Tuesday 27 September 2016

Sheep: Under-conditioned ewes will get preferential feeding

Tommy Boland

Published 10/08/2016 | 02:30

Preparation has started for next year's lambing
Preparation has started for next year's lambing

As hard as it is to believe we are now back preparing for lambing 2017.

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This may seem a bit premature as most of the 2016 lamb crop is still with us, but we are only eight weeks away from sponging the ewes. At weaning time we checked the BCS of the ewes and all were at a satisfactory level with an overall flock average on the Smartgrass study of 2.8.

These ewes were then restricted in terms of their energy intake post weaning to shut down milk supply, so we will recheck them tomorrow and make our decisions in terms of grass allocations between now and mating.

We target a BCS at mating of 3.5 and recent research carried out by Frank Campion highlights the positive relationship between BCS and subsequent ewe reproductive performance. There were some differences between the treatments on the Smartgrass study in terms of ewe BCS at weaning with the multispecies swards (either containing 6 species, or 9 species giving higher ewe BCS and live weight at weaning than the ewes grazing PRG or PRG plus white clover swards).

Ewes in all treatment groups were pretty consistent in terms of BCS so hopefully we will not have to sub-divide the flocks between thin and well-conditioned ewes between now and mating.

We already have eight separate flocks to manage so don't want to increase this any further.

At a commercial level however there is a strong argument to be made for targeted preferential feeding of under-conditioned ewes.

This may mean splitting off thin ewes and giving them some preferential feeding, either through better quality grass or a longer flushing period.

It is also important as we don't want to have ewes over fat at mating as this can also have a negative impact on fertility and reproductive performance.

Grass growth rate is currently running at 48 kg of DM per ha per day on the experimental site, with no difference between the multi-species mixes and PRG only.

This is despite the much lower nitrogen application rates on the multi-species treatments.

The lower fertiliser nitrogen application is being compensated by the presence of clover in these swards and the high temperatures of recent weeks have contributed to an increase in the clover content in the sward.

Herbage samples

As part of Connie Grace's PhD, herbage samples are collected during each rotation and manually separated into the different functional groups (grass, legumes, herbs).

We see an increase in the legumes from June onwards and also in the herb (chicory and clover content) of these swards.

Our last treatment for worms took place when lambs were twelve weeks of age.

At the time of writing we are still awaiting the FEC results at week 20, but no dosing has taken place in the intervening time.

Looking at the week 18 FEC results, I suspect that the PRG and PRG plus white clover treatments will need a dose now, while the multi-species swards will still be below threshold.

Since weaning lamb growth rate is averaging just below 200 grams per head per day, which, while below what we would like, the PRG only group are behind all other treatments.

Ewes were dipped last week and all lambs have been treated to prevent fly strike.

The warm wet conditions of late have presented ideal conditions for fly strike so its definitely easier to prevent this particular condition.

The next few weeks will see more of a focus on disseminating the results of our research with a number of discussion groups due to visit the farm and also Connie, will be presenting her work at the European Grasslands Federation meeting in Norway.

The opportunity to attend these conferences is an essential part of a student's training and it is also one of the few perks of a PhD that you get to travel to some interesting locations to communicate your findings.

We will continue to draft lambs at a live-weight of 45kgs for the moment though the recent price drop has really taken the bite out of the lamb market.

Dr Tommy Boland is a lecturer in sheep production at Lyons Research Farm, UCD. email: tommy.boland@ucd.ie @Pallastb

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