Genetic and environmental factors influence gestation period and birth weight. Genetic factors like species, breed, size of the species, and fetal genotype can impact gestation length. Larger species and exotic breeds tend to have longer gestations. Environmental influences include habitat, nutrition, and season of conception. Well-fed animals and those conceiving in favorable seasons may have slightly shorter gestations. Maternal traits such as age, parity, and body weight can also affect gestation length, with older, multiparous dams carrying young slightly longer. Fetal characteristics like maturity, litter size, and sex may impact gestation as well.

1. FACTORS INFLUENCING
GESTATION PERIOD AND
BIRTH WEIGHT
ROSHNI RAVINDRANATH
21-MVP-29

3. GESTATION/ INCUBATION
Time between conception and birth, embryo or foetus
develop in the uterus
Period of I/U development of an organism
Interval between fertile mating to parturition

4. Gestation: 3 Phases
PERIOD OF
BLASTULA
PERIOD OF EMBRYO
PERIOD OF FOETUS

6. FACTORS INFLUENCING GESTATION
LENGTH
GENETIC FACTORS
ENVIRONMENTAL FACTORS
MATERNAL FACTORS
FOETAL FACTORS

7. GENETIC FACTORS
Species
• Varies among different sps
Size of
species
• Larger the species –longer the GL
Foetal
genotype
• GL is average of sire & dam, inclined towards dam’s
Breed
• Greatest influence
• Exotic< Indigenous

8. Genetic Factors : Species
Equine > Bovine> Ovine> Porcine
Bos indicus> Bos taurus
Beef cattle> Dairy cattle
Buffaloes: Egyptian (315 d) > Indian & Pak(310 d)> Brazilian (280 d)
Swamp buffaloes (320-340) > Riverine buffaloes(305-320d)

10. German Shepherd Dogs had shorter gestation
durations when compared to Boxers, Bernese
Mountain dogs, Old English Sheep Dogs, and
Bouvier des Flandres
West Highland White Terriers had longer
gestation durations than German
Shepherd Dogs, Labrador Retrievers, and
Dobermans

11. CATTLE BREED GL in HEIFERS GL in PAROUS
ANIMALS
DIFFERENCE
Holstein 277.8 279.4 1.6 d
Jersey 2778.4 280.0 1.6 d
Milking Shorthorn 279.3 281.1 1.8 d
Ayrshire 281.6 281.7 0.1 d
Guernsey 284.8 285.5 0.3 d
Brown swiss 287.2 287.5 0.3 d
Nelore & Gir 292
Afrikander 295
Norman et al., 2009 Genetic and environmental Factors That Affect Gestation Length in Dairy
Cattle. J Dairy Sci, 92(5) 2259-69

12. Influence of foetal genotype on GL
JERSEY SEMEN  GIR DAM
(GL=280 Days) (GL=292 Days)
286 Days

13. King et al. (1985) demonstrated with embryo transfer
pregnancies that calf breed is more influential than recipient
breed in determining GL
JERSEY EMBRYO  GIR RECIPIENT
(GL=280 Days) (GL= 292 Days)
GL= 280 Days

14. Influence of fetal genotype on GL
◦ Strain difference in mean GL has noted within breed based on the %
of Holstein-Friesian versus Dutch Friesian genes
◦ When hybrids are produced by crossing two species with different GP,
the hybrid is carried for a period lying somewhere between those of
the two parents and towards the mother species
◦ A mare (GL=337 D) carries a mule foal ( fathered by a Jackass; GL=
365) about 10 days longer
◦ River * Swamp buffalo hybrids have an intermediate gestation length
of 315 days

15. Size of the species
SMALLER THE ANIMAL SPECIES ; SHORTER THE GESTATION LENGTH
◦ It takes a longer time for a big animal such as elephant grow its calf than for a
smaller animal such as mouse
◦ Mice (20 Days) < Rabbits (31 Days)
◦ Rhesus monkeys (164 Days ) < Baboons( 187 Days)
◦ Exception- Guinea pig
GL=22D GL=31 D GL=63 D
GL=68 D

16. ENVIRONMENTAL FACTORS
HABITAT
• Open terrestrial>
Trogloxenes &
Fossorials
NUTRITION
• Well fed<
Maintenance ration
SEASON OF
CONCEPTION
AND BIRTH

17. ENVIRONMENTAL FACTORS
HABITAT
GL in Open Terrestrial Animals > Tragloxenes & Fassorials
◦ Animals that dwells in the open tend to have longer gestation & to bear young
that have reached a state of greater maturity that do animals that can conceal their
young in underground burrows/ in caves

18. NUTRITION
GL in Well fed dam < Maintenance ration
◦ Well-fed mares have GL about 4 days shorter than those on
maintenance ration

19. Season of Conception and Birth
◦ In many species with restricted breeding season, gestation is adjusted so that birth coincides
with the period when food is abundant
◦ In horse, a spring breeder with 11 m gestation has it’s young the following spring
◦ For HF Cows GL was 2 d shorter for Oct conception than for Jan & Feb conceptions
◦ Summer conception produced longer gestation than did winter conception in Rhesus
monkeys
◦ The month of birth is significant
◦ High temperature in the summer speed up calving and shorten GL
◦ Favorable weather conditions affect the nutritional value of grassland, mare can have larger
nutritional intake and foal takes less time to reach proper wt for birth

20. MATERNAL FACTORS
• Young<Older
Age
• Heifers<Parous
Parity of dam
• As body wt increases-GL
Increases
Body weight of
dam

21. MATERNAL FACTORS
Age of dam
GL in Young Dams < Older Dams
•Older cows carried calves longer (< 1 d ) than did younger
cows
•The age of breeding has a significant effect on gestation
duration

22. FOETAL FACTORS
Fetal maturity at birth
Litter size(as size increases the G.L decreases
Sex of foetus
Fetal size and weight

24. SINGLETON PUPPY SYNDROME

25. Accurate prediction of a bitch’s gestation duration is
useful when managing whelping or scheduling an
elective cesarean section

26. ◦ Litters of four or less were likely to have a longer gestation duration
◦ Compared to Labrador Retrievers, German Shepherd Dogs, Golden Retrievers
and hounds were more likely to have a longer gestation duration

27. THANK YOU
BREED
LITTER SIZE
SEX
ENVIRONMENT
Nutrition