Spring grazing management is key to cutting farm costs

90pc of farmers who don't routinely measure and record grass growth are losing out on a simple means of boosting their bottom line, reports Margaret Donnelly

Advice: Michael O'Donovan of Teagasc speaking on grassland management at the Teagasc Moorepark 2019 Dairy Open Day in Fermoy, Co Cork. Photo: O’Gorman Photography
Advice: Michael O'Donovan of Teagasc speaking on grassland management at the Teagasc Moorepark 2019 Dairy Open Day in Fermoy, Co Cork. Photo: O’Gorman Photography

Only 10pc of dairy farmers in Ireland are routinely measuring and recording grass growth, according to Michael O'Donovan of Teagasc.

He told the Moorepark Dairy Open Day that every farmer should have a target figure for grass growth and a number of grazings achieved to support the farm stocking rate. The farm stocking rate, he said, should be aligned with the average annual grass growth of the farm over a number of years.

"The capacity to grow grass on the farm should be determined and the stocking rate matched accordingly," said Mr O'Donovan.

He also emphasised that grassland performance dictates the concentrate supplementation strategy and fertiliser application programme for the farm, saying: "Teagasc data indicates that the increased concentrate feeding during 2018 due to poor pasture growth rates resulted in €650/ha lower farm profit for dairy farmers."

Any increase in stocking rate, he advised, should be matched by an increase in grass growth.

Stocking rate

The number of grazings/cuts per paddock provides a good indication of herbage production and grass utilisation, he said, and every additional grazing is equal to an extra 1,386kg DM/ha herbage grown.

"A farm growing an annual average of 14t DM/ha across the whole farm is capable of supporting a stocking rate of 2.5 cows/ha, with a concentrate supplementation level of 500kg DM/cow.

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"If a farm can grow 10t DM/ha and the farmer feeds 500kg concentrate DM/cow, then the optimum stocking rate is 1.8LU/ha. If, on the other hand, the farm is capable of growing 16t DM/ha and the farmer also feeds 500kg concentrate DM/cow, then the optimum stocking rate is 3.0 LU/ha."

Spring grazing management

Good spring grazing management is crucial to reduce costs and increase output, Mr O'Donovan said.

"Three factors dictate the success of spring grazing: spring fertiliser management, turnout cover and grazing management."

The optimum level of N or early grass will depend on turnout date and grass demand/stocking rate.

Early spring growth, he said, is influenced by the genetic capacity within the sward to respond to the N application.

"Newly reseeded swards with high perennial ryegrass content have a greater response to N than older swards with more diverse grass species," he said.

"Grazing management in the first two months after turnout determines spring grass growth and cumulative growth for the remainder of the year."

Mid-season management

Mr O'Donovan said the primary objective during the main grazing season is to maintain high animal performance from an all-grass diet, while, at the same time, maintaining pasture quality.

He said that, in general, from late April onwards, grass supply exceeds demand and pre-grazing herbage mass should be maintained at 1,300-1,600kg DM/ha, with a residual of 50kg DM/ha (4cm post-grazing height). But he pointed out that one of the biggest issues at this time of the year is not stocking the farm appropriately to match grass growth.

"This results in large deficits or large surpluses of grass. Farm cover should be maintained between 150-180kg DM/cow from mid-April to mid-August, with a rotation length of 18-21 days," he explained.

Autumn grazing management

An early closing date is the main management factor influencing the supply of grass in early spring. Moorepark has developed general recommendations for autumn closing management: start closing between October 5 and 10; 60pc of the paddocks grazed by November 7 and 100pc grazed by the end of November.

"Farmers need to use the autumn planner, which allocates the area of ground to be closed from October to November and adapt according to farm requirements," said Mr O'Donovan. Studies in Moorepark show that extending the grazing season does not result in an improvement in milk production compared to earlier housing, but it lowered the quantity of silage required up to early December, compared with animals housed in early and mid-November (150, 310 and 450kg DM/cow respectively).

"Later closing did, however, result in a much lower closing farm cover compared to the earlier closed swards (350, 650 and 840kg DM/ha for the late, normal and earlier closing treatments)," said Mr O'Donovan.

"These differences in closing farm cover resulted in opening farm covers of 630, 860 and 1,100kg DM/ha, respectively."

Many farms, he said, rely on mechanical correction and use concentrate supplementation to overcome poor grazing management, which leads to reduced farm efficiency.

"Farmers that regularly monitor farm cover feed their cows more grass, achieve more grazings per paddock, improve grass production and increase farm profit."

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