Meeting Abstract

5.6  Monday, Jan. 4  Effect of chronic food restriction on gut morphology and digestive enzymes in nestling House sparrows KILLPACK, T.*; SINGH, N.; KARASOV, W.H.; Univ. of Wisconsin, Madison; California State Univ., Northridge; Univ. of Wisconsin, Madison tkillpack@wisc.edu

In adult birds, food restriction typically results in reductions in size of assimilation organs, such as intestine and liver, and in total enzymatic capacity, though mass-specific enzyme activities may not be altered. Food restriction due to periodic food shortage can occur during chick development, although their response has been little studied. In young chickens, food restriction had no significant effect on liver and intestine masses or on intestinal mass-specific enzyme activities. We hypothesized that masses and biochemical capacities of assimilation organs are maintained constant in developing nestling birds, despite food restriction, to support demands of growth and development. We present one of the first tests in birds exhibiting the altricial mode of development. House sparrow (Passer domesticus) nestlings were raised in the laboratory from day 3 to day 25 post-hatch and fed either age-specific meal sizes (control group) or meal sizes 75% of age-specific amounts (restricted group). On day 25, body and organ masses were measured and intestines were stored for digestive enzyme assays. Chronically restricted nestlings had significantly lower body mass (by 14%). Intestine mass and length were significantly lower in restricted birds (by 17% and 9%, respectively), even when corrected for differences in body mass. Liver mass was also significantly lower (by 18%) in restricted birds. Based on assays of enzyme activity so far, there was little difference between groups in maltase or aminopeptidase-N activity per unit intestine mass. Results so far show that response of the digestive organs of altricial nestlings facing chronic food restriction is not different from findings in restricted adults. Supported by NSF IOS 0615678 to WHK.