Lactation and thermal energetics of the eastern barred bandicoot, Perameles gunni (Marsupialia: Peramelidae)

In this study, the changes of the milk components (protein, carbohydrate, lipids and total solids) were investigated during part of the lactation period of the P. gunnii (4 to 8 weeks) and compared with other marsupial species and with Wombaroo¬¨vÜ milk formula. It was found that protein increased during early, mid and late stage of lactation (4.5, 10.2, 12units) lipid (3.1, 8.4, 17.4units) and total solids (28, 36, 54units!), while carbohydrate although increased by the mid stage of lactation (from 2 to 5.5 g 100 m1: 1 ) by the end of lactation dropped to almost initial levels (2.5 g 100 m1: 1 ). The highest value of the energy contents reached 8.86 ¬¨¬± 1.037 KJ mL-1at the end of lactation. The pattern of growth of the pouch young was observed and the changes of the metabolic rate at two different ambient temperatures (25 and 35¬¨‚àûC). The onset of endothermy occurred at 7 weeks while at 8 weeks the metabolic rate increased but by 9 weeks had dropped to almost adult levels (0.58 mL g -1h-1 ). The body mass of the young bandicoot increased sigmoidally from 14.84 ¬¨¬± 1.49 g (4weeks) to 120.54 ¬¨¬± 9.67 g (8 weeks), the head length from 31.82 ¬¨¬± 1.36 mm to 60.81 ¬¨¬± 2.16 mm, the tail from 17.4 ¬¨¬± 1.37 mm to 51.45 ¬¨¬± 3.34 mm and the foot length from 18.05 ¬¨¬± 1.82 mm to 53.2 ¬¨¬± 0.8 mm respectively. The fur of P.gunnii was first seen at the age of 6 weeks, while at 8 weeks it was well developed. Measurements of the metabolic rate and of the thermal conductance (TC) of adult P. gunnii were measured at different ambient temperatures. We observed that the thermoneutral zone (TNZ) of the P. gunnii lay between 25 and 30¬¨‚àûC. The change in metabolic rate before and after warm (25¬¨‚àûC) and cold acclimation (5¬¨‚àûC) was observed. Cold acclimated animals increased their metabolic rate, while warm acclimatised animals decreased significantly their metabolic rate (P = 0.03). Norepinephrine (NE) had a significant affect before and after cold acclimation at 25 and 5¬¨‚àûC and before (P = 0.03), but not after warm acclimation (P = 0.06). Additionally, electromyography (EMG) measurements showed a reduction of shivering after cold acclimation (P = 0.04). NE had a significant affect on what! before (P = 0.003) but not after cold acclimation (P = 0.08). On the other hand NE did not reduce significantly shivering at 25¬¨‚àûC before or after cold acclimation (P = 0.22, P = 0.25).