Dairy Cattle:reproduction

Question 1

Interval from one heat period to the next

Answer 1

Estrous cycle

Question 2

Time when female is receptive to male and will allow breeding

Answer 2

Heat or estrus

Question 3

Is the basic pattern of estrous cycle same or different for all mammals

Answer 3

Same, timing of stages is just different

Question 4

What controls the estrous cycle

Answer 4

Hormones from the ovary and brain

Question 5

Around what age does a heifer begin her estrous cycle

Answer 5

4-24 months of age

Avg age is 12 months

Question 6

What is a yearling

Answer 6

Cattle of either sex 1-2 yrs of age

Question 7

Once a heifer has her first heat she will repeat it every ____ days
Therefore, the length of the estrous cycle in cattle is ____days

Answer 7

21

21

Question 8

How long are cattle in estrus (heat) for

Answer 8

Approx. 12-18hrs

Question 9

Cattle are polyestrus which means

Answer 9

They have many beats per year

Question 10

Signs of estrus in cattle

Answer 10

Increased activity
Vocalize (bellow)
Interest in other animals (nuzzling, pushing around)
Stand to be mounted “standing heat” most prominent sign

Question 11

How often cows should be observed for heat

Answer 11

30 mins 2x daily

Question 12

Heat detection aid example

Answer 12

Mount detectors (crayon on back or vile of dye)

Question 13

What is ovulation

Answer 13

Time when females egg is released (from ovary and falls into ovaduct) and contraception is most likely to occur

Question 14

When ovulation happens in relation to estrous cycle

Answer 14

Towards end of estrus period

Question 15

Define Gestation

Answer 15

Period of carrying a baby

Question 16

How long cattle gestation is

Answer 16

285 days, aka 9months

Question 17

How many calves are most cows meant to have per year

Answer 17

1

Question 18

What are freemartin cattle

Answer 18

When a heifer is born as a twin to a bull. There is a 90% chance she will be sterile (testosterone production from bull flows into females blood vessels)

Question 19

Is twinning common in cattle

Answer 19

No

Question 20

Examples of aid to increase reproductive efficiency

Answer 20

Prostaglandin, embryo transfer

Question 21

What is prostaglandin

Answer 21

Naturally occurring female hormone, can be manufactured synthetically to aid with reproductive problems

Question 22

What prostaglandin does after injected

Answer 22

Cow comes into heat 2-3 days after injection

Question 23

When prostaglandin is usually utilized

Answer 23

When cow is hard to catch in heat, farmers want to synchronize cows so they can be bred at same time, shorten estrous cycle

Question 24

Options for breeding cattle

Answer 24

Natural service (cows bred by bull) or artificial insemination

Question 25

Pros and cons of natural service breeding

Answer 25

+cheaper and easier | -unsure of genetics and heritable traits, bulls are dangerous, STDs

Question 26

Pros and cons of artificial insemination

Answer 26

+better genetics available (selection traits), control of STDs, don’t have to keep bull -homogenous population

Question 27

How cows are artificially inseminated

Answer 27

Arms inserted into rectum, rod w semen on end inserted into vagina, feel for body of uterus (target of semen placement )

Question 28

How AI company company selects a bull

Answer 28

Based on pedigree, health and semen evaluation, free of genetic diseases, shape and motility (morphology) of sperm examined

Question 29

What AI companies do with chosen bulls semen

Answer 29

Semen is mixed w an extender and frozen in individual straws Bred to limited # of cows, daughter evaluated

Question 30

What embryo transfer is used for

Answer 30

Increase # of calves from valuable cows

Question 31

Procedure for embryo transfer

Answer 31

Valuable donor cow goes under hormone regimen to be super ovulated (many eggs develope at once) AI by valuable sire Several days later uterus is flushed and embryos collected Eggs examined to see which are fertilized Embryos implanted into recipient heifers or frozen in liquid nitrogen and sold

Question 32

Embryo splitting (breeding advancement)

Answer 32

Fertilized embryo is split producing 2 genetically identical twins (expensive)

Question 33

Sex control (breeding advancement)

Answer 33

Separating sperm into x& y so animals produce either male or female offspring. (Expensive)

Question 34

Cloning (breeding advancement )

Answer 34

Several methods available | taking cells from individual and allowing those cells to reproduce another identical individual