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Thursday 8 December 2016

A grazing plan that puts lambs in the clover

Growth rates in weaned lambs grazing grass/clover swards can be potentially double those of lambs grazing grass only

Published 08/07/2015 | 02:30

Sean Conway pictured some of his lambs grazing paddock where silage was removed in the previous rotation
Sean Conway pictured some of his lambs grazing paddock where silage was removed in the previous rotation
Sean Conway with the STAP The Lights sheep discussion group on the farm of Des Irwin, Ballinvoher , Co. Sligo discussing grassland management post weaning.

There has been a dramatic increase in clover in the paddocks on Sean Conway's farm at Lavagh, near Ballymote, Co Sligo.

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It is likely a result of Sean applying lime to the lands last year, grazing all paddocks to 4-4.5cm in early May and ensuring all fertiliser applied so far this year was down before the beginning of May.

Teagasc research has shown that grass/clover swards at post grazing heights of 6cm have the potential of achieving growth rates of 220g per day or 1.5kgs per week in weaned lambs. This compares with 100g per day for lambs on grass only when forced to graze to 4cm.

Sean weaned lambs from the mature ewes on June 29. He hit the Teagasc targets for a mid-season lambing flock, with 1.68 lambs per mature ewes put to the ram.

Ewes will be tightly stocked at high numbers on a bare paddock for seven days to dry them off.

Weaning will reduce the flock demand and allow the lambs to be selective and graze the best grass available on the farm.

Lambs will graze the paddocks ahead of the ewes going into covers of 7-9cm or 900-1500kgDM/ha. This will allow the plant to maximise growth while still maintaining a high percentage of leaf for the grazing lambs.

The lambs will leave the paddock at 5.5-6cm and ewes will come in and graze down to 4cm. This will supply adequate grass for the dry ewe and maintaining grass quality for subsequent grazing by the lambs.

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Sean is aware that the longer period spent grazing each paddock by the lambs and then the ewes will slow grass growth rates.

However, at existing stocking rates Sean does not see this as a problem and he hopes it will eliminate the need to top paddocks and maximise the use of grass grown on the farm.

As in previous years Sean is aiming to finish the majority of his lambs off grass by mid-September.

This year Sean's plan was to make the majority of his silage by removing surplus grass from paddocks.

Protein

To date three paddocks have been cut for silage on June 16 when the average farm cover reached 1,200kg DM/ha, with 58 days grazing ahead of the stock. The paddocks yielded five bales per acre of well-wilted silage.

Silage made from similar paddocks last year had a DMD of 78 at 35pc DM and 12.1pc protein. Sean says this year's silage should be as good if not better quality than last years.

The current number of days' grass ahead of the ewes is 36. Grass growth is currently at 66kg/ha a day and the demand at farm level of grazing livestock is 18kg DM/ha a day.

The target pre-grazing yield is 1,000kg DM/ha. It all looks very complicated, however when you look at the grass wedge on the graph it indicates that Sean can safely take out paddocks four and five over the next few days and still have adequate grass on the farm to meet livestock requirements.

The grazing days ahead will be reduced from 36 to 26 when paddocks are cut for silage.

At this stage Sean is confident that additional paddocks will have to be removed over the next few weeks as the farm is currently understocked.

The red line on the wedge is drawn from the target pre-grazing yield to the target post-grazing residual.

A perfect wedge is one where all the paddocks are meeting the line, that is there are no surpluses or paddocks above the line, or deficits with paddocks below the line, so everything is on target.

Paddocks four, five and seven are above the line and this indicates that a surplus of grass exists especially with grass growth rates at current levels of 66kg/ha a day. The PastureBase programme also allows Sean to compare the total amount of grass that each paddock has grown to date.

If you look at the graph it shows the comparison between paddocks up to June 29.

Paddock 10 has grown 9.5t of grass DM compared to the average of all paddocks at 4t of grass DM and paddock six which has grown just over 1t of grass DM. Paddock 10 has been reseeded three years ago, while paddock six is old pasture.

It clearly shows the benefits that reseeding can deliver.

Tom Coll is a Teagasc drystock business and technology advisor based in Mohill, Co Leitrim

PastureBase helps maximise growth

This year Sean is using the PastureBase programme to measure grass growth and as a decision support tool for the removal of grass surpluses to enable his flock to graze paddocks at the ideal heights that will maximise lamb growth rates from grazed grass. 

The main grazing block which Sean is measuring consists of 19.35ha divided into 11 paddocks. Sean measures the grass height in each paddock on a weekly basis and enters the heights into the PastureBase programme.

He also records the livestock numbers, the date that stock graze each paddock and the dates when surpluses are removed for silage.

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