Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

Production > Reproduction > Flashcards

Reproduction Flashcards

1
Q

What are some issues with pasture being the primary source of livestock nutrition?

A
  • Under nutrition
  • Trace Element deficiencies
  • Internal parasites and soil bacteria
  • Toxic plants
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

When is under nutrition the biggest issue in pastoral livestock?

A

In winter when grass growth is low

- Animals are reliant on the pasture to get all of their minerals and trace elements

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

Why can rotational and strip grazing become health challenges for livestock?

A

They have high stocking densities

- Potential rapid transmission of infectious diseases

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

Why can large herd or flock sizes become a problem?

A

It is easy for individual sick animals or dead animals to go unnoticed by the farmers

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

What farm events can predispose health problems in stock? e.g. pneumonia

A

Periods of acute severe stress

  • Mustering
  • Yarding
  • Shearing
  • Trucking
  • Docking
  • Weaning
  • Drenching
  • Dipping
  • Dogs on farm
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

What are the major health challenges facing NZ pastoral livestock?

A
  • Pasture primary food source
  • Management of grazing
  • Large flocks/ herds
  • Periods of acute stress
  • Outside all year round
  • Warm moist climate
  • Fleece provides warm moist micro-climate
  • Generally feed a monoculture
  • Subject to wounds and abrasions which can predispose to disease
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

What is the health issue created with farming outside all year round in NZ?

A

Animals are exposed to the extreme weather

- Mortality in calving/ lambing season

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

What is the health challenge created by the warm moist climate in NZ?

A

Fungi thrive in pasture in warm moist climates

Rapid development and good survival of internal parasites

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

What is the issue with sudden feed change in ruminants?

A

The rumen microflora need to adapt

- can cause stomach upsets

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

What can cause wounds on farm that predisposes animals to infection?

A
  • Deliberate wounds such as tail docking

- Accidental wounds caused by random objects such as wire

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

What is important in regards to the health management of flocks and herds?

A
  • Whole herd/ flock focus rather than individual focus
  • Prevention of poor production and disease instead of treatment
  • Subclinical and Clinical focus
  • Integrate animal health and husbandry and farm business - Be Proactive!
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

What are the steps in Investigating a herd/ flock problem as a veterinarian?

A
  1. Define the Problem
  2. Take History
  3. Environmental and Distance exam
  4. Individual clinical exam and Post-mortem exam
  5. Further logical and justifiable diagnostic tests
  6. Interpreting and decision making - effective communication
  7. Reporting back and future monitoring
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

What is fundamental on a sheep farm to achieving high productivity and profits?

A

High Lambing Percentage

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

What factors in regard to Lambing Percentage can we as Vets not influence?

A
  • Weather

- Topography

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

What about topography can we as vets influence?

A
  • Where ewes are mated
  • Where lambing occurs
  • Fert application or not
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

What does topography influence on a sheep farm?

A
  • Ram tupping capacity
  • Ewe feeding level (quantity and quality of pasture)
  • Neonate survival
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

What are factors important to lambing percentage that can be altered by good management?

A
  • Oestrus
  • Breeding season in ewes
  • Ovulation rates
  • Mating
  • Fertilisation
  • Embryo development and survival
  • Foetal development and survival
  • Birth
  • Ewe Survival rates
  • Perinatal survival
  • Growth of lambs
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

Describe Oestrus in sheep…

A
  • 17 day cycle
  • Ovarian follicular development occurs throughout the year
  • Out of season follicles regress
  • LH surge in breeding season
  • Mature ewe oestrus: 12-36 hours
  • 2ths 1-24 hours
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

When are higher conception rates achieved in ewes?

A

Late March to Mid May

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

On average when are the Rams put in with the Ewes in both North and South Island?

A

NI: 8th March
SI: 18 April

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

What does high altitude do to the breeding season of ewes?

A

Significantly decreases the length

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

If the North Island pushed back their average ram joining date what would be observed?

A
  • Higher first cycle submission rate
  • Less ewes returning
  • Shorter mating period
  • Shorter Lambing period
  • Lambs born later when more grass for ewes
  • Thus faster lamb growth rates
  • Increased lamb survival
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

Why does the North Island tend to have earlier ram joining dates?

A
  • Premium prices for early lambs

- late lambs may have no food to eat if it dries out early (drought)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
24
Q

What factors affect the ewes breeding season?

A
  • Breed of sheep
  • Latitude
  • Altitude
  • Age of ewe
  • Ram effect (teasers)
  • Photoperiod control
  • Stress
  • Hormonal induction of oestrus i.e. CIDRs
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
25
Q

How does breed affect breeding season?

A
  • Romneys have shorter breeding season than merinos
  • Romneys have less cycles than merinos
  • Poll Dorsets can breed almost all year round
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
26
Q

What Questions would you ask a farmer that had an abnormally low lambing percentage?

A
  • What was ram: ewe ratio?
  • When was start of mating?
  • When did mating finish?
  • Were teasers used?
  • Ewe BCS and weights pre mating?
  • Level of nutrition, pre mating?
  • Were ewes stressed prior to mating i.e. shearing, bad weather?
  • Were rams harnessed? What was submission rates for the 1st, 2nd and 3rd cycles?
  • Did you scan post mating?
  • Do you have abortions on farm and do you vaccinate for these?
  • What was lambing like? i.e. weather, dystocia etc.
  • Are there any reasons that you can see as to why this may have occurred?
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
27
Q

Why are young ewes difficult to get pregnant?

A
  • Cycle later
  • Shorter heats
  • Less cycles with lower O.R
  • Shy - don’t seek out rams
  • Lower conception rates
  • Higher embryonic death rates
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
28
Q

What should be done to increase young ewes conception rates?

A
  • Mate separately to main mob of ewes
  • Mate on easy rolling/ flat paddocks so rams can find them
  • Use ram: ewe ratio of 1:50
  • Use experienced rams
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
29
Q

Why are Hoggets usually mated in May?

A
  • They cycle later
  • Increase weights
  • Puberty
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
30
Q

What is the best way to improve Hogget conception rates?

A

Use teaser rams to synchronise oestrus

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
31
Q

When should vasectomies be performed?

A

At least 4 weeks prior to PSM

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
32
Q

Why is it beneficial to synchronise ewe Hoggets?

A
  • It gives 2 shots at mating in a single cycle

- Allows a condensed lambing period

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
33
Q

How do you synchronise Hoggets?

A
  • No contact with rams for at least 3 weeks prior to PSM
  • Flush on good quality feed >1250kgDM/ha
  • Be mated in small flat paddocks
  • Teasers out for 17 days prior to PSM is best
  • Rams go out at day 17 at ratio of 1:50
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
34
Q

What occurs after teaser effect?

A
  • within 10 minutes, increase LH pulses (main one 27-36 hours after teasers in)
  • Within 3 days most ewes have a silent ovulation
  • 60% of these ewes develop a CL which maintains the cycle
    • repeat ovulation 18-20 days after initial teaser intro
  • The other 40% of these ewes CL regresses 6-8 days later, they then have another silent heat 5 days later

Group 1: synchronised at day 18
Group 2: synchronised at day ~26

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
35
Q

Describe how melatonin affects the ewes breeding season…

A
  • Hormone responsible for photoperiod induced changes on hypothalamus and pituitary gland
  • Released from Pineal gland 10 mins after darkness and stops 10 mins after sunrise
  • Not very practical for increasing lambing percentage in a flock
36
Q

How can bad weather affect O.R in ewes?

A

Can slow ORs down

- especially if ewes have been shorn

37
Q

Is shearing a stress to ewes?

A

Yes - its a major stressor

  • especially if done 3 weeks either side of mating
  • Must have plenty of feed and no bad weather
  • Can increase O.R as the ewes increase intake (flushing)
38
Q

What happens if shearing is done during mating?

A

All oestrus activity stops

39
Q

How is hormonal induction of oestrus done?

A
  1. Insert CIDR/ sponge into vagine for 12-14 days
  2. Ewe injected with PMSG
  3. Oestrus 24-72 hours later
40
Q

What does O.R determine?

A

The maximum number of lambs that can be born

41
Q

What factors affect O.R in ewes?

A
  • Bodyweight and nutrition at mating
  • Time of mating
  • Ewe age
  • Genetics
  • Diet (phytooestrogens)
  • Mycotoxins
  • Level of feed when younger
  • Pre-mate shearing
  • Immunisation against ovarian steroids (androvax)
  • Pre-mating parasite burdens
  • Trace elements
42
Q

How heavy should ewes be at mating?

A

55-60kg

43
Q

Is there a correlation between O.R and Body weight?

A

Yes but only up to 65Kg

- then O.R plateaus

44
Q

What is the best way to manage different weights in ewes pre-mating?

A

Draft out lighter ewes and preferentially feed them

- aim to make tail enders have a weight of 55kg to make average ewe weight 55+Kg

45
Q

How does twinning rate increase with body weight?

A

As the live weight increases to 55-60Kg

- for every 1Kg gain you get a 1.3% increase in LP%

46
Q

What may be required in order to flush ewes well?

A

Supplements

  • Silage/ summer crop
  • No lucerne or red clover!
47
Q

Why is it best to sell last seasons lambs before feb/ march?

A

They will begin to eat the food saved for flushing

- may affect next years profits

48
Q

What questions should you ask when investigating a low LP%?

A
  • How many ewes mated?
  • How did this 2th compare to MA ewes?
  • Hogget mating? If so what was scanning %?
  • How many rams used?
  • Mating start date?
  • When were rams removed?
  • Were teasers used?
  • Do lambs finish on time or is there a tail end?
  • What are the lambs fed?
  • What are live weights or MA ewes, 2th and hoggets prior to mating?
  • Fed well prior to mating?
  • Pasture cover pre-mating?
  • Stocking rate different from last year?
  • Pre-mating parasite control programme with the ewes?
  • Used harnesses with rams?
49
Q

What can happen if you have poorly grown Hoggets?

A

They become poorly grown 2ths and MA ewes

50
Q

What should weight targets for ewes be at mating?

A

Hoggets: 42kg
2ths: 55kg
MA: 55-60kg

51
Q

How does the age of the ewe affect O.R?

A

Older ewes have more ovulations than 2ths or hoggets

52
Q

How does Genetics affect O.R?

A

Finnish Landrace ewes are very fecund
- often have 200% LP but this is poor for lamb survival

  • Have more developing follicles and secrete more oestradiol
  • Higher basal circulating rate of FSH and LH results in more ovulations per cycle

Finnish x are very successful

53
Q

What are the two fecundity genes in sheep in NZ?

A
  1. Booroola - merinos

2. Inverdale

54
Q

What occurs in the ewes non-breeding season in terms of oestrus?

A
  • The follicles develop but become atretic

- Ovary releases constant low levels of oestradiol which has a negative effect on LH

55
Q

What occurs in the ewes breeding season in terms of oestrus?

A
  • Hypothalamus loses sensitivity to low dose oestradiol and releases GnRH
  • GnRH stimulates pituitary to release FSH and LH
  • FSH stimulates follicles to mature and release high levels of oestrogens starting oestrus
  • High Oestradiol results in LH surge resulting in ovulation and development of luteal phase of cycle
  • Progesterone in luteal phase has a negative feedback on LH release
  • Progesterone declines after PGf2a is released from uterus at day 15 resulting in a pre-ovulatory rise in LH and a repeat cycle
56
Q

Which hormone primes the ewes vaginal and behavioural responses to oestradiol for the next oestrus cycle?

A

Progesterone

57
Q

What does lucerne contain that affects O.R?

A

Coumesterol

- Oestrogenic compound

58
Q

How does coumesterol affect lambing %?

A

It reduces it by 10-40% by decreasing ovulation rate
- due to -ve feedback that oestrogen has on pituitary and LH release

  • tends to affect multiples, i.e. doesn’t cause empty rates
59
Q

Which clover varieties contain phyto-oestrogens?

A
  • Mt Baker
  • Tallarook
  • Trifolium genus
  • Pawera red clover
60
Q

What are some other signs of phyto-oestrogen toxicity?

A
  • Histological cervix damage

- Udder development in young animals, empties and wethers

61
Q

What affect do mycotoxins have on reproduction in ewes?

A

Depress reproduction

  • pithomyces chartarum (facial eczema) in North Is
  • Zearalenone on East Coast
62
Q

What causes ovulation losses in ewes with facial eczema?

A
  • Liver damage: lighter ewes, lose condition and may die

- GGT increase of over 200IU over mating period

63
Q

Why does a GGT increase of 200IU over the mating period cause ovulation losses?

A
  • Direct -ve effect on ovulation by 4%
  • Decrease in multiple ovulations by 3-6%
  • Increase in empties by 3-5%
  • Decrease twins by 3-5%
  • Decreased lamb birthweight
  • Delay in onset on breeding
  • Decrease no. of oestrus cycles
  • Can shorten breeding season by 20 days
64
Q

How can FE be treated?

A
  • Oral drenching with Zinc Oxide
  • Time Capsule
    • Zinc Oxide slow release
    • Effective for 6 weeks
    • Give 2 weeks prior to risk
65
Q

Describe Zearalenone…

A
  • Most of NZ (espec East Coast)
  • Fusarium fungus
  • Saprophytic - lives in dead part of sward
  • Late summer
  • Ewes exposed prior to mating
  • Decreases OR and fertilisation rates
66
Q

What affect does Zearalenone have on Ewe breeding?

A
  • Increased no. of dry-dry ewes

- Less twins (lower scanning and LP%s)

67
Q

How is Zearalenone toxicity diagnosed?

A
  • Collect urine sample from pooled group of 15 ewes

- Partially smoother ewes mouths to get urine

68
Q

How do you immunise against ovarian steroids?

A

Use Androvax

- An immunisation against the ovarian androgen androstenedione which is the precursor for oestrogens

69
Q

What is Androvax?

A
  • Tries to artificially increase the fecundity of vaccinated ewes by removing the low level oestradiol from the system so -ve feedback doesn’t occur and LH levels are higher
  • Low level antibodies to androstenedione affect LH rather than FSH which allows more LH to circulate
  • More follicles ovulate in each oestrus = Increase LP%
70
Q

Describe the androvax Programme in ewes…

A
  • Unvaxed ewes require 2 doses before PSM
    • 1st dose 8 weeks prior to PSM
    • 2nd dose 4 weeks prior
  • Annual boosters 4 weeks prior to PSM
71
Q

Why can’t ewes be vaccinated too close to PSM with androvax?

A
  • Will get antibodies too high
  • this results in complete anoestrus and barren ewes (due to all oestradiol coming from Androstenedione -> Ostreone -> Oestradiol)
72
Q

What are the disadvantages of using androvax?

A
  • Poor substitute for good management
  • Can lead to problems with multiple births
  • Must scan to know who multiples are
  • Must have enough pasture at lambing
73
Q

How many chances do ewes usually have of concieving?

A

2-3 chances per breeding season

74
Q

What should the pregnancy target be after the end of the 2nd cycle?

A

95-98% in this 34-40 day period

75
Q

Describe Ram Harnesses…

A
  • Used to detect mating patterns within flock
  • Allows submission rates to be seen and lambing dates predicted
  • Change colour every 14 days
  • Ensure crayon not too soft or too hard
  • Wooly ewes harder to mark
  • Not all marked ewes will lamb
76
Q

Describe from fertilisation to day 30 pregnancy…

A

1-10 days: slow embryo growth
10+: embryo implants and rapidly grows

  • Most EED occurs before day 18
  • 20-30% fertilised eggs are lost
  • If embryo lost before day 12 = no effect on cycle
  • After day 12 the CL doesn’t regress as fast which results in long cycles
77
Q

When is early embryonic death a big problem?

A

When the EED occurs from the 2nd cycle or at the end of the mating period

78
Q

Describe Placental Development…

A
  • Starts 30 days after conception
  • Completed by 90 days
  • Size is determined by early nutrition of ewe
79
Q

What are the factors involved in EED?

A
  • Ewe age: young > old
  • Genotype
  • Nutrition: 1st 21 days important
  • Se deficiency
  • High temperature: 0-7 dasys before mating increases EED
  • Stress: 20 days post mating
  • Infectious causes
80
Q

When is scanning performed in ewes?

A

40-90 days post mating

- average is 45 days

81
Q

What are the benefits of scanning?

A
  • Ewes with multiples can be put in sheltered paddocks
  • Ewes with singles tightened up if feed gets scarce
  • Ewes with multiples get better lambing pasture cover for higher milk production and increased lamb growth
  • Multiples preferentially fed to get in better condition for next season mating and improved O.Rs
82
Q

When are there potential periods of loss on a sheep farm?

A
  • Pre mating
  • Mating
  • Early, mid and late gestation
  • Lambing
  • Perinatal losses
  • Post natal losses
83
Q

What factors can affect an entire flock/ property that will reduce the no. of lambs born?

A
  • Weather
  • Nutrition
  • Parasitism
  • Trace elements
  • Diseases
84
Q

What is a good question rule to apply to any clinical problem on farm?

A

W5 H5 W5

85
Q

What does W5 H5 W5 stand for?

A
  • What is the problem?
  • What are the signs?
  • Where has these been seen?
  • When has this happened?
  • Why does owner think it’s happened?
  • How many animals affected?
  • How often has this occurred?
  • How have you managed these animals this year?
  • How has this changed from previous years?
  • How am I going to diagnose this?
  • What did I diagnose?
  • What am I going to do about it now?
  • Where can farm client implement management changes to address these problems?
  • When should he/she do these changes?
  • Why should he/ she do these changes?

Production (4 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions