The Maintenance Nitrogen Requirement of the Zebra FinchTaeniopygia guttata

Abstract

A procedure is described for the accurate determination of the maintenance nitrogen requirement (MNR) of small granivorous birds. When used with the zebra finch (Taeniopygia guttata), it yielded a MNR of 403 mg kgW(-0.75) d(-1). This is lower than most other passerines so far measured and more similar to some nonpasserine species. Similarly, the value for endogenous nitrogen loss estimated for the zebra finch (153 mg kgW(-0.75) d(-1)) is less than that for passerines in general but higher than the nonpasserine value. We suggest that the low MNR of the strictly granivorous zebra finch is primarily an adaptation to seed diets in which high-quality protein is a limiting factor. Comparison with a wider range of species reported in the literature was restricted because inappropriate methods have been used to estimate MNR in many cases, including the use of growing or reproducing birds and the assumption that maintenance of body mass necessarily coincides with maintenance of zero nitrogen balance.

Low plasticity in digestive physiology constrains feeding ecology in diet specialist, zebra finch (Taeniopygia guttata)

“…2, Tables 2 and 3) but mechanisms controlling the expression of intestinal disaccharidases were not affected by diet (at least not in the direction predicted by the adaptive modulation hypothesis) and were affected relatively little by age. We studied birds that bred in captivity for several generations; however, domestication had little effect on the physiology of zebra finches (Allen and Hume, 2001). Therefore, our results are likely to represent the digestive flexibility typical of wild birds.…”

“…In the arid habitat typical of zebra finches, seeds can be quite a reliable food source, at least relative to other types of food (Morton and Davies, 1983). Adult zebra finches show some physiological adaptations to a proteinlimited, granivorous diet (Houston et al, 1995;Allen and Hume, 2001). Very narrow diet specialization, including relying only on seeds for feeding nestlings, is possible in granivorous birds when natural seeds have a relatively high protein content (Valera et al, 2005).…”

Maintenance nitrogen requirements of adult female ostriches (Struthio camelus)

“…Apparent metabolizable energy content of each diet was calculated as the total energy intake – total excreta energy output. Maintenance nitrogen requirements was calculated according to the method of Allen and Hume (2001). Briefly, corrected nitrogen balance (nitrogen intake – corrected nitrogen output) is regressed on nitrogen intake.…”

“…To establish the allometric relationships of MNR and TENL with body mass, we collected data for 46 species of adult non‐reproducing birds for which nitrogen balance data are available (Table 2). For those species where MNR and TENL were not explicitly estimated, the requirements were calculated from the available data according to Allen and Hume (2001), as outlined above. We calculated separate estimates for both wild and domesticated turkeys ( Meleagris gallopava ) and for both meat (Pekin duck) and egg‐laying type (Chinese egg‐laying duck) domesticated ducks ( Anas platyrhynchos ).…”

Shifting to an energy-poor diet for nitrogen? Not the case for wintering herbivorous Lesser White-fronted Geese in China

“…According to this hypothesis, we formulated the predictions that: (1) Carex was higher in nitrogen than Alopecurus, Cynodon and Eleocharis, or that the nitrogen assimilation efficiency of the Carex-dominant diet at Daxi Lake was higher than that at Caisang Lake, where geese mainly fed on Alopecurus, Cynodon and Eleocharis (Wang et al 2013); (2) the metabolisable dietary nitrogen intake at Daxi Lake was higher than at Caisang Lake; (3) the nitrogen budget, i.e. the balance of nitrogen income against expenditure, at Daxi was positive and higher than at Caisang Lake; and (4) daily uric acid excretion at Daxi was higher than at Caisang Lake, because the uric acid excretion generally increases as the nitrogen budget becomes more positive (Allen and Hume 2001). To examine these predictions, we estimated, for the first time in wild geese, monthly nitrogen budgets of wintering Lesser Whitefronted Geese in two distinct habitat types.…”