ANSC 3040 FINAL REVIEW QUESTIONS AND CORRECT
ANSWERS
Largest cost in Dairy Heifer Production? - Answers - Nutrition/Feeding
2nd Largest Cost in Dairy Heifer Production? - Answers - Replacement Heifers
When is Timed AI good? - Answers - When estrous detection is less than 70% because
timed AI does not require ED
When do we want puberty in dairy heifers? - Answers - 9-10 months of age/260-280 kg,
feeding and body weight are important factors for onset of puberty
When do we want 1st AI? - Answers - 3rd estrous
When do we want pregnancy? - Answers - 13-15 months (350-380 kg)
When do we want calving? - Answers - 22-24 months (600-640 kg pre calving weight)
What data should be monitored? - Answers - BCS, weight, activity level
How should we collect data? - Answers - either snapshot method where measure
groups at different stages (less accurate) or longitudinal where measure group of
heifers every day (accurate)
Which is worse over-feeding or under-feeding before puberty? - Answers - Both are
bad, overfeeding results in poor performance and underfeeding results in delayed
puberty/anestrous
Optimal ED rate? - Answers - more than 70%
Goal of Beef Cattle Production - Answers - Maximize quality and quantity of calves
What are the early embryonic development steps that are conserved? - Answers - 1.
Ootid 2. syngamy -> zygote 3. early blastocyst (2, 4, 8 cell) 4. Morula (can't cells
anymore) 5. ICM and trophectoderm differentiation 6. Hatching 7. Hatched
What happens at the early blastocyst stage? - Answers - Activation of embryonic
genome and regression of maternal genome (8 or 16 cell in cows, 4 cell in humans and
pigs, 2 cell in mice)
How does an embryo hatch? - Answers - enzymes from inside blastocyst are activated
to degrade, cell grows quickly, fluid accumulates inside which increases pressure and
eventually zona pellucida breaks
, True or False preimplantation occurs in all species? - Answers - False: not in humans,
primates, rodents
What occurs during preimplantation? - Answers - conceptus elongates rapidly,
becoming a filament (except not in mares; it remains spherical)
What's the difference between hemotroph and histotroph? - Answers - histotroph
supplies nutrients to embryo prior to implantation in uterus (uterine milk)
hemotroph supplies nutrients to embryo after implantation through blood supply
Maternal recognition of pregnancy in cows... - Answers - ... is known by secretion of
INFT (interferon tal) which blocks oxytocin receptors preventing PGF2a from being
secreted and causing luteolysis
Maternal recognition of pregnancy in sows... - Answers - ... is known by estrogen
rerouting PGF2a into the lumen for degradation instead of to its receptors
it also requires 2 pregnancies per horn for this to work
Maternal recognition of pregnancy in mares... - Answers - ...is recognized by the
movement of the embryo around the uterus. The spherical embryo is covered in a
glycoprotein "shell" and secretes prostaglandins to induce myometrial contractions for 7
days until the conceptus fixes into the uterus
Maternal recognition in bitches and queens... - Answers - ... is not required because of
their anestrus periods
What are the phases of the embryonic development period? - Answers - 1. morulation
2. blastulation(totipotent to pluripotent, formation of blastocyst) 3. gastrulation(
mesoderm, ectoderm and endoderm/hypoblast) 4. organogenesis (from neural tube)
What are the phases of the fetal period? - Answers - 1. growth 2. maturation 3.
remodelling of organs 4. parturition
True or False: Fetal growth (length and weight) is linear - Answers - False: only length is
linear, weight is exponential and birth weight depends on many factors
Factors that affect fetal weight at birth - Answers - genetics, type of embryo, gestation
length, maternal BCS/weight, nutrition, health, temperature, twins/littersize
How can we classify placenta? - Answers - by chorionic villi and by level of invasiveness
to the maternal endometrial epithelium
Types of placenta - Answers - diffuse, discoid, zonary, cotyledonary (convex and
concave), epitheliochorial, synepthiliochorial, endotheliochorial, hemochorial
ANSWERS
Largest cost in Dairy Heifer Production? - Answers - Nutrition/Feeding
2nd Largest Cost in Dairy Heifer Production? - Answers - Replacement Heifers
When is Timed AI good? - Answers - When estrous detection is less than 70% because
timed AI does not require ED
When do we want puberty in dairy heifers? - Answers - 9-10 months of age/260-280 kg,
feeding and body weight are important factors for onset of puberty
When do we want 1st AI? - Answers - 3rd estrous
When do we want pregnancy? - Answers - 13-15 months (350-380 kg)
When do we want calving? - Answers - 22-24 months (600-640 kg pre calving weight)
What data should be monitored? - Answers - BCS, weight, activity level
How should we collect data? - Answers - either snapshot method where measure
groups at different stages (less accurate) or longitudinal where measure group of
heifers every day (accurate)
Which is worse over-feeding or under-feeding before puberty? - Answers - Both are
bad, overfeeding results in poor performance and underfeeding results in delayed
puberty/anestrous
Optimal ED rate? - Answers - more than 70%
Goal of Beef Cattle Production - Answers - Maximize quality and quantity of calves
What are the early embryonic development steps that are conserved? - Answers - 1.
Ootid 2. syngamy -> zygote 3. early blastocyst (2, 4, 8 cell) 4. Morula (can't cells
anymore) 5. ICM and trophectoderm differentiation 6. Hatching 7. Hatched
What happens at the early blastocyst stage? - Answers - Activation of embryonic
genome and regression of maternal genome (8 or 16 cell in cows, 4 cell in humans and
pigs, 2 cell in mice)
How does an embryo hatch? - Answers - enzymes from inside blastocyst are activated
to degrade, cell grows quickly, fluid accumulates inside which increases pressure and
eventually zona pellucida breaks
, True or False preimplantation occurs in all species? - Answers - False: not in humans,
primates, rodents
What occurs during preimplantation? - Answers - conceptus elongates rapidly,
becoming a filament (except not in mares; it remains spherical)
What's the difference between hemotroph and histotroph? - Answers - histotroph
supplies nutrients to embryo prior to implantation in uterus (uterine milk)
hemotroph supplies nutrients to embryo after implantation through blood supply
Maternal recognition of pregnancy in cows... - Answers - ... is known by secretion of
INFT (interferon tal) which blocks oxytocin receptors preventing PGF2a from being
secreted and causing luteolysis
Maternal recognition of pregnancy in sows... - Answers - ... is known by estrogen
rerouting PGF2a into the lumen for degradation instead of to its receptors
it also requires 2 pregnancies per horn for this to work
Maternal recognition of pregnancy in mares... - Answers - ...is recognized by the
movement of the embryo around the uterus. The spherical embryo is covered in a
glycoprotein "shell" and secretes prostaglandins to induce myometrial contractions for 7
days until the conceptus fixes into the uterus
Maternal recognition in bitches and queens... - Answers - ... is not required because of
their anestrus periods
What are the phases of the embryonic development period? - Answers - 1. morulation
2. blastulation(totipotent to pluripotent, formation of blastocyst) 3. gastrulation(
mesoderm, ectoderm and endoderm/hypoblast) 4. organogenesis (from neural tube)
What are the phases of the fetal period? - Answers - 1. growth 2. maturation 3.
remodelling of organs 4. parturition
True or False: Fetal growth (length and weight) is linear - Answers - False: only length is
linear, weight is exponential and birth weight depends on many factors
Factors that affect fetal weight at birth - Answers - genetics, type of embryo, gestation
length, maternal BCS/weight, nutrition, health, temperature, twins/littersize
How can we classify placenta? - Answers - by chorionic villi and by level of invasiveness
to the maternal endometrial epithelium
Types of placenta - Answers - diffuse, discoid, zonary, cotyledonary (convex and
concave), epitheliochorial, synepthiliochorial, endotheliochorial, hemochorial
