Bioenergetics of growth, pregnancy and lactation in the laboratory mouse, Mus musculus

1. 1. Multiple regression models for reproductivity active (RA) female mice show bioenergetic parameters to be functions of total live weight of the reproducing unit and reproductive day but not related to litter size or daily weight gain.2. 2. For growing, non-reproductively active (NRA) females, bioenergetic parameters are linear functions of live weight.3. 3. Weight specific daily energy budgets are constant for RA and NRA females.4. 4. Productivity of RA females exceeds that of NRA mice reaching a peak at 10% at the end of lactation.5. 5. Weight specific average daily metabolic rate of pregnant females is lower than that of NRA mice.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/23738/1/0000710.pd

Energetic advantages of slight drops in body temperature in little brown bats, Myotis lucifugus

1. 1. At constant ambient temperatures (Ta) below their thermal neutral zone (TNZ), little brown bats, Myotis lucifugus, maintain a wide range of steady-state body temperatures (Tb).2. 2. The relationship between oxygen consumption and Tb-Tb differential at constant Tbs below the TNZ is curvilinear.3. 3. Small drops in Tb from high Tb levels result in significantly greater energy savings than subsequent Tb reductions of equal increments.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/24566/1/0000848.pd

Differential in rectal and chest muscle temperature during arousal in Eptesicus fuscus and Myotis sodalis (Chiroptera: Vespertilionidae)

1. 1. Chest muscle warms slightly faster than rectal temperature (Tr) during arousal in Eptesicus fuscus and Myotis sodalis.2. 2. Chest muscle temperature (Tc) to Tc differential rises slightly more rapidly in M. sodalis than in E. fuscus.3. 3. Tc mean minimum Tr required for flight in M. sodalis is 23-8[deg]C, while Tc at mean minimum Tr required for flight in E. fuscus is 30-1[deg]C.4. 4. During arousal in both species, differential warming occurs both anterior and posterior to the diaphragm as well as between the deep chest area and the adjacent flight muscles.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/22422/1/0000872.pd

Live mass, water content, nitrogen and mineral levels in some insects from south-central lower michigan

1. 1. Live and dry mass, water content, nitrogen, sodium, potassium, magnesium, calcium and total iron concentrations are reported (or are available from the authors or the Faculty/Staff Collection of The University of Michigan-Flint Library) for members of 16 orders (360 species) of mostly adult, flying insects from south-central lower Michigan.2. 2. Compared to published nutritional requirements (when meeting caloric requirements) for growth and reproduction in birds and mammals, insects are excellent sources of nitrogen, potassium and magnesium, highly variable sources of sodium and iron, and, very rarely, adequate calcium sources.3. 3. Elemental composition of some insects differs by size, sex, season and after culling.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/29762/1/0000100.pd

Concentration and composition of natural urine of some michigan small mammals

Analysis of bladder urine of small mammals collected during the summer in Michigan shows that: 1. 1. Snap-trapping rodents and insectivores can be an effective technique for collecting natural urine.2. 2. Individuals not immediately killed by the trap produce abnormally concentrated urine.3. 3. Natural urine is very dilute compared to maximum concentrating abilities of the species tested.4. 4. Brief periods of captivity (Eptesicus fuscus.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/23382/1/0000327.pd

Natural urine concentrations and composition in neotropical bats

1. 1. Among neotropical bats with subdivided renal medullae, some natural urine samples are equal in concentration to mean maximum calculated levels.2. 2. Natural urine osmotic pressures in frugivorous phyllostomids are less than in other phyllostomids which, in turn, are less than in insectivorous bats.3. 3. Urinary sodium (Na+) concentrations show no difference between frugivorous. insectivorous, and others, but urinary potassium (K+) levels in frugivores are higher than in other bats.4. 4. Natural urine concentrations are primarily related to diet and secondarily to environmental dehydration pressure.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/25423/1/0000872.pd

Effects of captivity on thermoregulation and metabolism in Artibeus jamaicensis (chiroptera: phyllostomatidae)

1. 1. In the Jamaican fig-eating bat, Artibeus jamaicensis, oxygen consumption (OC in cm3/g per hr) and deep body temperature (Tb in [deg]C) are significantly related to ambient temperature (Ta in [deg]C) and length of time in captivity, but not to the direction (low to high or high to low) of Ta change.2. 2. OC and Tb levels as functions of Ta rapidly change from those characteristic of a non-homeothermic endotherm on the day of capture to values characteristic of a homeothermic endotherm within 3-6 days in captivity.3. 3. Jamaican fig-eating bats examined within 12 hr of capture were physiologically distinct from individuals of this species kept briefly (3 days) in captivity.4. 4. Bats tested within 12 hr of capture at Tas of 30 and 25[deg]C required 1/3 and 2/3 less metabolic energy, respectively, than bats maintained briefly in captivity.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/23721/1/0000693.pd

Thermal sensitivity and activation energy of intrinsic intestinal motility in small vertebrates

1. 1.|In vitro thermal sensitivity (t.s.) of mammalian small intestine is significantly greater than t.s. of the gut of ectothermic vertebrates. In vitro contraction frequency (c.f.) of endothermic gut is an order of magnitude greater than ectothermic gut at equivalent temperatures.2. 2.|Gut contraction t.s. is generally consistent within a given order of mammals and differs between orders. Differences in gut contraction t.s. found in the ectothermic vertebrates do not relate to taxonomic grouping.3. 3.|An inverse relationship exists between gut c.f. and body weight in ectotherms and also probably in mammals. This relationship is seen within an individual species rather than among species.4. 4.|Secondary intrinsic contractions occur regularly in gut of ectotherms and much less frequently in mammalian gut. In ectothermic vertebrates, these thermally sensitive gut contractions are often at higher frequency than major contractions at high gut temperatures but cease at the same minimum temperatures.5. 5.|Unlike all other species tested, fish (bullheads, I. nebulosus) gut contractions were not rhythmic although they were thermally sensitive.6. 6.|Activation energies for thermally sensitive gut contractions in mammals are consistent with most values rangign from 14.5-18.5 Kcal/M while activation energies for secondary contractions were much more variable with a range of 4.4-29.0 Kcal/M.7. 7.|In laboratory mice, c.f. and c. amplitude are unaffected by pH in any biologically significant manner. Additionally, t.s. of neonatal (4-24 days old) lab mice are indicative of endotherms and are only slightly lower than adult levels 4 days after birth.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/22943/1/0000510.pd

Nutritional implications for nitrogen and mineral budgets from analysis of guano of the big brown bat Eptesicus fuscus (chiroptera: vespertilionidae)

1. 1. Analysis of nitrogen, sodium, calcium, magnesium, iron, and potassium levels in big brown bat guano throughout much of the summer roosting period was performed.2. 2. Based on the tenet that low, non-variable levels of an element in feces indicate dietary inadequacy for that element, female big brown bats are routinely and severely stressed for calcium and may become stressed for iron by the end of the summer. Similar elemental stresses, although not as severe, exist for males.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/29657/1/0000746.pd

Proximate, caloric, nitrogen and mineral composition of bodies of some tropical bats

Proximate (live mass, water, lipid, ash, non-fat organic), caloric, nitrogen, and mineral (sodium, potassium, calcium, magnesium, and iron) concentrations and total body content of individuals of 24 species of Neotropical and Paleotropical bats were determined. Mass-related, concentration patterns were found for all measured variables, except iron. Concentrations increase with size for nitrogen, calcium, and magnesium but are concave, opening upward, for sodium and potassium. These last two elements reach minimal concentrations in bats weighing about 22 and 28 g dry mass, respectively. Total body content of nitrogen and minerals was compared with amounts in similar-sized birds and tetrapodal mammals.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/31225/1/0000127.pd