Managing fertility and manipulating the breeding season workshop

Question 1

What are the reproductive aims of pigs

Answer 1

aim to produce > 20 live piglets each year (≥ 2 litters

Question 2

what are the reproductive aims for sheep

Answer 2

aim to produce 1-2 lambs each year- depends on upland/lowland

Question 3

what are the reproductive aims for cows

Answer 3

aim to produce one live calf once a year

Question 4

What is the target scanning percentages for upland/lowland/hill sheep farming

Answer 4

upland= 200%
lowland= 175%
hill= 115%

Question 5

what is the target abortion rate in sheep/ cattle

Answer 5

<2%

Question 6

List 7 factors that can cause failure to breed in ewes

Answer 6

Body condition score
General health
Stage in annual cycle
Season
Anatomical/congenital abnormalities
Errors in synch protocols
Ram problems

Question 7

List 5 factors that can cause failure to breed in rams

Answer 7

Low/absent libido
Pathologies of the penis/prepuce affecting intromission
Lameness
Inexperience
Too high ewe:ram ratio

Question 8

List 4 factors that can cause failure to conceive in rams

Answer 8

Pathologies causing orchitis/epididymitis
Penile abnormalities
Inadequate testicular circumference
Sperm abnormalities

Question 9

what is the target calving interval

Answer 9

herd average of 365days

Question 10

decribe how to calculate the barren cow rate and what is the target

Answer 10

Number of non-pregnant cows ÷ number of cows bred x 100
<5%

Question 11

Describe how to work out calving pattern

Answer 11

When calculating % calved in 1st 3 weeks, include all cows calving prematurely as well as those actually calving in the 1st 3 week window

Question 12

How is heifer submission rate calculated and the target for this

Answer 12

Heifers bred ÷ heifers eligible to be bred x 100
>80%

Question 13

At what age/ weight do you want to serve dairy heifers

Answer 13

13.5months
397kg

Question 14

How do you work out fertility efficiency and the target for this in all year round herd

Answer 14

Conception rate x submission rate
>25%

Question 15

List 6 potential factors that can cause failure to conceive in cows

Answer 15

Body condition score
General health
Milk yield (dairy)
Anatomical/congenital abnormalities
Errors in synch protocols
Bull problems

Question 16

List 4 potential factors that can cause Failure to conceive/maintain pregnancy in cows

Answer 16

Reproductive pathology
Early embryonic death / abortion
Errors in synch protocols
AI errors  AI commonly used in dairy herds

Question 17

List 3 ways that increased yeilds has resulted in decreased fertility in dairy cows

Answer 17

Problems with postpartum resumption of cyclicity
Reduced oestrus behaviour
Oocyte and embryo quality

Question 18

To acheive 365 calving interval when do dairy cows need to conceive

Answer 18

need to start breeding before 58 DIM
conceive before 84DIM

Question 19

List 3 ways NEB after calving can reduce fertility

Answer 19

adverse effects on resumption of cyclicity
reduced embryo quality
associated with increased risk of postpartum disease

Question 20

why do high yeilding cows have shorter oestrus

Answer 20

have lower oestradiol concentration
due to increased metabolism of the oestradiol and decreased production of the oestradiol if animal is stressed

Question 21

why may we manipulate the breeding season in lambs

Answer 21

Aim to breed as early as possible to maximise breeding opportunities and capitalise on higher lamb prices in Spring

Question 22

what makes up ‘cows that are eligible for breeding’

Answer 22

Those outwith the voluntary waiting period
Those that are not pregnant

Question 23

Can hormones be used to improve submission rate in dairy

Answer 23

Yes
Can do:
- synchro protocols and fixed time AI- submission rate should be 100% not always effective
- synchro protocols and AI to observed oestrus

Question 24

after giving PGF2a to cow with mature CL when will the cow come into oestrus

Answer 24

in 3-5 days time

Question 25

How can we manipulate the cow oestrus cycle to shorten breeding season

Answer 25

Synchronise cows so more of them come into oestrus in the first 6 weeks

Question 26

which synchronisation protocol has the best conception rate

Answer 26

one which includes progesterone

Question 27

what is the most common cause of anoestrus in beef herds- how to treat

Answer 27

suckling calves present- causes reduced LH pulse
CIDR/ PRID- synch

Question 28

List 3 ways to advance the breeding season in sheep

Answer 28

Ram effect

Melatonin implant

Progesterone (or synthetic progestogen) + equine Chorionic Gonadotrophin (eCG)*

Question 29

how does ram effect work

Answer 29

Entire or vasectomised ram presence –> stimulates ovulation
advances breeding season by 2weeks

Question 30

Much much can a melatonin implant advance the breeding season

Answer 30

brings forward by up to 2 months

Question 31

how do melatonin implants work in sheep

Answer 31

Melatonin implant mimics effect of shortening photoperiod
GnRH is produced by hypothalamus at an earlier point in the year

Question 32

Describe how to implant melatonin implant

Answer 32

Day 1= 30 weeks before desired start of lambing - remove all rams from sight or smell of ewes
Day 7= implant ewes
Day 42= 35 days after implantation- introduce rams
Peak mating activity occurs about 25 days after ram introduction

Question 33

By how much does progesterone devices and eCG advance the breeding season in sheep

Answer 33

by 4-6 weeks

Question 34

what is an advantage of progesterone devices on advancing sheep breeding seasons

Answer 34

Suitable for cycling and non-cycling ewes
- Non-cycling –> eCG is needed otherwise results are poor
- Cycling –> eCG is optional but synchronisation is optimised if used