Words by: Louise Hanlon
Owl Fam has always grazed their heifers off-farm, but this year’s TB outbreak in Hawke’s Bay forced them to reassess their strategy. They were getting good results from their grazier, but he lost access to grazing for more than 1000 heifers, including the Owl Farm calves. This forced a rapid rethink, but fortunately the team had plenty of data on hand to enable a thorough analysis of their options.
The simplest solution was to find alternative grazing off-farm, but this proved challenging, with fierce competition from other operations in the same predicament. The next step was looking into onfarm options.
“Preventing any impact on our milking herd was a non-negotiable for us – we didn’t want to reduce our herd numbers or their feed allowance,” Owl Farm demonstration manager Jo Sheridan says.
“So, it was a matter of coming up with strategies to provide the extra feed the calves would add to our daily demand over the summer months. In an average year the pasture on Owl Farm produces 6.8 tonnes drymatter (DM)/ha over the period from December to May. This means the calves would require 13ha if they were fed on pasture alone.
“We also had to factor in the additional demands on labour and infrastructure (for weighing and handling), and in summer the calves would need feed that contains more energy and protein than our pasture can provide.”
With these requirements in mind, they came up with some alternatives which might fit the bill: primarily feeding pasture and buying in feed – silage and palm kernel, and/or planting a specialist crop that would fill the summer gap – either chicory or a brassica crop, such as forage rape or raphno.
They decided their best bet was either to go with supplementing both the cows and calves with palm kernel, or growing a chicory crop which would then form the bulk of the calves’ diet (see Table 1).
Analysis with Farmax showed they could achieve the same production results by keeping the calves on the milking platform and supplementing them, but the cost was significantly different. Feeding chicory would cost a lot less (see Table 2).
A chicory crop also made good logistical sense.
“We have a support block adjoining the milking platform that is not ideal for the milking herd – it is further away from the shed and we find we don’t get good pasture utilisation when the cows graze there; it is better suited to the heifers,” Owl Farm manager Tom Buckley says. “We were going to use it for silage, so we bought that in to free the land up. It will also give us the chance to use the heifers to graze our new grass in autumn, which went really well last season, and we can carry out an analysis of calf growth rates on a summer crop to share with the industry.
“I’m excited about tackling the challenge, and it means we will be able to keep a close eye on our heifers – weighing them regularly to check they are on track to meet their MINDA targets, carrying out vet checks when we need to, and intervening with farm feed or bought-in feed if the summer is dry again.”
Kyle Gardyne, from PGG Wrightson Seeds, helped with the decision-making process.
“They could have gone with a grass system, but, although it would be low cost, they would take feed away from the milking herd.
“As the lease block next door is a large area to crop, around 4.7 ha, it lends itself to chicory. They can set the 93 heifers up in a rotational grazing system on the chicory, supplemented with 30-40% silage and palm kernel. This will create a complete diet for growing young animals, as chicory is such a high quality, high protein feed (11.5-13 MJME/kg DM, CP 20-26% DM). If there was less area available they could have used a high yielding brassica crop and strip grazed it. A benefit of brassicas would be a reduced cropping area – not so many hectares out, but because they have that amount of land available it made sense to utilise the full area for chicory.
“Chicory will give an exceptionally good growth rate over the summer, whereas a grass-only diet may not deliver a desirable liveweight gain. Also, the heifers won’t be grazing pasture in the summer, so their exposure to facial eczema is greatly reduced. In terms of negatives, it is more of an intensive system; there is more to do, break fencing every day or two. There is a feed cost too; they would need silage, and adequate freshwater, every day.”
Once the decision was made, the focus shifted to making sure they produced an optimal crop.
“The grass will be sprayed out in mid- October,” Kyle says, “and then a contractor will use a cross-slot drill to direct drill the seed. We will be looking out for slugs and snails, and applying slug bait as a default option as well. Then it is a matter of waiting 42-56 days for the first grazing, this should happen in early December. From that point on the heifers will probably be on a 21-day rotation on the chicory all summer; they will require around 3kg DM/ calf/day as well as ad-lib silage, around 1-2kg DM silage/calf. Of course, as the calves grow their intake will increase (see Table 3).
“We also need to keep in mind that if we get another dry season the chicory growth rate might drop away, and we may need to budget for more supplement feeding so that the calves are fully fed.”
Table 3. Farmax modelled heifer feed allocation for a 600g/day liveweight gain (December 2020 – May 2021).
Soil testing carried out by JB Mikkelsen, from Ballance Agri-Nutrients, showed some of the cropping area’s pH was a bit low for the pasture that would follow on after the chicory, at 5.9, so JB recommended a lime application. Then she suggested following up with a base fertiliser application of DAP, MOP, and Kieserite. The DAP would encourage vigorous seedling establishment, while the MOP would offer some extra potassium – chicory prefers QTK levels of 7-14, on this block they ranged from 4-8, and the magnesium levels were a bit low too, QTMg 8-13, so the Kieserite would lift that measure. Post-emergence, her recommendation was to apply 100 kg/ ha SustaiN, with an additional 65kg/ha SustaiN after grazing.
The shift to onfarm heifer grazing has added benefits unique to Owl Farm’s set-up too. “It is a great chance to involve St Peter’s School students in a new learning opportunity,” says Jo. “
Some of the students adopted a calf in spring, now they will be able to follow them through the whole season, and be involved in regular activities, like weighing.”
Although the switch to onfarm grazing will fit the bill this season, long term the intention is to continue grazing the heifers off. However, a successful season at home will broaden their options, and give additional flexibility to shift with any changes in circumstances in future seasons.
