Feather Mass Research Articles

Estimates of the Mass of Structures Other than Plumage Produced during Molt by White-Crowned Sparrows

Analysis of the caloric or nutritional demands of molt requires a thorough inventory of the mass and composition of all molted structures and of the ephemeral nonmolted structures (e.g., feather pulp) that accompany the process. Only plumage mass and composition are adequately known in a selection of species. We reported previously that the air-dried plumage mass of a 27-g White-crowned Sparrow (Zonotrichia leucophrys gambelii) is about 2,000 mg at the end of the postnuptial (PN) molt, during which about 400 mg of feather sheaths were grown and shed. In this report we show that the stratum corneum (air-dried mass = 88 mg) of captive Z. 1. gambelii is totally shed and replaced during the PN molt, and that the podotheca (19 mg, both legs) is molted about 10 weeks later, in November. The rhamphotheca is not shed during feather molt, but appears to be renewed continuously in response to wear of the tomia. It is unlikely that the molt of the podotheca is delayed because of nutritional stringency during the PN molt, since its mass is only about 1% of the combined mass of feathers, sheaths, and stratum corneum. Very little is known in other species about the renovation of corneous structures other than feathers. It is thought that skin, beak, and claws grow continuously in response to wear, and that the skin also molts totally during feather molt. In some species, claws and parts of the beak may also be shed episodically during or near the time of feather molt. The podotheca is probably shed annually in all species, often during feather molt but sometimes earlier or later.

Amino Acid Composition of Feather Barbs and Rachises in Three Species of Pygoscelid Penguins: Nutritional Implications

To evaluate the nutritional challenge faced by molting penguins we studied the composition of contour feathers of three species of penguins, Pygoscelis adeliae, P. antarctica, and P. papua. The feathers of these species are nearly identical in structure and chemical composition. They have a unique broad, flat rachis that accounts for 60 to 70% of the total feather mass. Their barbules are pennaceous and able to interlock tightly, which probably accounts for the shedding of plumage in sheets rather than as individual feathers. Compositionally, the penguin feathers are remarkably similar to feathers of other species of birds representing six different orders and varied life-styles. Whole penguin feathers averaged 8-10% water. Ash contents of P. adeliae and P. antarctica feathers averaged less than 1%, but P. papua averaged 2.6%. The nitrogen contents of the barbs were nearly identical in the three species and averaged 16.4%. The nitrogen content of the rachises of P. adeliae and P. antarctica feathers averaged 16.4%, but was slightly less in P. papua (15.5%), probably due to the higher ash content and slightly higher pigment content in this species. The most abundant amino acids in barbs and rachises were gly, pro, ser, cys/2, val, and leu. Six nonessential amino acids (ala, asp, glu, gly, pro, ser) made up 52.5 and 54.3% of the barbs and rachises, respectively. The basic amino acids (lys, his, arg) were among the least concentrated amino acids. This amino acid profile is typical of mixed feather keratins. The high cys/2 contents of feather proteins results in a large mismatch between nonkeratinous mixed tissue proteins and feathers that could result in highly inefficient reutilization of tissue amino acids in feather synthesis during the molt fast. Some compensatory mechanisms that penguins might use to minimize this inefficiency are discussed.

Annual Variation of Primary Molt with Age and Sex in Cassin's Auklet

Annual Variation of Primary Molt with Age and Sex in Cassin's Auklet

Rates of Primary-Feather Growth in Nestling Birds

Rates of primary-feather growth with respect to increase in length and increase in feather mass were estimated for nestlings of a range of bird species. The relationships between primary feather growth-rate constants and adult primary-feather length, primary-feather mass and adult body mass for these species are described. As adult body size increases, flight-feather growth is completed in a shorter proportion of the post-hatching growth period. The rate of deposition of primary-feather mass scales to final (asymptotic) primary-feather mass with a similar scaling exponent as that relating rates of overall growth in body mass to adult weight.

Chemical Composition and Energy Content of Duck Feathers in the Post-hatching Period

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FEATHER GROWTH, MASS LOSS AND DURATION OF MOULT IN MACARONI AND ROCK-HOPPER PENGUINS

Summary Brown, C. R. 1986. Feather growth, mass loss and duration of moult in Macaroni and Rockhopper Penguins. Ostrich 57:180-184. The development of new feathers, loss of body mass and the duration of moult were investigated in Macaroni Penguins Eudyptes chrysolophus and Rockhopper Penguins E. chrysocome at Marion Island, southern Indian Ocean. New feathers began developing under the skin before the birds returned ashore to moult, and only began protruding through the skin about five days later when they were already over half their final length. Feather synthesis was complete by 21 days after the birds returned ashore. Loss of body mass was similar to previous observations for the species, but previous reports on the duration of moult do not take into account that moult begins while the birds are still at sea.

Sensible heat transfer from the bowl: thermal resistance of the pelt.

1. Measurements of the pelt resistances of laying hens showed a five‐ fold difference for pelts ranging from feather scores of 1 to 5. Pelt resistance decreased linearly with increasing feather score. 2. Feather mass per unit area [Wf , kg/m2) is related to pelt resistance rp, m2K/W) by rp = 0–53 Wf+0.12.

The substitution of protein feed by lysine-supplemented protein-rich wheat during the raisung and laying periods in hens. 6. Report. The effect of graded lysine supplemented on the crude nutritional content of the carcas of laying hens.

In the present work 8 hens taken from each of the 16 experimental groups (90 birds per group) were killed at the end of the trial period (52 weeks). The weight of the organs was determined and bones, the utilizable parts and the residual carcass were analyzed for their crude nutrient content. The experimental birds received rations containing a large proportion of high-protein wheat supplemented with varying levels of lysine. Variations in the lysine supply did not affect the mass of blood, feathers, bones, liver, stomach, heart and ovaries, including ovarian follicles. An analysis of the utilizable parts (flesh, stomach, heart, liver, follicles, fat) for crude nutrients showed that the heavier birds receiving adequate amounts of lysine contained less crude protein and more crude fat than the smaller birds. A positive correlation was found to exist between the crude ash content of these samples (expressed as %) and the levels of lysine supplied during the laying period. All the birds receiving the lysine-deficient ration during the time of rearing or during the laying period contained significantly less crude ash in their bones. Alongside with the crude ash content the phosphorus content of the bones decreased when the birds where fed the diet for laying hens.