Depending on farming region and subsequent climatic conditions crop choices will vary. It is important to seek professional assistance if you are looking to put in a seasonal crop to ensure that the variety and timing is suited to your specific area.
Forage brassicas and fodder beet are both sown as supplementary feed for animals. The two are different species although often treated similarly by farmers. In cooler regions the key requirement is for high yielding crops such as swedes and kale, or fodder beet, that provide maintenance feed from small areas of the farm. This enables pasture covers to recover over winter and respond in spring to provide the high quality forage required.
These crops are commonly sown to provide high quality feed during periods when pasture growth or quality is poor, such as winter and mid-summer. One advantage, when done well, is the ability to produce a high DM yield off a small area of the farm. Brassicas are also grown in summer in some areas to avoid potential health risks associated with pasture such as facial eczema and ryegrass staggers.
These forage crops encompass a wide range of different plant forms including bulb (turnips and swedes); leafy (rape); swollen stem (marrow stem kale); and long stem (kale). These all have different fits within the farm system.
Deer are fed all types of brassica crops depending which fit best into the farm system, however very little research has been reported from these forages. The different brassica species are introduced briefly below.
Fodder Beet Notes
The use of fodder beet has been increasingly adopted in the dairy industry due to the ability to grow a high yielding crop on a small area. Increasingly deer farmers are also utilising fodder beet with varied success.
Fodder beet is not related to the winter brassicas but to sugar beet and beetroot. The agronomic requirements to ensure a high yield include correct soil fertility, ground preparation, an early sowing date and intensive weed control in the early life of the crop.
Although farmers report very high yields, commonly yields range between 18-20 t DM/ha. Approximately 75-80% of the DM yield is bulb. This is important when estimating yield and allocating feed. In addition, fodder beet has low crude protein levels (6-7%), lower fibre and high soluble sugar levels. To balance the diet of ruminants including deer a high quality supplement (baleage or lucerne silage) should be used to provide fibre and some of the protein that may be required.
The transition to a fodder beet diet is longer (14-21 days) that that required for brassicas or lucerne (7-10 days) and more care is required. As the leaf is a small proportion of the yield it is not feasible to rely on this to help balance the diet. The recommendation for dairy cows is that fodder beet supplies less than 2/3 of the diet with the rest as supplement. The recommendations for deer have yet to be fully tested but should be similar to dairy cows in the first instance. Anecdotally farmers have found that after 60 days the performance of deer wintered on fodder beet can drop off and may be due to low protein or calcium in the diet. More on Fodder Beet here
These are the most common winter brassica crops, potentially yielding 10-20 T DM/ha.
Swedes are sown between November to early December, either ridged in cool areas, or conventionally drilled to provide specialist winter feed.
Higher sowing rates lead to thinner and more palatable stems.
Kales are winter active and mainly used as a "winter feed".
Kale can provide high dry matter/ hectare yields however for best results kale requires high soil fertility and good soil moisture.
Kale is suitable for cattle, sheep, and deer but the taller or giant types are best used for only cattle grazing, while the shorter, leafier cultivars are more suited to sheep and deer.
Feeding forage brassicas
Ruminant animals take some time to attain maximum voluntary intake when presented with a change of diet, an effect dictated by the population of microflora within the rumen. When the diet of a ruminant changes dramatically, from high to low fibre, or low to high feed quality and vice versa, rumen microbes must likewise adapt to the new conditions. The time this takes will vary depending on what type of brassica is being introduced, the cultivar and the stock type grazing the crop.
To limit the effects of diet change stock should be gradually adapted to the new crop by using a runoff paddock of pasture for 7 days or more, ensuring that the diet is only partly brassica based. Ensuring animals are relatively full when first introduced to the crop will reduce issue of over eating causing problems.