Pasture Management

As for dairy cows, dairy goat pasture is at its optimum at the three leaf stage,  At the three leaf stage, rye grass has an approximate ME of 11.5 and crude protein of 25%.  Once the rye grass satrts to go to seed, the crude protein drops to around 15% and ME drops to around 10.

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Pasture management is largely focused on keeping grass at optimum quality, although this isn’t always easy to achieve.  Because a cut and carry system means farmers are not restricted so much by paddock sizes, they can cut as much or as little as is required in any given period.  There is also the flexibility to cut a bit more generously, let the goats pick out ‘the good bits’ and then feed the leftovers to other stock on the farm (such as drystock). This can be a good tool to help keep on top of grass growth when there isn’t quite enough (or the timing doesn’t suit) for making silage. 

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With a cut and carry system, the residuals left are always relatively consistent as it is determined by the cutting height of the mower which is typically set to leave approximately 1500 cover.  The making of supplements (grass silage) is used to control surpluses and manage grass quality.  In late summer when the length of the pasture is low, fresh forage is often removed from the diet as it simply takes too long to get a wagon load of grass.  During this time, additional grass silage would be offered. 

 

Likewise, in periods of wet weather, fresh forage is reduced or removed from the diet. Whilst the grass itself may be available, the heavy cut and carry machinery destroys the paddocks and so is not used. 

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Ideally a spring grazing management plan needs to focus on achieving highly digestible (low NDF) grass by keeping rotations short and harvesting as soon as possible after the 3-leaf stage. As goats can only consume an average of 0.9 kg NDF per day, this factor is highly important for optimum health and productivity. Where possible, grass should be harvested at between 2500 and 3000 kg/DM and leaving approximately 1500.  The regular use of a pasture meter will help  assess when paddocks are reaching this stage and if the mower is set at the correct height for the desired residuals.  Carefully managed intensive grazing in spring can see pasture digestibility increase from approx. 67% to 75% DM.

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Knowing the dry matter of your grass is important, but for goats, the digestibility of that material is even more important.  Whilst green leaves have around 70-80% digestibility , once the plant matures and the stem starts to harden, the digestibility drops to around 45%.  As digestibility of the pasture increases, each mouthful eaten delivers more energy to the goat. In addition to this, because the highly digestible pasture ferments faster, the goats can eat more of it.  On the other hand, as digestibility of the pasture decreases, each mouthful eaten delivers less energy to the goat and because it takes longer to ferment the goats eat less of it per day. Once pasture reaches this stage at which it  is no longer highly digestible, the energy levels in the goats diet can be increased through the use of supplements. 

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The nutritional value of typical NZ rye grass / clover mixed pasture can be found on the DairyNZ website.

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Measuring forage quality is important for the effective use of concentrates in the diet. A dairy goat nutritionist will be able to determine if a diet is balanced for the stage of lactation and growth/body condition needs using advice from our nutritionist but in order for this to be as accurate as possible, knowing the pasture quality is important.  Because it is not feasible to be sending off samples for lab analysis every couple of weeks, and because grass quality is constantly changing, estimates need to be used. Again, advice from a nutritionist or consultant can help in this area.   

 

Ideal milk production pasture components for Dairy Goats

Source: King et al, 2018

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