The farm walk held last autumn on the farm of Terence, Richard and Tim Sheil included a valuable presentation on grazing forage crops.
The farm is located a short distance from Enniscorthy and grew a mixed crop of Interval, a rape-cross-kale hybrid, and Samson stubble turnips. The crop was sown after winter barley in two five-acre fields on 31 July.
Tim said it was sown in a simple manner, with the field grubbed, followed by the seed being broadcast with a fertiliser spreader and rolled. Two bags of 18:6:12 were applied at sowing, with another bag of 18:6:12 plus sulphur applied three weeks later. The crop was also sprayed to control volunteer barley, while an insecticide was also applied.
Local Teagasc business and technology adviser James Doran said the first step in putting a plan in place for grazing forage crops is to establish the volume of dry matter feed available. This will set the basis for the stocking rate the crop can carry and also outline a feeding programme or allocation rate.
Simple tools
James said the volume of dry matter can be calculated with three simple tools – a shears, clippers or knife to cut the crop, a measuring tape or quadrant to measure out a 1m2 area and a weighing scales. A bag is also useful to hold cuttings for weighing.
Where there is variability in the crop, it is advisable to take two to three cuts at different areas in the field to give a more accurate assessment of the volume of forage available.
Where dealing with a mixed forage and root crop, as in the case of the Sheil farm, then roots will also need to be factored into the weighing.
Once the weight is available, this figure is multiplied by 10,000, as there are 10,000m2 in a hectare. Note that this is the volume of forage available on a fresh weight basis.
The dry matter content of forage rape or hybrid brassicas, such as Interval and Redstart, is typically 12% to 14%, but James cautioned farmers that this can be lower during periods of wet weather. Stubble turnips has a lower dry matter of 8% to 10% and fodder beet has a dry matter of 19%.
Using the example from the farm walk of 1.8kg fresh weight in 1m2 and a dry matter of 12%, this gives 2.16t DM/ha (1.8kg x 10,000 x 12%).
The next factor that needs to be taken into account is the level of utilisation. In good weather, like we are currently experiencing, a typical level of utilisation can be taken at about 75%, but James says this can drop to as low as 40% to 50% during periods of inclement weather and difficult ground conditions.
Continuing with the example and taking 75% utilisation gives 1.62t of available dry matter (2.16t x 75% utilisation).
Carrying capacity
James outlined that lowland lambs weighing in the region of 35kg to 44kg have a dry matter intake potential of 1.25kg DM, while light hill lambs weighing 28kg to 35kg have an intake potential about 70% lower (0.9kg to 1kg), with mature ewe intake much higher at 1.6kg DM.
However, it is recommended that 30% of the diet should be made up of an additional forage or fibre source to help prevent digestion problems. James advises that the first 10 days are critical as animals adjust to a change in diet, with a runback area particularly beneficial in this regard.
Looking again at our example above and 1.62t of dry matter available; taking a forage intake of 1kg DM/ day for lambs (0.25kg provided by concentrate), there are 1,620 days of grazing available. Another way of looking at it is 1ha will graze 231 lambs for one week.
Looking at it differently, if there are 80 lambs going on to the crop for example, 1ha will provide 20 days of grazing (1,620 grazing days/80 lowland lambs consuming 1kg DM/day) or an acre of crop will provide eight days of grazing (20 days/2.471 acres in 1ha) for the 80 lambs.
Farmer experience points to lambs being slow to consume hay or silage once adjusted to the crop earlier in the season, but as the dry matter drops as the year progresses, it is important to have a source of additional fibre present. The level of additional forage offered can also be used to stretch the length of grazing in the forage crop where daily or two- to three-day allocations are being offered.
Top tips
Allocating smaller volumes for grazing, as opposed to free access, will greatly enhance utilisation levels and allow for a much more concise feeding programme to be implemented. Grazing the crop in a long and narrow manner will work better than grazing with a short feeding face and wide allocation. Lighter animals generally work best. Target grazing animals close to finish if in doubt about volume of feed present. A good current in electric fencing is vital at the outset to train animals into grazing. A mineral bolus or access to minerals may be required where animals are grazing for a prolonged period and no minerals are provided via concentrate. Crops must be grazed before they start flowering. Avoid grazing frozen crops where possible.
The farm walk held last autumn on the farm of Terence, Richard and Tim Sheil included a valuable presentation on grazing forage crops.
The farm is located a short distance from Enniscorthy and grew a mixed crop of Interval, a rape-cross-kale hybrid, and Samson stubble turnips. The crop was sown after winter barley in two five-acre fields on 31 July.
Tim said it was sown in a simple manner, with the field grubbed, followed by the seed being broadcast with a fertiliser spreader and rolled. Two bags of 18:6:12 were applied at sowing, with another bag of 18:6:12 plus sulphur applied three weeks later. The crop was also sprayed to control volunteer barley, while an insecticide was also applied.
Local Teagasc business and technology adviser James Doran said the first step in putting a plan in place for grazing forage crops is to establish the volume of dry matter feed available. This will set the basis for the stocking rate the crop can carry and also outline a feeding programme or allocation rate.
Simple tools
James said the volume of dry matter can be calculated with three simple tools – a shears, clippers or knife to cut the crop, a measuring tape or quadrant to measure out a 1m2 area and a weighing scales. A bag is also useful to hold cuttings for weighing.
Where there is variability in the crop, it is advisable to take two to three cuts at different areas in the field to give a more accurate assessment of the volume of forage available.
Where dealing with a mixed forage and root crop, as in the case of the Sheil farm, then roots will also need to be factored into the weighing.
Once the weight is available, this figure is multiplied by 10,000, as there are 10,000m2 in a hectare. Note that this is the volume of forage available on a fresh weight basis.
The dry matter content of forage rape or hybrid brassicas, such as Interval and Redstart, is typically 12% to 14%, but James cautioned farmers that this can be lower during periods of wet weather. Stubble turnips has a lower dry matter of 8% to 10% and fodder beet has a dry matter of 19%.
Using the example from the farm walk of 1.8kg fresh weight in 1m2 and a dry matter of 12%, this gives 2.16t DM/ha (1.8kg x 10,000 x 12%).
The next factor that needs to be taken into account is the level of utilisation. In good weather, like we are currently experiencing, a typical level of utilisation can be taken at about 75%, but James says this can drop to as low as 40% to 50% during periods of inclement weather and difficult ground conditions.
Continuing with the example and taking 75% utilisation gives 1.62t of available dry matter (2.16t x 75% utilisation).
Carrying capacity
James outlined that lowland lambs weighing in the region of 35kg to 44kg have a dry matter intake potential of 1.25kg DM, while light hill lambs weighing 28kg to 35kg have an intake potential about 70% lower (0.9kg to 1kg), with mature ewe intake much higher at 1.6kg DM.
However, it is recommended that 30% of the diet should be made up of an additional forage or fibre source to help prevent digestion problems. James advises that the first 10 days are critical as animals adjust to a change in diet, with a runback area particularly beneficial in this regard.
Looking again at our example above and 1.62t of dry matter available; taking a forage intake of 1kg DM/ day for lambs (0.25kg provided by concentrate), there are 1,620 days of grazing available. Another way of looking at it is 1ha will graze 231 lambs for one week.
Looking at it differently, if there are 80 lambs going on to the crop for example, 1ha will provide 20 days of grazing (1,620 grazing days/80 lowland lambs consuming 1kg DM/day) or an acre of crop will provide eight days of grazing (20 days/2.471 acres in 1ha) for the 80 lambs.
Farmer experience points to lambs being slow to consume hay or silage once adjusted to the crop earlier in the season, but as the dry matter drops as the year progresses, it is important to have a source of additional fibre present. The level of additional forage offered can also be used to stretch the length of grazing in the forage crop where daily or two- to three-day allocations are being offered.
Top tips
Allocating smaller volumes for grazing, as opposed to free access, will greatly enhance utilisation levels and allow for a much more concise feeding programme to be implemented. Grazing the crop in a long and narrow manner will work better than grazing with a short feeding face and wide allocation. Lighter animals generally work best. Target grazing animals close to finish if in doubt about volume of feed present. A good current in electric fencing is vital at the outset to train animals into grazing. A mineral bolus or access to minerals may be required where animals are grazing for a prolonged period and no minerals are provided via concentrate. Crops must be grazed before they start flowering. Avoid grazing frozen crops where possible. 
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