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April 26, 2020
Across most of New Zealand, lambs are only just being conceived, or not even conceived yet.

However, it is never too early to start planning.  It is important to already be thinking about what we will do the day after the pregnancy scanner has been.  It is largely too late to do much about the scanning result now as it will reflect the condition score the ewes are in and the nutrition and weight trajectory over the tupping period. But this doesn’t mean we can’t have an impact on the number of lambs we expect to see in the tailing yards.  By optimising ewe nutrition between now and lambing, we can give the ewes the best chance of bringing in thriving lambs in spring.

If you are not already doing these things, it is time to ask why not?

  1. Calculate how many twin-bearing ewes you are likely to have.  Last year’s scanning result will be a good guide here.
  2. Analyse all feed sources on the property to know exactly what you are feeding.  Silage and balage can vary widely in terms of the energy they provide to ewes.  Knowing the energy content of all available feeds enables you to plan with precision.
  3. Condition score your ewes at your earliest convenience.  This can be just a mob sample of 50 ewes.  If you don’t measure something you can’t manage it.  The quicker you understand what you are dealing with the better you will go.  If you can measure something, why would you guess?
  4. Review last year’s lambing data and start thinking about your best lambing paddocks. This is where you will be lambing your lightest twin-bearing ewes this year.
  5. Start running energy budget options.
  6. Do the math – calculate the value of a surviving twin born lamb (and its mother) and compare this with the investment in feed required to achieve a good outcome. There is no better return on dry matter than feeding a skinny twin-bearing ewe.

Once the rams are removed our focus needs to be on keeping the ewes maintaining weight until pregnancy scanning and, once scanning has been completed, preparing options to provide the necessary requirements to twin-bearing ewes. This obviously isn’t an easy task particularly in a year like this, but as a wise person once said, “hope is not a course of action”.  It is not the year for getting it perfect, but getting our hands on our ewes and condition scoring them as often as practical, will be critical in a year like this. Small tweaks to which ewes get which feed will have a big impact on the overall outcome. Twin-bearing ewes present the greatest opportunity on a sheep farm. They have the potential to deliver two great lambs, but if they are not managed well all of this potential can easily end in naught.  

Ewes tend to be grazed on low quality feed in early autumn.

 

Twin-bearing ewes have a big demand for energy

It is important that we think now about what our twin-bearing ewes will be eating between scanning and lambing.   Once scanning comes around, the feed that we have available is relatively set in stone. The task then becomes focused on allocating this feed to the sheep that need it most.  The earlier that we start thinking about this, the better the planning will be.  We know that in the last two months of pregnancy the requirements of twin-bearing ewes really start to ramp up.  The difference at the point of lambing is 4MJ of energy per day between a twin-bearing and single-bearing ewe.  This difference equates to 1.5kg of average silage per day over and above what a single-bearing ewe requires – just to maintain weight and the growing foetus.

Ewe condition and lamb birth weight drive lamb survival

Ewe condition score at lambing is a critical driver of lamb survival because it is the biggest driver of lamb birth weight.  Light lambs result from poor nutrition during pregnancy and the likelihood of survival is a lot lower in these light lambs. This is particularly true under the cold and wet weather that can be experienced at lambing time.

source: A Thompson Lifetime Wool

For the most part, single lambs are born near the optimum birth weight range.  One of the concerns with single-bearing ewes is them getting too fat.  If they lamb at greater than condition score 3 there is a good chance lamb birth weight will start getting into the dystocia territory. Single-bearing ewes can happily lamb in an average condition score just below 3 (average 2.7).

The twin-bearing ewes are the ones that require close attention to detail to maximise the opportunity.  Our aim is to have as many twin-bearing ewes as possible above condition score 3 at the point of lambing.  Ideally these ewes are in an average condition score of around 3.2.  This takes some focused management because the increased energy requirement of twin-bearing ewes means that they will naturally be in poorer condition than single-bearing ewes (if no management intervention is made).

source: A Thompson Lifetime Wool

Hands out of pockets

Condition scoring ewes and making decisions about their nutrition based on that score is the cheapest, easiest, and most effective tool that we have for improving lamb survival – particularly in a year like this where feed is limited. The highest priority ewes should be the twin-bearing ewes in lighter body condition.  The skinny twin-bearers are highly likely to deliver light lambs with a significantly increased risk of lamb mortality as well as ewe mortality.  By separating off these ewes and offering them some better nutrition we can lift lamb survival, lift ewe survival and enhance profitability.

It does not matter how many years of experience anyone has at assessing sheep by eye, getting our hands on their backs is the only true way of assessing the fuel tank of that ewe. Condition scoring is quick, simple and powerful. In fact, it is our most powerful tool for navigating this season.

Need a bit of help?

If this all sounds overwhelming and you don’t know where to start, please get in touch with the team here at neXtgen Agri.  

We are launching an online course in a few weeks designed specifically to guide you through these decisions, calculations and analyses.  We will provide coaching on carrying out these tasks as well as online discussion with like-minded farmers to talk through the opportunities and challenges. If that sounds of interest to you please register your interest by emailing info@nextgenagri.com or call +64 3 550 2442.

Dr Mark Ferguson & Darren Gordon
Article by:
Dr Mark Ferguson & Darren Gordon

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