Comparative Physiology of Emu and Ostrich

Emu

• Recognized as Agricultural commodity in Australia in 1987
• Scientific knowledge about emu is fragmented
• Significant homology with chicken (88%) for gender determining gene DMRT1
• Distribute large quantities of seeds

Phenotype of emu

• Females weigh 55kg; height 1.8m
• Males weigh 38kg; height 1.5m
• Runs at a speed of 50km /h
• Vertebrae -54 (ostrich -56)
• Foot – emu – 3 digits; ostrich 2 digits
• No crop and no oil gland in emu

Physiological characters

• BMR 61-79%
• Metabolic rate differs between males and females (2.53 vs 3.08ml oxygen/kg/min)
• Respiratory rate -7.1/mon
• Heart rate -41/min
• BP -149/116
• Temperature – males -37.7ºC; females 38ºC

Phy contd…

• Not susceptible to respiratory alkalosis even after R/rate increased to 52/min
• Limited ability to concentrate urine
• considerable water absorption - Cloaca + rectum
• Maintains homeothermy (-5 to 45ºC)
• Low oxygen demand for its size

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Nutrition

• High fiber digestibility (35-45%)
• Passage rate 5.5h – may aid in digestibility
• Emu requires 16-17% CP with 2700kCal
• Emu layers require 20-21% CP with 2850kCal
• Certain feed additives safe to poultry may be toxic to emu eg., furazolidone and monensin
• Poultry feed cannot be used to emu because of high mineral content

Reproductive behavior

• Assumed to be monogamy
• Recent research indicates sequential polyandry, promiscuity
• Significant extra-pair copulations
• Analysis showed 51% of chicks hatched are not fathered by incubating male
• Males incubating as soon as 5-10 eggs are laid for 56 days

Reprod contd..

• Female lay fertile eggs after 6-24 days of mating
• Sperm survives in female reprod. tract for 21 days
• Mean of 25 eggs/female/season with a span of 84 days
• Clutch size of 6.7 from Apr to Sep

Semen collection

• Semen collected-by two methods
• Method -1; using artificial cloaca. By massage and using a teaser
• Method -2; trained to develop sexual character towards semen collector and allowed to mount on semen collector’s back
• Semen vol. varies from 0.6 to 5ml depending on the frequency of collection

Eggs�

• Egg wt 450-630g
• Less vapor conductance 51.8mg/d/torr might be an adaptation to arid ; semiarid
• Green colour of eggs- methyl ester of biliverdin IX alpha
• Egg pores- vent into plexus before opening
• Special matrix proteins are present

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Eggs contd..

• Egg weight loss during incubation was 10% as against 15% for all other sp, irrespective of incubation period and initial egg weight
• Emu chicks are precocious and become ambulatory after 2 days

Emu oil and meat

• Emu oil believed to have cosmetic value
• Better skin penetration ability ; moisturizing characters
• Hypolipidemic in consumers compared to coconut oil
• Less atherogenic
• Anti-arthritic
• Considerable variation of oil beneficial effects
• Emu meat – low pH; more flavor, juicier

Ostrich

• Largest living bird 2.75m – upto 150kg bwt
• Valued for feathers and meat
• Seasonal breeder
• Ostriches are very resitant to high level of salt
• Not suitable for mixed farming

Anatomy�

• Lack uropygeal gland
• Clavicle absent
• Cerebral hemispheres lack sulci and gyri
• Colon/ rectum 16m long
• No gall bladder

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Physiological characters

• Frugal water economy
• H/R -80/min in young; adults

30-60/min

• Ostrich regulate body temp better than emus
• R/R fall in two category

4-5 beats/min and 40-60 beats/min

• Birds use costal pump for respiration
• Water intake may be 3.5 to 7 l / day

Time- activity budget

• Spend 43% of daylight hrs for walking, fighting and running (sheep 18%)
• Eating and drinking 19%
• Ostrich are inactive during darkness
• In chicks (time %), feeding from floor 27%, walking 23%, pecking 10%, feeding from tray 3.5%

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Nutrition

• Selective grazer
• Select plants low in Ca and oxalate
• Avoids high sodium plant (>9%)
• Trahelase absent
• pH of GIT is similar to mammals
• Passage rate – similar to ruminants
• VFA – major source of energy
• Silage- tremendous potential for ostrich industry
• Cellulose- digestibility 66%; hemicellu- 40%

Feeding program

• Day old -2 mon pre-starter

20.5 -22% CP

• 2-4 mon - 18-20% CP
• 4-6 mon - grower 15.5-17% CP
• 6-10 mon- Finisher 13-14% CP
• 10-14 mon- Post-finisher 10-12% CP
• Typical feeding schedule followed in South Africa

Semen Collection

• Manual method
• Massage uroduem after removing phallus from cloaca
• Inj of oxytocin via basilic vein 2-4 min priot to collection – better yeild
• In excitable males- 2^nd inj is required
• Oxytocin inj- better ejaculate and volume
• AI limited information is available

Female reproduction

• 1-8 cm in dia
• 20-30 ova matures in a breeding cycle
• puberty at 2 years
• Mucosa of uterus and vagina is darker in appearance
• Sperm host glands are present
• Reproductive quiescence for 3-4 weeks in a cycle

Nest scrapes�

• Territorial males dig no. of nests which he shows to any female enters his territory
• Major female lays eggs (10 eggs)
• Minor females also lay eggs
• Major female selectively eliminates minor female eggs
• Eggs are laid in the late afternoon
• Incubation does not proceed until clutch is complete

Egg production

• Unusual egg size ave. wt. 1545g (range 1-2kg)
• Largest egg laid by a bird, yet smallest for body weight
• Egg production 50±20 eggs / 120 days breeding season
• EPP- South Africa 40-50%; Israel 54%; Australia 50% ; UK 25%

Fatty acids composition of eggs

Fatty acids composition (%)

Conclusions

• Emu industry has been characterised as Breeder Phase- results in high price
• Cannot compete beef and poultry industry – no return on investment / investor may not show interest
• Hatchability, fertility, performance in captivity needs investigation
• Similarly, ostrich industry is still in infant stage

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