ANFS 350: Biological Rhythms

Sense of Time Dogs

will wait for owners at certain times

Sense of Time Sows

know length of time being crated

Sense of Time Chimps

display understanding of delayed gratification

Sense of Time Zoos

big cats and elephants pace at mealtimes

Biological Rhythym

cyclic change in behavior or physiological process at a regular rate

Types of Biological Rhythyms

exogenous, endogenous

Exogenous Rhythym

depends on external stimuli to persist regularly

Endogenous Rhythym

independent of external stimuli, rely on internal clock mechanism

Internal Clock

self regulating and self sustaining neural signals that occur at regular intervals

Frequencies of Biological Rhythyms

high frequency, ultradian, circadian, diurnal, infradian, annual

High Frequency Rhythm

cycles of 30 minutes or less

High Frequency Rhythm Examples

heart rate, respiratory rate

Ultradian Rhythm

cycles between 30 minutes to under 24 hours

Ultradian Rhythm Examples

growth hormone, feeding

Growth Hormone Rhythm

produced by the pituitary gland in cattle every 3.5 hours, ultradian

Feeding Rhythm

every 2-3 hours when free fed in dogs, cats, sheep, horses, pigs, cattle, ultradian

Circadian/Diurnal Rhythm

every 24 hours

Infradian Rhythm

cycles less often than 24 hours but more than a year

Infradian Rhythm Examples

estrous cycles

Estrous Cycle Rhythms

cow and sow every 21 days, mares every 17-24 days, ewes every 16-17 days, infradian

Annual Rhythm

cycle every year

Annual Rhythm Examples

seasonal breeders, zugunruhe

Seasonal Breeder Rhythms

horses are long day breeders, sheep/goats are short day breeders, annual

Zugunruhe Rhythm

anxious behavior that migratory animal exhibit when unable to migrate, annual

Zugunruhe Behaviors

increased activity at dusk/dark, change in sleep patterns

Circadian Rhythm

every 24 hours using internal clock mechanism

Zeitgeber

time giver for the circadian rhythm, entrainment of a behavior

Circadian Rhythm Examples

sleep/wake cycle, hormone secretion, body temperature

Hormone Secretion Rhythm

cortisol peaks early in the day, circadian

Body Temperature Rhythm

body temperature peaks in the afternoon and is lowest in the morning, circadian

Properties of Circadian Rhythms

24 hours period, endogenous, persist in constant conditions, can reset or entrain to an environmental factor

Most Studied Internal Clock Mechanism

superchiasmatic nucleus

Superchiasmatic Nucleus

cluster of paired nuclei above optic chiasm, cells in the nuclei work together to create 24 hour rhythm

Diurnal Rhythm

cycle of 24 hours, relies on external cues

Diurnal Rhythm Examples

foraging and hunting, stereotypies, perching

Foraging and Hunting Rhythm

changes based on temperature and prey, diurnal

Sow Stereotypic Rhythm

bar biting peaks 2 hours after feeding, diurnal

Perching Rhythm

in poultry, depends on photoperiod and timing of darkness, diurnal

Reason To Sleep

replenish neurotransmitters, conserve energy, consolidate memory, fill time

Levels of Alertness

alert wakefulness, drowsiness, quiet sleep, active sleep

Measuring Alertness

EEG, electroencephalogram

Alert Wakefulness

eyes fully open, responsive

Alert Wakefulness EEG

low voltage, fast activity (1)

Drowsiness

relaxed upper eyelids, high arousal threshold, reduced alertness

Drowsiness EEG

combination of low voltage, high activity, and high voltage, low activity

Quiet Sleep

eyes closed or nearly closed, high arousal threshold

Quiet Sleep EEG

high voltage, slow activity

Active Sleep

eyes fully closed, rapid eye movement

Active Sleep EEG

low voltage, fast activity (2)

Paradoxical Sleep

active sleep, EEG is like alert wakefulness but animal is clearly asleep

Dog Sleep Schedule

50% sleeping, 20% REM, depends on housing and schedule

Cat Sleep Schedule

45-65%, 20% REM

Cattle Sleep Schedule

25%, lying down but rarely lateral

Horse Sleep Schedule

20%, 5 min REM while lateral, sleeps mainly standing

Pig Sleep Schedule

30%, many bouts of REM if stress free environment

Poultry Sleep Schedule

dependent on light cycle, resting with neutral head versus sleeping with tucked head