Straw grinding with a Roto Grind 760 has become an integral part of the livestock contract services provided by Shropshire-based CR Bowen Contractors. Geoff Ashcroft reports.
Having developed a forage wagon service for its dairy customers throughout the last nine years, CR Bowen Contractors based at Church Stretton, Shropshire, is no stranger to the forage requirements of the livestock sector.
Steven Bowen, who shares day-to-day responsibilities with his dad Colin and brother Allan, explains; "We have focussed on high-quality forage over the last few years and, since 2017, have doubled our forage wagon fleet to cover around 2,000 acres each season for customers."
While the lion's share of the business is based on two Pottinger Torro forage wagons, the Bowens also carry out pasture renovation and fencing, alongside cultivations and drilling services.
However, the firm has also found a niche service to complement its focus on forage quality - it also provides a straw grinding service, which supplements grass silage for those looking to prepare different ration formulations for their groups of animals.
"Straw is a great addition for dry cow mixes, so it fills their bellies without letting them put on too much condition," says Mr Bowen. "In our experience we can put up to 16-17kg of straw into a mix - and if we are shot of straw, we will add hay."
He says that grinding straw saves on processing time for those using a TMR prepared by a mixer wagon. "We have found from our own experiences that many feeder wagons can be slow to process straw, and you could never get it to mix properly," he says. "Cows would simply sort through the grub and leave the straw behind.
"And when you have lots of different feed mixes to prepare for different groups of cattle, leaving a mixer wagon running for half an hour or so, while it deals with straw, can add up to a lot of wasted time, along with over-processed grub," he says. "It is also very hard on the feeder wagon's blades. You are better off grinding straw before it is put into a ration."
For processing, the business invested in a trailed, US-built Roto Grind 760 about eight years ago. Mr Bowen says their services extend down towards Hereford and north towards Wrexham, handling all manner of straw types at a cost of about £120/hour. "It is surprising what it can do, even to lower quality, wetter straw and mouldy bales," he says.
"When combined with good quality minerals, lower quality roughage can offer an increase in palatability when ground. And while the Roto Grind does have the ability to deal with non-food stuffs, we have never used it for anything other than straw."
"In our experience, we have found that this tub grinder works best with square bales, rather than round. We make smaller round bales in the UK compared to our US counterparts, so they tend to chase themselves around in the tub. A larger diameter round bale would probably work more effectively given the tub's nine foot upper diameter.
"Whereas it will go through large square bales like wildfire, as the wads just keep feeding into the mill," says Mr Bowen. "And with 200hp on the shaft, we have found that we can comfortably process around 20 bales in an hour."
He says that while the straw grinder's capacity is variable, the machine's settings have not been touched for years. "We have got the tub set just right, so it delivers a sensible length of straw," he says. "We do not want dust, and we do not want long straw - typically, it produces a material from 5-10cm, that incorporates into a mix to provide a good scratch to the diet.
"We have found a useful blend of speed and quality, that also leaves us with a decent end product that the cows do not pick through," he adds.
He says that the machine is on its second set of hammers and there have been a few repairs and modifications, over time. "It really needs to be sat on better running gear, given the distances we often travel to our customers," he says. "Fortunately, we do not hire it out - it only goes out with our own tractor and operator."
Mr Bowen says the hinged discharge chute has been modified to help operators fold it from transport to working position. "The chute can be a bit of struggle to lift, so we have fitted a telescopic lever to help swing the chute upwards," he says. "The lever is then secured by a pin, when the chute is laid flat for transport."
Running a Fendt 720 in 1,000 Eco does bring fuel savings, as there is more than enough power to run the Roto Grind. "It just takes a bit to get the flywheel spinning, but once we are away, it will plug away sipping 16-20 litres of fuel per four, which is quite economical for what it is doing.
"Overall, the processor provides a useful complimentary service to our business, which can be carried out all year round."
About the processor
The Roto Grind 760 is effectively a large-scale hammer mill. It uses six sets of four free-swinging hammers on a flywheel, with all hammers being reversible to allow them to be used on all four corners. Shear plates allow control of the straw grind, and the rotating tub that sits on top of the flywheel comes with an adjustable speed control.
Should there be a notable reduction in tractor rpm, the tub rotation will stop to prevent stalling and avoid blocking the machine.
"It works really well," says Mr Bowen. "Once the flywheel is up to speed, you can just keep feeding the bales into the tub using a telehandler. While the chute's end flap is hydraulically adjustable using the spools, should you need to rotate the chute tower, you will need to make a manual adjustment."
Specifications
- Model: Roto Grind 760
- Tub: 2.74m diameter reducing to 2.28m by 1.29m high
- Tub speed: 0-9rpm
- Mill: Six sets of four, free-swinging hammers on a flywheel
- Shear: Five individually adjustable plates, 0-5cm
