Incorporating a zero grazing system into dairy cow diets has become more popular recently, thanks to its potential to improve grass utilisation and reduce costs.
For those looking to manage unpredictable weather or a growing herd size, the zero grazing system’s flexibility to extend grazing platforms, as well as being a management tool for fragmented grazing, has made it attractive.
Debbie McConnell, Agri-Food and Biosciences Institute (AFBI) dairy research project leader, has been involved in several studies on zero grazing, including one in 2016 looking at dairy cow performance and grass use on a zero grazing system compared to others.
This study saw an increase in yields of close to four litres per cow per day for animals on the zero grazing system, compared to those which had been on a full-time grazing or silage-based system.
She says: “On the whole, zero grazing performed well.
“Of the 111 Holstein-Friesian cows in the study over the 22-week period, zero-grazed cows yielded 29.5kg per day, compared to 25.69kg/day [grazing] and 27.88 kg/day [grass silage].
“We put this down to the fact that forage intake was the highest in cows on the zero grazing system [12.1kg dry matter per day], compared to grazing [11.2kg DM/day] and grass silage [11.6kg DM/day].”
Grass use was also examined in the same study and taking into account the waste in the field and at the feed face, this worked out at 76.5 per cent (zero grazing), compared to 70.4 per cent (grazing).
With improved utilisation comes the potential for increased stocking rates, farm output and net margin per hectare, although consideration is needed around grasses and cutting conditions as well as the type of field to ensure a successful cut and carry system.
She says: “Studies have shown that maintaining covers slightly lower at about 3,500kg DM/ha increased grass quality, grass growth and usage compared to sward covers exceeding 4,500kg DM/ha.
“At these heights, cow intakes did increase and we saw improvements in milk production and quality compared to cows fed grass from high cover swards.”
Consideration and potential investment is needed ahead of implementing a zero grazing system, says Dr McConnell.
“Rough estimates suggest it would take about one hour to feed 100 cows on a zero grazing system, so labour requirements should be considered, although this is variable from farm to farm depending on infrastructure, distance the fields are from the farm and equipment.
“Zero grazing systems are also dealing with a more volatile product in comparison to a silage system for example, and this can be challenging, particularly for high yielding cows.”
She says some capital investment is likely to be needed longer term for specialist machinery, as well as the potential for higher costs around slurry storage and spreading. A greater indoor feed space is also needed.
Foodstuff for UK dairy herds – the numbers
6p/kg DM: The cost of grazed grass
10p/kg DM: The cost of grass silage
25p/kg DM: The cost of purchased concentrates
33 per cent or 9.5ppl: The total production accounted from feed and forage
1,000 litres: The increase in milk from forage figure which equates to a £10,798 net profit difference on a 100-head herd
IN THE FIELD: TOM KIMBER, WINCANTON, SOMERSET
TOM Kimber, Wincanton, Somerset, is a ‘convert’ to cut and carry and has been using it through the shoulders of the season since 2016, when the late spring prevented him from turning out his cows.
With the 220-strong Friesian herd split into a spring and autumn calving block, Mr Kimber says he relies on producing milk from summer grazing to achieve a 7,000-litre annual yield, at 4.4 per cent fat and 3.45 per cent protein.
The bad weather three years ago, coupled with depleted silage stocks and land close to the farm being too wet to support grazing, gave him no option but to turn to dryer fields some distance away for grass, which he cut and took back to the cows.
He replaced the fourth cut silage element of the total mixed ration (TMR) the cows were being fed at that point with grass and was impressed with effects after milk yields rose back to where they were before he started using the fourth cut.
The system that year continued until grazing could resume, by which time Mr Kimber was sold on the cut and carry concept.
Yields have increased by 1.5 to two litres per day in comparison to a TMR based on maize and fourth cut, with milk from forage on target to exceed 4,000 litres per year.
As the summer approaches, cows will go out by day and receive cut and carry during housing at night and eventually, during the summer, will graze full-time and only receive concentrates in the parlour. The system goes into reverse in autumn, with cows continuing to graze by day and given cut and carry at night.
Mr Kimber says: “After they are fully housed they will have one feed of TMR and one of cut and carry grass which will continue as the season allows, often to late October, before finally moving to the full TMR.”
Winter rations are based on a TMR of about 60 per cent maize, 40 per cent grass silage and 2.5kg of a 36 per cent protein blend, with one feed of TMR replaced by grass as soon as it can be cut, which Mr Kimber says is usually from March onwards. With higher levels of protein introduced through the fresh grass, a saving has also been made on the blend fed in the TMR.
“When the fresh grass comes into the ration, we switch from a 36 per cent crude protein blend to one containing 16 per cent protein, which saves us about £50/tonne,” he says.
Although some investment is needed for cut and carry, Mr Kimber explains that he used a neighbour’s adapted mower which would tow a trailer when he first started with it.
The borrowed machine has since been replaced by a second-hand zero grazing machine, which he bought for £7,500.
“It would be hard for us to justify a £50,000 investment in one of the more modern zero grazing machines,” he says.
“We can still get the parts for our old machine although there is nothing much to go wrong, so we will continue with this system for as long as we can.”
Tips for the shed
■ Allow enough space and regular push-ups needed to achieve optimal intakes
■ Feed rate – offer 110 per cent of herd requirement to factor in wastage
■ Regular testing to monitor quality
■ Deliver food every day to avoid heating and spoilage and remove wastage
■ Monitor dry matter intake so buffer feed can be fed if required
Tips for the field
■ Consider field size (not too large), previous use (avoid grazed land) and access (minimise soil compaction)
■ Increased nutrient requirement
■ Grass quality - pre-cutting covers target for cut and carry is between 3,500 and 4,000kg dry matter per hectare.
■ Time of day – peak DM content from midday to early afternoon