Validation of animal factor algorithms

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4.5 Validation of animal factor algorithms

During May 2010, the methodology and algorithms being proposed for the estimation of critical temperatures and the total, sensible and latent heat in version 2 of LATSA were reviewed by third-party expert reviewers nominated by EnviroAg Australia, MLA and LiveCorp. Adjustments or modifications were then made to reflect any recommendations made by these reviewers. Comparisons were also made at this time between the values obtained using these algorithms and those sourced from tabulated or graphical data in publications such as:  Design of Ventilation Systems for Poultry and Livestock Shelters ASAE, 1986;  Effect of Environment on Nutrient Requirements of Livestock NRC, 1981;  Live Animal Regulations IATA, 2009a;  SAE AIR1600 SAE Aerospace, 2003; and  Standards for the Microclimate inside Animal Transport Road Vehicles SCAHAW, 1999. 4.5.1 Sensible heat loss The following graphs provide comparative plots of the estimates of sensible heat loss obtained using the equations in CIGR 2002, as previously presented in Section 0 page 29, and those of the Society of Automotive Engineers SAE, 2003, as provided in the documentation for the existing version of the LATSA software refer Figure 6 in Marosszéky, 2009. The plotted values cover ambient temperatures ranging from 5°C to 35°C, which would be broadly analogous to the thermoneutral zone in most cases. Figure 8 depicts estimates, from the CIGR 2002 and SAE 2003, of the sensible heat generated by a 45 kg and a 135 kg calf 18 . Liveweight gain in these animals was 0.5 and 1.0 kgd respectively for the values derived from the CIGR 2002 equations. No liveweight gains were specified in respect to the SAE 2003 data, but growth rates of a similar magnitude might be expected to apply. 18 At ambient temperatures above ~35°C, the sensible heat generated by the animals in Figure 8 decreases to less than zero. While this extrapolation of the plot line is an artefact of the curve fitting software used in this example, at these temperatures the animals are indeed likely to be gaining heat from external environment i.e. the animal would not be generating or shedding sensible heat Upgrade of LATSA Page 43 of 148 10 20 30 40 Ambient temperature °C -2 2 4 6 S ens ib le h eat W k g CIGR lwg of 0.5 kgd SAE 10 20 30 40 Ambient temperature °C -2 2 4 6 S ens ib le h eat W k g CIGR lwg of 1.0 kgd SAE 45 kg calf 135 kg calf Figure 8: Sensible heat transfers a 45 kg and 135 kg calf Both plots in Figure 8 show a good level of agreement; although growth rates other than those shown here in respect to the CIGR 2002 estimates would provide more disparate plots. Figure 9 likewise provides estimates of sensible heat generated by mature cattle and sheep taken from the same two sources. For the estimates derived using the CIGR 2002 equations, the following conditions were assumed to apply:  The ‘dry’ or non-lactating cow had a liveweight of 400 kg, was pregnant and was close to calving;  The lactating cow similarly had a liveweight of 400 kg, was not yet pregnant and was yielding 35 kg or milk per day; and  The sheep had a liveweight of 40 kg, and either a non-pregnant and not lactating ewe or whether, but with an unspecified coat wool length. The SAE 2003 estimates in Figure 9 for ‘cattle’ are for animals of no particular type, liveweight or condition. Similarly the estimates for sheep do not identify a liveweight or stage of gestation or lactation, but do provide estimates for shorn and unshorn sheep – although the associated coat lengths are not specified. Upgrade of LATSA Page 44 of 148 10 20 30 40 Ambient temperature °C -2 2 4 6 S ens ib le h eat W k g CIGR dry cow CIGR lactating cow SAE 10 20 30 40 Ambient temperature °C -2 2 4 6 S ens ib le h eat W k g CIGR 40 kg sheep SAE sheep SAE shorn sheep mature cow mature sheep Figure 9: Sensible heat transfers by mature cattle and sheep In Figure 9 there again is good general agreement between the SAE 2003 and CIGR 2002 values for ‘cattle’ and a dry cow respectively. However, some disparity is evident between the CIGR derived values for a high-yielding lactating cow, and the generic cattle values in SAE 2003. Nevertheless, a difference of this nature is not an unreasonable expectation in regard to a high producing animal. It is also an important one if animals in peak production are to be transported. In respect to sheep, the plotline for a 40 kg sheep obtained using the CIGR 2002 equations coincided well with the SAE 2003 values for a shorn sheep, but less well in respect to an unshorn one. Mindful that the SAE derived values plotted in Figure 8 and Figure 9 are not specific to any particular liveweight, production level or the like, there generally appears to be reasonable agreement between the two publications in respect to sensible heat loss. Upgrade of LATSA Page 45 of 148 4.5.2 Latent heat loss Similar to the comparisons of sensible heat loss in Section 4.5.1, here Figure 10 and Figure 11 provide comparisons of the latent heat loss values obtained using the approach described in Section 4.2.5 above 19 , with those provided in SAE 2003 for similar livestock. The SAE 2002 values correspond to those in the documentation for the existing version of the LATSA software Marosszéky, 2009. The assumptions regarding the different animals that were listed in respect to the CIGR 2002 equations in Section 4.2.3 also apply here. 10 20 30 40 Ambient temperature °C 2 4 6 8 Lat e n t he at W k g CIGR lwg of 0.5 kgd SAE 10 20 30 40 Ambient temperature °C 2 4 6 8 Lat e n t he at W k g CIGR lwg of 1.0 kgd SAE 45 kg calf 135 kg calf Figure 10: Latent heat loss by a 45 kg and 135 kg calf Unlike in Figure 8 page 43, the differences between the two sets of estimates plotted in Figure 10 are more marked – particularly in respect to the 45 kg calf. Further, since total heat production is the sum of latent and sensible heat, similar discrepancies might be expected in total heat estimates. However, owing to limited descriptions available for the animals in the SAE 2003 datasets, it is not possible to make an emphatic decision as to which of the two estimates is the more accurate. It may be observed though, that at around 20°C the latent heat loss estimates in the SAE 2003 data represent close to 50 of total heat production, whereas those obtained using the CIGR 2002 equations are closer to 30 of total heat production, and thus more in accordance with expectations. 19 Derived from CIGR 2002 Upgrade of LATSA Page 46 of 148 Figure 11 provides comparisons of the latent heat loss estimates obtained from the two sources in respect to mature cattle and sheep. 10 20 30 40 Ambient temperature °C 2 4 6 8 Lat e n t he at W k g CIGR dry cow CIGR lactating cow SAE 10 20 30 40 Ambient temperature °C 2 4 6 8 L a tent he at W k g CIGR 40 kg sheep SAE sheep SAE shorn sheep mature cow mature sheep Figure 11: Latent heat loss by mature cattle and sheep The estimates of latent heat loss for the mature cows show reasonable agreement, although the CIGR derived estimates for the lactating cow are closer to that for ‘cattle’ in the SAE 2003 data – the converse of the case in regard to sensible heat plotted in Figure 9. The two sources also differ significantly in respect to latent heat loss is sheep, but in this instance the CIGR-derived values are higher than the SAE 2003 values for both shorn and unshorn sheep. Again, based on the available information regarding the different animals, there is no compelling argument for supporting one or the other of these estimates being the more accurate or reliable. Upgrade of LATSA Page 47 of 148 4.5.3 Carbon dioxide production In respect to CO 2 emission data from livestock and other animals, the current LATSA software documentation Marosszéky, 2009 references Boeing Aircraft Corporation documents D6U10192, D6U10192-1 and D6-33380. Sheep and cattle are the only species of interest in this review for which values are presented in the chart provided in the LATSA documentation. Figure 12 provides a plot of these values, redrawn from the original chart after conversion to SI units i.e. m³hrkg in lieu of the original ft³hrlb. Also plotted in Figure 12 are alternative estimates of CO 2 production by sheep and cattle in the same liveweight ranges, but in this instance based on the estimation methodology described in Section 4.2.6 above. 1 10 100 1000 Liveweight kg 0.0001 0.001 0.01 CO 2 p rod uc ti o n m ³ h rkg Sheep Cattle cur ren t d ocu m en tatio n cur ren t d ocu m en tatio n Pe de rsen e t a l Ped erse n et a l Figure 12: Comparison of CO 2 production in sheep and cattle referred to in the existing LATSA software and values based on estimated production values in Pedersen et al. 2008 The alternative CO 2 production rates for sheep and cattle plotted in Figure 12 are both consistently higher than the values reference in the current LATSA software documentation Marosszéky, 2009. It is unclear whether these differences reflect 1 fundamental differences in the approach to estimation and the algorithms applied; 2 the influence of recently revised values for component variables in estimation algorithms e.g. k in Equation 17, or its equivalent in alternative predictive equations; or 3 continually improving levels of productivity in modern livestock and hence comparatively higher levels of energy intake and thus CO 2 production. Upgrade of LATSA Page 48 of 148

4.6 Validation of aircraft ventilation algorithms