A group of 80 lambs for finishing, of mixed breeds and all from the college flock, were grazed on a field with popular varieties of stubble turnips typically used as a fodder crop for grazing sheep and cattle.
“We compared three commercially available stubble turnips; Samson, Hector and Vollenda,” says Robert David, forage crops technician at Limagrain, who ran the trial at Bishop Burton College in East Yorkshire.
A 1.33ha field was drilled with the stubble turnips in mid-August 2015. The sheep moved from grass leys on to the field at the end of November.
“We started them on an area with a mix of the varieties to get them used to the stubble turnips, and after a week we moved the fence and let them on to a section of the fresh crop where each variety was in a defined strip. We put in a back fence to keep the lambs on the trial plots. Two replicates of each variety were included on the trial site.”
Monitoring was in three parts. In mid-November a yield assessment was made of each variety. Then, once grazing started, the number of lambs feeding from each strip was monitored four times an hour during the day, at intervals through the day and for a three week period.
As the back fence was moved down the field exposing a fresh crop each week, a measure of the residual yield was made on the grazed crop to compare the amount of each variety that that lambs had eaten and how much was left.
Although further analysis is still to be published, the initial results indicated a grazing preference for the new variety Hector, followed by the market leading variety Samson.
“Hector is a new variety bred for sheep production and expected to be commercially available in 2017. It is a tetraploid variety with a higher proportion of the root growing above the ground, making it easier for the lambs to access, which may contribute to its grazing preference in this trial,” adds Mr David.
Samson is also a tetraploid variety that produces big tankard shaped purple bulbs. “This variety is already known to be very palatable to sheep, and Limagrain’s recently published trial data for 2016 shows that it produces a root dry matter yield 22% higher than the control variety. We anticipate that Hector will be a fantastic addition to our variety portfolio and the results so far at Bishop Burton College would support this.
Stubble turnips are a fast growing crop which are best sown in July to early August. “They can produce dry matter yields of 4- 5 tonnes/ha in 12 weeks,” adds Mr David. In the trial work at Bishop Burton College, we are demonstrating the benefits of getting the most from this valuable crop by selecting varieties that are grazed in preference to others. This can result in higher intakes and improved live weight gains.”
Third year Agriculture and Resource Management student Ben Hutchinson was involved in monitoring the crop and recording the grazing preferences of the sheep as part of his dissertation project.
“It was interesting to see that certain varieties of stubble turnip were definitely favoured,” he says. “I noticed that by Thursdays and Fridays, the lambs had finished the most popular varieties and had moved on to their less favoured options. This occurred consistently across the three weeks.”
Ben Hutchinson is now analysing yield data of the crop pre and post grazing “I anticipate that this data will support our visual observations and confirm that selecting more palatable varieties will help to improve animal performance.”