Development of enzyme activity in the gut of the grey kangaroo (Macropus giganteus).

Abstract

16A Development of enzyme activity in the gut of the grey kangaroo (Macropus giganteus) S.R. Moll and I.R. Godwin Physiology, School of Rural Science and Natural Resources, University of New England, Armidale NSW 2351 igodwin@metz.une.edu.au Unlike eutherian mammals, marsupials undergo most of their `foetal' development in the pouch. Immediately upon entering the pouch the young fasten to a teat and begin drinking milk at an age equivalent to a 4 week human foetus. The digestive tract is obviously fully functional, but very little is known of its physiology. We investigated the activity of the disaccharidase enzymes in various segments of the gut of 19 grey kangaroo pouch young and their mothers. Ages of the pouch young were determined by measuring hind foot length (Kirkpatrick 1965) and the activities of lactase, maltase and sucrase were determined in both tissue and contents from the saccular and glandular stomachs, the duodenum, ileum and colon. Data for the duodenal tissue and duodenal contents are shown in Table 1. The major finding was that the activity of sucrase was significantly higher in the 0_50 day age group than all other age groups for all the gut sites tested. There was no appreciable activity of lactase in the adult gut. During early lactation the milk of Ta m m a r wallabies is high in carbohydrate. It is mostly in the form of oligosaccharide composed of a single glucose unit linked to varying numbers of galactose molecules. As the lactation progresses the content of carbohydrate declines and becomes present lar gely as free monosaccharides (Green and Merchant 1988). The high levels of sucrase activity in the very young animals in the present study may be a response to the presence of sucrose_like compounds in the early lactation milk of the grey kangaroo. It also suggests that sucrose could be substituted for more expensive sugars in artificial rearing formulae for very young animals. Green, B. and Merchant, J.C. (1988). The composition of marsupial milk. In: The Developing Marsupial, pp. 41_54 (eds. C.H. Tyndale_Biscoe and P.A. Janssens), Springer_Verlag, Heidelberg. Kirkpatrick, T.H. (1965). Studies of Macropodidae in Queensland 2. Age estimation in the grey kangaroo, the red kangaroo, the eastern wallaroo and the red_necked wallaby, with notes on dental abnormalities. Queensland Journal of Agricultural and Animal Sciences 22, 3317. Table 1 Disaccharidase activities in the duodenum and duodenal contents of pouch young and adult grey kangaroos. Age (days) Maltase activity (� mol/min/g protein) Tissue 0_50 50_100 1150 151_200 Adult 10.3 � 6.5 23.2 � 17.2 10.8 � 1.3 6.4 � 2.1 14.5 � 2.5 Contents 32.5 � 28.0 21.2 � 11.3 14.1 � 3.9 20.9 � 8.5 64.6 � 6.6 Sucrase activity (� mol/min/g protein) Tissue 302.6 � 169.3 34.5 � 11.3 5.0 � 4.6 a b b b ab Lactase activity (� mol/min/g protein) Tissue 22.5 � 10.1 42.3 � 20.3 10.7 � 3.0 15.8 � 3.1 0.1 � 0.1 a a a a b Contents 411.3 � 259.0a 83.6 � 21.5 � 10.2 � 20.9 � 35.8 6.4 3.3 7.6 b b b b Contents 105.0 � 52.1a 50.8 � 16.3 45.7 � 15.1 a a 22.8 � 13.3 52.7 � 16.7 51.6 � 6.6a 0.2 � 0.1b Means with different superscripts are significantly different (P<0.05) Recent Advances in Animal Nutrition in Australia, Volume 13 (2001)