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Theriogenology > Sheep and Goat Breeding Programs > Flashcards

Sheep and Goat Breeding Programs Flashcards

1
Q

age at puberty for sheep vs goats

A

sheep = 4-7m
goat = 3-7m

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2
Q

age at first breeding for sheep vs goats

A

both = 6-8m

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3
Q

source of P4 during pregnancy for sheep vs goats

A

sheep = CL and placenta after day 75
goat = CL only

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4
Q

gestation length for sheep vs goats

A

sheep = 144-151d
goat = 147-155d

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5
Q

pseudocyesis for sheep vs goats

A

sheep = uncommon
goat = common

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6
Q

length of estrus cycle for sheep vs goats

A

sheep = 17d
goat = 21d

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7
Q

ovulation rate for sheep vs goats

A

sheep = breed dependent
goat = most breeds are prolific

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8
Q

behavioural estrus for sheep vs goats

A

sheep = anorexia, vulvar swelling, small amounts of mucus, will follow ram

goat = restless, wag tail, vocalize, swollen vulva, clear vaginal mucus, follow buck

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9
Q

do sheep or goats have more subtle estrus behaviour

A

sheep

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10
Q

what is the long day breeding based on

A

based on the decreased day length causing increased melatonin secretion…. this stimulates the hypothalamus to secrete GnRH after about 45d (early august)

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11
Q

the first estrus is _____

A

silent. so they are fertile but non-behavioural

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12
Q

how long is the ovulatory season

A

4 months

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13
Q

when do females give birth naturally

A

spring

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14
Q

when are lambs/kids weaned

A

60 days

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15
Q

when are replacement females bred

A

7 months

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16
Q

what is the reason for implementing accelerated lambing programs

A

-decreases/eliminates the open and dry period

17
Q

what is required for successful accelerated lambing programs

A

-out of season breeding
-needs good organizational management
-two program options (3 in 2, cornell star)

18
Q

why should we manipulate the estrus cycle in small ruminants? (4)

A

to shorten the lambing window
* Synchronization can yield a shorter breeding period, which means a shorter lambing period
* Easier to observe females, manage dystocias
* Easier to observe neonates, better manage
* More uniform crop of animals for marketing

19
Q

what is the benefit of manipulating the estrus cycle? (3)

A
  • Year-round milk production for dairy farms
  • Off-season markets (higher prices)
  • Employ accelerated lambing systems (more efficient use of animals)
20
Q

what are some methods of hormones for estrus synchronization

A

-prostaglandin injectable (off label for sheep and goats)

-progesterone (CIDR) (approved for sheep, off label for goats)

-progesterone (MGA); given in feed, only for meat animals

-eCG or PMSG injectable; stimulates FSH and LH

21
Q

what is required for ovulation in the anovular period

A

injetion of eCG or PMSG

22
Q

two names of prostaglandin drugs

A

estrumate, lutalyse

23
Q

what is the one criteria for a prostaglandin program in the ovulatory program to work

A

will only work when females have a CL

24
Q

what is the purpose of the prostaglandin program during the ovulatory season

A

to synchronize estrus

25
Q

how does a long CIRD program work during the ovulatory season

A

put CIDR in for long enough that it eventually becomes the ONLY P4 source for the sheep. it acts like a CL

this will allow all females to come into estrus at the same time

26
Q

when does a male need to be introduced in a CIDR program

A

24h after CIDR removal

27
Q

what is an extra step that is needed for the short CIDR program compared to the long CIDR program

A

concept is the same but we MUST inject prostaglandin 1-3 days before we have to remove the CIDR to eliminaete any CLs that are still present

28
Q

what needs to occur for a CIDR program during the ANOVULATORY OR TRANSITION period?

A

-insert CIDR like the short CIDR program
-inject a prostaglandin 1-3d before CIDR removal IF you suspect any animals are still cycling
-required to inject eCG/PMSG at the time the CIDR is removed to induce ovulation

29
Q

when do you introduce males when using MGA?

A

males introduced 24-26h after feeding stopped

30
Q

what is the difference between MGA program during ovulatory season vs anovulatory season

A

ovulatory = eCG 8h after last feeding is OPTIONAL. and feed for longer

anovulatory = eCG 8h after last feeding is REQUIRED. dont have to feed for as long

31
Q

when is the male effect good vs bad

A

best during transition season, worst during ovulatory season, variable during anovulatory season

32
Q

what does the introduction of males cause

A

silent heat…. CL regresses prematurely and then a behaviourally normal heat follows

33
Q

when do teaser rams need to be removed and replaced with fertile rams?

A

no later than 14d after teasers are introduced

34
Q

when is the teaser effect used

A

in the first few weeks prior to the expected onset of natural breeding season. no exposure to rams at least 30d prior

35
Q

how does the teaser effect work

A

rams and teasers give off pheromones which stimulate non sexually active ewes to ovulate within 2-3d of joining with teasers

36
Q

what are the two ways ewes will respond to teasing

A
  1. show behavioural estrus and mate with rams ~3w after teaser introduction (early mating group)
  2. or display estrus and mate some 4 weeks after teaser introduction (late mating group)
37
Q

what is the dormitory effect

A

occurs during the transition season. its when some animals start to cycle, ~25% of the anestrus group will cycle as well. the rest will respond within a few weeks

38
Q

what is the expectation of # of ewes lambing from FIRST cycle breeding success?

A

75%

39
Q

what are some factors affecting success in small ruminant breeding programs/?

A

-some breeds are more seasonal than others
-ram to ewe ratio is critical
-CIDR losses
-MGA and feed management
-nutrition (BCS, flushing)
-timing of male intro for synch programs (if too early, can be bred before ovulatory window)

Theriogenology (12 decks)

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