Pay attention at every stage to realise full potential of maize

21 August 2026

As ‘King of the Forage Crops” maize represents a cost-effective route to improving ration efficiencies, as British Dairying reports from the Volac Maize Symposia.There’s room to increase maize inclusion rates in the diet and boost milk from forage, if attention is paid at every stage, from variety selection to ensiling and feed out.

That was the take home message from the recent Volac Maize Symposia at Harper Adams University, Shropshire.

Iwan Vaughan, ruminant nutritionist at Dairy Diagnosis said re-assessing maize inclusion levels in the diet could help meet growing processor requirements to lower dairying’s environmental impact by improving nitrogen (protein) utilisation. 

He said, typically only 20-30% of dietary protein was utilised and converted into a saleable protein product like milk or meat, the rest was excreted as urea which had the potential to be converted to nitrous oxide – a greenhouse gas. 

Maize is very low protein, we’re talking 8% protein in the diet as a percentage dry matter, and it’s full of carbohydrates so it’s full of starch. Effectively with maize, you put in less nitrogen and put in more carbohydrate so it reduces your total crude protein of the diet but also increases the carbohydrates or starch,” he explained.

“As we feed more maize, we get a better balance, so lower crude protein going in, more carbohydrates, so that means we get a lower requirement of crude protein into the diet and a higher output of microbial protein which means higher total milk volume, but also higher total protein in the milk too, so that’s what helps your protein efficiency.”

This would translate into less nitrogen excretion into the environment. Mr Vaughan said in an ideal world, maize silage would make up 60-70% of the forage component of the diet. Although on some farms, over 40% would get the effect needed. 

Hopefully off the back of that you’ll be more cost effective and hopefully you’ll be up on margin per litre because you’re feeding a lot of maize which hopefully is more efficient to grow (compared to grass) and then you can reduce your total concentrate input,” he said.

To get the most from maize, Mr Vaughan stressed it was important to get the balance of fibre correct in the diet to optimise throughput and utilisation. He said maize complemented quality, multi-cut grass well. Both had a relatively low total NDF to help increase total forage DM in the diet, but maize had a higher percentage of uNDF (undigestable NDF) to balance the passage through the rumen and optimise forage utilisation.

He stressed that the volume of maize fed would depend on an individual farm’s location and ability to grow maize well. 

Thomas Turner, KWS technical advisor and regional sales manager said choosing varieties with the right maturity class to suit farm location should be a key priority when looking to grow maize successfully. 

Maturity class gave an indication of how many days needed to reach harvest date, so choosing the right maturity would avoid having to harvest crops too late in the season when rainfall could create harvesting and environmental challenges. The maturity class chosen would be influenced by factors such as altitude and aspect, latitude, soil type and drill date, he said. A variety’s FAO number gave an indication of maturity, with a higher FAO (200 plus) being later maturing.

For example, farms on heavy clay - which may delay drilling date and available growing days - should opt for a lower FAO. A higher FAO could be used on south facing, light ground. He stressed that FAO numbers were not the same between breeders, and the best way to compare varieties was to use the Descriptive List to benchmark.

He also highlighted the need to prioritise crop nutrition for optimal quality which would translate into better milk from forage. He said a common mistake was growers applying nitrogen (N) too early or not enough of it. This year was “a case in point” with many trying to save costs by dropping back fertiliser rates. 

This is where you start to see a huge reduction in quality of your product. You’re spending an awful lot trying to get this into the clamp and get more milk from forage. If you’re not spending money on the nutrition that the crop needs, you are going to lose out on a huge amount of quality.

He advised treating maize like a cereal and applying fertiliser incrementally through the growing season using sap testing to identify key nutrients that were missing and replacing them accordingly.  As N and sulphur (S) were highly mobile and readily lost in the soil profile, front loading fertiliser at the start of the season could mean the nutrients were gone by the time the crop needed them.

Dr Mark Leggett, head of R&D and technical for Volac said with the cost and effort associated with growing a quality maize crop, it was essential to safeguard as much quality as possible in the clamp. 

Excluding oxygen and ensuring a rapid drop in pH as part of the fermentation process played a significant role in doing so as “bad” microbes – that would cause a reduction in nutrients and dry matter - favoured high pH and oxygen. 

This would be helped by thorough consolidation, rapid sealing, the use of an oxygen barrier sheet, side sheets and appropriate weighting, he said. Using a proven silage additive with Lactobacillus plantarum MTD/1 could also tip the balance in farmer’s favour.  This would help lower the forage pH rapidly through the production of lactic acid and prevent bad microbes from proliferating.

Preventing aerobic spoilage once the clamp was opened and exposed to air was also a must as this was when yeasts could proliferate causing heating/spoilage and dry matter and energy losses. 

A study looked at maize silage treated with Ecocool silage additive, which contained L.buchneri PJB/1 to create acetic acid – a powerful inhibitor of spoilage yeasts and moulds. The crop ensiled had a naturally high microbial count at ensiling, including over 10,000,000 yeasts per gram of forage. The study found the treated silage remained cool for 4.7 days more than the treated silage and had no visible silage spoilage. The untreated silage had visible spoilage. 

Dr Leggett said additional research showed this spoilage would have a negative impact on dry matter intakes and lower NDF digestibility (see table). 

What you will wind up with is less of a lower quality forage and they can’t eat as much. It’s a double whammy,” he said.

This would translate into less milk in the tank. For example, a one percentage point increase in NDF digestibility was associated with a 0.17kg increase in dry matter intake and 0.25kg increase in fat corrected milk. So, a four-point change, as seen in the treated silages, would be worth a kilo of milk, he said.