ANSC 3040 final Examination with
Complete Rationales 2026-2027 Edition.
What is the close up period? (Cows) - Answer last 3 weeks before calving
- moved to maternity pens
why do reproductive management strategies change according to categories? - Answer the
reproductive scenarios are different to fit the needs of the animals
- heifers = still growing
lactating cow = in process of lactation
define puberty within dairy cows - Answer first ovulation followed by a REGULAR luteal phase
most important factor to puberty - Answer body weight
- heavier = faster
why is over feeding an issue with dairy heifers? - Answer Overfeeding can cause accumulation
of fat in the mammary glands
- causes less mammary tissue to be developed
- less functional tissue
Can have health issues
- mobilize fatty tissues after calving = predispose to metabolic and immune diseases
how can under feeding be an issue for dairy heifers? - Answer reach puberty and calve later =
more costs
less milk during first lactation
higher risk for dystocia and limited capacity to compete for food among larger heifers
what 3 factors impact puberty age - Answer genetics, breed and weight
when should dairy heifers reach puberty and when should they become pregnant and calve?
(ideal) - Answer puberty = 9-10moa
,pregnant = 13-15moa
calving = 22-24moa
why is having bulls present within a dairy farm for reproduction not recommended? - Answer
1. expensive - another mouth to feed
2. increased probability of accidents
3. not able to select for genetic traits we want (can do with AI)
what are the 3 AI protocols for dairy cows? - Answer 1. detection of spontaneous estrus
2. detection of spontaneous and induced estrus (PGF2 alpha injections every 14d to induce
estrus)
3. times AI programs
most important estrus behavior - Answer standing to be mounted
estrus characterizations (cow) - Answer 1. vocalization
2. mucous vaginal discharge becomes clear
3. mounting attempts to other heifers
4. standing to be mounted
is it easier to detect estrus in dairy cows or other cows? - Answer dairy cows - going to the
barn at least twice a day
- able to see more of them
- more chances of seeing expression of estrus behavior
how does tailk chalk work for estrus detection? - Answer paint the back of a heifer
- if accepting to be mounted paint spreads
how do activity monitors work for estrus detection? - Answer place on ankles when in
breeding pen
- constant measurement of activity which allows for tracking of activity to see for spikes
, how do patches work for estrus detection? - Answer normally start off silver (placed on cows
back)
- as they are mounted silver rubs off to expose color
- more color = likely estrus
what is the effect of body weight at the entrance in breeding pen to proportion of pregnancy? -
Answer heavier weight = more likely to get pregnant
what is the purpose of using PGF2 alpha as an exogenous hormone? - Answer acts as the
endogenous prostaglandin and induces luteolysis
- CL regresses
- promote decrease in progesterone production
met estrus = 4-5 days after estrus (CL still maturing)
- if given here, CL will not regress because still growing and too young
- ie. no response
what is the purpose of giving exogenous GnRH? - Answer release gonadotropins
- recruits a new follicular wave by causing small FSH surge
- induce ovulation by LH surge
what is an intravaginal device of progesterone used for? - Answer release constant
concentrations of progesterone (normally kept in for 5-8 days)
- mucosa of vagina is good at absorbing levels of progesterone (need high levels for longer to
see effects)
- try to stimulate effect of a CL with high progesterone for longer time
injection would cause peak but then fall down (not good to induce fake CL)
what is the hormonal protocol for dairy heifers? (injections PGF2alpha) - Answer two
injections of prostaglandins (14d apart)
- promote regression of CL = decrease in progesterone and allows follicle to finalize growth and
ovulate
- induce estrus
- within 3-5 days of injection = show estrus
Complete Rationales 2026-2027 Edition.
What is the close up period? (Cows) - Answer last 3 weeks before calving
- moved to maternity pens
why do reproductive management strategies change according to categories? - Answer the
reproductive scenarios are different to fit the needs of the animals
- heifers = still growing
lactating cow = in process of lactation
define puberty within dairy cows - Answer first ovulation followed by a REGULAR luteal phase
most important factor to puberty - Answer body weight
- heavier = faster
why is over feeding an issue with dairy heifers? - Answer Overfeeding can cause accumulation
of fat in the mammary glands
- causes less mammary tissue to be developed
- less functional tissue
Can have health issues
- mobilize fatty tissues after calving = predispose to metabolic and immune diseases
how can under feeding be an issue for dairy heifers? - Answer reach puberty and calve later =
more costs
less milk during first lactation
higher risk for dystocia and limited capacity to compete for food among larger heifers
what 3 factors impact puberty age - Answer genetics, breed and weight
when should dairy heifers reach puberty and when should they become pregnant and calve?
(ideal) - Answer puberty = 9-10moa
,pregnant = 13-15moa
calving = 22-24moa
why is having bulls present within a dairy farm for reproduction not recommended? - Answer
1. expensive - another mouth to feed
2. increased probability of accidents
3. not able to select for genetic traits we want (can do with AI)
what are the 3 AI protocols for dairy cows? - Answer 1. detection of spontaneous estrus
2. detection of spontaneous and induced estrus (PGF2 alpha injections every 14d to induce
estrus)
3. times AI programs
most important estrus behavior - Answer standing to be mounted
estrus characterizations (cow) - Answer 1. vocalization
2. mucous vaginal discharge becomes clear
3. mounting attempts to other heifers
4. standing to be mounted
is it easier to detect estrus in dairy cows or other cows? - Answer dairy cows - going to the
barn at least twice a day
- able to see more of them
- more chances of seeing expression of estrus behavior
how does tailk chalk work for estrus detection? - Answer paint the back of a heifer
- if accepting to be mounted paint spreads
how do activity monitors work for estrus detection? - Answer place on ankles when in
breeding pen
- constant measurement of activity which allows for tracking of activity to see for spikes
, how do patches work for estrus detection? - Answer normally start off silver (placed on cows
back)
- as they are mounted silver rubs off to expose color
- more color = likely estrus
what is the effect of body weight at the entrance in breeding pen to proportion of pregnancy? -
Answer heavier weight = more likely to get pregnant
what is the purpose of using PGF2 alpha as an exogenous hormone? - Answer acts as the
endogenous prostaglandin and induces luteolysis
- CL regresses
- promote decrease in progesterone production
met estrus = 4-5 days after estrus (CL still maturing)
- if given here, CL will not regress because still growing and too young
- ie. no response
what is the purpose of giving exogenous GnRH? - Answer release gonadotropins
- recruits a new follicular wave by causing small FSH surge
- induce ovulation by LH surge
what is an intravaginal device of progesterone used for? - Answer release constant
concentrations of progesterone (normally kept in for 5-8 days)
- mucosa of vagina is good at absorbing levels of progesterone (need high levels for longer to
see effects)
- try to stimulate effect of a CL with high progesterone for longer time
injection would cause peak but then fall down (not good to induce fake CL)
what is the hormonal protocol for dairy heifers? (injections PGF2alpha) - Answer two
injections of prostaglandins (14d apart)
- promote regression of CL = decrease in progesterone and allows follicle to finalize growth and
ovulate
- induce estrus
- within 3-5 days of injection = show estrus
