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ANSC 355 > Breeding > Flashcards

Breeding Flashcards

1
Q

what kind of breeders are most sheep breeds

A

-most are:
-sexually active as the days get shorter
-aug-jan
-peak oct-nov
-gestation 147 days (150 for goats)
-sheep and goats closer to equator show less seasonality

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2
Q

short season breeders

A

-4 months or less
-sept-dec
-north country cheviot
-leceister
-scottish blackface
-taxel
-shetland

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3
Q

extended/medium season breeders

A

-4-6 month season
-aug-jan
-hampshire
-oxford
-canadian arcott
-cjarollais

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4
Q

long season breeders

A

6-8m
-july-feb
-finnish landrace
-romanov
-dorset
-rideau arcott
-rambouillet
-polypay

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5
Q

goats short season breeders

A

-6 month
-sept-feb
-alpine
-la mancha
-toggenburg

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6
Q

goat long season breeders

A

-10m
-july-april
-boer
-nubian
-pygmy

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7
Q

lambing percentages

A

-lambs born/ewe=1-3
-ideal L%= 200
-L%= # of lambs born/# of ewes exposed x 100

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8
Q

what is an influence you can make on your sheep for higer lambing precent

A

-nutrition of ewes pre breeding
-well fed ewes have higher ovulation rates (flushing)

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9
Q

how to flush

A

-start 2-3 wks per breeding
-provide increase of energy of the ration
-grazing ewes=fresh pasture, supplement tub
-0.5-1.4 lb of grain
-want body condition score of 3-3.5 and gaining at breeding time
-maintain for 30 days after rams go in (1 month)
-early embryonic death tends to occur in the first month of gestation and likely due to poor ewe nutrition

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10
Q

flusing effect

A

-works best on skinny ewes and goat (BCS less then 3 out of 5)
-improve ovulation, conception, and implantation rates
-can also improve ewes showing estrus
-not effective on ewe lambs as they are all ready on high plane of nutritional growth
-not effective on good condition sheep and goats
-not beneficial on high fecundity breeds

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11
Q

body conditioning scoring

A

-used to estimate condition of muscling and fat
-scale of 1-5 (1 skinny, 5 fat)
-over the loin area feel for the spinous process and transverse process

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12
Q

when to body condition score and what is an idea range

A

-pre-breeding=2.5 if flusing
-mid gestation=3-3.5
-paturation=3-3.5
-weaning=???

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13
Q

female to male ratios for sheep

A

mature ram 1:30-50
ram lamb 1:14-25
synchronized flocks 1:5-10

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14
Q

female to male ratios for goats

A

mature buck 1:50
buckling 1:10-25
-avoid more then one buck per breeding group

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15
Q

light control of estrus

A

-melatonin is produced by pineal gland in response to decreasing hours of light
-melatonin secretion is required to stimulate GnRH secretion
-melatonin is produced at night when its dark
-light entering the eyes inhibits the pineal gland from converting serotonin to melatonin

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16
Q

things to help out of season breeding

A

-use long season breeds
-eg. dorset, finn, rideau, romanov or crosses with these breeds
-light treatment
-temperature
-reduce male to female ratio to lower requires serving capacity (1:10)
-melatonin treatment

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17
Q

light treatment for ewes

A

-light treatment:
-artificially reduce day length to trick pineal gland
-lock up ewes in darkness except for 8 hours
-6-8 weeks prior to breeding (at least)
-continue light treatment over breeding

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18
Q

light treatment for rams and bucks

A

-rams and bucks also need short day lengths
-greater testicular size
-improves libito
-better semen quality

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19
Q

light treatments for goats

A

-artificial lighting for 16-18 hrs/day
-can have natural light and a 1 hr light stimulus at time of desired sunset
-more practical is inside dark barn followed by natural daylight

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20
Q

disadvantages of light treatment

A

-cost of lighting-tight barn with space for all animals
-labor of moving animals in and out

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21
Q

temperature for out of season breeding

A

-high temps affect embryo survival and sperm quality
-make sure shade is available

22
Q

melatonin treatment for out of season breeding

A

-mimics day length adjustment
-dose melatonin orally of implant
-three month protocol
-works for sheep and goats
-can be combined with, or in place of, light treatment
-disadvantage: ewes might become unreceptive to melatonin

23
Q

estrus synchronization advantages

A

-short breeding and lambing period
-space advantages for lambing multiple groups
-most ewes will lamb within a 10 day period if tightly synchronized
-can manage floods with lambing by managing group size

24
Q

estrus synchronization disadvantages

A

-higher # of rams needed (1:10) or hurts conception
-cost of hormones
-extra labor

25
Q

what is estrus synchronization needed for

A

AI and embryo transfer

26
Q

estrus synchronization natural breeding

A

-21 day ram exposure
-catches the second estrus if any ewes were missed
-7 days- easy mamagement, only first estrus
-raddle marker and remove rams once all ewes are marked
-make sure rams have sufficent break before using on nxt group (7wks)

27
Q

non hormonal synchronization

A

-ram and buck effect
-most effective in “shoulder” season 4-6 wks before normal breeding season
-introduction to the ram will include silent heat in ewes with short-lived corpus luteum and then will ovulate without showing estrus
-must have been separated for at least 3wks
-rams and ewes must have been separated by at least 500m, 1-2km is better
-buck and does need to be separated by 1 mile
-not effective for ewes that are already cycling

28
Q

options for hormonal estrus manipulation

A

-intra-vanginal progesterone insert
-pregnant mare serum gonadotrophin
-synthetic prostoglandin

29
Q

intra vaginal progesterone insert

A

-sponges
-controlled internal drug release (CIDR)

30
Q

CIDRs

A

-in place for up to 14 days to outlast existing corpus luteums
-out of season use-depends on protocol
-once CIDR is removed should show estrus 48-96 hrs
-works in goats but only labeled for sheep
-can be combined with other hormones such as PMSG
-out of season PMSG protocol:
-5-7 days insertion
-PMSG injection and removal
-goats are good at pulling out (and so are sheep)

31
Q

pregnant mare serum grandotrophin (PMSG)

A

-acts similar to FSH
-stimulates ovaries to produce mature ova
-promotes signs of estrus
-dosage varies 300-1000IU
-higher dose if trying to stimulate estrus out of season
-lower doses if synchronizing in season
-lower doses for more prolific than less prolific

32
Q

synthetic prostaglandin (cloprostenol)

A

-shortens life of corpus luteum
-induces abortion within first 50 days pregnant (sheep)
-can be used to induce estrus for synchronization
-ewes 2 doses 7-9 days apart
-does 2 doses 11-13 days apart
-females must be cycling to work (if pregnant will abort and she wont catch)

33
Q

lambing once per year

A

-only get 1 crop of lambs per year
-range
-new producers should start here
-farm flocks that are not just sheep
-breed in fall, lamb in spring

34
Q

phase lambing

A

-ewes only lamb once per year
-groups lamb at different times

35
Q

accelerated lambing

A

-3 times in 2 year
-ewes lamb every 8 months
-each ewe has 1.5 lamb crop per year
-intensive (lamb every 8m)
-can utilize light+hormone treatment
-wean early (8wks gives ewe 1m to dry off and recover)
-use extended of long season breeds

36
Q

accelerated lambing managed with two flocks

A

-breed dec to lamb may
-breed aug to lamb jan
-breed april to lamb sept

37
Q

what does the star system require to work

A

-long season breeds to work (dorset)
-no light treatment of hormones are utalized
-3 groups of sheep:
-ewes (breeding and gestating, and rams)
-ewes-lambing and lactating
-growing lambs-market and replacement ewe lambs

-intensive program (7.2m between lambing events)
-could be managed with 5 groups of ewwes
-lambing 5x per year (year round)
-breeding 5x per year (year round)
-mostly twins

38
Q

pure breeding (outbreeding)

A

-breeding unrelated animals
-how far back?
-offspring must meat breed requirements for registering
-produce breeding stock and market lambs
-utilize reproductive technologies to bring new genetics
-embryo transfer
-AI

39
Q

cross breeding

A

-combining two or more breeds
-high bred vigor or heterosis is achieved
-individual
-maternal
-paternal

40
Q

individual heterosis

A

-offspring perform better than purebred progeny
-improves traits with low heritability the most
-fertility
-hardiness
-growth

41
Q

maternal heterosis

A

-differences in performance of crossbred dams when both raise crossbred progeny

42
Q

traits influencing productivity

A

-reproduction rates
-growth
-fleece traits
-carcass traits

43
Q

reproduction rate characteristics and ways is impacts productivity

A

-ovulation rate
-fertility/prolificacy
-survival rate
-overall reporduction
-lambing precent
-all relatively low in heritability
-complicated inheritance

44
Q

growth characteristics and ways it impact productivity

A

-birth weight
-weaning weight
-rate of gain (birth to weaning 50d and weaning to 100d)
-yearling weigh
-mature body weigh
-body length/height
-efficiency of gain
-age of puberty
-high heritability

45
Q

how does fleece traits influence productivity

A

-more important to range producers
-make sure they can stay warm and use less energy
-high heritability

46
Q

carcass traits and how they influence productivity

A

-fat depth
-loin eye area
-percent fat
-precent lean
-dressing percentage
-many factors involved, hard to define, difficult to measure on live animals

47
Q

breed complementary

A

-utalize genetics from different breeds for specific traits
-a maternal breed is crossed with terminal breed

48
Q

what would you want out of crossing a maternal breed and a terminal sire

A

-wan growth rate and size from terminal sire
-maternal ewe should be:
-fertile: high rates of ovulation, long season
-easy lambing with good maternal instinct
-milk production and longevity
-stable for environment

49
Q

what is british “mule sheep”

A

-F1 cross of a hardy ewe (scottish black face) with a prolific heavy milking ram (bluefaced leicester)
-result is a hardy good milk producing ewe that is prolific and has longevity

50
Q

2 breed crisscross or rotation cross

A

-A x B
-AB x A males sold, replacement ewe lambs 50:50
-AB x B males sold, replacement ewes 75:25
-need 2 breeding groups
-at eq 2/3:1/3
-achieves 67% of the potential heterosis effect
-both individual and maternal heterosis

51
Q

3 breed crisscross or rotational cross

A

A x B
AB x C
ABC x A, then x B, then x C
-need 3 breeding groups
-at eq 5/32: 9/32: 18/32
- 40%,29%,57%
-achieves 87% or potential heterosis
-both maternal and individual

ANSC 355 (8 decks)

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