Reproduction

Question 1

what is the advantage of having Christmas lambs?

Answer 1

better lamb price at easter market

Question 2

what is the advantage of spring lambs?

Answer 2

easy management due to better grass growth and weather

Question 3

how is seasonality of sheep triggered?

Answer 3

light enters the eye, triggers the optic nerve which sends impulses through the hypothalamus to the superior cervical ganglion which then reaches the pineal gland, this then does/doesn’t produce melatonin depending on the day length which then leads to GnRH release

Question 4

how does light effect melatonin production?

Answer 4

light blocks melatonin production

Question 5

how does melatonin effect GnRH?

Answer 5

low melatonin release leads to low GnRH

Question 6

is melatonin secreted more during light or darkness?

Answer 6

darkness

Question 7

how long is the oestrus cycle of a sheep?

Answer 7

roughly 16 days

Question 8

how many follicular waves do sheep have?

Answer 8

2-5 waves

Question 9

how many ewes should you have per ram?

Answer 9

30

Question 10

how is most commercial artificial insemination of sheep carried out?

Answer 10

laparoscopically into the oviduct with sedation

Question 11

what are some ways reproduction can be modified in sheep?

Answer 11

genetics
ram effect
day length
nutrition
ram and day length
melatonin implants
pharmacological

Question 12

what determines the fecundity of a ewe?

Answer 12

bone morphometric protein signalling in the ovary

Question 13

what is the ram effect?

Answer 13

introduction of a novel male or after 2 weeks of male absence to inducing cycling in ewes

Question 14

how does the ram effect alter the oestrus activity of ewes?

Answer 14

some ovulate silently after ram is introduces
those who didn’t have a silent heat ovulate around day 19
day 25 silent heat ewes ovulate again

Question 15

why would a teaser ram be used for achieving the ram effect?

Answer 15

don’t won’t ewes mated on their first silent heat

Question 16

how can seasonality be manipulated in sheep?

Answer 16

exposure to artificially shortened/lengthened days

Question 17

what is an easier way of manipulating the seasonality of ewes than altering the day length of all the ewes?

Answer 17

just do it for the rams then use the ram effect to bring on the ewes

Question 18

how can melatonin be given to ewes?

Answer 18

implant into ear (regulin)

Question 19

what is the programme for using melatonin implant to manipulate the seasonality of ewes?

Answer 19

30 weeks before chosen lambing time remove ewes from sight/smell of ram (day 1)
put melatonin implant on day 7
introduce ram 30-40 days after implantation
use teasers for first 14 days to get a tighter lambing block

Question 20

what are the two effects of flushing?

Answer 20

short term on the growing follicular waves
long term to bring them out of seasonal fertility trough sooner

Question 21

what is the static effect of flushing?

Answer 21

ewes with a greater BCS have a higher ovulation rate

Question 22

what is the dynamic effect of flushing?

Answer 22

ewes with an increasing live weight gain have a higher ovulation rate