Look to forage to find out about the health of your ewes

Livestock mineral and trace element specialist, Chris Williams, is still searching for the 'perfect' forage analysis. He outlines the main deficiencies revealed in testing and points to some of the nutritional content trends in recent years.

Forage analysis presents a more reliable profile of a sheep’s nutritional status compared with blood-testing to identify mineral and trace element deficiencies, according to Mr Williams of Clinwil Nutrition Services.

“Blood-testing a ewe will give a snapshot of her nutritional status, but the results can vary from day-to-day,” he said. “A number of factors can influence the results, including hormonal levels. There are also several antagonistic minerals and trace elements and their presence can inhibit the uptake of other vital nutrients.

“In addition, stress can lead to the release of copper into the bloodstream and this may be difficult to avoid during handling when the tests are being taken.”

‘“Off the shelf’ mineral and trace element supplementation can potentially exacerbate nutritional imbalances, he commented.

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“Manganese in particular is antagonistic and it can reduce selenium and cobalt availability, if present at excessive levels. These two trace elements are essential for a healthy immune system, with cobalt deficiency sometimes showing up as flaking skin behind the ears.

“If the farm soil is already high in manganese, this is likely to be reflected in the forage, although that is not always the case. Therefore the wrong supplementation is not only a waste of money, it could also cause health issues.

“Soil manganese levels vary across the country, but high readings are commonplace in the North of England. The same also applies to forages, which are grown on leys which are part of an arable rotation, as manganese is frequently found in foliar crop sprays.”

Another mineral that is believed to be increasing to levels where it has the potential to pose a health threat is iodine, he added.

“It is unclear why iodine levels appear to be rising in many forage analysis reports, but it is added to many nutrient boluses. Iodine is also more prevalent in soils close to the coast and it is present in seaweed.

“If blood profiling reveals a high iodine reading, it may be worth choosing a product where it is excluded from the ingredients. High levels of iodine can delay colostrum production following birth, so it is very important that it is not over-fed.”

It is fairly common to uncover a low salt content in a forage analysis, he pointed out.

“Salt promotes saliva production and is associated with a healthy digestive system; it also encourages a good appetite. A shortage can increase the risk of prolapse in ewes. This is because ewes are often fed quite hard around lambing time, to meet their increased nutritional demand. This often takes the form of additional protein, some of which may not be fully digestible. At the same time, their womb is becoming enlarged, putting pressure on the rumen. Salt will help to maintain correct digestive function and mitigate the risk of prolapse.

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“Lambs also need adequate salt and a deficiency may impair growth rates and feed efficiency. Concerns are sometimes expressed about over-feeding salt, if it is allowed on a free access basis. However, a product like Himalayan rock salt is extremely dense. A sheep that uses this type of lick will only be able to ingest minute amounts at any one session. This method of supplementation carries virtually no risk of over feeding.”

Producers are warned against the over-use of copper supplements, but Mr Williams pointed to its benefits.

“Some breeds can be susceptible to copper toxicity, but the mineral is required for fertility, as well as for lamb growth. It also promotes overall good condition. It is not advisable to feed it in excess, but many of my forage analyses show that it is not meeting maintenance levels.

“It is a question of achieving the correct balance. I can often pinpoint flock health problems simply by studying the forage analysis – a low zinc profile can be reflected in ongoing difficulties with lameness and ewe mastitis, for example.”

A short of essential minerals or trace elements can be rectified using a bespoke molassed lick or bagged powder following analysis, he advised.

“If deficiencies are evident in preserved forage, supplements should be fed all year round. Issues in silage or hay will often be translated into grazed grass. Fresh grass sampling can also be very revealing.

“Significantly low levels of essential vitamins and minerals could be remedied by a drench at critical periods. This would include supplementation for ewes in the approach to lambing, or for lambs that are close to finishing. My overall recommendation is for producers to carry out forage sampling every three of four years, to ensure that flock performance stays on track,” concluded Mr Williams.