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First published online April 17, 2009
Journal of Experimental Biology 212, iii (2009)
Copyright © 2009 The Company of Biologists Limited
doi: 10.1242/jeb.032060
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Inside JEB |
DIET CHANGE INFLUENCES HATCHLINGS' DIGESTION
kathryn{at}biologists.com
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It's in every newborn's job description: eat lots and grow fast. In their
early days, freshly hatched house sparrows dine on a high protein diet of
insects before their parents begin delivering starchy seeds to their voracious
offspring. Pawel Brz
k and his colleagues from the University of
Wisconsin and Universidad Nacional de San Luis wondered how the youngsters'
digestive tracts respond to the drastic diet change while working full-out to
keep pace with the youngsters' growth
(p. 1284).
Feeding young sparrows on either a high-protein starch-free diet or a diet supplemented with starch, the team tracked the youngsters' growth, digestive tract enzyme levels and their ability to maintain their own body temperature until the birds were close to fledging.
The team found that although the birds on a starch-free diet were slightly
smaller and took a little longer to maintain their own temperature, removing
starch from the diet didn't seem to compromise the youngsters' growth. And
when they checked the birds' intestines, the team also found that the levels
of a carbohydrate-digesting enzyme, maltase, doubled when the birds were on a
starchy diet; their intestines were definitely responding. Brzk and his
colleagues suspect that the hatchlings' maltase increase is `important for
maintaining digestive efficiency and rate at the whole animal level,' allowing
the youngster to process the enormous amounts of starch they consume. They
believe that although some of the changes in the youngsters' intestines are
`hard wired' by a genetic programme, others are governed by the diet change
itself.
References
Brzek, P., Kohl, K., Caviedes-Vidal, E. and Karasov, W.
H. (2009). Developmental adjustments of house sparrow
(Passer domesticus) nestlings to diet composition. J. Exp.
Biol. 212,1284
-1293.
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