"Since working with Advanced Robot, milk yield increased significantly from 29 to 35 kilograms, but milk solids have also been sustained at 4.6% butterfat and 3.4% protein, with total milk solids at 2.73 kilograms sold."
A Maize Masterclass
Unlocking the potential of maize silage (First Published in British Dairying)
Maize offers a nutritional profile that supports milk production and can play a valuable role in a cow’s diet. But how can producers maximise utilisation? Ruth Wills finds out.
Maize silage is a popular choice but what makes it special? “It’s basically a total mixed ration (TMR) in a plant,” explains John Winchell at Alltech, who travelled from the US to host a series of workshops in collaboration with Advanced Ruminant Nutrition. “There’s starch, there’s moisture, there’s neutral detergent fibre (NDF), protein and digestibility, so if producers can grow maize, it’s good because of all of these reasons.”
Understanding what is in a forage sample is the first step to maximising its impact. “I want everyone to play an active part in their forage programme – which might sound weird because you may think you can’t get any more active than making the forage,” he says. “But I sometimes think we don’t actually know what our forage samples are telling us.” The road to getting more from maize begins with understanding what it brings to the diet. “Back in the day, I would look at dry matter (DM), crude protein, NDF, acid detergent fibre (ADF) and lignin,” John explains. “But with modern samples, digestibility is much more important than we thought it was. We’ve only been looking at it for 10-15 years, and the labs have progressed so they can see how digestible a sample is at 12 hours, 24 hours, 200 hours and 240 hours.” NDF is a measure of fibre, and how much fill the cows will have. “The higher the NDF, the less the cows are going to eat; the lower the NDF, the more they’ll eat. But digestible NDF (DNDF) is how digestible that fibre actually is.” This is also where undigestible NDF (UNDF) comes in. “Looking at the UNDF after 240 hours, which is around 10 days, if it hasn’t been digested, it basically won’t be,” says John.
Controlling production
“So I like all UNDF 240s to be under 10%. If we can control UNDF, we’re controlling the rate of passage through the cow, and if we can control that, we can control milk production.” Hot weather stress can lead to higher UNDF, so is something for farmers to look out for this year. Milk per tonne is one element to take with a pinch of salt. “If you make silage at the right DM, milk per tonne will be good, but at the wrong DM, it doesn’t give a fair reflection. If it’s harvested at 38-40% DM, milk per tonne says it’s junk,” he notes. “So a lot of people are moving away from milk per tonne; we all know drier silage doesn’t eat as well.” Variety choice could help introduce resilience into the crop. “We can’t control the weather, but we can work with it,” says John. “Not all maize is created equal, and not all fields are equal.” Farmers should look at each variety’s heat units and use local data to help select the most appropriate one. “The LG Heat Map tool is a free phone app which will tell you the Ontario heat units (OHU) that are right for your farm. “Maize doesn’t like to grow when it’s under 10°C, or over 30°C.” That’s why later maturing varieties don’t finish in the autumn, because the temperatures aren’t conducive. Dry matter is key when it comes to choosing when to harvest. “Maize will dry down by 0.5% a day, which is important to know in drought conditions,” says John. “If it goes past where it should be, where it gets really dry, it will give up and quit.”
Delaying harvest can therefore have a negative impact on the crop. “It could end up at 40% DM and like popcorn, so it’s important to plan for these situations.” Producers should monitor DM levels carefully, and aim for 32-35% DM. “If it’s 32% DM and all burned up on the bottom and the first two leaves, but the kernels are still wet, I would say it needs another week, but if the plant doesn’t look good, just harvest it. When you think of the plant and the leaves, that’s where photosynthesis is created. If the plant is really rough, there won’t be a lot of photosynthesis going on to create more starch. I’ve learned that the hard way, waiting a week to see if we get 5% more starch but losing the digestibility and the fibre.” When harvesting, it’s also important to process the maize effectively. “Often, to process it properly involves harvesting slower, which is hard.” Chopping height can also influence the ration. “Most of my farms are chopping at 15-16 inches, which is the normal cutting height in the US; those that are chopping higher will have 3-3.5% ash, so ash level tells you what height the corn was chopped at.” Maize is a great option for dairy cow diets, but there are many factors which need to be managed carefully. “Maize is easy to grow, if you have the right DM, the right day length (days to maturity), and it’s harvested at the right time. But a lot happens in the lifespan of the crop that we don’t see,” notes John. “This is where flexibility and adaptability to the season is important, and where the varieties selected, managing harvest correctly, and using local data can pay off.”
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