Planning for good grazing infrastructure

Improved grassland management relies upon robust grazing infrastructure; suitably sized and shaped paddocks with multiple access points, serviced by roadways of sufficient quality and adequate drinking water.

It is vital to consider the quality of your grazing infrastructure and acknowledge where deficits have arisen in recent years. Maximum grazing efficiency will not be achieved unless all grazing infrastructure is sufficient.

Paddocks

Paddock size will have to be changed as the herd size increases. The size of the paddock should be based on either two or three grazings of the planned number of cows in the herd. Between mid-April to August, three grazings is preferred as this maximises pasture intake and milk production. The guideline paddock area is 1.2ha per 100 cows for two grazings and 1.8ha per 100 cows for three grazings (with a target pre-grazing cover of 1,400kg DM/ha). For a 21 day rotation in mid-summer, this means that 21 (two grazings) or 14 (three grazings) paddocks are required. Ideally paddocks should be square to rectangular in shape, with the depth no more than three times the width. As a general rule, the distance from the roadway to the back of the paddock should be between 50–100m on heavy land, 100–170m in medium land and 170–250m on light land. The upper limits are more applicable to larger herds. Use multiple gateways especially on heavy land and during wet weather.

Paddock fencing

Good fencing is an essential element of any paddock grazing system. A specialised fencing contractor will be more skilled and better equipped to erect top quality fencing. Plan the location of fences carefully based on a paddock plan on the farm map, and plan the system to aid grassland management. It should be easy to quickly set up access to paddocks between grazings. Good maintenance is essential.

Roadways

Design, construction and maintenance of farm roadways have a big impact on cow flow, walking speed and lameness incidence. Does your current farm roadway system service all of the potential grazing area, and is it in good condition? If the current roadway system is inadequate, it needs to be upgraded and/or extended. Essential elements of a good roadway are adequate width, a smooth surface, adequate crossfall, raised above the grazing area and sweeping bends at corners and junctions. The main roadway should be wide enough for good cow flow (e.g. 100 cows 4m wide; 200 cows 5 wide).

New farm roadways must be laid in good weather with dry soil conditions. Cows like to walk with their heads down to see where to put their front feet. The hind foot is also placed on ground that the cow has seen. When cows cannot place their feet safely, they will slow down. They also slow down due to a poor roadway surface or if forced to move on from behind. If forced to move on from behind, cows become bunched and stressed and they lift up their heads and shorten their stride.

All farm roadways need to be assessed in the light of regulations that oblige all farmers to take appropriate measures to prevent water runoff from roadways to water bodies. For more information contact your local advisor/consultant or the ASSAP advisor covering your area. DAFM Specification S199 outlines construction details and measures farmers can undertake to prevent runoff from roadways.

Water systems

Ask the following questions when assessing your current water supply to paddocks:

• Are pipe sizes adequate?
• Are ballcocks restricting flow?
• Are water troughs big enough and correctly located?
• What water flow rate is needed for your herd?

A flow rate of 0.2L/cow/minute and a trough volume of about 5–7L/cow per cow is generally recommended. For example, a flow rate of 20L/minute and approx. 600L troughs per 100 cows.

Don’t be tempted to solve water supply problems with very big troughs; focus on flow rates and larger pipe sizes instead. Farms vary widely in terms of cow numbers, pipe length, farmyard location and topography, so take all these factors into account when deciding on pipe size and system layout. The aim is to minimise pressure loss due to friction in water pipes so that enough pressure is available to overcome lift and maintain a good flow rate in troughs.

Err on the high side with pipe size bore. A ring main (loop system) is a cost effective way to enhance water flow rates and ensure an even flow rate to troughs. Main pipe size bores should typically be 25mm, 32mm or 40mm and branch pipe bores to individual troughs should be 20mm, 25mm or 32mm.

Use ‘full flow’ type ballcocks in all new troughs. These ballcocks typically have 9–12mm jets, providing a good flow rate even with low pressures at the ballcock. A standard high pressure ballcock jet (3mm diameter) is very restrictive even where pressure at ballcock is high. Position troughs to minimise walking distances to water and to avoid unnecessary smearing of grass. Keep troughs away from gaps and hollows. Troughs should be level and have no leaks. Isolate, monitor, locate and repair leaks. Troughs on roadways will slow cow movement and make roadways dirty. Allow trough space for at least 10% of the herd to drink at once. Assess costs in advance.

Table 1: Water pipe sizes

This paper was written by Tom Fallon, Pat Touhy and Paul Maher and was originally published in the Irish Dairying Delivering Sustainability, Moorepark open day book.

Also read: Grazing infrastructure incentivised under TAMS 3

Also read: Managing farm roads to protect water quality