Essentially they can all be thought of as being nutrient dense, meaning they carry much higher mineral and nutrient content per kilogram of drymatter (DM) than grass species – see Table 1.
Chicory remains a premier forage herb for intensive finishing systems with plenty of research results confirming its high levels of nutritive performance in sheep and deer enterprises.
In many cases they have much lower structural carbohydrates (fibre) and high soluble carbohydrates (sugar, starch) while still offering more than adequate levels of crude protein (CP% >15%) for growing animals.
When combined, these three basic nutritional factors result in faster animal liveweight gain (LWG) and higher dressing out percentages (DO%) for sheep, deer, and beef animals.
The response to these nutritionally dense forage species can be explained by the growing animals grazing them:
- They have high voluntary feed intake (VFI) levels, or put simply they eat more of these forages in the course of a grazing day than they would grass-based pastures
- Forages spend considerably less time in the animal’s rumen which in turn leads them to eat more forage – ie: increased VFI, and
- They are offered more energy a bite of drymatter eaten, measured as megajoules of metabolisable energy (MJ ME).
Greater animal production gains can be achieved when these forages are sown in simple mixtures (one to three compatible species) or just as monocultures (single species, eg: lucerne). Used in this way, an animal’s VFI is further increased because of a reduction in their diet selection time, or preference.
It has been well-documented that young sheep, cattle, and deer are highly selective in their grazing patterns. Legumes (clovers) and herb species are typically preferred in their diet ahead of grasses.
When these species are presented in a pasture mixture as companion species to grasses – for example, perennial ryegrass – young animals waste a lot of grazing time and energy seeking them out, thereby reducing grazing time and VFI, and resulting in a poorer liveweight gain. Simple mixes and monocultures of these desirable species avoid this issue.
Forage species selection
Finishing systems developed around these specialist forages are at their highest levels of efficiency – carcaseweight (CW) kg/ha – where there is a weaned-on and slaughtered-off approach. Breaks in their grazing rotation back to standard pasture inevitably result in reduced liveweight gain.
Therefore it is important that farmers move towards having critical mass of these high-performance forages to enable the maintenance of closed rotations of finishing animals through to slaughter.
It’s difficult to generalise on how much of a farm’s pastures should be in specialist forages because there are many factors to consider, including:
- The area of appropriate soil types
- Numbers and classes of capital stock wintered
- The proportion of trading stock to be finished
- The demand for spring pasture supply for lambing and calving, and
- The need for supplement production (silage).
Typically the proportion would lie between 15-35% of the finishing area.
There is also the consideration that three of these specialist forage species – see Table 1, lucerne, lotus and chicory – are winter dormant.
Birdsfoot trefoil (Lotus corniculatus).
