Elephants

elephant article key points

• once aquatic animals

• have mitochondria similar to manatees

• have intra-abdominal testes because of stress of cold water

• no pampiniform plexus that cools sperm but still able to maintain temp of 94-97 F

• no epididymis - primary site of sperm storage is ampulla

elephant basic info

• herd species

• communicate with complex vocalizations

  • infrasound

  • chemical signaling via hormones, proteins and volatile compounds released in urine, feces, breath and secretion from the temporal gland

elephant behavior

• matriarchial

• young cows remain with birth group before eventually separating to make their own family

• young bulls at puberty leave group or are driven off

• up to 50% of elephants die before reaching 15y

elephant female reproductive tract

• bull stays near the cow to guard her from other males and occassionally mates with her with courtship lasting 1 hr to 4 days

• inter-partum interval averages 5 years

• the semen is deposited in the urogenital canal

• hymen is perforated only after the delivery of the first calf

elephant bulls exhibit the flehmen response

male uses trunk to bring urine to vomeronasal receptors in the mouth to determine if a female is receptive

elephant estrous cycle

• 14-16 weeks

• 4-6 week follicular phase when progesterone is low

• 8-10 week luteal phase when progesterone is high

elephant LH surge

• two surges of LH during follicular phase

• first LH surge is the anovulatory surge(no ovulation) and occurs roughly 2 weeks after progesterone drops

• When progesterone comes down have her first LH peak… she won’t ovulate just yet… 21 days after that she will have a second LH peak and THEN finally ovulate shortly after

• So you want to monitor for the FIRST LH peak and know that 21 days after that she will have a second and ovulate shortly after (warning system) - blood is collected daily into order to capture the first 24 hour rise in LH and this surge is used as a 3 week notification to prepare for artificial insemination during second LH surge

elephant male reproductive tract

• elephants testicles are intra-abdominal, no epididymis

• ampulla is the primary storage site for sperm

• only older and larger bulls mate

• Bulls are sexually mature between 10-15 years but become sexually active when >35 years of age

elephant bulls

• experience a period of heightened aggressive state called MUSTH – complex hormonal phenomenon

• Large amounts of thick discharge from temporal glands seen in both sexes - dark liquid tracts on sides of face

• During musth, a complex array of chemicals are released from breath, ruine and temporal glands

• Damp patches on hind legs from urine

• In males this signals an increase in testosterone

• Low frequency vocalizations to announce presence - “musth rumbles”

elephant gestation and parturition

• 22 months gestation

• Lactational anestrous is 20 months (this is the time a mother is lactating and therefore, she will not cycle)

• Entire herd cares for calves (not just mothers)

  • Are fully weaned only around 5-6 years causing the lactational anestrus (this is why there is such a long period between calves)

• Sexual maturity occurs between age 4-12 years ● Intercalf interval is 4-6 years

• Gestation is 21-24 months (average 659 days)

• 5a-reduced-pregnane is the primary progestogen in elephants (NOT progesterone)