Relying totally on home-grown forages and using no concentrate or other bought-in feed may seem like a radical approach to profitable milk production, but it’s one that’s being put to the test in the latest trial work under way at the SAC’s Crichton Royal Farm, Dumfries.
The farm has 100 cows on this system which, for comparison, is being run alongside a trial where another of the college’s 100 cows are being managed on a regime totally reliant on bought-in by-product feeds. The two trials started last October.
The aim is to focus on how dairy farmers can make the most efficient use of land, says SAC’s Mizeck Chagunda who is running the trial with Dr David Roberts, head of SAC’s dairy research.
“Land use is going to become a crucial factor, not only for Scottish dairy farmers but for all global dairy production. There will be increasing demands on our land that go way beyond livestock and the needs of dairy cows. As well as growing food for human consumption, land will be needed to produce energy crops and for forestry,” he says.
The two trials will look at how a dairy herd can be fed on a diet of forages grown on the farm and comparing that system with one that feeds its cows on nothing more than by-products – in other words feeds that cannot be used for human consumption and so are not taking up land use purely for the sake of providing feed for livestock.
Mr Chagunda believes these are issues that will become increasingly relevant to the advice given to the UK dairy industry over the next 10 years and it’s the intention of the trial to provide data that can be used for modelling this advice and which can provide practical and innovative alternatives to milk producers looking for the most efficient approaches to land use and to profitable milk production.
Cows on both feed regimes are milked three times a day and there is an all-year calving pattern to allow differences in fertility between the systems and the two genetic lines of Holstein breeding that are kept at Crichton Royal Farm, to be investigated.
The home-grown winter ration consists of grass silage, maize silage, lucerne, red clover silage, field beans, crimped wheat and vitamins and minerals fed as a complete TMR. The analysis of the diet is: dry matter 344g/kg; crude protein 171g/kg DM and ME 12 MJ/kg DM.
“When the cows being fed the home-grown diet are at grass in the summer, grazed grass makes up a significant proportion of the daily intake, so overnight they are being offered a feed of appropriate ingredients from the range of home-grown forages to balance the high protein and relatively low NDF of the grazed grass.
“We will also extend the grazing season in both spring and autumn to maintain maximum milk production from grazed grass. But one of the challenges with this system is the ability to grow high-quality protein for the winter ration. To help us achieve this we’re growing red clover, beans and lupins. And as we’ve seen this summer, weather will also have a major impact on the ability to grow enough of the high quality forage and protein crops this feeding regime relies on.”
Fertiliser will be restricted to strategic applications to allow the most efficient use of nutrients in the manure and slurry. The herd on the home-grown forage regime has a target average yield of 8,000 litres.
The group of cows being managed on the by-product system is being fed a diet based on ingredients that are available following a primary production process and which are not normally used for human food. These include draff and distillery grains as well as feeds such as rape seed and soya – which are available following oil extraction – bakery by-products such as biscuit-meal and animal-grade molasses following sugar processing. Feeds that are not the primary crop, such as straw, are also eligible for use in this trial.
The by-product ration consists of straw, Vitagold, sugar beet pulp, biscuit meal, feed-grade breakfast cereal meal, soya bean meal, wheat distiller’s dark grains, molasses, protected fat as well as vitamins and minerals. Overall ration analysis is: crude protein 171g/kg DM and ME 11.5 MJ/kg DM.
The diet is fed as a TMR but because it’s a high dry-matter mix some water is added at the rate of 10kg/cow to achieve a DM of around 500g/kg.
Mr Chagunda comments: “To achieve a herd average of 11,000 litres, the TMR diet may be short of energy so it might be necessary to feed a protected fat as an energy supplement”.
The cows on this trial will be housed all year round with access to a loafing area.
“This is a system based on the high-cost of bought-in feeds but no land is required for growing crops to feed livestock, although land will still be required as somewhere for slurry to be spread.”
In the trial’s financial evaluation, slurry will be considered as a saleable product and the opportunity of the earning value of the released land will also factor in the assessment.
“The land could be used for human food production, growing energy crops, forestry or extensive land management to increase biodiversity. This is a system that’s not dependent on local weather conditions but will be challenged by its susceptibility to changes in world feed prices,” says Mr Chagunda.
“It’s too soon to be able to fully evaluate these systems in terms of milk yield and cow health and fertility but cows on both systems are currently milking well and there have been no health or adverse management issues. But we need to ensure the conserved forages aren’t too wet.
“The yield of beans was lower than we expected last year because of the delayed harvest and high field losses and so to spread the risk we are now growing other protein crops,” says Mr Chagunda.