed, etc. ), because it is directly affected by the thermal balance.”

May combine two claims.

The NRC model has limited accuracy, so thermoneutral food intake was corrected using experimental data to reduce errors.

“Because the NRC model has limited accuracy, thermoneutral food intake was corrected using experimental data, as described with the calibration of the model, such that the errors in accuracy were reduced.”

May combine two claims.

The model's sensitivity may change because the response may not be linear and the reference heat loss value may differ.

“This occurs because the response may not be linear and the reference value of heat loss may be different.”

May combine two claims.

At 15°C, relative humidity had no effect because conditions were within the thermoneutral zone and animals could completely compensate for humidity changes.

“This happened because the conditions were within the thermoneutral zone, and the animals were able to completely compensate for changes resulting from varying humidity.”

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

In a cold environment, although food intake may increase, approximately all the additional energy is used to generate heat, and growth is not improved.

“Although food intake may increase, approximately all the additional energy is used to generate heat, and growth is not improved (Black et al., 1986).”

• cites Black et al., 1986Not matched

  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), S4 (based).

Advances in reducing backfat thickness suggest that ct may have changed in past years.

“Although a 1% increase will only raise heat loss by 0·20%, the significant advances in reducing backfat thickness suggest that this parameter may have”

• AssumptionRests on an assumption: Modern pig genotypes are leaner and grow faster, producing more heat at the same body weight compared with genotypes of the past.

May combine two claims.

One of the most significant deficiencies of the metabolism model is food intake prediction, which was corrected for thermoneutral values.

“One of its most significant deficiencies is food intake prediction, which was corrected for thermoneutral values, so that the focus remained on the deviations from thermoneutrality.”

May combine two claims.

The metabolism model described by de Lange (1995) has many limitations, some of which were corrected and some not.

“This model has many limitations, pointed out by Black (1995), some of which were corrected, while some were not.”

• cites Black (1995) sourceNot checked — no full text of the source

May combine two claims.

The food intake model does not consider the limiting effect of gut fill and is not valid for very cold environments where the animal cannot eat enough to compensate for heat loss.

“This model currently does not consider the limiting effect of gut fill on food intake. Therefore, it is not valid for very cold environments, when the animal would not be able to eat enough food to compensate for heat loss.”

Probably not a substantial claim: may not pass S3 (load-bearing), S4 (based).

The consequence of including the simplifying assumptions (no sunlight, no conduction to floor, wall temperature equal to air, negligible heating of ingested food and water) is the same as having a slightly different air speed, temperature or humidity, shifting the thermal comfort zone on an ambient temperature scale.

“The consequence of including these assumptions is the same as that of having a slightly different air speed, temperature or humidity, in the sense that they would shift the thermal comfort zone on an ambient temperature scale.”

• AssumptionThe authors state this as an assumption: Animals were not exposed to sunlight.
• AssumptionThe authors state this as an assumption: There was no heat exchange by conduction to the floor.
• AssumptionThe authors state this as an assumption: Temperature of walls was the same as air.
• AssumptionThe authors state this as an assumption: Heating of ingested food and water was negligible.

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

The reduction in tolerance to cold could have been caused by reduced tissue insulation.

“which could have been caused by reduced tissue insulation.”

• AssumptionRests on an assumption: Advances in pig breeding have led to leaner animals, which have less fat acting as a thermal insulator under the skin surface.

Probably not a substantial claim: may not pass S3 (load-bearing), S4 (based).

Changing many parameters by a small amount or one parameter by a large amount would yield similar results (an increase in heat loss under heat stress).

“For the purpose of testing the model, changing many parameters by a small amount or one parameter by a large amount would yield similar results (i.e. , an increase in heat loss under heat stress).”

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

This cessation of eating is unlikely to be maintained if the experiment was conducted for a longer period of time.

“which is unlikely to be maintained if the experiment was conducted for a longer period of time.”

May combine two claims.

The evaluated heat balance model may be used to predict heat loss from a pig to its environment and changes in a conceptual body temperature.

“The evaluated heat balance model may be used to predict heat loss from a pig to its environment and changes in a conceptual body temperature.”

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

Using the equations described by Noblet (1996), digestible energy of the Collin et al. diet was calculated to be 14.91 MJ/kg.

“Using the equations described by Noblet (1996), digestible energy was calculated to be 14·91 MJ/kg.”

• cites Noblet (1996)Not matched

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

Probably not a substantial claim: may not pass S2 (checkable), S3 (load-bearing).

It is likely that a combination of factors is responsible for the adaptation of the experimental animals to hot conditions.

“It is likely that a combination of factors is responsible for this adaptation”

May combine two claims.

The bias (underestimation of observed values) is responsible for a large proportion of the error in food intake prediction, and for most of the error in body weight prediction.

“This indicates that the bias (the underestimation of the observed values) is responsible for a large proportion of the error in food intake prediction, and for most of the error in body weight prediction.”

May combine two claims.

The experiment of Collin et al. (2001) involved 105 piglets with an initial average body weight of 15.5 kg, raised for 17 days under temperatures between 19 and 35°C with intervals of 2°C.

“In this experiment, a total of 105 piglets with an initial average body weight of 15·5 kg were raised for 17 days under one of a series of experimental temperatures ranging between 19 and 35ºC with intervals of 2ºC”

• cites Collin et al. (2001) sourceNot checked — no full text of the source

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

Mean body temperature synthesizes the effect of all environmental factors that affect an animal's thermal comfort in a single value.

“It synthesizes the effect of all environmental factors that affect an animal's thermal comfort in a single value.”

May combine two claims.

In the Giles (1992) experiments, a total of 11 pigs were exposed to different thermal environments for 24 h, and voluntary food intake was measured.

“In these experiments, a total of 11 pigs were exposed to different thermal environments for a period of 24 h, and voluntary food intake was measured.”

• cites Giles (1992)Not matched

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

May combine two claims.

The experimental animals were able to dissipate more heat than was predicted by the model, and could therefore maintain a greater heat production and higher food intake level.

“In order to maintain the same body temperature under these environmental conditions, the experimental animals were able to dissipate more heat than was predicted by the model. They could therefore maintain a greater heat production, and consequently a higher food intake level.”

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

The surgical procedure may have made the animals more susceptible to stress.

“which may have made the animals more susceptible to stress.”

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

The pigs used in the Giles (1992) experiment may have been more sensitive to heat stress than the ones used to calibrate the model.

“It may be that the pigs used in this experiment were more sensitive to heat stress than the ones used to calibrate the model.”

• cites Giles (1992)Not matched

  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). May combine two claims.

The underestimation may indicate that the parameters of the model may need to be better estimated, or that the animals used in the experiment were genetically more resistant to heat than the animals used to calibrate the model.

“This may indicate that the parameters of the model may need to be better estimated, or that the animals used in the experiment were genetically more resistant to heat than the animals used to calibrate the model.”