Friday, March 29, 2024

Happy sheep, happy farmer

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Managing ewe feed requirements over winter is not an easy task but an important one. Looking after the ewe allows her to look after your profit earning potential – the lambs.  Given where a lamb gets its energy from in the early stages of its life it is easy to understand that a well-conditioned and well fed ewe has what it takes to produce lambs that survive and grow well.  The challenge is getting that condition on and the feed in front of the ewe when it really counts. ‘By the time ewes are scanned at 80 to 100 days the die is cast.’
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PGG Wrightson recently ran a series of workshops to help kick start farmers into planning ewe feed management.

Veterinarian and PGG Wrightson national manager of animal health Andrew Dowling said the key was to make decisions in early winter. 

“Late winter the energy demand of a pregnant ewe is too great to be met solely by grazing.”

So the ewe relies on body reserves to get her and her lambs through.

For a while now scientists and advisors have been urging farmers to body condition score (BCS) their ewes at critical times of year. Relying on liveweight alone or simply assessing ewes by eye can lead to an inaccurate judgement of ewe condition, especially where ewes are woolly or there is a range in frame size.

This can lead to underestimating and failing to manage the feed requirements of the tail end of the ewe flock, compromising the ewes ability to build the body reserves needed to meet the high energy demands of late pregnancy and lactation. 

A hand on the back to feel the amount of body fat covering the spine and lumbar along the loin area is a simple and quick way to evaluate ewe condition on a scale of one to five.

The information can then be used to prioritise ewe feed requirements. Thin ewes can have first pick to ensure high quality feed intake, well-conditioned ewes can be maintained and if numbers are significant, over fat ewes can be held back.

Dowling said adding condition to ewes with a BCS of 3-4 was not likely to improve performance. However, identifying the thin ewes early and lifting their body reserves would provide the buffer they need in late winter. 

From conception through to lambing there are some critical times to be aware of, where energy supply to the ewe can affect the factors that contribute to lamb survival. 

Dowling said about two thirds of the variation in lamb birthweight was influenced by ewe nutrition before day 80 of pregnancy. 

“By the time ewes are scanned at 80 to 100 days the die is cast”

Relying on liveweight or just assessing ewes by eye can lead to an inaccurate judgement of ewe condition.

Placental development occurred over this period. A good placenta was needed to transfer nutrients from the ewe to the unborn lamb and underdevelopment could increase the risk of getting small lambs at birth. 

So feeding over this time not only supported ewe condition for later in the season, nutrition prior to scanning lays the ground work for growth of the unborn lamb. 

“Up to day 100 you can still gain BCS on your ewes”. 

He said this was the time in-lamb hoggets must be well fed to allow them to grow, after day 100 the energy demands of pregnancy take over. 

As pregnancy progresses the ewe is often battling a decline in gut capacity because of her growing lambs and quality feed becomes ever more important for ensuring she supports live lambs through to docking. 

Dowling explained that udder development occurs in the two to three weeks prior to lambing and ewes in poor condition over this time can experience poor colostrum production and their peak lactation levels be compromised. 

The unborn lamb does the majority of its growing after scanning time and studies show that underfeeding ewes over this time can lead to light lambs with less body fat reserves. These are two factors critical for supporting survival in the first few hours after birth. 

Dowling said from set stocking to docking a ewe should lose a BCS.

If so, it was likely to have two or even three well-grown lambs making the ewe an efficient converter of grass to lamb. From docking through to weaning the ewe would be putting that condition back on.

“Any who fall short when condition scored again pre-mating can be priority fed.”

The timing of feed demand over gestation means that it is critical to ensure ewes are getting what they require when they require it. Over a time where feed is limited and pasture may not even be growing it is equally important to ensure none is wasted.

Along with condition scoring, detailed information on the pregnancy status of the ewe allows a better understanding of the feed requirements and when the critical times are likely to occur. This allows mobs to be prioritised after pregnancy scanning to ensure ewes with high energy demands get the best possible opportunity to satisfy these. 

All in order

Veterinarian Andrew Dowling suggested an order of priority for pregnant ewes.

Top priority for ewes bearing triplets then early twins, next the low BCS late twins, followed by ewes with lesser energy needs such as late twins and all singles (early and late).

He said let twin and triplet bearing ewes graze longer, higher quality pastures.

“This allows them to get a full mouthful of feed each bite.”

It might require some thought into supplementary feed to maintain pasture covers and the use of modern pasture cultivars to provide quality.

Dowling said farmers who got caught short this year, should review their feed budgets for next year. 

In parts of the country’s harder hill-country areas it is not always easy or economical to adopt these recommendations – however, prioritising wherever possible still has the potential to assist the ewe in her role of converting of grass to lamb. It is important to note that it is worth looking after today’s high fertility ewe. 

Work by Paul Kenyon at Massey University shows that, for the amount of grass eaten, the higher fertility ewes of today are more efficient than the traditional single bearing ewe.

Dowling said even if a triplet only ended up rearing twins she was still more efficient than a single. 

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