Advancing the breeding season and increasing production in early lambing flocks

August 17, 2022

Spring lamb prices this year were high, even when increased numbers appeared in April, with farmers receiving 630 p/kg carcase. Brian Hanthorn, Beef and Sheep Adviser from the College of Agriculture, Food and Rural Enterprise (CAFRE) reported that prices remained high and peaked in June at around 675p/ kg carcase. Although concentrate costs have been challenging in early lamb production farmers remain hopeful that concentrate costs will fall to some extent going forward. The main challenges for many early lambing flocks to drive profit are to target a tight lambing, a litter size of around 1.65 lambs reared per ewe and to have all the lambs away within 16 weeks, before any significant price drop occurs.

The place for early lambing

Early lambing integrates very well with other enterprises on the farm from a labour and cash flow point of view. Growing early spring grass is essential for the system to work well and to reduce concentrate usage.  

Some specific lowland breeds will mate early in the year however most lowland breeds and cross breeds within the Northern Ireland flock need hormonal intervention to encourage them to lamb early in the season and to improve prolificacy. There are several different programmes that can be used to help ewes come into season early and produce a good crop of lambs. Two of the most common programmes are progestogen impregnated sponges with PMSG and secondly melatonin implants.

Sheep sponges and PMSG

Using progestogen impregnated sponges as part of the breeding programme allows a group of ewes to be mated as a batch on one day, and the use of a hormone injection PMSG will increase ovulation rates and in turn improve litter size.

One of the main benefits of sponging and PMSG is that it gives a tight lambing with most ewes lambing over 4-5 days which could suit part time farmers. Sponging sheep will advance the normal breeding season by around 6 weeks.

A typical programme for synchronising ewes is suggested below in Table 1.

Table 1. Synchronisation programme for early lambing ewes

 ProcedureTimeframe
Insert spongesDay 0 AM
Remove sponges and inject PMSGDay 12 AM
Mating hogget ewes (36 hours after sponge removal)Day 13 PM
Mating mature ewes (48 hours after sponge removal)Day 14 AM
Remove ramsDay 16
Introduce rams for repeatsDay 28
Remove ramsDay 34
Scan ewes and return non pregnant ewes to ramDay 80

Improving the performance of sponging

To obtain the best results with sponging it is important to have the ewes weaned at least 6 weeks in advance and in body score of around 3.5. Have plenty of mature rams available, ideally 3 rams per 20 ewes. Ram lambs are generally not recommended. Order the sponges well in advance and store the PMSG in a fridge according to manufacturer’s instructions. PMSG is administered into the muscle immediately after the sponge removal, the amount given per ewe will depend on breed of sheep and month of the year. Consult your veterinary surgeon for specific advice and read the instructions clearly.

Melatonin implant

This is a hormone administered at the base of the ear around 35 days prior to ram introduction to the flock. It works by releasing a small amount of melatonin similar to what the ewe produces naturally as daylight hours decrease. It therefore has the ability to make the ewes come into season earlier in the year and produce a lambing percentage similar to a March lambing flock.

Table 2. Melatonin implant programme

ProcedureTimeframe
Remove rams/ teasers from neighbouring fields and paddocksDay 1
Implant the ewes at the base of the ear. Keep isolated from male sheep, this includes sight, sound and smell.Day 7
Introduce rams (35 days after implantation). Peak mating activity will occur 25-35 days after introduction of rams.Day 42

Summary

Lamb prices this spring have been encouraging, but it is still very important for early lambing flocks to produce at least 1.65 lambs per ewe. Either sheep sponging /PMSG or Melatonin implants are useful programmes to bring forward the lambing season for early lambing flocks, make lambing more compact and achieve their targets to improve output and profit. Consult your veterinary surgeon about which programme is most suitable for your flock and follow their advice.

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