Different pasture feed types offer varying energy, protein, fibre and micronutrient content. Because many soils in the Derwent Valley naturally have relatively low major nutrient and trace element levels, we have to be mindful of the adequate supply of these nutrients both from the perspective of pasture and animal nutrition.
That said, the primary pasture feed concerns are quantity (is there enough feed available to be grazed effectively?), energy concentration (does it provide sufficient megajoules of metabolisable energy to fuel the animal?) and protein concentration (are minimum requirements for the livestock class met?) – roughly in that order, though they do each interact in practice.
In the paddock, the pasture mass as kilograms of dry matter per hectare can help tell us if the animal is able to graze enough quantity of feed. If the feed’s too short, they simply can’t graze enough, it takes too much time and energy to eat, or it’s simply not there in the first place. (Dry matter refers to the feed with all the water removed, and it’s the way we can make feed comparisons.)
Higher energy concentration is a function of more green vs dead, more leaf vs stem, more clover vs grass. While low pasture mass restricts the quantity of feed eaten, so too does low energy concentration. There is an interaction between the two. To some degree, high energy can compensate for low mass, but high mass can’t compensate for low energy. If it’s carboard (dead stem), lots of cardboard makes little improvement.
Protein is associated with the % of green feed and % of clover or other legumes.
Assessing the nutritional value of pasture is an important component of your farming management. At the same time, you need to know what your animals require to maintain good health. Cows require different nutrition than sheep. Older animals generally need less protein, while growing or lactating animals need more digestible feed and more protein. It’s a matter of matching feed type to the animals’ requirements and a critical balance between quality and quantity.
If your animals aren’t getting enough nutrients from pasture, what should you be feeding them? Might you need to fill the gaps with drought-lotting? Can you prioritise animals’ access to the feed source that’s best for them right now? Is it time to supply additional non-pasture feed supplements or trace elements?
The same nutrition principles of quantity supplied, energy and protein concentrations, apply to supplementary feeds too. Knowing the animals’ needs and what the feed provides is useful health and welfare information. The better you manage your feed resources overall, the more likely you’ll be to meet your feed and production targets.