Evaluation of somatotype in the reticulated giraffe (<i>Giraffa camelopardalis reticulata</i>) using three-dimensional laser measurement

Abstract

The giraffe (Giraffa camelopardalis) is a difficult animal to keep in captivity as it has high mortality due to nutrition-related disorders, perhaps because the giraffe’s condition is difficult to evaluate. Image analysis techniques have recently become popular and may be useful for evaluating the giraffe’s somatotype. The present study aimed to evaluate the giraffe somatotype using a three-dimensional laser measurement device, and to examine the usefulness of this method. First, ten zoo staff members visually evaluated the somatotypes of three giraffes housed at Kanazawa Zoological Gardens, Japan. Next, three-dimensional point cloud datasets were obtained from these giraffes using the device. The point cloud datasets indicated that the cross-sectional area and width of the largest giraffe’s body were large in the abdominal region in the transverse sections. However, by visual examination, the ten zoo staff members deemed a different giraffe to be the largest. These results indicated that the three-dimensional laser measurement device could be used to evaluate giraffe somatotype in detail, and that this method may be an alternative to visual evaluation.

Body Shape Analysis in Reticulated Giraffe, Okapi, and Black Rhinoceros Using Three-Dimensional Laser Measurements

“…Although the dataset is obtained within a short time (1-2 min) and the laser instrument can be operated on a moving target, to obtain an accurate dataset, the animal should not move during measurements. Second, as described in our previous study, this technique does not directly evaluate the subcutaneous or visceral adipose tissue; thus, results might only reflect differences in skeletal structure [39]. In addition, in reticulated giraffe and okapi, the rumen volume due to recent feed intake may affect the results.…”

“…The present study adopted relative change rates and scatter plots to evaluate body shape and showed that both might become regular evaluation factors. As described in our previous study [39], the dataset obtained by the three-dimensional laser measurement technique varied among individual animals. Therefore, standardized evaluation factors not affected by individual size are required.…”

“…Whole-body and transverse-section body images were obtained once. In transverse sections, cross-sectional area, width, and height were measured at 5 cm intervals over the distance between the axillary and inguinal regions, according to a previously [39] described method (Figure 1). In areas where data were missing (especially the abdominal region, as shown in Figure 1c,f), the data were estimated based on the datasets obtained for the other individuals of the same species.…”

“…The body length was measured from the protrusion of the proximal end of the humerus to the buttock of the animal (Figure 1, black line on the body). The accuracy of three-dimensional laser measurement was evaluated by our previous study, comparing between the direct measurement and the value by the three-dimensional measurement of the body circumference [39].…”

“…In dairy cattle, several studies have evaluated BCS using three-dimensional laser measurement analysis [34][35][36][37][38]. Previously, we examined three giraffe somatotypes using three-dimensional laser measurements and showed the effectiveness of the method for this species in zoos [39]. However, further studies are required to evaluate the effectiveness of this method in more individuals and in other species and the volume of animal body.…”