How to stop losses when grazing youngstock on herbal leys

A fundamental misunderstanding of how to manage stock grazing herbal leys has caused heartache on some farms this summer, as more yearling cattle and weaned lambs have died from twisted guts.

Many businesses have embraced GS4-type leys because of the attraction of a £382/ha stewardship payment, and the potential to lift performance while lowering feed and fertiliser costs.

But an explosion of growth in a warm, wet July led to a worrying rise in fallen stock, resulting in businesses left with a bill instead of a cheque.

However, providing management is right and plans are made, advisers say the challenges of herbal leys can be overcome to realise the benefits.

See also: 8 expert tips for efficiently grazing herbal leys

Concerning trend

Soil and grassland adviser Jonathan Holmes, of Lordington Park Agronomy, says he has heard several reports of farmers losing lambs and yearling cattle on herbal leys this summer.

His worry is that these swards have been marketed as “bigger, better and sexier”, without enough knowledge transfer.  

“I’m concerned that because these leys have been sold as the answer to all farmers’ problems – including nitrogen and feed bills – they think it’s a magic-bullet solution. But we must never forget about the fundamentals of stock management.

“These leys are very different to a permanent pasture or standard ryegrass ley and need managing carefully or the consequences can be disastrous.”

He said several farmers had experienced a raft of issues, namely:

  • Yearling cattle dying from bloat
  • Losing two to three weeks of performance by not transitioning rumens onto the forage properly
  • Losing lambs within days of being weaned onto it
  • Having the wrong mix for the wrong environment, lacking fibre, and too many herbs, resulting in gaps in the sward
  • Cheap mixes with too much ryegrass or cheap varieties, and not enough timothy, fescues and cocksfoot.

How it kills stock

Vet Ben Strugnell of Farm Post Mortems, Hamsterley, County Durham, says this year’s sudden warm and wet weather led to rapid growth of clovers and herbal leys. This produced lots of leaf relative to stem.

“If we have a dry spring and the weather turns wet and warm in the summer, I can guarantee I will see lambs with twisted guts turning up within a couple of days; suddenly I will get 10-20% of my throughput as lambs with red gut,” he says.

According to Ben, lambs (sometimes calves), die through the following four-step process:

  • Clover-rich or herbal leys become too leafy and not fibrous enough. This means excessive carbohydrate and sugar is produced, making animals uncomfortable, which stops them from lying and ruminating.
  • Some sugars escape the rumen, entering the small intestine and colon where they are fermented by different bacteria, producing gas. While rumen gas can escape through belches, this gas cannot escape.
  • Gas build-up causes the small intestine to twist, cutting off the blood supply and so producing “red gut”.
  • Because artery pressure is stronger than vein pressure, blood can force its way in but not out, which causes breakages in the gut lining. This means bacteria access the bloodstream, leading to issues such as septicaemia.

What to do with herbal leys and high-quality pastures

The following points and information comes from beef and sheep consultant Liz Genever and independent grass and forage seed specialist Francis Dunne.

  • Carefully select your seed mix Ensure there is fibre and a range of grass species other than ryegrass; consider how it will work on your soil type and farm.
  • Transition This could take two weeks to be sure that rumen microbes have adjusted. If animals are going from a pasture with some similar species, such as clover, it will help.
  • Offer supplementary fibre Animals will self-regulate. This could be field margins of fibrous grasses, access to an adjacent field, or haylage.

More common seed mix options

  • Chicory If you want an entire field of chicory you tend to plant only about 2kg/acre, so 0.2kg/acre is quite a lot of chicory.
  • Timothy Often worth including, but you don’t need a lot. 1kg/acre is often enough and 5-6kg/acre is a full seed rate.
  • Cocksfoot Needs hard grazing or cutting in early summer. The best varieties are more palatable after late June as they don’t re-head, instead going vegetative for the rest of the year. It also has an earlier and later growing window than perennial ryegrass. Up to 2kg/acre can be used.
  • Mixes A lot of mixes with moderate diversity include something like 0.2kg of chicory, 0.3kg of plantain and 50g of yarrow.
  • Other species Alsike clover is quite dependable. It is a biennial and tends to be easy to establish and manage, doing well on heavier, acidic soils. Birdsfoot trefoil is quite expensive and often not very successful, but has done well in the limestone areas of the Cotswolds and Yorkshire Dales. Yarrow is a good choice as it grows just about anywhere and is drought-tolerant, often being the last plant in the pasture to die.
  • Management High-quality swards with herbs and clover require rotational grazing to minimise selective, preferential grazing. Chicory can become very stemmy and unpalatable. If cut too late, stalks poke through silage wrap. Aiming to cut every 30-35 days for silage will help manage it. Move every two to three days if you can, but daily is even better.

Adapt what you do to the risks associated with the crop

  • Stemmy chicory can cause scald in lambs’ feet.
  • Ewes and lambs can be slow to transition onto chicory as they need to adjust to the high tannin levels in the leaves.
  • Red clover might increase the chances of bloat. Try introducing lambs after clover has been silaged, so the crop can grow with the lambs, rather than going into 30cm of red clover.

Consider what the stock are used to

  • Plan where the herbal ley will be. Can it be in a field with large field margins to offer other forages, or next to a field to offer run back to a pasture they have been eating?
  • Don’t move stock if they are hungry – time the movement of lambs or calves when they are full and content, so they don’t gorge on the new crop.
  • Introducing animals onto the high-quality ley for a few hours before returning back to the rotation will help rumen transition.

Do it right and benefit

  • Adapt your business around herbal leys and managing it for best results.
  • Used well, the GS4-type ley can bring in subsidy income, increase daily liveweight gains in youngstock, cut fertiliser, reduce diesel use on the farm, and look good in a carbon audit.
  • Clovers drive production through nitrogen production and optimising summer growth and nutrient density. Issues can be overcome through successful transition and grazing management.
  • Including white clover (at least 1kg/acre) can increase annual dry matter production by >1.5t/ha.