Daily gains for all three groups were comparable, but poor yield in the kale meant that it provided the least gain per acre. Since starting this project, I have learned that kale will probably not be a good choice as a brassica following a spring-planted crop in New England. The growing season simply isn’t long enough. It might work following a winter crop, such as winter rye, winter wheat, or fall-planted triticale that is overwintered and harvested earlier than spring-planted oats and peas. But in order to produce satisfactory yields, it probably needs to be planted before June 15. In areas with longer growing seasons, or in circumstances where it can be the only crop on a field in a given year, kale might be a better choice.
Turnips, on the other hand, produced a large yield in a very short period of time. They would have fared better if they had been planted in early July rather than late July, but the yield was still acceptable.
The cereal silage crop of oats and peas did a good job of suppressing weeds and producing a stored forage crop for the flock for the winter. As it turned out, there were enough volunteer oats in both the turnip and kale that none of the silage needed to be fed out to meet the lambs’ need for fiber. The Italian ryegrass provided some fiber as well, and was very readily consumed by the lambs.
We set out to see whether fall-grazed brassicas planted following the production of a cereal-grain silage crop – a production system common in the UK – could be adapted to the Northeast, and if so, whether turnips or kale would be a better choice. A spring-planted crop of oats and peas was harvested as balage in July, and swaths of turnips and kale with a strip of Italian ryegrass down the middle of the field were planted. Separate groups of lambs were grazed on both brassica crops at the same time, and a third group was grazed on permanent pasture with supplemental feeding of whole shelled corn. Lambs were assigned to the groups in such a way to ensure that a similar number of small, medium, and large lambs received each feed treatment, and each lamb in all three groups were weighed at the outset, every two weeks during the test, and at the end of the test. Lambs in all three groups gained at about the same rate (.3 lbs per head per day) over the course of the six weeks they were on the test. The major difference was that the cost per pound of gain in the three groups varied greatly: 31 cents per pound of lamb gain for the pasture plus corn group; $1.66 per pound for the turnip group; and $1.96 per pound in the kale group. Yields on the brassicas were low due to dry conditions and late planting, and higher yields would have meant longer grazing time without additional production costs, resulting in lower costs per pound of lamb gain.