Sheep and Goat Breeding Programs

Question 1

age at puberty for sheep vs goats

Answer 1

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

Question 2

age at first breeding for sheep vs goats

Answer 2

both = 6-8m

Question 3

source of P4 during pregnancy for sheep vs goats

Answer 3

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

Question 4

gestation length for sheep vs goats

Answer 4

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

Question 5

pseudocyesis for sheep vs goats

Answer 5

sheep = uncommon
goat = common

Question 6

length of estrus cycle for sheep vs goats

Answer 6

sheep = 17d
goat = 21d

Question 7

ovulation rate for sheep vs goats

Answer 7

sheep = breed dependent
goat = most breeds are prolific

Question 8

behavioural estrus for sheep vs goats

Answer 8

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

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

Question 9

do sheep or goats have more subtle estrus behaviour

Answer 9

sheep

Question 10

what is the long day breeding based on

Answer 10

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

Question 11

the first estrus is _____

Answer 11

silent. so they are fertile but non-behavioural

Question 12

how long is the ovulatory season

Answer 12

4 months

Question 13

when do females give birth naturally

Answer 13

spring

Question 14

when are lambs/kids weaned

Answer 14

60 days

Question 15

when are replacement females bred

Answer 15

7 months

Question 16

what is the reason for implementing accelerated lambing programs

Answer 16

-decreases/eliminates the open and dry period

Question 17

what is required for successful accelerated lambing programs

Answer 17

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

Question 18

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

Answer 18

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

Question 19

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

Answer 19

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

Question 20

what are some methods of hormones for estrus synchronization

Answer 20

-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

Question 21

what is required for ovulation in the anovular period

Answer 21

injetion of eCG or PMSG

Question 22

two names of prostaglandin drugs

Answer 22

estrumate, lutalyse

Question 23

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

Answer 23

will only work when females have a CL

Question 24

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

Answer 24

to synchronize estrus

Question 25

how does a long CIRD program work during the ovulatory season

Answer 25

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

Question 26

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

Answer 26

24h after CIDR removal

Question 27

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

Answer 27

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

Question 28

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

Answer 28

-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

Question 29

when do you introduce males when using MGA?

Answer 29

males introduced 24-26h after feeding stopped

Question 30

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

Answer 30

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

Question 31

when is the male effect good vs bad

Answer 31

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

Question 32

what does the introduction of males cause

Answer 32

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

Question 33

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

Answer 33

no later than 14d after teasers are introduced

Question 34

when is the teaser effect used

Answer 34

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

Question 35

how does the teaser effect work

Answer 35

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

Question 36

what are the two ways ewes will respond to teasing

Answer 36

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)

Question 37

what is the dormitory effect

Answer 37

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

Question 38

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

Answer 38

75%

Question 39

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

Answer 39

-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)