Ewe Breeding

Question 1

What is a commonly-used technique that can both synchronise and advance the breeding season without the use of chemicals?

Answer 1

Use a teaser ram. Put them in 4weeks before AI/breeding can advance the breeding season. Shortens lambing period and encourages ewes to mate 2-3 weeks earlier. Before intro of teaser ram, the ewes should be avoiding the sound, smell and sight of the ram – the first ovulation post introduction will be silent for 3-5 days.
Nutrition – flushing the ewes. BCS 2.5-3.0

Question 2

What commercially available pharmaceutical options does he have to advance the breeding season for these BFL ewes

Answer 2

Melatonin implants (1)

Progesterone sponges alone (1)

Progesterone sponges with follicle-stimulating treatment (eg PMSG or eCG) (1)

(NB there are no prostaglandins licensed for sheep in UK)

Question 3

Mr Bainbridge has heard from his neighbour that ‘hormone treatment would be just what he needs’ and he asks you to explain the options (total 6 marks)

a. In note form, outline the advantages and disadvantages of melatonin implants

Answer 3

Advantages

• Triggers natural hormonal events giving multiple fertile cycles (1)
• Low pressure on the rams as oestrus not synchronised (1)
• Minimal additional labour required (1)
• Some data to show improved ewes pregnant & more lambs born (1)

Disadvantages –

• Cost (1),
• Need to plan well in advance (1),
• No synchronisation (1)

Question 4

Having heard you explain that, he says he wants to know about sponges. Explain the advantages and disadvantages of progesterone sponges and PMSG injection in note form (total 6 marks)

Answer 4

Advantages

Will both synchronise (1) and advance breeding season (1), potential to improve prolificacy due to PMSG (1)

Disadvantages

Cost (1), potential for too many multiples if over-estimate PMSG dose (1)

Requires lots of ram power (1), high labour requirements (1)

If too deeply in anoestrus, may only get one cycle and then return to anoestrus (1)

Question 5

Should he have wanted to do AI in these ewes, which procedure would he need to use?

Answer 5

Progesterone sponges with PMSG/eCG injection

Question 6

Once he has heard you explain all the options and the costs, he says that he really likes the thought of a simple option (‘one that doesn’t involve chemicals and cost’). He wants to get these 30 ewes to lamb in February. Outline the steps he needs to go through to achieve this and indicate the expected dates of lambing. (total 8 marks, 1 for each stage).

Answer 6