Farmer preferences, time of year, farm type and experience will dictate which system is chosen. The theory and realities of each system can also be quite different.

Rotational grazing

The simplest form of rotational grazing is to simply shift mobs between small paddocks every 2-3 days, using an ‘eyeometer’ to assess when sheep need shifted, and to assess which paddock has the most grass for next grazing. At the most technical level, rotational grazing uses accurate assessments of grazing covers to calculate how many grazing days are in a paddock and shift accordingly (see example below), usually using feed budget tools as an aid. Positives include better grass utilisation and growth, lower parasite intakes and an easier way of rationing grass during “pinch” periods. Negatives include increased labour/movements, and more precision and calculation required to make it work. Lambs post tailing (6-12 weeks of age) tend to do better because of a regular higher quality grass (fresh pick) being offered.

Even simple “eyeometer” rotational grazing can be a good tool to reduce drench inputs, incorporate different stock classes to paddocks and utilise more grass. The calculation based grazing needs skill and someone committed to the process to be successful. Don’t let spread sheets lead you astray – numbers might look right, but are sheep getting what they need? Are they eating it or wasting it? Are cover estimates accurate? Matching up the requirements with what’s in front of you seems more of an art than a science to sheep farmers.

Set Stocking

Less technical, but can still produce the goods, but is at the mercy of the season more. In a good year lamb growth rates can be higher than in a rotational grazing system, as (provided feeds not limited) sheep will select out the best diet, theoretically grazing 5% area each day. But rank feed can result. Positives include short covers can better quality. Labour and infrastructure requirements are lower. Negatives; parasite intakes are higher on short pastures; grass utilisation is poorer as, when left to pick and choose, stock overgraze tastier areas and leave less palatable areas to grow long. Stock numbers have to be fairly well matched to grass growth which takes experience of your farm to get right. It can also be hard to assess if stock are actually getting enough and good stockmanship is important to get the best out of it. The farm will grow less grass (as grass grows grass) compared with calculated rotations.

Both systems definitely have their place and many farms will end up using a combination of the 2 over the year. Close monitoring of weaning weights and comparing to other years will help direct you to which system plays best to your strengths. In the trickier years, it seems to be farmers that keep ewes and lambs on the move, draft more lambs. They are likely not to run into as many worm issues. The fertility and response of grasses is obviously key to a good rotation. This does not happen over night.