Joanna Grigg

Give poor condition multiple-bearing ewes and the earliest lambers the best and the most feed.

If August is tight for feed, rank stock according to risk of metabolic issues and feed the highest risk class.

These are the messages from Massey University’s Professor Paul Kenyon, on the best use of what are likely to be low feed supplies.

Late pregnancy is too late to alter lamb birth weights significantly. Any attempt to increase them through high levels of ewe feeding in late pregnancy is limited by placental development. Placenta size was set by day 100. For these reasons, feeding in late pregnancy is all about setting up for maximum lactation and avoiding metabolic issues like sleepy sickness.

Speaking at a Taranaki Farming for Profit day via podcast, Kenyon said farmers should manage stock to avoid ups and downs in feeding levels. Stress to the ewe must be avoided, so aim for minimal yarding time and easy-paced mustering. Avoid any break in eating and moving stock during bad weather.

Kenyon suggests that farmers still to pregnancy scan should consider hiring an extra person to condition score ewes as they are walked up into the cradle. Identifying the poorest 20%-30% of ewes, and marking them, is more important than worrying about exact scores. These ewes are typically less than 2.5 out of 5 in condition score.

“Just raddle these really skinny ewes with another colour from that for dry or multiples, take them out and give them the most and best feed.”

At any point post-scanning, an option is to put the poorer condition singles in with the early multiples and feed preferentially. This cuts down on mob numbers.

The trend seen in early-mated mobs, tupped in drought affected areas during 2020, has been for fewer ewes than the expected 80% to conceive in the first cycle. Some mobs had only 30% conceive in the first cycle, with most in the second.

Splitting the poorer condition twinning mob again, into first cycle and second/third cycles, gives more intake options. The early ewes could be given the priority feed while the later ewes could be held on lower covers for a few extra days.

Kenyon calculates that at scanning, some ewes may be 100 days pregnant and some may be only 50 days pregnant. This is with three breeding cycles.

“Why feed them the same?”

The lates can be held on lower covers as it’s likely that, when they are set-stocked, spring covers will be much higher and grass growing anyway, he said.

“I don’t mean having 10 mobs to manage pre-lambing but early multiple ewes should, at least, be out on their own.”

Kenyon said the energy requirements to lift a ewe from 2.0 to 2.5 condition score requires 75 megajoules (MJ) of energy above maintenance, but to lift from 3.0 to 3.5 takes 240 MJ of energy above maintenance. As a result, adding condition to poorer-condition ewes is the most efficient use of feed.

Plan to give the best paddocks for lamb survival to multiples. Kenyon said tailing tallies collected over the years will quickly show the number of tails per block compared with what was set stocked in there initially.

“Which blocks are worst for survival? Avoid these for multiples.”

Once paddocks are over 30 degrees gradient, the chance of ewe and multiple lamb separation in the first 24 hours increases greatly, he said.

To slow the decline in lactation volume, ewes should be lambed on pasture covers over 1200kg DM/ha, and covers should not drop below this. Peak lactation is two weeks post lambing. The onset of lactation and colostrum production are affected by ewe nutrition in late pregnancy. Total milk production is influenced by feeding during late pregnancy and lactation as well as body condition.

ALLOCATING TWIN TUCKER

The first autumn for Tom Cranswick was a baptism of fire with a drought at Winterhome, the sheep and beef farm he manages in south Marlborough.

Despite the feed shortage January to March, the pregnancy scanning percentage has been maintained in the crossbred ewes at a pleasing 175%. The dry rate for the mixed age ewes was 1.8%, and 7% of the ewes are expecting triplets. Two-tooths scanned 173%.

Ewe condition was boosted by preferentially feeding 650 lighter ewes with peas from January through to tupping in March. These ewes, below condition score 2.5, were taken out of the main mob in January.

Another portion of the mixed-age ewe flock (between condition score 2.5 and 3.0) went onto rape crops four days before joining with the ram in late March. They were left alone, stress free, for 24 days. This rape crop was sown early December as a provision for tupping feed.

To reduce the call on feed, cows were weaned at the beginning of March and calves were weaned onto balage and sold two weeks early. Half the hoggets were sent away on grazing and not put to the ram, while the remainder were also run dry.

Now, with 175% lambs on board the ewes, Tom has the challenge of feeding them through to lambing. Growth has recovered, helped along with additions of phosphate, sulphur and nitrogen.

The plan is to graze multiple-bearing ewes on rape and on saved pasture to meet maintenance. Mob size will be kept under 600 to reduce competition for feed. The poorer-condition multiples will be mobbed together and go in front of the singles and cows.

Tom said because the condition score range across the flock is quite a tight bell curve without a big group of light, single-bearing ewes, the singles will be all treated the same. They will follow up after the twins, cleaning up pasture.

“Ewes always have enough milk for a single, even under condition score three.”

Ram harnesses were used and, in combination with foetal aging, this will allow twinning ewes to be grouped into early, mid and late mobs.

“Aging is extremely useful when it comes to allocating feeding.”

Lambing starts August 20, and more ewes conceived in the middle of the 2.5 cycles this year.

Pre-lamb feed strategies

  • Use scanning results to create preferential feeding mobs
  • Pull out light tail-end first cycle single ewes (after scanning) and preferentially feed with first cycle multiples
  • If feed is tight before set stocking, allocate shorter pasture to the best-conditioned ewes lambing a single in the second cycle. They will lamb later, potentially as feed is growing faster.
  • Use winter rotation to set up good covers for lambing i.e. those paddocks that multiples will lamb in should not be grazed before set stocking
  • Avoid sudden changes in feeding (use break fences to control).