Debbie McCallum

Dairy Trust Taranaki (DTT) has four farms operating as research units in Taranaki with 400 hectares effective and 1250 cows.

The DDT Gibson farm (ex WTARS farm) is just south of Hawera opposite the Fonterra Whareroa plant. The farm is 110ha effective ha milking 320 cows. In the past two seasons the farm has been investigating the biophysical and economic effects of supplementing grazing dairy cows with palm kernel compared with a palm kernel blend or grain.

In-shed feeding has become more common in recent years, due to improved utilisation of the imported feed (vs feeding in trailers or feed pads), ability to feed blends, and to incorporate minerals.

With Fonterra imposing fat evaluation index (FEI) grading, feed blends are being used as an alternative to straight palm kernel so more can be fed during feed deficits. This trial investigated the marginal benefit, and or cost of 1) increasing stocking rate and utilising palm kernel within the limitations of Fonterra’s FEI or 2) increasing stocking rate and offering a palm kernel blend or maize grain/barley compared to a pasture-only system.

In June 2017, 227 Friesian cows were split into three farmlets – pasture only (All Grass; 69 cows – 2.9 cows/ha), palm kernel (79 cows – 3.3 cows/ha) and kibble maize/ barley (79 cows – 3.3 cows/ha). Palm kernel was fed throughout lactation at a rate of 1-5kg/cow/day (716kg drymatter (DM)/ cow) and kibble maize or barley was fed if required to achieve pasture targets in early and late lactation (633kg DM/cow).

At a payout of $6.75/kg MS, in shed feeding of kibble maize or barley to lactating dairy cows was not profitable, compared with all grass or palm kernel, due to the high cost of the grain (kibbled maize/barley) purchased for $504/tonne (58.6 cents/kg DM) delivered.

Feeding palm kernel in trailers during periods of feed deficit and through spring to harvest extra pasture silage was more profitable than the all grass system at a cost of $231/t delivered. There was no effect of system or supplement feeding on mating performance, with the all grass/lower-stocked system achieving the same six week in-calf rate and not-in-calf rate as the two supplemented herds at a higher stocking rate. There were also no differences in cow liveweight and condition score between the herds.

In the 2018/2019 season the maize grain/barley was replaced by an in-shed blend consisting of 33-50% palm kernel, 25-33% DDG, 12-15% tapioca, 15% high-starch pellet, and up to 15% soya hull pellet. The blend was formulated to be higher in starch during late winter and spring, and higher in protein during summer and autumn.

Cost of the feed blend averaged $440/t compared with straight palm kernel at $260/t delivered. Supplements were mainly fed in early spring and late lactation to fill feed deficits, based on management decision rules (grazing residuals, targeted cow intakes).

The palm kernel and in-shed blend produced more milksolids than the grass-only herd per cow and per hectare. The herd fed the in-shed blend produced more milksolids throughout the season, especially over summer, compared with the palm kernel herd, but was less profitable. Again, there was no difference in reproductive performance and cow liveweight. Both the palm kernel and in-shed blends achieved FEI regulations.

These trials have highlighted that pasture utilisation must be kept high, and feed price must be kept low to obtain profitable response to bought supplements. Additionally, data from the two years indicate that any additional milksolids from feeding a high-starch or blended supplementary feed via an in-shed system, does not offset the greater cost of this feed.

DTT would like to acknowledge the funding and support from DairyNZ and other sponsors.

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