ENERQETICS A N D ANIMAL PRODUCTIVITY
85
mention because of its importance as a standard reference on energetics.
This work is concerned with domesticated farm animals and thus is
useful in calculating farm productivities. However, many of the chapters
are of a general nature and contain a wealth of information concerning
such vital subjects as energetics and energy units ; energetic efficiencies
of growth and work processes; nutrition, the principle of diminishing
increments in efficiency; homeostasis and organismic theories; methods
in animal calorimetry; and the energetic efficiencies of muscular work.
For the most part, the book discusses such aepects as the processes of
growth and metabolism. Marshall “Biology and Comparative Physiology
of the Birds”, Vol. 11, contains much information on energetics. The
chapter on energy metabolism, thermo-regulation, and body temperature contains information on calorimetry, met.a,bolic rates, energy metabolism and the variation in energy metabolism. The chapters on flight,
long distance orientation, behavior, and bird populations also contain
information which is potentially useful in making field energy estimates.
The study undertaken by West (1960) on the tree sparrow, Spizella
arborea, met all but one of the requirements of a complete field productivity study; field data are lacking on numbers of individuals. West’s
primary concerns were: (1) the number of calories necessary to support
the birds in their environment; (2) the caloric burden of migration and
incubation. Food consumed and excrement produced (West used this
term to mean egestion plus excretion) by the ;birds was measured both
in the laboratory and in outdoor cages at Churchill, Manitoba, Canada
(the birds’ breeding range) and a t Urbana, Illinois, U.S.A. (the wintering range). Values averaged around 4.4 kg cal f m the food and 3.7 kg cal
for the feces. The energy consumption of the birds varied with the
ambient temperature from 34-23 kcal/bird/day (1 -64 kcal/g/day) at
-30” C to 10.77 kcal/bird/day (0.49 kcal/g/day) at 30” C. Day length
also caused variation in calorie requirements rmd caloric consumption.
From these and other data West constructed a series of equations and
a graph for the annual energy budget of an adult bird. The equation
which related grow energy intake of the bird to temperature was
GE = 25.89 kcal/bird/day-0.254 To C. The equation which represented
metabolizable energy with relationship to temperature was M E = $9.05
kcal/bird/day-0-167 To C. Each bird required roughly 7 460 kg cal each
year to live, migrate and reproduce in the wild. West had no figures on
the area necessary to provide these calories and, thus, no productivity
figures per unit area for the population were given.
The last paper of a primarily physiological nature I wish to discuss
is that of Pearson (1960) which has many elements of the Bornebusch
approach although emphasizing the homeostatic mechanisms of the
harvest mice. Pearson considered oxygen consumption and its relationD
85
mention because of its importance as a standard reference on energetics.
This work is concerned with domesticated farm animals and thus is
useful in calculating farm productivities. However, many of the chapters
are of a general nature and contain a wealth of information concerning
such vital subjects as energetics and energy units ; energetic efficiencies
of growth and work processes; nutrition, the principle of diminishing
increments in efficiency; homeostasis and organismic theories; methods
in animal calorimetry; and the energetic efficiencies of muscular work.
For the most part, the book discusses such aepects as the processes of
growth and metabolism. Marshall “Biology and Comparative Physiology
of the Birds”, Vol. 11, contains much information on energetics. The
chapter on energy metabolism, thermo-regulation, and body temperature contains information on calorimetry, met.a,bolic rates, energy metabolism and the variation in energy metabolism. The chapters on flight,
long distance orientation, behavior, and bird populations also contain
information which is potentially useful in making field energy estimates.
The study undertaken by West (1960) on the tree sparrow, Spizella
arborea, met all but one of the requirements of a complete field productivity study; field data are lacking on numbers of individuals. West’s
primary concerns were: (1) the number of calories necessary to support
the birds in their environment; (2) the caloric burden of migration and
incubation. Food consumed and excrement produced (West used this
term to mean egestion plus excretion) by the ;birds was measured both
in the laboratory and in outdoor cages at Churchill, Manitoba, Canada
(the birds’ breeding range) and a t Urbana, Illinois, U.S.A. (the wintering range). Values averaged around 4.4 kg cal f m the food and 3.7 kg cal
for the feces. The energy consumption of the birds varied with the
ambient temperature from 34-23 kcal/bird/day (1 -64 kcal/g/day) at
-30” C to 10.77 kcal/bird/day (0.49 kcal/g/day) at 30” C. Day length
also caused variation in calorie requirements rmd caloric consumption.
From these and other data West constructed a series of equations and
a graph for the annual energy budget of an adult bird. The equation
which related grow energy intake of the bird to temperature was
GE = 25.89 kcal/bird/day-0.254 To C. The equation which represented
metabolizable energy with relationship to temperature was M E = $9.05
kcal/bird/day-0-167 To C. Each bird required roughly 7 460 kg cal each
year to live, migrate and reproduce in the wild. West had no figures on
the area necessary to provide these calories and, thus, no productivity
figures per unit area for the population were given.
The last paper of a primarily physiological nature I wish to discuss
is that of Pearson (1960) which has many elements of the Bornebusch
approach although emphasizing the homeostatic mechanisms of the
harvest mice. Pearson considered oxygen consumption and its relationD