Weaning is done, nothing much more to think about for the ewes? Or is there? Don’t turn your back on ewes over the summer months. Loss of ewe body condition is costly to your business. A ewe mobilising condition is like drawing down a bank loan – useful in the short term, but costly in the long run.
A 60 kg ewe dropping 0.5 body condition score (BCS) loses about 3.0 kg LW. Each kg of LW mobilised “spares” feed demand by 3 kilograms of dry matter (DM) – allowing a ewe to lose 0.5 of BCS spares you 9.0 kgDM of summer feed.
Just like the bank, body condition needs to be repaid, and here’s where the interest payable becomes expensive. One kg of LW loss spares you around 3.0 kg of dry matter, but requires 5.5 kg of DM to regain 1 kg of LW lost. That’s over 80% interest payable on the body bank loan – not efficient for anyone’s business.
Mating success reflects both the flushing effect of pre-tup LW gain and ewe LW (BCS) at the start of mating.
Every extra kg of LW at mating increases ovulation rate 1.5-2.0% and potential lambing by 1.3%. Target ewe BCS at mating is 3.0.
Summer planning aims to maintain body condition (for ewes already at BCS 3.0) or to lift lighter conditioned ewes to reach target mating BCS.
Energy requirements (MJME/ewe/day) for maintenance and LW gain by mature ewes
|
Liveweight gain (g/day) |
45
|
50
|
55
|
60
|
65
|
70
|
|
0 (maintenance)
|
7
|
8
|
9
|
10
|
10.5
|
11
|
|
50
|
10
|
11
|
12
|
13
|
13.5
|
14
|
|
100
|
12.5
|
13.5
|
14.5
|
15.5
|
16
|
16.5
|
|
150
|
15.5
|
16.5
|
17.5
|
18.5
|
19
|
19.5
|
Hitting target body condition score for ewes
Tip 1: One BCS works out to 10% of ewe LW. 60 kg ewes needing to gain 0.5 BCS works out to a target of 3 kg of LW gain.
Tip 2: To convert MJME requirement to kgDM, divide demand by the MJME of the feed
Example: If ewes are normally 60kg LW and 0.5 of a BCS gain is needed over the next 60 days (3kg LW gain over 60 days) you’ll need to feed for 50g of LW gain/day. This works out to an extra 3.0 MJME a day or another 30 kgDM offered per 100 ewes per day for a feed that is 11 MJME/kgDM, over and above what you’re already feeding for ewes at maintenance.