Volume 22 • Issue 03 • 2018
Age Related External Characteristics – Bovine Fetus.
Age days
18
24
26
30
38
40
50
56
Age months
1
60 2
110 4
76
100
150
196
230
278-290
3
5
6
8
9
External characteristics
Primitive streak present, amnion complete
3 primary brain vesicles + forelimb bud
4th brachial arch, mammary ridge + hind limb bud
Eye pits, eyes pigmented + hard palate
Eyelids forming, ear forming.
Ear partly covers acoustic groove
Eyelids partially cover eyes
Palate fused
Eyelids fused, external genitalia, hooves
Tactile hairs appear on face
Hooves become firm and opaque
Tooth eruption begins
Lower lip and chin covered fine hair, eyelashes present, tactile hairs on
chin, colour m arkings appear, hooves become hard, teats well formed,
descent of testes complete.
Eyelids separated
Body fully covered with hair
Birth
Age Related External Characteristics – Small Ruminant Fetus.
Age days
21-30
35-42
49-63
70-91
98-126
133-147
Age months
1
2
3
4
5
External Characteristics
Head, body and limbs discernable
Hoofs are visible at end of digits
No hair, rumen development near the end of this period
Large tactile hairs appear on lips and upper eyelids
Eyelashes are well developed, some hair on tail and head
Fetus becomes fully developed with the body covered with hair;
hooves complete but soft
In-utero growth retardation (IUGR) reduces
neonatal survival, has a permanent stunting
effect on postnatal growth and efficacy of feed
conversion, negatively affects body composition
and meat quality and impairs long term health
including fertility. Therefore, it is well worth your
while to critically examine fetuses for evidence
of in-utero growth retardation so that remedial
action can be implemented as soon as possible.
Fetal growth is influenced by genetic, epigenetic
(alterations of gene expression), environmental
factors, nutritional factors and maternal
maturity. These factors impact on placental
efficiency, uteroplacental blood flow, transfer
of nutrients and oxygen to the fetus, nutrient
availability to the conceptus, fetal endocrine
milieu and metabolic pathways. Alterations in
fetal nutrition and endocrine status may result
in developmental adaptions that permanently
change the structure, physiology, metabolism
and postnatal growth of the offspring. There is
growing evidence that maternal nutritional status
can alter the epigenetic state of the fetus resulting
in alterations of gene expression impacting on
growth, reproduction and immune function.
Causes of intra-uterine growth retardation
include maternal malnutrition (protein and
energy in the last trimester), micronutrient
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