WOJCIECHOWSKI, M.*; KORINE, C.; DANIEL, S.; PINSHOW, B.; Ben-Gurion Univ. of the Negev, Israel & N.Copernicus Univ., Poland; Ben-Gurion Univ. of the Negev, Israel; Ben-Gurion Univ. of the Negev, Israel; Ben-Gurion Univ. of the Negev, Israel: Dual energy X-ray absorptiometry is a reliable method for measuring body fat content in small insectivorous bats.

We examined whether Dual Energy X-Ray Absoptiometry (DEXA) is a reliable method for measuring the body fat content in live small insectivorous bats. The initial body fat in 6 Pipistrellus kuhlii (m_b = 5.99 � 0.14 g) was measured by with a Lunar PIXImus� DEXA. They were divided into two groups of 3. For three weeks one group was fed mealworms ad libitum while the other was fed a restricted quantity of larvae, calculated to allow body mass maintenance. Once a week, duplicate DEXA measurements were made on all the bats. After the final measurement, the bats were killed by anesthetic overdose and their fat mass (m_f) was measured by gravimetry after chemical extraction using petrol ether. A seventh animal that died accidentally was added to the final analysis. There was no significant change in m_b in any of the animals during the 3-week experiment. However, bats fed the restricted diet maintained both significantly lower m_b (5.33 � 0.076 vs. 6.44 � 0.16 g) and m_f (0.91 � 0.081 vs. 1.48 � 0.10 g) than animals on the ad libitum diet (t₁₆ = 5.08, P<0.001 and t₁₆ = 4.40, P < 0.001, respectively). m_f in bats fed ad libitum continuously increased over the course of experiment (Friedman ANOVA: P = 0.059). In bats on the restricted diet, m_f did not change significantly. However, there was a trend towards an initial decrease and subsequent increase in m_f over the 3 weeks. m_f, as measured by DEXA and by chemical extraction were significantly correlated: m_f [g] = 1.1597 m_{f DEXA} + 0.3435 (r² = 0.92; P < 0.001), indicating that DEXA is a reliable method to determine body fat content of small bats. This project was supported by a grant by the ARI program of the European Commission to MW and Israel Science Foundation grant # 653/01-1.