Responding to Reduced Forage Quality with Maize Grain
26 September 2024
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It has been a challenging summer for making silage and this has had a knock-on effect on silage quality. First cuts on dairy farms are, on average, poorer than last year, with slightly later harvest in many areas resulting in more stemmier, higher fibre and lower energy silages. Slightly lower protein levels are also evident, with less slurry or N applications due to wet conditions and not being able to get applications on early enough in the spring.
Analysing the forages you are currently feeding is important to balance rations accurately and help to feed as efficiently and cost-effectively as possible while optimising milk output. Is it also worth knowing the quality of unopened clamps and bales, even if they are not planned to be fed for some time. This enables decisions to be made about what silage to feed to what class of stock, keeping the higher quality silage for milking cows.
Mixing wet with dry silages can help improve overall intakes and if one cut is of particularly poor value, can it be fed alongside a better-quality silage to limit fluctuations in milk output when changing clamps and maintain more stable milk volumes. In addition, knowing the dry matter of all forages on the farm can help with forage budgeting and working out whether stocks need to be conserved, and forage replacers purchased. It is always better to plan ahead and make smaller, more gradual changes to milking rations to maintain animal performance throughout the winter.
With feed prices easing back and maize looking competitively priced in the UK against wheat (~£15/t more and ~£45/t more than barley), it is worth considering some maize grain in milking rations, especially where silage is lacking in energy.
The benefits of mazie inclusion
Maize is a high energy, high starch cereal which helps drive milk production in dairy cows. It compares favourably to barley in terms of energy and starch content, being more similar to wheat in nutritional value (see table 1). Its downside is that the protein content is slightly lower that other cereals, but its main benefit is the nature of the starch. Maize contains higher levels of bypass starch compared to other cereal grains, meaning less starch is readily fermented in the rumen and more is digested in the small intestine. This means that it is less “fizzy”, with a slower rate of fermentation in the rumen, reducing the risk of acidosis. Therefore, higher levels can be fed more safely.
Table 1. The nutritive value of maize versus other cereals.
| Nutritional Parameter | Maize | Wheat | Barley | Oats | Rye |
|---|---|---|---|---|---|
| Metabolisable energy (MJ/kg DM) | 14.0 | 13.8 | 13.2 | 12.2 | 13.5 |
| Crude protein (% DM) | 9.0 | 12.8 | 12.1 | 11.0 | 11.6 |
| Starch (% DM) | 72 | 69 | 59 | 42 | 45 |
Maize inclusion suits diets that are high in cereals or cereal based concentrates to help reduce the acid loading on the rumen. Therefore, replacing some wheat with maize can help achieve a more stable rumen pH, which may in turn support butterfats. An increase in milk output will likely be seen when substituting some barley with maize, mainly due to its higher energy content. Less of a response may be seen when substituting wheat unless the rumen is already under acidotic conditions. There may also be a beneficial effect on milk protein percentage with maize inclusion.
In newly calved cows that are transitioning from a high forage, low starch dry cow ration, the inclusion of a slower digesting cereal such as maize may help ease the transition to the higher concentrate milking ration and aid feed intakes in early lactation.
Guidelines for feeding
Maize must be well processed and ideally ground for efficient digestion. Coarsely cracked grain is only digested at around 60% compared to nearly 80% for ground maize. A typical inclusion rate in a milking ration would be around 2kg but up to 4kg can be fed and it would typically replace one third to half of the total cereal content. The lower protein content of the grain means that slightly more supplemental protein is required. Make sure you take nutritional advice if looking to feed maize this winter to get the best from it cost-effectively.
Lorna MacPherson, SAC Consulting
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