Airlie Feedlot Cover was designed and constructed as a retrofit over standard feedlot pens. The design satisfies the challenges of pen slope, deep pens, and long rows; promoting natural light, ventilation, and management of stormwater, all while the Feedlot remained operational throughout the construction period.
Rarcoola has entered this innovation into the ALFA Award for Innovation 2022, proudly supported by Integrated Animal Production. The winner will be announced at the ALFA BeefEx22 Conference in October. Read on to find out more about this innovation within the feedlot industry.
Tell us, how is the innovation original/innovative?
Airlie Feedlot was never going to be a standard construction build and from the outset it required detailed thought and planning to go into the project. The scale of the project makes this one of the largest solid roof feedlots constructed in Australia, with three covers required to cover the finishing pens of 360m x 60m, 300m x 60m and 150m x 60m.
As with traditional feedlots, the pens themselves fall 2.5% of the 50m width, however the 360m and 150m pens also have a 1% fall over the length which meant the design had to go away from traditional. As part of the design brief, Rarcoola had to take into consideration the pen size with preference for very few or no internal columns. The client also wanted the feed alley covered, therefore creating a 60m span. By covering the feed alley, this allows for the roof to be removed from feed bunkers which means more efficient labour costs as no need to lift and lower roofs. This in turn means the feed quality lasts longer than if it was weathered.
Having no internal columns and the truss sizes being larger, for Rarcoola this indicated the construction methodology was going to take some working. For the Airlie Feedlot, this meant it was going to provide the best practice for not only managing pen cleaning, but also for animal welfare as there are no internal column or posts for them to push and bump into, eliminating the risk of the cattle harming themselves.
Another key design criteria was to ensure the external column placements were aligned with pen boundaries. To achieve this, 10m bay spacings were placed throughout the project. By utilising 10m bays, this reduced the overall portal frames used throughout the entire project and allowed for columns, fences and the covers to all align.
A traditional standard gable roof would not have been suitable for this project, as the lower side columns would then need to be more than 7m high to achieve this. With aid of Rarcoola’s innovative structural engineer, the “off centred ridge” gable design was created. The 360m and 150m covers run north to south, with the feed alley to the western side of the pens, while the 300m cover runs west to east with the feed alley to the south. The 20m fall on the higher end of the roof covers the feed alley, while the 40m fall on the low side covers the feedlot. The light tunnel/vent ridge is set 10m into the pens. By creating the cover with an off-set ridge, we could keep all columns to similar sizing and heights to both sides are now identical. This also allowed for improved weather protection, especially on the eastern side of the 360m and 150m feedlots and the northern side of the 300m feedlot.
Along with the fall in pens, we also had to make allowances for the 1% fall over the length of the 360m and 150m covers. This was done by adding steps into the roof at certain distances. In creating the steps, it allowed to increase the natural ventilation through the covers with the steps remaining open, but the roof sheets overlapping the void for weather proofing. There is one step in the 150m cover and three steps in the 360m cover.
A big concern with a solid roof was natural lighting and ventilation throughout the covers. Careful consideration was taken during the design process to come up with the best methods to combat what could be an ongoing issue. An oversized ventilated tunnel was created at the apex of the gable with 1500mm opening to let ammonia and odour escape from under the roof. We utilised a commercial opaque fibreglass roof sheet for the roof of the tunnel, this allows for natural lighting throughout the pens. The natural lighting throughout the three covers also assists with reducing odour under the roof. To assist with construction and in addition to the vent tunnel, we used 10m long roof sheets with a 250mm overhang and 200mm air gap. Each overlap also increases the natural ventilation.
Having an average of 478mm rainfall per year created another design hurdle, this time in being able to manage the stormwater run-off and collection. With an entire roof area of 48,500sqm, this would mean approximately 23ML of water would run-off the roof each year. Our client had existing catchment / sediment ponds and a dam that was increased in size to hold 38ML of the clean water from the roof. In managing the rainwater from the roof, a large commercial oversized half round gutter was utilised, along with custom designed laser cut rain heads and 250mm downpipes. The rain heads were placed at 20m intervals to the 20m side of the gable and on every column to the 40m side of the gable. Each rain head and downpipe were designed to manage 40L of water per 1mm of rain on either side of the roof.
Another key aspect during the design phase was how to manage the logistics, materials and construction during the build. The property and feedlot was set to remain operational with as little disturbance as possible during construction. Plus, we had a very tight timeframe to practically complete the project within 8 months from the time we were awarded the contract, to beating the break of season into Winter.
The roof trusses were designed in a manner for not only ease of handling and construction, but also for transport to site. Having the tight timeframe meant managing the logistics to ensure construction teams were never held up. In total 37 x double trailer road trains were utilised to get all materials to site. Lay down areas were created in key parts of the site to avoid having to transport materials too far and keep construction underway.
Construction methodology had to be well considered due to the unevenness of the site, retaining an operational feedlot and the sheer quantity of materials.
Total numbers as part of construction:
168 footings = 300m3 concrete
84 x 60m trusses
168 Universal beam columns
60kms of roof iron
48,600m2 roofing iron
approx 350,000 roof screws and 6.5Tonne bolts and fixings
All footings and hold down bolts were poured prior to structural steel arriving on site, meaning construction teams had a clear run. From the first column being stood to the completion of the fixed cover was 16 weeks and the first pen of cattle was moved under roof within 4 weeks. This was achieved by working closely with our construction team to develop a schedule that would allow a steady flow of material to site and enabling minimal handling of materials after unloading. The process of installation was carefully planned between the construction team, project management team, fabrication workshop and most importantly the client.
All working together to enable minimal disruption to the operation of the feedlot. Installation was carried out between three onsite teams:
material unloading, sorting and handling
cladding, stormwater, and finishing
This allowed the process to flow smoothly with materials always readily available for the construction teams and structural steel being installed ahead of the cladding team. Working rosters were also set around these teams so that work continued 7 days a week onsite and still enabled workers to have time off and rest between rosters. The roster system was important in keeping each team ahead of the other and allowing material delivery and sorting to keep up with the installation. By having workers onsite 7 days a week, this allowed us to take advantage of good weather onsite meaning no construction days were lost during this period.
Safety of workers was always paramount onsite; with site facilities arriving ahead of time, inductions for all workers and site visitors, plus weekly toolbox meetings to discuss each team’s work tasks. Cleanliness and organisation were imperative to run a safe site and efficient material handling. Safety of animals was of utmost importance and was managed through regular communication with the client around loading pens, keeping construction equipment and materials away from penned animals, cleanliness of site and discussing animal welfare and site movements in the weekly toolbox meetings. The onsite construction from start to finish was seamless and this was achieved through careful planning, communication with all parties and a well-trained and highly experienced team of construction workers.
So, how does it benefit the Australian Lot Feeding Industry?
As the property is predominantly off the grid and wanting to remain “Green”, the stormwater from the roof is now clean in comparison to it previously having to be run through sediment ponds. The water can now be reused for cattle drinking troughs and irrigation throughout the property. All waste, compost and stormwater is utilised on the farm and reduces the need of inputs coming in from outside services. This also reduces the heavy reliance on bore water and therefore the overall water table and surrounding lakes.
Animal welfare is critical in current times and with Airlie Feedlot’s full undercover structure, this was taken into consideration throughout the entire design phase. Natural lighting, ventilation, pen flooring quality, protection from the weather (including being out of direct sun during Summer and harsh rains during Winter), all adds to the animals’ welfare. As the cattle are not having to expel energy to remain warm or cool and are in a controlled environment, it is allowing for greater feed conversion. Instead of cattle dropping weight during Winter months, they are either maintaining weights or incurring slight weight increases. This all adds to the improved return on investment for the cover.
Having the cattle undercover, creates better and safer working conditions for staff as they are always out of the elements all year round. The feed alleys are now maintained at a higher level due to not getting Winter rains on them, which would result in them becoming dangerous and slippery. The pens are easier to clean out as waste is settling quicker and not as deep. The cattle are quieter and more settled, meaning it is easier to move them and not having to lift and lower feed bunker roofs constantly, is also a bonus.
The benefits of adding a solid, fixed cover to feedlots in the industry are many and varied, with a lot of research still being undertaken. There are still very few Feedlots with solid fixed covers.
In respect to the Airlie Feedlot project, the benefits have been significant and while still in its infancy of operation undercover, they are already seeing the rewards.
The most significant improvement that was an immediate return on having a full solid and fixed roof, was the higher stocking rates per pen. Under a solid roof, this can be as high as 6sqm per head of cattle, meaning Airlie could have up to 250 head per pen should the feed space allow. Ultimately, greater stocking numbers will assist with higher turnover and a greater return on investment for the cover.
Ongoing maintenance is always a big cost outlay for feedlots, such as cleaning of the pens, managing sub-bases and even repairing or replacing shade covers. With a fixed, solid cover such as the one at Airlie, the overall maintenance is significantly less on all fronts. While there is a slight increase in waste per pen, these are not getting the slurry run-off and at the same time the waste during Winter is nowhere near as deep or sloppy. Less run-off and the decreased need for soakage ponds, creates a drier overall area and makes it easier and faster to clean the pens. Waste composts quicker, allowing it to be used for spreading around the farm sooner. As the levels of nitrogen in the waste are remaining higher it means the quality of the compost is more attractive to other end users, in cropping or horticulture and therefore providing another potential income stream for Lot feeders.
And how does it integrate into Australian Lot Feeding operations?
There is significant interest in the adoption of fully covered housing within the Australian feedlot sector. The Australian Lot Feeders’ Association (ALFA) is supporting this interest through three new large, covered housing projects being managed by Meat & Livestock Australia, including one to develop guidelines for covered housing systems. Airlie Feedlot is a leader in this movement, demonstrating that covered housing can be a successful and functional retrofitting over existing feedlot pens, even without support poles within the pens themselves. The research leader for the covered housing guidelines project has visited the site to learn about design and management of fully covered feedlots and this information will be incorporated into the new guidance.
Finally, with higher demands on “Paddock to Plate”, we will see a greater turnover of cattle to ensure both domestic and export markets are being met. With the constant need for improvement to animal welfare and the need for clean on-farm water storage increases, solid fixed roof covers will become a regular fixture around the country.
For More Information Contact:
Graham Dowie, Business Development Manager - Rarcoola 0456954115 | firstname.lastname@example.org
About the ALFA Award for Innovation
All BeefEx exhibitors & sponsors with an innovative product or service are encouraged to enter the Australian Lot Feeders’ Association’s (ALFA) Innovation Award – designed to acknowledge excellence in innovation from companies supplying and servicing the lot feeding sector.
With thanks to our sponsor, Integrated Animal Production Pty Ltd, for their support of this Award.