Cow-calf Final Exam Questions with correct Answers
What are the objectives in selecting replacement heifers? - 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 - Answer-False
How do I calculate adjusted 205 day weight? - Answer-(WW-BW/Age) x
(205d+BW+AoD Adj.)
Should I use adjusted 205 day weight to select replacement heifers? Why? - 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? - 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? - Answer-
What two factors are most important in selecting heifers? - Answer-Age and weight
Heifers should reach puberty 1-3 months before being bred - T/F - 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 - 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) - Answer-Breed, age, weight,
and BCS are the top 4 factors affecting puberty in beef heifers.
How does breed impact puberty? - 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? - 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 - 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? - 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)? - 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. - 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? - 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 - 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? - 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. - 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? - 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)
What is the ideal BCS for heifers at breeding? At calving? Why? - Answer-Target BCS
is 5-6 at beginning of breeding, and 6 at calving
How do these ideal BCS compare to cows? - Answer-Cows can have a lower BCS at
weaning (closer to 4) but should still be a 5-6 at calving/breeding. They can more easily
fluctuate between 2 whole BCS in a year compared to heifers.
Restriction of dietary energy/protein is a good way to reduce calf birth weight and this
dystocia in heifers - T/F - Answer-False.
What are the consequences of restricting feed to replacement heifers? - Answer-
Restricting feed does not reduce birth weight and dystocia. Instead, it causes weak
calves with delayed suckling, poorer quality colostrum and reduced colostrum volume,
calves susceptible to the cold, calves with scours/pneumonia, and poor rebreeding
performance.
Why is creep feeding detrimental to future cow productivity? - Answer-It makes them fat,
the fat replaces milk secreting tissue so they will make less milk in the future.
Decreases weaning weights of future calves from the cows that were creep fed
Should I select for pelvic area in order to reduce calving difficulty? What are the
consequences of this? - Answer-Selecting for larger pelvic area to reduce calving
difficulty is not a good management tool. Selecting for bigger pelvic area leads to
selecting for bigger cows/larger mature weight, leading to selection of bigger
calves/larger birth weight. This will increase overall herd size and not reduce calving
difficulty. It is more effective to control calf size through bull selection.
I can basically look at the width of a cows hooks and pins and tell if she has a larger
pelvic opening - T/F - Answer-False. Pelvic area is not correlated with any external
measurement.
How could I use the pelvic area on a large ranch? - Answer-Pelvic area on a large ranch
can be used as a culling tool. Cows with smaller pelvis areas can be frequently
monitored (or never bred/culled) compared to larger pelvic areas to try and prevent
calving difficulties.
What are the problems with using reproductive tract score to select heifers? - Answer-
Timing of the RTS changes the outcome and can change selection decisions. By the
time heifers are cycling, the scores will be higher, and by this time significant heifer
What are the objectives in selecting replacement heifers? - 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 - Answer-False
How do I calculate adjusted 205 day weight? - Answer-(WW-BW/Age) x
(205d+BW+AoD Adj.)
Should I use adjusted 205 day weight to select replacement heifers? Why? - 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? - 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? - Answer-
What two factors are most important in selecting heifers? - Answer-Age and weight
Heifers should reach puberty 1-3 months before being bred - T/F - 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 - 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) - Answer-Breed, age, weight,
and BCS are the top 4 factors affecting puberty in beef heifers.
How does breed impact puberty? - 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? - 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 - 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? - 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)? - 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. - 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? - 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 - 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? - 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. - 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? - 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)
What is the ideal BCS for heifers at breeding? At calving? Why? - Answer-Target BCS
is 5-6 at beginning of breeding, and 6 at calving
How do these ideal BCS compare to cows? - Answer-Cows can have a lower BCS at
weaning (closer to 4) but should still be a 5-6 at calving/breeding. They can more easily
fluctuate between 2 whole BCS in a year compared to heifers.
Restriction of dietary energy/protein is a good way to reduce calf birth weight and this
dystocia in heifers - T/F - Answer-False.
What are the consequences of restricting feed to replacement heifers? - Answer-
Restricting feed does not reduce birth weight and dystocia. Instead, it causes weak
calves with delayed suckling, poorer quality colostrum and reduced colostrum volume,
calves susceptible to the cold, calves with scours/pneumonia, and poor rebreeding
performance.
Why is creep feeding detrimental to future cow productivity? - Answer-It makes them fat,
the fat replaces milk secreting tissue so they will make less milk in the future.
Decreases weaning weights of future calves from the cows that were creep fed
Should I select for pelvic area in order to reduce calving difficulty? What are the
consequences of this? - Answer-Selecting for larger pelvic area to reduce calving
difficulty is not a good management tool. Selecting for bigger pelvic area leads to
selecting for bigger cows/larger mature weight, leading to selection of bigger
calves/larger birth weight. This will increase overall herd size and not reduce calving
difficulty. It is more effective to control calf size through bull selection.
I can basically look at the width of a cows hooks and pins and tell if she has a larger
pelvic opening - T/F - Answer-False. Pelvic area is not correlated with any external
measurement.
How could I use the pelvic area on a large ranch? - Answer-Pelvic area on a large ranch
can be used as a culling tool. Cows with smaller pelvis areas can be frequently
monitored (or never bred/culled) compared to larger pelvic areas to try and prevent
calving difficulties.
What are the problems with using reproductive tract score to select heifers? - Answer-
Timing of the RTS changes the outcome and can change selection decisions. By the
time heifers are cycling, the scores will be higher, and by this time significant heifer
