Alternative options for feeding ewes before lambing

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Thompsons’ Dr. Ronald Annett

When it comes to feeding ewes before lambing, grass silage, hay and haylage accounts for nearly all of the forage that is fed in Northern Ireland. And with the great grass growth in 2021, silos are now well filled and bale stacks have never been larger, so hopefully there should be more than enough forage to see us through the winter.  

But have you ever wondered if there are other options for feeding your ewes that might be worth exploring? In this article, we look at a few novel forages and feeding systems for ewes and examine if there is a viable alternative to grass-based forages.

Maize silage

Maize silage is a very palatable feed for sheep and ewes will readily consume maize silage when it is offered. The nutritional value of maize silage is determined mainly by its starch content, hence the maturity of the cob immediately before harvest is very important. Feeding a good quality, high starch maize silage is well proven to boost dry-matter intakes and performance in dairy cattle, and the same is true for sheep.  

In a recent study at AFBI Hillsborough, where ewes were fed a basal diet of high digestibility grass silage, replacing 50% or 100% grass silage with high quality maize silage was found to increase forage dry-matter intake by 16% and 21% respectively. In this study, ewes were fed concentrates at a flat rate 0.55kg/day, but in practice, the boost in forage intake means that concentrate levels could be reduced by as much as 150-200g/ewe/day when maize silage is included in the diet. However, the quality of the maize is crucial. In other studies where the maize silage was of much poorer quality (i.e. low starch content), feeding maize silage to ewes did not stimulate higher intakes, and in some cases, performance was inferior to that of ewes feed grass silage.  

Nutritionally, good quality maize silage is a high energy, high starch forage but it lacks protein.  Where a 18-19% protein supplement is normally sufficient to balance a grass silage-based diet, maize silage needs at least a 25-26% protein supplement to meet the protein requirements of ewes.  Additional minerals are also required, particularly calcium and phosphorus.  

The greatest challenge with feeding maize silage to sheep is the aerobic stability of the clamp face. Daily usage when feeding ewes is low – around 400kg per 100 ewes - so unless a large number of sheep are being fed, or the clamp is very narrow, it will be difficult to keep the forage fresh. For most sheep farmers, growing a dedicated crop of maize is not a realistic prospect, unless there is another enterprise on the farm (beef or dairy) that can utilize the crop as well.  However, if you have a neighbour who is willing to part some of their maize silage, then it is a feed well worth considering as an alternative to grass silage.  

Complete (all-grain) diets

While you normally associate complete diet feeding with pigs and poultry, this system can work successfully with breeding ewes as well.  Although feed costs are higher than a traditional grass silage-based system, the benefits of complete feeding include: 1) reduced labour inputs, 2) a consistent high-quality ration, 3) zero requirement for silage, and 4) no need for the machinery and infrastructure used to store and feed silage.  

Research undertaken recently at AFBI Hillsborough found that silage could be eliminated altogether from pre-lambing rations by feeding a controlled amount of concentrates along with a small amount of straw. There were no adverse effects for ewe health or lamb performance, and in fact the research reported fewer lambing problems among ewes fed a complete diet. It is thought that the reduced level of gut-fill in ewes fed a complete diet may aid lambs during the birthing process, making it easier for them to assume their normal birthing position.

To minimize the risk of digestive upsets, complete diets for ewes must supply a high level of digestible fibre, so they need to be based on high fibre raw materials such as soya hulls or sugar beet pulp. Standard ewe rations designed to complement grass silage-based diets are usually cereal based and therefore are not ideal for this purpose. A crude protein level of 13-14% is more than adequate for a complete diet.

Also crucial for success with complete feeding is the level of feed space available. Ewes must have enough space that they can all eat together at the same time, without bullying other ewes or gorging themselves. To encourage these types of behaviour, 500-550mm feed space per ewe is recommended as a minimum. Given the high dry matter content of the diet, ewes also need good access to and a plentiful supply of clean drinking water.  

Even with a ration based on soya hulls or sugar beet pulp, some ewes will crave some ‘long’ fibre in the diet. Feeding a small amount of chopped straw – as little as 0.1 kg/ewe/day – will be adequate to encourage rumination and ensure ewes remain content.       

Wholecrop cereal silages

Production of wholecrop cereals has grown in popularity in the last 10 years, aided by growth in the dairy industry and the expansion of anaerobic digestion. However there remains very little research on the feeding of wholecrop cereal silages to pregnant ewes. These forages are characteristically low in energy and high in fibre, so in practice, it is difficult to satisfy the energy and protein requirements of ewes fed wholecrop cereals without feeding very large amounts of concentrates, as in the case of complete diet feeding. Wholecrop cereals could be used as an alternative to straw in this scenario.

Wholecrop cereals can play a useful role in feeding ewes at a much earlier stage of pregnancy when their nutrient requirements are relatively low. If ewes are to be offered very high quality grass silage prior to week 15 of pregnancy, including up to 50% wholecrop silage in the ration will help avoid ewes gaining excess body condition and becoming overfat before lambing.

Conclusion

Given our natural advantage for growing grass, grass-based forages will inevitably continue to dominate ewe rations for many years to come.  However it is important to be aware that other options do exist, and, provided the diet is well balanced, they can be utilized successfully.

  

 

Posted 27,01,22 by allison.

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