Lung volumes in giraffes, Giraffa camelopardalis

Abstract

We have measured lung mass and trachea dimensions in 46 giraffes of both genders ranging in body mass from 147 kg to 1441 kg, calculated static and dynamic lung volumes, and developed allometric equations that relate changes in them to growth. We found that relative lung mass is 0.6 ± 0.2% of body mass which is significantly less than it is in other mammals (1.1 ± 0.1%). Total lung volume is significantly smaller (46.2 ± 5.9 mL kg −1 ) than in similar sized mammals (75.0 ± 2.1 mL kg −1 ). The lung volume:body mass ratio decreases during growth rather than increase as it does in other mammals. Tracheal diameter is significantly narrower than in similar sized mammals but dead space volume (2.9 ± 0.5 mL kg −1 ) is larger than in similar sized mammals (2.4 ± 0.1 mL kg −1 ). Our calculations suggest that tidal volume (10.5 ± 0.2 mL kg −1 ) is increased compared to that in other mammals(10.0 ± 0.2 mL kg −1 ) so that the dead space:tidal volume ratio is the same as in other mammals. Calculated Functional Residual Capacity is smaller than predicted (53.4 ± 3.5 vs 33.7 ± 0.6 mL kg −1 ) as is Expiratory Reserve Volume (47.4 ± 2.6 vs 27.2 ± 1.0 mL kg −1 , but Residual Volume (6.0 ± 0.4 mL kg −1 ) is the same as in other similar sized mammals (6.0 ± 0.9 mL kg −1 . Our calculations suggest that Inspiratory Reserve Volume is significantly reduced in size (11.6 ± 1.6 vs 3.8 ± 2.4 mL kg −1 ), and, if so, the capacity to increase tidal volume is limited. Calculated dynamic lung volumes were the same as in similar sized mammals. We have concluded that giraffe morphology has resulted in lung volumes that are significantly different to that of similar sized mammals, but these changes do not compromise ventilatory capacity.

The digestive morphophysiology of wild, free-living, giraffes

“…min -1 , which is not significantly different to the BMR predicted by the allometric equations developed by Stahl (1967), Hayssen & Lacy (1988) and Schmidt-Nielsen, (1997), and can be described by the allometric equation 9.7*Mb^-0.23 (mlO 2 /kg. min -1 ; Mitchell & Skinner, 2011) Our data indicate that of all energy produced by fermentation, the amount produced by the rumen declines as Mb increases from 74% in young giraffes to 61% in adults (Table 4). Conversely the amount produced by the hindgut increases from 26% in young giraffes to 39 % in adults.…”

Case Studies in Physiology: The Case of the Giant Giraffe

“…The giraffe with its very long neck is expected to have a large dead space, but this is not the case. Giraffes have a low dead space-tidal volume ratio that is explained on the basis of a relative large tidal volume combined with a narrow trachea (9,14,20). As this study confirms, the physiological dead space is 700 ml, which is much lower than expected for an animal of this size.…”

Mechanism of augmented exercise hyperpnea in chronic heart failure and dead space loading

“…In long-necked animals such as giraffes and swans, the increased anatomical V D is compensated for by a slow-and-deep breathing pattern such that physiological V D /V T remains relatively unchanged compared with similar-sized animals (Bech and Johansen, 1980; Hugh-Jones et al, 1978; Mitchell and Skinner, 2011). In this case, the increased anatomical V D affects primarily ${\dot{V}}_{\mathrm{normalC}{\mathrm{O}}_2}^o$, and Whipp’s law applies as noted above.…”