Cow/Calf Final Exam UPDATED Exam
Questions and CORRECT Answers
What are the objectives in selecting replacement heifers? - CORRECT ANSWER - In
heifer selection, you want to identify heifers that will conceive early in the breeding season
(meaning they should reach puberty earlier), calve easily, give a flow of milk consistent with the
environment, wean an acceptable calf, and make positive contribution to the calves postweaning
growth and carcass traits.
We can tell by looking at a heifer if she will be fertile - T/F - CORRECT ANSWER - False
How do I calculate adjusted 205 day weight? - CORRECT ANSWER - (WW-BW/Age) x
(205d+BW+AoD Adj.)
Should I use adjusted 205 day weight to select replacement heifers? Why? - CORRECT
ANSWER - No, favors younger heifers that reach puberty later
What is the simple way to select my heifers if I don't have a set of scales? - CORRECT
ANSWER - Choose the oldest, visibly larger heifers
In the lab exercise on selecting replacement heifers, why did we cull the Angus and Brahman
heifers out first? - CORRECT ANSWER -
What two factors are most important in selecting heifers? - CORRECT ANSWER - Age
and weight
Heifers should reach puberty 1-3 months before being bred - T/F - CORRECT ANSWER -
True. The first pubertal estrus is less fertile, so having at least one cycle before the breeding
season is ideal (although 2 cycles is ideal).
,It is not really important when a heifer conceives in the breeding season as long as she does - T/F
- CORRECT ANSWER - False, heifers that become pregnant early in the breeding season
have a higher lifetime production potential
What are major factors affecting puberty? (list the top 4) - CORRECT ANSWER - Breed,
age, weight, and BCS are the top 4 factors affecting puberty in beef heifers.
How does breed impact puberty? - CORRECT ANSWER - In general, dairy breeds are the
youngest at puberty, bos indicus are the oldest at puberty, heavy milking beef breeds are younger
at puberty. There are large variations within and between breeds.
Can we modify age at puberty by crossbreeding? - CORRECT ANSWER - Yes, crossbred
cows usually reach puberty earlier than their straightbred counterparts due to hybrid vigor
effects. The way to do this is crossbreeding with another breed that has a similar or younger age
at puberty.
Timing of gain in heifers is not as critical as making sure that heifers reach their target weight -
T/F - CORRECT ANSWER - True. There is currently no statistical difference in the timing
of gain in heifers, meaning they could gain consistently, gain slowly and then rapidly, or rapidly
and then slowly, and still reach the correct weight at puberty (all timing produces the same final
weight, age at first estrus, and pregnancy rate)
What is the target weight for heifers at breeding? Is this the average weight? - CORRECT
ANSWER - The target weight for heifers at breeding should be 65% of their mature
weight.
Why should heifers be sorted into management groups (if you have a large number of heifers)? -
CORRECT ANSWER - There are social effects between heavier and lighter heifers, such
as dominance/competition for food. Heifers should be sorted into heavy and light groups if you
have a large number of heifers to reduce competition, balance their ADG, increase weight, and
overall decrease age at puberty and increase pregnancy rate. (Pregnancy rates will increase by
about 20% in lighter heifers that are sorted into a different management group)
, Calculate the target weight for a set of heifers. - CORRECT ANSWER - Example: 1100 lb
mature wt x 65% = 715 lbs at the start of breeding. All heifers in the set should weigh at least the
715 lbs
Should I implant my heifers? Why? Should you implant all heifers or replacement heifers? When
should you implant them? - CORRECT ANSWER - If replacement heifers are identified at
an early age, don't implant
If replacements are not identified at an early age, implant all between 2 months and weaning
-Heifers not kept as replacements will be heavier
Exposing prepubertal heifers to a bull improves conception rates - T/F - CORRECT
ANSWER - False. The results of experiments are inconclusive and show no significant
improvement in pregnancy rates. It is also difficult to coordinate in an intensive management
scheme.
Should I use an ionophore in replacement heifer supplements? Why? - CORRECT
ANSWER - Yes, it can help them reach puberty earlier and increase conception rates
Compare and contrast the advantages and disadvantages of calving heifers first at two years of
age. - CORRECT ANSWER - Advantages: shorter interval to return investment, increased
lifetime production per cow, increased output per year on a herd or cow basis, fewer groups to
manage
Disadvantages: increased cost associated with early breeding (with more feed needed), increased
cost associated with calving difficulty, lower re-breeding rates for 2 year olds (often due to
shedding first pair of teeth and body adjusting to metabolic demands of lactation), difficult to do
with high Bos indicus percentages
What is a potential problem with calving replacement heifers 30 days prior to the mature cow
herd? - CORRECT ANSWER - -Less time to get them to their target weight, could
increase costs if you have to increase feed to push them to reach the target
-Also would push the biological window to breed younger (12 to 14 months versus 12 to 15
months)
Questions and CORRECT Answers
What are the objectives in selecting replacement heifers? - CORRECT ANSWER - In
heifer selection, you want to identify heifers that will conceive early in the breeding season
(meaning they should reach puberty earlier), calve easily, give a flow of milk consistent with the
environment, wean an acceptable calf, and make positive contribution to the calves postweaning
growth and carcass traits.
We can tell by looking at a heifer if she will be fertile - T/F - CORRECT ANSWER - False
How do I calculate adjusted 205 day weight? - CORRECT ANSWER - (WW-BW/Age) x
(205d+BW+AoD Adj.)
Should I use adjusted 205 day weight to select replacement heifers? Why? - CORRECT
ANSWER - No, favors younger heifers that reach puberty later
What is the simple way to select my heifers if I don't have a set of scales? - CORRECT
ANSWER - Choose the oldest, visibly larger heifers
In the lab exercise on selecting replacement heifers, why did we cull the Angus and Brahman
heifers out first? - CORRECT ANSWER -
What two factors are most important in selecting heifers? - CORRECT ANSWER - Age
and weight
Heifers should reach puberty 1-3 months before being bred - T/F - CORRECT ANSWER -
True. The first pubertal estrus is less fertile, so having at least one cycle before the breeding
season is ideal (although 2 cycles is ideal).
,It is not really important when a heifer conceives in the breeding season as long as she does - T/F
- CORRECT ANSWER - False, heifers that become pregnant early in the breeding season
have a higher lifetime production potential
What are major factors affecting puberty? (list the top 4) - CORRECT ANSWER - Breed,
age, weight, and BCS are the top 4 factors affecting puberty in beef heifers.
How does breed impact puberty? - CORRECT ANSWER - In general, dairy breeds are the
youngest at puberty, bos indicus are the oldest at puberty, heavy milking beef breeds are younger
at puberty. There are large variations within and between breeds.
Can we modify age at puberty by crossbreeding? - CORRECT ANSWER - Yes, crossbred
cows usually reach puberty earlier than their straightbred counterparts due to hybrid vigor
effects. The way to do this is crossbreeding with another breed that has a similar or younger age
at puberty.
Timing of gain in heifers is not as critical as making sure that heifers reach their target weight -
T/F - CORRECT ANSWER - True. There is currently no statistical difference in the timing
of gain in heifers, meaning they could gain consistently, gain slowly and then rapidly, or rapidly
and then slowly, and still reach the correct weight at puberty (all timing produces the same final
weight, age at first estrus, and pregnancy rate)
What is the target weight for heifers at breeding? Is this the average weight? - CORRECT
ANSWER - The target weight for heifers at breeding should be 65% of their mature
weight.
Why should heifers be sorted into management groups (if you have a large number of heifers)? -
CORRECT ANSWER - There are social effects between heavier and lighter heifers, such
as dominance/competition for food. Heifers should be sorted into heavy and light groups if you
have a large number of heifers to reduce competition, balance their ADG, increase weight, and
overall decrease age at puberty and increase pregnancy rate. (Pregnancy rates will increase by
about 20% in lighter heifers that are sorted into a different management group)
, Calculate the target weight for a set of heifers. - CORRECT ANSWER - Example: 1100 lb
mature wt x 65% = 715 lbs at the start of breeding. All heifers in the set should weigh at least the
715 lbs
Should I implant my heifers? Why? Should you implant all heifers or replacement heifers? When
should you implant them? - CORRECT ANSWER - If replacement heifers are identified at
an early age, don't implant
If replacements are not identified at an early age, implant all between 2 months and weaning
-Heifers not kept as replacements will be heavier
Exposing prepubertal heifers to a bull improves conception rates - T/F - CORRECT
ANSWER - False. The results of experiments are inconclusive and show no significant
improvement in pregnancy rates. It is also difficult to coordinate in an intensive management
scheme.
Should I use an ionophore in replacement heifer supplements? Why? - CORRECT
ANSWER - Yes, it can help them reach puberty earlier and increase conception rates
Compare and contrast the advantages and disadvantages of calving heifers first at two years of
age. - CORRECT ANSWER - Advantages: shorter interval to return investment, increased
lifetime production per cow, increased output per year on a herd or cow basis, fewer groups to
manage
Disadvantages: increased cost associated with early breeding (with more feed needed), increased
cost associated with calving difficulty, lower re-breeding rates for 2 year olds (often due to
shedding first pair of teeth and body adjusting to metabolic demands of lactation), difficult to do
with high Bos indicus percentages
What is a potential problem with calving replacement heifers 30 days prior to the mature cow
herd? - CORRECT ANSWER - -Less time to get them to their target weight, could
increase costs if you have to increase feed to push them to reach the target
-Also would push the biological window to breed younger (12 to 14 months versus 12 to 15
months)
